SCAN ARRANGEMENT WITH SCAN HEAD

Description

[0001] The technical field of the invention relates to a scanning arrangement according to the preamble of claim 1, as well as a method for scanning a scanning area according to the preamble of claim 13.

[0002] When scanning the inside of the mouth—or when scanning impressions of the inside of the mouth, i.e., models or impression materials that reproduce the shape of the inside of the mouth—it is common practice to place reference points in the inside of the mouth or on the model. These serve as orientation points and also improve the quality of the so-called "stitching," which aligns different imaging areas to provide a complete three-dimensional image.

[0003] Although considerable progress has been made in scanning results, certain problems still exist. For example, the scan head must be guided three-dimensionally, which introduces corresponding errors in precision. The contrast of the scanned areas to be captured also varies considerably. To capture smaller elevations and depressions, it has been suggested to use oblique light incidence and the corresponding shadow effect.

[0004] To eliminate detection errors, however, backlighting, i.e., light coming from the opposite direction, must also be used. However, depending on the layout of the scanning area, oblique light also requires masks.

[0005] To counteract these disadvantages, it has also become known to arrange at least two scanners at a distance from each other and point them at the same scanning area, thus recording the height profile stereometrically. However, this leads to significant cost disadvantages and potentially spatial problems, especially in confined spaces such as the oral cavity.

[0006] Various optical inspection devices according to the prior art are described, for example, in US2014 / 0276094A1, DE3400781A1, US2014 / 0330133A1, WO2010 / 081498A1 and WO03 / 087717A1.

[0007] European patent application 15 180 555.3 proposes placing a balloon around a scanner and inflating it so that it rests against the scanning area. The balloon's deformation is intended to detect the shape of the scanning area.

[0008] However, it would be desirable to provide an even more flexible solution.

[0009] In order to scan complex-shaped cavities, attempts have been made to improve the scanning radiation and its delivery through the scan head. For example, working with different frequency ranges of electromagnetic radiation has already been proposed. For a moist surface, for example, it may be advantageous to use visible or UV light. However, the reflective properties of certain materials from which the cavity may be made are better for ultrasound radiation on the one hand, and for X-rays on the other.

[0010] The disadvantage here is that scanners with different frequency ranges have to be provided, which makes the solution more expensive overall and sometimes even impractical.

[0011] Therefore, the object of the invention is to provide a scanning arrangement according to the preamble of claim 1 and a method for scanning a scanning area according to the preamble of claim 13, which are significantly improved with regard to the scanning result without any significant investment expenditure.

[0012] This object is achieved according to the invention by the subject matter of claim 1 or 13. Advantageous further developments emerge from the subclaims.

[0013] It is particularly advantageous for the film-like or flat, elastically stretchable material to adhere to the scanning area. This can be achieved by mechanical means such as suitably designed frame elements, or, for example, by adhesion between the scanning area and the material.

[0014] According to the invention, the material—or, in a modified embodiment, at least one frame element—carries a pattern that is particularly easy to scan. This good scanability results in significant progress in the field of direct scanning of the scanning area, which is often low-contrast and generally unpatterned.

[0015] In this context, it is particularly advantageous for the material to be curved toward the scan head. This allows for particularly good capture of the contours of the correspondingly curved scanning area, even if the scanning area itself is monochrome and unstructured.

[0016] It is particularly advantageous if the material, which can be film-like or mesh-like, like a membrane, and fits tightly to the scanning area, has the same thickness throughout. This can be, for example, 50 µm or even 100 µm. Surprisingly, the accuracy of the detection is not affected in any way by the thickness of the material; in fact, it is significantly higher than with a direct scan of the scanning area.

[0017] The invention is also particularly suitable for combining images captured by the scanning head using a three-dimensional sequence, known as "stitching." According to the invention, the pattern can be selected in any suitable manner to enable unambiguous spatial localization.

[0018] While clamping the material between frame elements, optionally coupled with or separated by adhesion, is preferred, a modified embodiment of the invention provides for the material to be fixed to the scanning area using a removable adhesive. This solution has the advantage that no relative movement occurs between the scanning area and the material, even in the event of vibrations and movements.

[0019] In contrast, the pre-stressed solution has the advantage that no wrinkles can form, or that any existing wrinkles are automatically removed.

[0020] It goes without saying that the design of the pattern on the material can be adapted to meet specific requirements. For example, a structure with very fine elements can be provided that closely matches the resolution of the scan head. A combination of regular and irregular pattern elements is particularly advantageous.

[0021] The pattern can be applied or formed on the side facing the scanning head, or on the side facing the scanning area, in which case it is understood that the material is then transparent to the scanning radiation.

[0022] In a further preferred embodiment of the invention, the scanning device is provided with frame elements that extend laterally alongside or even on the scanning area and follow it. If the scanning area is, for example, a jaw ridge, the elongated frame element can extend vestibularly and / or lingually to the edentulous jaw ridge or run on it. The frame element then has a height profile—viewed in the horizontal direction—that corresponds to the occlusal surface of the jaw ridge, which in this embodiment forms the scanning area.

