Intraoral camera device and method to produce an aligned image of an intraoral object, preferably of a patient tooth

p0001The present invention relates to an intra-oral camera device according to the preamble of claim 1 and a method according to the preamble of claim 12th

p0002The use of intraoral video and / or image recording systems (hereinafter referred to as "intra-oral camera system" and called the camera device), has increased in the field of dentistry in the last few years strongly. Such systems are used in a variety of environments, even in situations where the dentist will show and illustrate certain features of a patient's mouth. This intraoral camera systems are increasingly the key to complex diagnostic and treatment planning. Research has shown that about 30% of practicing dentists in the age group 35-54 years have, using intraoral camera systems. It is expected that this percentage will increase with increasing familiarity with such systems, as it is from the Dental Procedures Report, page 22 to 24 February 1995 ersichlich.

p0003Intraoral camera systems are often used in dental restoration procedures. Many people now opt for clinical interventions to enhance their smile and their appearance by restorative procedures. In most of these methods, the change of the tooth shape, the tooth position and / or the color of the tooth is involved.

p0004A necessary step in changing the color of a tooth of a patient is to determine the "hue" and "shade" of the present tooth. For this purpose, for example, the tooth color of the existing teeth of those aiming for a whiter, brighter smile, rated, so that a comparison between before and after can be done. The color identification is even more important for people who need dentures; it is an object of such restoration methods to attain a natural appearance. For this reason it is important to know the color of the existing tooth so that the new restoration can be matched exactly to him.

p0005Typically, an image of a tooth shade is taken and used in analysis systems in order to obtain appropriate information regarding color and shape. Operator of such systems often find it difficult to align the intraoral camera correctly. However, a proper axial alignment and goal setting is extremely important for a software analysis, which is performed for the image to detect the color or "shade" of existing Chewy.

p0006Such dental camera is in the <patcit id="pcit0001" dnum="EP1252858A2"><text>Patent Application EP 1252858 A2</text></patcit> described.

p0007The size of the region of interest, the camera size, intraoral point the area of ​​interest, and other factors make it difficult to accurate analysis because they affect the two-dimensional recording. This can lead to even images in which a section of the respective tooth is cut off, or images that are not matched to the tooth of interest.

p0008Another disadvantage with systems using free hand-held cameras, is that even slight hand movements (eg moving your fingers when pressing the shutter button itself) can cause significant changes in the targeting of the camera.

p0009Therefore often requires the inclusion of a satisfactory image of interest intra-oral object in the use of the known systems, repeated attempts and / or a cumbersome operation of various facilities.

p0010The invention is therefore based on the object, an intraoral camera device according to the preamble of claim 1 and a method for generating an axially oriented image of an intraoral object according to the preamble of claim 12 to create, enable rapid uptake, with a cumbersome operation can be avoided shall, without the quality of the recording is suffering.

p0011This object is achieved by claims 1 and 12. FIG. Advantageous developments emerge from the dependent claims.

p0012According to the invention provides an intraoral camera, a computer-based target setting for capturing images of intraoral objects ready. ensured The objective setting, that the image of an intraoral object or a region, for example, a patient's tooth, is added to the desired size, the desired angle and in the desired position. Experience shows that all relevant imaging parameters are previously fixed and set so that an erroneous handling is ruled out. The target setting means may use a substantially point source of light that is directed to the object of interest, which is aligned precisely targeted by the camera or to this. In the point-shaped light source may be a laser diode or other light source that produces a light spot or a limited light area. The point light source can also be integrated in the camera.

p0013Under punctiform Lichquelle is not so in the form of the light source itself understood, but the type of output from the light source and incident on an illumination area radiation. This is preferably punctiform, so substantially circular so that it can be referred to as a point of light or a light spot.

p0014From the point light source emitted light that is reflected from an object of interest, according to the invention evaluated to determine if a camera is pointed straight at a location from which the desired image to be recorded. To evaluate an image with the camera is used. The image can be selected so that it is suitable in shape and size of the light spot, which is generated from the point light source when it strikes a related object or intessierenden area. The distance between the camera and its target is preferably be a fixed distance which is determined by the use of a short spacer sleeve or a spacer.

p0015In a modified embodiment, the operator can be provided with information that determine at what distance the images to be recorded.

