Lens thread, camera body with a lens mount, lens with a lens thread, method for manufacturing a lens thread, and component with a lens thread

Abstract

Lens threads for connecting lenses, camera bodies, extension rings or optical filters, including: a cylindrical circumferential surface (121), - a receiving thread (122) produced by grinding, rolling, machining, whirling or stamping or not produced by a primary forming process, with a thread depth in the cylindrical circumferential surface (121) that corresponds to a fastening thread and ◯ a thread entry area extending from a thread start and ◯ comprises a main thread section adjoining the thread entry area, in which the receiving thread (122) has a nominal thread depth, - wherein the thread diameter of the objective thread is chosen to be large enough to allow an imaging beam path to pass through the cylindrical circumferential surface (121) defined by the receiving thread (122), wherein the thread root width and / or the thread depth of the receiving thread (122) increases in the entry area from zero at the thread start within a circumferential angle of less than 180° to the nominal thread root width or the nominal thread depth, wherein in the cylindrical circumferential surface (121) in the thread entry area, in the direction of the receiving thread (122) from the thread start to the main thread section, a recess (130) and a thread start area adjoining the recess (130) are formed, wherein the recess (130) is helical and extends over a circumferential area of ​​more than 360°.

Description

[0001] The invention relates to a method for producing a lens thread, in particular for attaching a lens to a camera housing, comprising the steps of: producing a cylindrical surface, followed by cutting a thread into the cylindrical surface using a tool. A further aspect of the invention is a lens thread comprising a cylindrical circumferential surface, a receiving thread produced by grinding, rolling, machining, whirling, or stamping, or produced without a primary forming process, with a thread depth in the cylindrical circumferential surface that corresponds to the mounting thread, and with a thread entry section extending from a thread start and a thread main section adjoining the thread entry section in which the receiving thread has a nominal thread depth. Such a lens thread can, for example, be a lens mount for attaching a lens to a camera housing.

[0002] It is generally known to mechanically connect lenses, camera bodies, extension rings, optical filters, and other components used for imaging moving and still images by means of a threaded connection, or to implement adjustability within such components using a threaded connection, for example, for focus or focal length adjustment. Typically, a thread is used for this purpose, the thread diameter of which is chosen to be large enough to allow the imaging beam to pass through the cylindrical surface defined by the thread. Single-start threads are typically used for this purpose, manufactured according to various standardized dimensions to allow for the connection of optical components conforming to the standard.

[0003] Threads used to connect such optical components are hereinafter referred to as "lens threads"—regardless of whether they are used to connect a lens or other optical components. Lens threads are subject to general and specific requirements that differ from threads found on ordinary screws, bolts, or pins designed to interact with internal threads or nuts.Screws, pins, and similar fasteners typically serve solely to create a high-strength mechanical connection. Their threads are tightened to a predetermined torque, typically a predetermined percentage below the thread's load-bearing capacity. This is achieved, for example, by allowing the screw to stretch elastically by a certain amount due to the tightening torque, or by achieving a specific tightening torque just below the screw connection's load-bearing capacity. With lens threads, it is generally neither necessary nor desirable to select the tightening torque to create a high-strength connection. It is sufficient for the threaded connection to be tight enough to connect the lens to the camera body or to join the two optical components together.Instead, the focus with lens threads is on the precise positioning of the two components relative to each other, as this influences optical precision. A high-strength connection, in this context, refers to one achieved using separate fasteners such as screws and nuts, which are often tightened to a predetermined axial preload using torque or angle tightening to apply defined forces to the two components being joined.

[0004] Typically, fine threads, meaning threads with a comparatively shallow thread depth and pitch, are used as lens threads. These threads are manufactured with high precision, usually through machining. It is generally known to produce threads using a primary forming process such as casting or by rolling, either through a stamping, cold, or hot forming process. While these methods can produce high-strength standard and fine threads, they are not the preferred methods for creating geometrically precise threads. For this purpose, machining processes are preferred, such as thread cutting, thread milling, thread grinding, or thread whirling. These processes utilize a cutting tool with a defined or undefined cutting edge.