[0023] Advantageously, frame elements of the frame extend along the scanning area, particularly in close proximity to it. They have a height profile that corresponds to the height profile of the scanning area, with the frame elements having at least one two-dimensional or three-dimensional pattern. This pattern can also be provided in addition to the pattern on the material to improve the scanning result.

[0024] Such a realization is also possible with an edentulous prosthesis.

[0025] The frame element can be selected in any suitable manner. It is preferably highly plastically deformable. For example, a soft metal such as tin or a tin alloy can be used as the core of the frame element. This metal can be coated with a protective coating that prevents contact with the metallic core of the frame element.

[0026] Another possibility is to make the frame element out of a sheet metal that is particularly ductile and easy to deform.

[0027] The plate thus designed preferably extends distally-mesially in its main direction and with a width of a few millimeters in the lingual-vestibular direction. This allows the plate to be adapted as precisely as possible to the height profile of the scanning area and bent accordingly.

[0028] It can be simply pressed onto the scanning area and then scanned.

[0029] In this case, too, it is possible to create a protective coating, which, however, should not impair the plastic bendability of the sheet.

[0030] Another possibility is to make the core of the frame element out of a plastically deformable organic material, for example bitumen, which in turn is covered with a protective coating.

[0031] Further advantages, details and features will become apparent from the following description of several embodiments of the invention with reference to the drawings: Fig. 1 a schematic arrangement of a scanning device in partial sectional view; Fig. 2 the arrangement according to Fig. 1 , but with a differently arranged material; Fig. 3 the embodiment of the scanning device according to Fig. 1 and Fig. 2 , with an exemplary pattern; Fig. 4 shows a further embodiment of the material; Fig. 5 shows a further embodiment of the material held taut by frame elements of a frame; Fig. 6 shows a sectional view of a further embodiment of the frame according to Fig. 5 ; Fig. 7 a sectional view of another embodiment of the frame according to Fig. 6 ; and Fig. 8 a sectional view of another embodiment of the frame according to Fig. 7 .

[0032] As from Fig. 1As can be seen schematically, in the illustrated embodiment, a scanning arrangement 10 comprises a scanning head 12 and a scanning area 14 which is to be scanned by the scanning head 12.

[0033] According to the invention, the scanning area 14 is covered by a material 16, which in the illustrated embodiment forms a membrane 18.

[0034] The scanning area 14 is part of a larger structure that extends three-dimensionally. Overall, the structure can form a cavity that at least partially surrounds the scanning head 12.

[0035] The Fig. 1The scanning area 14 shown is partially covered by the material 16 in the illustrated embodiment. For scanning, the scanning head 12 can be moved along the arrows 20, but also in any other three-dimensional direction, for example, perpendicular to the plane of the drawing. The scanning head 12 is directed toward the scanning area 14 and thus toward the material 16, and detects its structure 22.

[0036] As from Fig. 1 As can be seen, the material 16 is curved toward the scanning head 12. This is due to the corresponding shape of the scanning area 14. The material 16 rests against the scanning area 14. In the illustrated embodiment, it is held taut between two frame elements 26 and 28 of a frame 30 so that it rests tightly against the scanning area 14.

[0037] In the condition according to Fig. 1 the frame elements 26 and 28 are approximately at the same height.

[0038] The material 16 can cover the entire scanning area, i.e. the area to be scanned. However, it is also possible to move the material 16 along the scanning area 14. This is also Fig. 2 evident from the comparison of the Figures 1 and 2 It follows that the extension of the material 16 is the same length, but the frame element 26 according to Fig. 2 is arranged higher than the frame element 28 in this figure.

[0039] In the illustrated embodiment, material 16 is formed as a thin membrane. The wall thickness of the membrane is, for example, 200 µm. Due to the tension between frame elements 26 and 28, the wall thickness is further reduced, for example, to 150 µm.

[0040] The structure 22 of the membrane 18 is selected so that it is particularly well recognizable by the scanning head 12. An example of such a structure 22 is shown in Fig. 3The structure consists of a plurality of pattern elements 32, 34, which are regularly spaced from one another, but preferably also of pattern elements that are irregularly arranged relative to one another ( Fig. 4 ).

[0041] The deformation of the membrane 18 results in a changed arrangement of the pattern elements 34 and 32 relative to one another, corresponding to the expansion of the membrane, from which the shape of the scanning area 14 can be determined.

[0042] This can be achieved particularly favorably if regularly arranged and irregularly arranged pattern elements 32 and 34 are combined. An example of such irregularly arranged pattern elements is shown in Fig. 4 visible.

[0043] Out of Fig. 5 A modified version of the membrane 18 is visible. In this version, the frame 30 is circumferential and spans the membrane 18.

[0044] The frame 30 and thus the membrane 30 is three-dimensionally deformable. In plan view, the shape of the frame according to Fig. 5 a U, and according to the Figures 6 to 8 the frame 30 is deformable so that a U can also be realized in the side view in section.