p0016According to the invention it is provided that a geometric pattern like a grid, grid points, an intensity distribution or the like, so a two-dimensional reference system, is laid over the image to determine the magnitude of the angular deviation in the alignment of the camera and at the same time to provide guidance for the correction , The correction can be realized by a corresponding signaling "swinging" in that direction. It is also possible to give a visual or audible signal indicating that the camera is now target exactly aligned.

p0017In a modified embodiment, it is provided only to release the shutter button for the camera, if the targeting is done. It is also possible to use the target orientation as a type of trigger signal for triggering, so that the pressure of the release button, the image pickup is only realized when the target position is given.

p0018Under light point to be understood here a limited light area. Typically, a beam emitted from a point light source light spot on a circular shape, the center has the highest intensity. Such a light area or spot is referred to herein as a light spot.

p0019The picture of a camera, which is used for evaluating the camera orientation, is in an advantageous embodiment for use in evaluating in subdivisions. The content of the cuttings (eg their light properties) can be assessed to determine whether the camera is targeted essentially set. For this purpose, two or more subsections are compared. The subdivisions can be, for example grating fields of the aforementioned grid. It is also possible to carry out the implementation of sub-cuttings about intensity gradations of light intensity.

p0020Target setting means, such as a goal setting software can be used to indicate when the camera is goal set primarily based on light information from the field generated by the point-like light source. It can be an audible or visible sign provided. For example, a specific part of a display of a camera showing a green light to indicate a proper alignment. In response, can be taken a picture of the current camera view and automatically or manually saved. If desired, the system may be configured so that it will allow the operator to make a selection to allow an automatic image capture.

p0021In an advantageous embodiment of the invention, the intraoral camera is automated to provide a fast, accurate and reliable image acquisition of intraoral object. A point light source such as a laser diode, is used to determine when a camera has reached the desired position for recording an image in an intra-oral camera system.

p0022The intraoral camera system captures the image automatically, without any involvement of an operator is required if certain criteria are met. For this, the image is divided into image segments that are each rated. The image sections have a shape which is suitable for the generated from the point light source light point, which appears on the intra-oral object. The section is preferably divided into sub-sections which can be used for comparative analysis, thereby setting the target of the intraoral camera is detected.

p0023Further details, advantages and features of the invention will become apparent from the following detailed description of embodiments of the invention with reference to the accompanying drawings, in which like reference numerals indicate the same components.

p0024Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>a functional block diagram of an inventive embodiment of an intraoral camera device, said camera device is also referred to as Kameraystem;</dd><dt>FIG. 2</dt><dd>a functional block diagram of the intra-oral camera in accordance <figref idrefs="f0001">Fig. 1</figref> with a PC;</dd><dt>Fig. 3</dt><dd>a schematic side view of one embodiment of an intraoral camera device according to the invention, according to showing the image capture and target setting means which are directed onto the surface of a tooth, according to the embodiment <figref idrefs="f0001">Fig. 1</figref> and <figref idrefs="f0002">2</figref>;</dd><dt>Fig. 4</dt><dd>a schematic side view of another Ausfühform an intraoral camera device according to the invention, said image acquisition, Zieleinstellungs- and focus facilities that are directed onto the surface of a tooth, are shown.</dd><dt>Fig. 5</dt><dd>a flow chart of the steps which are carried out in a computer-aided target setting, in accordance with embodiment of the present invention;</dd><dt>Fig. 6</dt><dd>a flow chart of the steps that are performed when an assessment of targeting a camera according to an embodiment of the present invention;</dd><dt>Fig. 7</dt><dd>a flow chart of the steps which are carried out in an identification of an image section, in accordance with another embodiment of the invention;</dd><dt>Fig. 8</dt><dd>a view of a camera image and a section that will be used in the target setting of the camera, according to an embodiment of the invention;</dd><dt>Figs. 9 and 10</dt><dd>different perspective views of the camera with laser diodes for the target setting of the camera according to an embodiment of the invention; and</dd><dt>Fig. 11</dt><dd>a view of the <figref idrefs="f0008">Figs. 9</figref> and <figref idrefs="f0009">10</figref> camera shown, further comprising a camera diaphragm according to the invention as a short spacer tube.</dd></dl>