[0005] It is generally known and advantageous for easy starting and coaxial tightening of threaded connections to give the thread a geometry in the thread entry area, from which the thread begins, that facilitates the clean alignment of the two threaded partners. A well-known solution for this is, for example, a chamfer on such threads, also referred to as a countersink in the case of internal threads, which facilitates starting and coaxial screwing of the threads and reduces the risk of misalignment. Especially in applications where repeated loosening and tightening of such threaded connections is functionally desirable, the ability to correctly align the two threaded partners relative to each other during starting and carrying out the screwing process is of particular importance.

[0006] From US 447 775 A and DE 73 597 A and DE 694 05 048 T2, a thread geometry on a screw and nut is known in which, in the initial area of ​​the screw, there is a thread-free section with the core diameter of the screw bolt and the thread only begins after this thread-free section.

[0007] WO 2012 / 103 660 A1 discloses a nut for bone screws in which, for the purpose of preventing tilting, a special thread entry geometry is formed, in which threads are only present in the thread entry when they are formed to the full flank height.

[0008] From DE 10 2007 040 517 A1, a metal threaded body intended for interaction with a plastic threaded body is known in a similar manner, in which the thread begins with at least a predominant full cross-sectional area of ​​the thread turn.

[0009] From US 2021 / 0048596 A1, a lens module and a lens mount are known in which a lens is attached to a lens mount by means of a positioning ring. A threaded groove is provided on at least the outer circumferential surface of the positioning ring or a positioning section of the lens mount, which is filled with an adhesive to secure the positioning ring in the lens mount.

[0010] For this reason, threads often have a larger inner diameter (for internal threads) or a smaller outer diameter (for external threads) in the entry area than further along the thread beyond the entry area. This can be achieved, for example, by the chamfer described earlier. Such a design results in a reduced thread depth in this entry area, which is advantageous for the screwing-in process. However, according to the inventors, this thread design also has a disadvantage. This disadvantage lies in the fact that, due to the shallow thread depth, or the thread depth starting from zero and increasing with increasing thread length up to the nominal thread depth, unfavorable chip removal occurs in the entry area.Even with a threading tool with an intact and unworn cutting edge, but especially with threading tools that already show signs of cutting edge wear, a shorter or longer, incompletely cut thread profile can occur in the thread entry area. In particular, only partially separated metallic chips and partially separated metallic chips can occur. Furthermore, the thread in the entry area has a reduced wall thickness, i.e., a narrower width at the root of the thread, which makes it mechanically less resilient than the fully formed part of the thread. According to the invention, this root width is the axial width of a thread in the root area, i.e., at the minor diameter of an external thread or at the nominal diameter of an internal thread. Every thread has a nominal thread depth and a nominal thread root width; these are the geometric dimensions of the fully formed thread.However, these are not immediately reached if a chamfer is present and at the beginning of a thread, i.e., in the entry area. Therefore, it can happen that the thread section in the entry area is sheared off under mechanical stress, for example during the screwing in or out process, or even during the thread manufacturing process itself.

[0011] While such effects generally do not adversely affect the connectability and functional connection of the thread, an incompletely separated chip or thread turn can detach completely during further use of the thread, causing contamination. This contamination is undesirable and disruptive inside optical devices, medical devices, or other precision-engineered products with high quality requirements. In particular, it can impair image quality, functionality, or operational reliability, especially if the chip can enter the area of ​​printed circuit boards, electronic components, or the optical path.

[0012] The invention is based on the objective of reducing this disadvantage and preferably avoiding it completely.

[0013] According to the invention, this problem is solved by a receiving device according to claim 1 or claim 2.

[0014] The problem underlying the invention primarily arises in machining, whirling, rolling, stamping, or grinding processes for manufacturing threads, i.e., in manufacturing methods that utilize a tool for deformation and / or material removal. In contrast, primary forming manufacturing processes are essentially unaffected by this underlying problem.

[0015] The invention is characterized in that the entry area of ​​a thread, which is critical for potential chip formation and resulting contamination, is designed such that the thread increases from zero to the nominal root width or nominal thread depth over a very short circumferential section. It is understood that this increase to the nominal root width or nominal thread depth can preferably also occur within an even shorter angular range than mentioned above, for example, within less than 20° and, most preferably, within less than 10°.