[0045] One application would be, for example, scanning an already created prosthesis to determine its surface, or scanning a jaw in a patient's mouth.

[0046] In order to maintain the tension in the membrane and to ensure that even the smallest irregularities in the scanning area are recorded, it is intended to Fig. 6 illustrated arrangement of the frame 30 and the membrane 18 (not visible and stretched in the frame) or to ensure in any other way that the contact between the scanning area and the membrane 18 is reliably maintained.

[0047] In order to ensure the desired double tilting of the frame 30, according to Fig. 6 The implementation of film hinges 40 and 42 between the base leg and the side legs of the U can be provided. These can be easily implemented by thinning the material from which the frame 30 is made.

[0048] According to Fig. 8 only a film hinge 40 is provided, which extends centrally - approximately in the base of the U - and ensures the desired pre-formability, while the areas of the frame 30 adjacent to the film hinge 40 are thin and therefore flexible.

[0049] It is understood that the invention is not limited to the illustrated embodiments. For example, instead of structure 22, any other structure with other pattern elements 32, 34 can be implemented. It is also possible to adapt the reflection or absorption maximum of pattern elements 32 and 34 to the wavelength range covered by scan head 12. Furthermore, instead of frame 30, a removable adhesive can be used to hold membrane 18 to scan area 14. This can also be achieved simply by adhesion.

[0050] Instead of the foil-like membrane, a modified embodiment can also use a mesh or other structure with recesses and pattern elements. Depending on the application, this can also be held in contact with the scanning area 14 via a frame 30, an adhesive, or adhesion.

[0051] The scope of the invention is defined in the appended claims.

Claims

1. A scanning arrangement for scanning a three-dimensional spatial structure which forms a scanning area, comprising a scan head and a flat or a film-like material (16) forming a membrane (18), which is configured to cover the scanning area (14) at least partially in such a way that the material (16) is in flat contact with the scanning area, characterized in that the material (16) is held by tension between plastically deformable frame elements (26, 28) of a frame (30) in such a way that the material (16) extends towards the scan head (12) in a bulged manner.

2. The scanning arrangement according to claim 1, characterized in that the material (16) is elastically stretchable and follows the three-dimensional surface shape of the scanning area. (14) when it is in contact therewith.

3. The scanning arrangement according to claim 2, characterized in that the elastically stretchable material (16) is in contact with the scanning area (14) over the entire scanning area (14), prestressed in at least one direction under a predetermined prestress.

4. The scanning arrangement according to one of the preceding claims, characterized in that the elastically stretchable material (16) is held between two frame elements (26, 28), between which it is prestressed, the prestress in particular triggering a material stretch of between 1 percent and 20 percent in the direction between the frame elements (26, 28), and in that the material (16) is held between the frame elements (26, 28) paired with adhesion.

5. The scanning arrangement according to one of the preceding claims, characterized in that the elastically stretchable material (16), as seen from the scanning area (14), extends concavely around it.

6. The scanning arrangement according to one of the preceding claims, characterized in that the membrane (18) and / or at least one frame element (26,28) has a two-dimensional or three-dimensional pattern which extends substantially over the entire extent of the membrane (18) and thus over the scanning area (14), wherein the pattern has in particular a structure (22) with elements whose spacing is at most 10 times the resolution of the scan head (12).

7. The scanning arrangement according to claim 6, characterized in that the pattern has a three-dimensional structure (22) with pattern elements (32, 34), which has at least partially a regularity and / or periodic sequences.

8. The scanning arrangement according to claim 6 or claim 7, characterized in that the pattern has a two- or three-dimensional structure (22) whose pattern elements (32, 34) are arranged irregularly.

9. The scanning arrangement according to one of the preceding claims, characterized in that the membrane (18) has a wall thickness of less than 0.5 mm, in particular of about 200 µm in an undeformed state, and is applied with the pattern on one side, in particular the side facing the scan head (12).

10. The scanning arrangement according to one of the preceding claims, characterized in that the scan head (12) is connected to an evaluation device with an image processing device which, in particular by stitching, combines adjacent images of the deformed membrane (18) to form an overall image.

11. The scanning arrangement according to one of the preceding claims, characterized in that the frame elements (26, 28) are connected to one another to form a frame (30) at the end faces of the membrane (18), in particular, when viewed in cross-section, prestressed in a U-shape.

12. The scanning arrangement according to claim 11, characterized in that the frame elements (26, 28) are hingedly connected to one another at the end faces of the membrane (18).

13. A method of scanning a scanning area with a scanning arrangement according to one of the preceding claims, wherein the scan head (12) is guided to scan the scanning area (14), wherein the scanning area (14) is covered by the membrane (18), which is held in contact with the scanning area by tension between plastically deformable frame elements (26, 28) of the frame (30), and wherein the scan head (12) is connected to an evaluation device which detects the shape of the scanning area (14) based on the deformation of the membrane (18), which is recognized via a pattern applied thereto.