[0016] According to the invention, a thread or a main thread section is understood to be a fastening thread in a typical design, as a standard thread or fine thread, i.e., for example, a metric thread with a correspondingly standardized thread geometry, but also other thread forms, such as trapezoidal threads or threads according to other standards. The thread runs continuously through the main thread section, i.e., it is designed as a continuous thread.

[0017] Overall, the strength of the thread in the entry area is increased by the design according to the invention, since the thread achieves a sufficient width at the thread root within a small circumferential angle, ideally even starting directly with its full width. This stabilizes the thread in the immediate initial area with its narrow thread root width, thanks to the subsequent thread section with its increased thread root width. Thus, the thread designed according to the invention prevents unwanted chip shedding and the resulting contamination, without requiring a thread geometry that makes simple and straightforward starting and tightening of the thread difficult.

[0018] The nominal thread depth is defined as half the difference between the nominal thread diameter and the thread's root diameter. For external threads (bolt threads), this is half the difference between the thread's outside diameter and the diameter at the root of the thread (or the thread's root diameter). For internal threads (nut threads), it is half the difference between the thread's inside diameter and the diameter at the root of the thread (or the nominal thread diameter). The thread depth, therefore, describes the radial distance between the thread crest and the root of the thread. The nominal thread depth is the thread depth specified by the applicable standard.

[0019] It is particularly preferred if the thread depth of the receiving thread in the entry area increases from zero at the thread start to the nominal thread depth within a very small circumferential angle. It is particularly preferred if this circumferential angle is less than 30°, less than 20°, and especially less than 10°. For the stability of the thread, it is particularly preferred if the circumferential angle is 0°, i.e., the start of the thread extends along the radius of the cylindrical circumferential surface.

[0020] According to the invention, a recess and a thread start area adjoining the recess are formed in the cylindrical circumferential surface in the thread entry area, extending from the thread start to the main thread section, and preferably no thread is formed in the recess. In this embodiment, a recess is incorporated into the cylindrical surface in the thread entry area. This avoids, or shortens to such a length, the area of ​​the thread where the thread has a shallow thread depth and tooth thickness, i.e., the area of ​​a chamfer, that the disadvantages observed therein do not occur or are significantly reduced.The invention is based on the understanding that in the thread entry area, a very fine thread is produced due to the geometry of the threading tool, the chamfer or countersink present for starting, or both, and that the cut may also be incomplete, resulting in undesirable chip formation with residual chip junctions to the solid material. This effect is avoided by placing the area with shallow thread depth and tooth thickness within the recess and thus eliminating it entirely. Consequently, the thread begins with a sufficiently large thread depth and tooth thickness in the circumferential area following the recess, thereby avoiding the disadvantageous fragile structures and unfavorable chip-forming properties. The circumferential surface in this context refers to either an inner or outer circumferential surface.

[0021] In this embodiment, starting from the thread entry area, the main thread section is arranged behind the recess in the direction of the thread (i.e., the screwing-in or screw-on direction), and there is no thread in front of the recess in the direction of the thread. The recess itself preferably has no thread; however, in some embodiments, the recess can have such a radial depth that a thread or threaded portion is formed in it during manufacturing and is therefore present.

[0022] In the embodiments according to claims 1 and 10, this recess is helical in shape, and in the embodiments according to claims 2 and 11, it can also be helical. In this case, the recess preferably follows the pitch of the thread and can thus prevent the formation or presence of a thread with reduced thread depth and thread root width over a defined circumferential section. In principle, this helical recess is then located directly in the screw-in direction upstream of the first fully formed thread, which also follows a helical path with the thread pitch.

[0023] It is particularly advantageous if the recess extends over a circumferential area that has such an angular position relative to the thread that the beginning of the thread is completely covered, i.e., removed, or not formed at all by the recess. In this design, the area not formed with the full thread depth and tooth thickness is covered and removed by the recess in such a way that the thread only runs behind the recess, but not in front of it.

[0024] The recess can be created before the thread is cut, for example, by forming it during a primary forming process such as casting, or by machining it. Alternatively, the recess can be created after the thread has been cut, for example, by machining it, removing the shallow thread area completely or partially and also removing any remaining chips adhering to the workpiece. This can be achieved in a single operation by using a threading tool that, in a continuous process, first creates the thread and then, in the same operation, the recess, without requiring any additional settings or tools.

[0025] The recess is positioned in such a way that it extends over the theoretical starting area of ​​the thread, i.e., the area of ​​overlap between the thread geometry and the cylindrical surface or chamfer.

[0026] According to a preferred embodiment, it is particularly preferred if the recess extends over a limited axial and / or a limited radial depth and extends over a limited circumferential section, in particular by extending over a circumferential angle of less than 360° or by extending over a circumferential angle of more than 360° and being helical, preferably with a pitch that is further preferably the same as the pitch of the receiving thread.

[0027] The recess provided according to the invention can therefore extend over a limited axial depth. In principle, the effect according to the invention can be achieved if, in the case of single-start threads, the recess extends over an axial depth, i.e., a distance in the direction of the longitudinal axis of the thread, which corresponds to the pitch or thread pitch. The pitch here refers to the axial distance between two successive flanks of a thread turn. The pitch here refers to the axial distance between two adjacent thread flanks; in single-start threads, the thread pitch is equal to the thread pitch. In multi-start threads, it is generally advantageous to select the axial depth of the recess to be at least equal to or greater than the thread pitch.In this case, a recess with an axial depth corresponding to the thread pitch would result in an unnecessarily large proportion of the thread being lost through the recess.

[0028] It is particularly preferred if the limited axial depth is greater than or equal to the thread pitch of the fastening thread. In particular, the axial depth can be 0.5 to 1.5 times, preferably 0.75 to 1.2 times, the thread pitch.

[0029] The recess provided according to the invention can therefore alternatively or additionally extend over a limited radial depth, which is preferably greater than or equal to the thread depth. If the radial depth of the recess is set smaller than the thread depth, a thread can also form in the recess using certain thread manufacturing processes. In particular, the radial depth of the recess can correspond to 0.5 to 1.5 times, preferably 0.75 to 1.2 times, the thread depth.

[0030] The recess according to the invention generally extends over a circumferential region, i.e., not over the entire circumference. This means that the circumferential angle can be greater or less than 360°, but does not itself occupy exactly 360° in a cross-sectional plane that is perpendicular to the central longitudinal axis of the thread, i.e., does not correspond exactly to a closed circumference. The recess can extend over 360° and be helical or otherwise such that it is not closed, but has a beginning and an end. It is preferred if the recess extends over a circumferential region of more than 360° and is helical, or alternatively, if the recess extends over a circumferential region of less than 360° or less than 345°, preferably less than 180° and particularly less than 90°.If the recess extends over a circumferential angle of less than 360°, 345°, 180°, or 90°, it can also be helical, but it can also lie entirely within a cross-section oriented perpendicular to the thread's longitudinal axis, thus not having a helical shape. The circumferential angle at which the thread rises from zero to its nominal thread depth / native foot width can correspond to the circumferential angle over which the recess extends or differ from this circumferential angle.

[0031] It is further preferred that the thread depth of the receiving thread in the entry area increases from zero at the thread start directly, i.e., within a circumferential angle of 0° or preferably within a circumferential angle of more than 5°, to the nominal thread depth. Such a design of the initial area facilitates the assembly of the two threaded parts and the commencement of the screwing process, and prevents tilting. In particular, the circumferential angle can be more than 1°, more than 2.5°, more than 7.5°, or more than 10° to achieve this effect while simultaneously avoiding the risk of a weakly formed thread breaking off. According to the invention, a thread, thread section, or thread segment is always to be understood as a helically extending groove structure along the circumference, in which a recess is axially limited on both sides. Recesses or chamfers or the like that are only axially limited on one side are not to be considered threads.To understand thread pitch or thread section.

[0032] It is further preferred that the thread depth of the receiving thread in the entry area increases at a constant angle of inclination between a tangent to the circumferential surface and a straight line along the thread crest. This achieves a favorable alternating reinforcement and stabilization effect in the thread entry area. A constant angle of inclination here refers to a profile in which the outer diameter of the thread pitch, plotted against the circumferential angle, exhibits a constant pitch in the thread entry area.

[0033] The problem underlying the invention is also solved by a lens mount for attaching a lens with a lens thread, comprising: a cylindrical surface, a fastening thread extending from a thread entry area to a thread exit area in the cylindrical surface, which corresponds to the lens thread, with a recess arranged in the thread entry area of ​​the fastening thread, which extends over a limited axial and radial depth and a limited circumferential section.The proposed lens mount has the advantage of a high-precision thread that completely avoids or at least significantly reduces the formation of unwanted chips, some of which may still be partially attached to the cylindrical surface. Therefore, there is no risk of such chips detaching during use of the lens mount, for example, when changing a lens or, in particular, when screwing it in for the first time, and adversely affecting the optical imaging properties. The mounting thread of the lens mount according to the invention can preferably be manufactured using the method described above. It should be understood that the mounting thread behaves in terms of its properties and functions according to the preceding descriptions, examples, and explanations of the manufacturing method according to the invention.

[0034] Another aspect of the invention is a lens with a lens thread for attaching the lens to a mounting thread, comprising: a cylindrical surface in which the lens thread extends from a thread entry region, with a recess arranged in the thread entry region of the lens thread, which extends over a limited axial depth and a limited circumferential section. With regard to this lens thread, reference is made to the preceding explanations concerning the mounting thread of the lens mount according to the invention and the preceding explanations concerning the method for producing such a mounting thread, which are mutatis mutandis applicable to the lens thread.It is generally understood that a common, partially standardized method of attaching lenses to camera bodies involves providing an external thread on the lens and an internal thread on the camera body, which can be connected to each other. However, in principle, inverse attachment methods with an internal thread on the lens and an external thread on the camera body are also possible and can be implemented according to the invention.

[0035] Another aspect of the invention is a camera housing with a lens mount of the previously described design.

[0036] Another aspect of the invention is a method according to claim 10 or 11.

[0037] In the method according to the invention, the thread is produced after the circumferential surface has been manufactured. This is to be distinguished from the simultaneous production of the circumferential surface and the thread, as is the case, for example, in a primary forming manufacturing process.

[0038] It is particularly preferred if a recess is provided in the cylindrical surface in the thread entry area, which extends over a limited circumferential area and over a limited axial and radial depth.

[0039] According to the invention, the recess is provided for over a circumferential range of less than 345°, preferably less than 180°, and particularly less than 90°. As previously explained, the recess does not generally extend over the entire circumferential range, i.e., not over 360°. For some thread geometries, it may also be advantageous for the recess to extend over a circumferential range greater than 360°; in this case, the recess must be helical. The recess creates a desired radial step at which the thread can begin immediately with sufficient thread depth and root width. The angular range over which the recess extends depends primarily on the manufacturing method of the thread and its geometric properties.If a manufacturing method or thread-cutting tool is used that has a short circumferential thread entry area in which the thread depth increases from zero to the nominal thread depth when the thread is cut into a geometric cylindrical surface or a cylindrical surface with a chamfer in the thread entry area, then the recess can also extend over a correspondingly small circumferential area, for example, a circumferential area between 10°, 15°, 20°, 25°, 30°, or 45° as the lower limit and 20°, 30°, 45°, 60°, 90°, or 120° as the upper limit. Conversely, if the thread has an angular entry area extending circumferentially over a large angular range with a thread depth reduced compared to the nominal thread depth, then it may be necessary to extend the recess over a correspondingly large circumferential area as well.In this case, the recess can extend up to 180° and, in a few exceptional cases, up to 270°.

[0040] According to a further preferred embodiment, the recess is provided to have an axial depth corresponding to 0.5 to 1.5 times the thread pitch, preferably less than or equal to the thread pitch. In principle, for most thread forms, it is sufficient if the recess extends over an axial length corresponding to the thread pitch, such that the first thread is partially uncut or removed by the recess in a limited circumferential area. In this case, the thread can be produced in such a way that it achieves a rapid or immediate increase in thread depth over a short circumferential section at the start, for example, to a thread depth that already corresponds to the nominal thread depth or to a thread depth that already exceeds 30%, 50%, or 75% of the thread depth.Only in thread geometries with a very long, circumferential thread entry area and reduced thread depth and root width may it be necessary to extend the recess axially over twice the thread pitch. In this case, the recess runs over a circumferential angle of more than 360° and is helical, corresponding to the thread pitch.

[0041] According to a further preferred embodiment, the recess is provided to a radial depth corresponding to 0.5 to 1.5 times the thread depth, preferably greater than or equal to the thread depth. In principle, the recess can be provided over a radially limited area or with a radially limited dimension; that is, it is not necessary, although possible, to make the recess significantly deeper than the thread depth. In particular, the recess can be produced in the range of the thread depth, for example, in the range of 0.75 times the thread depth or 1.2 times the thread depth, in order to achieve the advantages of the invention.

[0042] According to a further preferred embodiment, the recess is created using a non-forming manufacturing process, such as machining, whirling, rolling, stamping, or grinding. This can be done before or after threading, or simultaneously with threading. "Simultaneously" does not mean at the same time, but rather in a single operation of the tool, for example, by a suitably shaped tap or by guiding another cutting tool along a machining path that includes the thread and the recess. Machining, for example, using a milling tool, allows the invention to be implemented in any material from which the thread can be produced, such as metallic materials or plastics.In principle, the recess can be created by a machining process with a defined cutting edge or an undefined cutting edge, for example by means of a milling process or by means of a grinding process or by means of a primary forming process.

[0043] According to a further preferred embodiment, the recess is formed using a primary forming process to create the circumferential surface. In this embodiment, the circumferential surface and the recess can be produced simultaneously using a primary forming manufacturing process, and subsequently the thread can be formed in the circumferential surface, which, according to the invention, is not done by the primary forming process.

[0044] Furthermore, it is preferred that the cylindrical surface is an inner circumferential surface. The manufacturing method according to the invention is particularly well suited for the production of internal threads, i.e., threads that are machined into an inner circumferential surface. In this case, the recess therefore extends from the inner circumference of the cylindrical surface radially over a predetermined depth, for example, the thread depth, and axially over a predetermined axial length, for example, the thread pitch. Using the invention for the geometric design of external threads is also advantageous in many applications.

[0045] According to a further preferred embodiment, the thread is produced by thread cutting, thread milling, thread grinding, or thread whirling. In these manufacturing processes, a thread is created by a machining operation, for example, with a tap or a thread milling cutter, which is a preferred method, particularly for producing very precise threads and fine threads. In particular, machining or cold- or hot-forming manufacturing processes avoid the effects of undesirable and unfavorable chip formation or the development of structurally weak thread sections in the thread entry area, and these effects can therefore be avoided by the method according to the invention.

[0046] According to a further preferred embodiment, the recess is provided for before the fastening thread is formed, e.g., during the primary forming process in the casting of the cylindrical surface. Forming the recess prior to the production of the fastening thread allows for a particularly precise chamfer in the thread entry area when the fastening thread is produced, especially when this is done by a machining or stamping process such as thread milling, thread cutting, or thread rolling.

[0047] In an alternative embodiment, the recess is created after the fastening thread has been inserted. This allows for particularly precise placement of the recess, since the position of the thread entry area is clearly identifiable in this manufacturing sequence, making it possible to precisely create the recess from the start of the thread over a circumferential section.

[0048] Finally, it is still preferred that the thread, starting from a thread depth of zero at the thread start, is increased in the thread entry area with a constant increase in thread depth to the nominal thread depth.

[0049] Finally, another aspect of the invention is a component with a thread, which is manufactured according to a method of the type described above.

[0050] A preferred embodiment of the invention is explained with reference to the accompanying figures. These show: Fig. 1 a longitudinal section view of an internal thread according to the state of the art, Fig. 2 a top view of a thread according to Fig. 1, Fig. Figure 3 is a longitudinally sectioned side view of an internal thread according to an embodiment of the invention. Fig. 4 a top view of the embodiment according to Fig. 3, Fig. Figure 5 is a detailed view of the thread entry area according to the state of the art, and Fig. Figure 6 is a detailed view of the thread entry area according to the embodiment of the invention.

[0051] Referring first to Fig. 1 and Fig. Figure 2 shows a camera housing 10 with a lens mounting flange 20 attached to it. The lens mounting flange 20 is shown in a longitudinal section. It can be seen that a cylindrical inner passage 25 is formed within the lens mounting flange 20, which serves to guide the imaging beam from the lens to the image sensor.

[0052] A lens can be attached to the lens side of the lens mounting flange 20 by screwing it into the flange. For this purpose, an internal thread 22 is cut into an inner circumferential surface 21 of the lens mounting flange 20. To facilitate positioning the lens, a 45° chamfer 23 is countersunk on the side of the lens mounting flange 20 facing the lens. The lens can rest flat against an end-face surface 24, which serves as a stop for the screwing process.

[0053] In the Fig. 3 and Fig. Figure 4 shows an embodiment of the invention. In this embodiment, as in the one described in Figure 4, the following applies: Fig. 1 and Fig. In the embodiment shown in Figure 2, according to the prior art, a camera housing 110 with a lens mounting flange 120 attached thereto and a through-opening 125 arranged therein is provided as a basic component.

[0054] The lens mounting flange 120 also has an internal thread 122 cut into the cylindrical inner surface 121, which defines the through-opening 125. A 45° chamfer 123 is countersunk on the end face facing the lens to facilitate mounting the lens in a coaxial orientation.

[0055] In the thread entry area of ​​the internal thread 122, a recess 130 is provided in the embodiment according to the invention. Starting from the end face and contact surface 124 for the lens, the recess 130 extends axially over a depth a equal to one thread pitch of the internal thread 122. The recess 130 extends over a circumferential area c of 45° and has a radial depth b that is slightly greater than the thread depth t.

[0056] Fig. Figure 5 shows a detailed view of the thread entry area of ​​a conventional lens mounting thread. It can be seen that the 45° chamfer 23 runs continuously and that the first thread 22a in the thread entry area widens from a shallow thread depth at the contact surface 24 to the nominal thread depth. Particularly in the initial shallow thread depth, there is a risk with the prior art of unfavorable or incomplete machining, with chips still adhering to the lens mounting flange 120. These chips can detach during subsequent use and fall onto the image sensor or similar components, thus impairing image quality.

[0057] Fig.Figure 6 shows the embodiment according to the invention. It can be seen that in this embodiment a radial recess 130 is provided in the thread entry area, so that the first thread 122a only begins at the end of this recess 130 and rises to a sufficient thread depth within a short circumferential angle range of approximately 25° to prevent unfavorable chip formation.

Claims

[1] Lens thread for connecting lenses, camera bodies, extension rings or optical filters, comprising: a cylindrical circumferential surface (121), - a receiving thread (122) produced by grinding, rolling, machining, whirling or stamping or not produced by a primary forming process, with a thread depth in the cylindrical circumferential surface (121) that corresponds to a fastening thread and ◯ a thread entry area extending from a thread start and ◯ comprises a main thread section adjoining the thread entry area, in which the receiving thread (122) has a nominal thread depth, - wherein the thread diameter of the objective thread is chosen to be large enough to allow an imaging beam path to pass through the cylindrical circumferential surface (121) defined by the receiving thread (122), wherein the thread root width and / or the thread depth of the receiving thread (122) increases in the entry area from zero at the thread start within a circumferential angle of less than 180° to the nominal thread root width or the nominal thread depth, wherein in the cylindrical circumferential surface (121) in the thread entry area, in the direction of the receiving thread (122) from the thread start to the main thread section, a recess (130) and a thread start area adjoining the recess (130) are formed, wherein the recess (130) is helical and extends over a circumferential area of ​​more than 360°. [2] Lens threads for connecting lenses, camera bodies, extension rings or optical filters, comprising: - a cylindrical circumferential surface (121), - a receiving thread (122) produced by grinding, rolling, machining, whirling or stamping or not produced by a primary forming process, with a thread depth in the cylindrical circumferential surface (121) that corresponds to a fastening thread and ◯ a thread entry area extending from a thread start and ◯ comprises a main thread section adjoining the thread entry area, in which the receiving thread (122) has a nominal thread depth, - wherein the thread diameter of the objective thread is chosen to be large enough to allow an imaging beam path to pass through the cylindrical circumferential surface (121) defined by the receiving thread (122), wherein the thread base width and / or the thread depth of the receiving thread (122) increases in the entry area from zero at the thread start within a circumferential angle of less than 180° to the nominal thread base width or the nominal thread depth (t), wherein in the cylindrical circumferential surface (121) in the thread entry area in the direction of the receiving thread (122) from the thread start to the main thread section a recess (130) and a thread start area adjoining the recess (130) are formed, wherein the recess (130) extends over a circumference of less than 360°. [3] Lens thread according to claim 1 or 2, characterized by, that the recess (130) extends over a limited axial and / or a limited radial depth (b) and a limited circumferential section (c), and / or that the recess (130) is helical, preferably with a pitch that is consistent with the pitch of the receiving thread (122). [4] Lens thread according to claim 3, characterized by , that the limited axial depth (a) corresponds to 0.5-1.5 times the thread pitch of the fastening thread and / or the limited radial depth (b) corresponds to 0.5-1.5 times the thread depth. [5] Lens thread according to one of the thread depths of the preceding claim, characterized by , that the receiving thread (122) increases in the entry area from zero at the thread start within a circumferential angle of more than 0°, preferably more than 5° to the nominal thread depth. [6] Lens thread according to any one of the preceding claims, characterized by, that the receiving thread (122) is produced by a two-stage manufacturing process in which a cylindrical basic geometry is produced in a first step and the thread geometry is introduced into the cylindrical basic geometry in a subsequent second step. [7] Lens thread according to one of the preceding claims, characterized by that the receiving thread (122) is not produced by a primary forming process and is not made of plastic. [8] Camera body with a lens mount, characterized by , that the lens mount is formed according to a lens thread according to one of the preceding claims 1-7. [9] Lens with a lens thread for attaching the lens to a camera body, characterized by , that the lens thread is designed according to one of the preceding claims 1-7. [10] Method for producing a lens thread, in particular for attaching a lens to a camera body, comprising the steps: - Producing a cylindrical circumferential surface (121), - Subsequent introduction, in particular by machining, grinding, rolling, whirling or stamping, of a receiving thread (122) into the cylindrical circumferential surface (121) with a tool, - wherein the thread diameter of the objective thread is designed to be so large that an imaging beam path can pass through the cylindrical circumferential surface (121) defined by the receiving thread (122), characterized by , that the receiving thread (122) extends from a thread start into a thread entry area in the cylindrical circumferential surface (121) and a thread main section adjoining the thread entry area with a nominal thread depth and that the receiving thread (122) is increased from a thread depth of zero at the thread start within a circumferential angle of less than 180° in the thread entry area to a thread depth corresponding to the nominal thread depth in the main thread section, wherein a recess (130) is provided in the cylindrical circumferential surface (121) in the thread entry area, and wherein the recess (130) is helical and extends over a circumferential area of ​​more than 360°. [11] Method for producing a lens thread, in particular for attaching a lens to a camera body, comprising the steps: - Creating a cylindrical circumferential surface (121), - Subsequent introduction, in particular machining, grinding, rolling, whirling or stamping, of a receiving thread (122) into the cylindrical circumferential surface (121) with a tool, - wherein the thread diameter of the objective thread is designed to be so large that an imaging beam path can pass through the cylindrical circumferential surface (121) defined by the receiving thread (122), characterized by , that the receiving thread (122) extends from a thread start into a thread entry area in the cylindrical circumferential surface (121) and a thread main section adjoining the thread entry area with a nominal thread depth and that the receiving thread (122) is increased from a thread depth of zero at the thread start within a circumferential angle of less than 180° in the thread entry area to a thread depth corresponding to the nominal thread depth in the main thread section, wherein a recess (130) is provided in the cylindrical circumferential surface (121) in the thread entry area, and wherein the recess (130) extends over a circumference of less than 360°. [12] Method according to claim 10 or 11, characterized by , that the recess (130) is machined before, simultaneously or after the insertion of the receiving thread (122). [13] Method according to any one of the preceding claims 10-12, characterized by , that the recess (130) is created using a primary forming process to produce the circumferential surface. [14] Method according to any one of the preceding claims 10-13, characterized by , that there is no thread in the thread path before the recess (130). [15] Component with a lens thread manufactured according to a method according to any of the preceding claims 10-14.

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