p0025<figref idrefs="f0001">Fig. 1</figref> shows a functional block diagram of a first embodiment of an intra-oral camera system. <figref idrefs="f0001">Fig. 1</figref> shows an intraoral camera system 10, which is used to obtain image information of patient's tooth. The camera system 10 can be used in particular to generate values ​​for color or shape characteristics of a tooth. This allows the tooth shade determined depending considered over the teeth, and it can be any other observations to be made. In the illustrated embodiment, the intraoral camera system 10 on an image pickup device 12, a display device 14, a memory 16, a user interface 18, a processing device 22 and a device for setting the 26th

p0026In the image pickup device 12 is a means for obtaining information on physical and / or color characteristics of a patient's tooth. The image recording device comprises a digital camera (such as an intraoral camera). Examples of the image pickup device 12, the camera Power 0/00, which is produced by Insight in San Carlos, California, and the model Cygenascope, manufactured by Cygnus Instruments, Inc., Goleta, California. Another example is a model VistaCam. In such cameras is in the hand-held cameras. The cameras typically include a display, a memory, software, and an interface for communicating with a PC. Such cameras are able, the brightness, the color, hue, chroma or color saturation to collect and thereby take a picture. The color can be in any suitable coding, be in any other suitable manner, for example, recorded disaggregated by RGB, by L *, a *, b *, or.

p0027In a further embodiment, it is provided to detect other characteristics of the image or sections of photos, for example, the focus parameters, or the like. Typically, the image pickup device 12 is a built-in display such as an LCD display on the back of the digital camera.

p0028With the display device 14, an operator can view an image of a patient's tooth. certain software analysis functions can be used, too, for example, noise analysis. Such sensed parameters can be recorded on the display device. It is inventively provided that the display device 14 in any case indicative of what is currently in the sights of the camera, is therefore covered by the camera. Instead of the digital LCD display of a camera may also be a computer monitor can be used which is coupled to the camera so that the display information are supplied to the computer monitor.

p0029The inventive memory 16 typically stores the image and additionally certain image parameters. For example, shade-guide information, for example, certain color characteristics of tooth shades, according to an appropriate color scheme table stored. In addition, the memory 16 serves as a buffer. He may be a semiconductor memory or a hard drive or any other storage, such as in a computer, be. It is also possible, apart from the frame buffer to use a separate memory, for example, in the image pickup device 12, whereby also the storage on media such as a CD or a DVD is possible.

p0030As user interface 18 known elements can be used per se. These include a keyboard, a mouse, a voice recognition system and the like. The user interface 18 allows the operator to interact with the image pickup device 12 in a suitable manner, for example, take a picture, select the resolution of the images to determine the male tooth and the like.

p0031The processing means 22 is typically a microprocessor or a microcomputer, whose software is used the analysis and identification of tooth shades, and with which the required function is provided for the image acquisition. It is known that the necessary elements for this purpose can be provided both by respective circuits as well as by appropriate software. For example, it can be provided as a PC for processing device 22 is a computer, it is also possible, of course, the already in the PC provided elements, such as memory, display, user interface and communication means and output means, for the inventively provided elements of the display device 14, the user interface 18, the memory 16, the communication device 20 and the receiving device 22 to use at least partially. It may also be used separate processors or combinations of various processors, which can be provided partly in the camera and partly in the PC.

p0032According to an alignment or target setting means 26 is provided. The target setting means 26 assists the operator in the direction of the image pickup device 22. For this purpose, several devices can be provided in the system 10th For example, this includes a point light source such as a laser diode, or a sharply focused light emitting diode. but this includes the hardware and the software that assess the image information of the light spot, which is generated from the point light source on the tooth.

p0033The intraoral camera device 10 may be part of a device for color analysis. Examples of color-analysis devices are in the<patcit id="pcit0002" dnum="US6305933B1"><text>US patent 6,305,933 B1</text></patcit> and in the <patcit id="pcit0003" dnum="WO0025696A"><text>WO 00/25696</text></patcit> described, with reference to these two documents incorporated by reference. It is preferred that a short pipe is used for the sub light shielding, so that the recorded images are not distorted by stray light. Such a pipe is, for example, in the<patcit id="pcit0004" dnum="US6210159B"><text>US Patent 6,210,159</text></patcit> is shown, also incorporated herein by reference.

p0034An example of an intra-oral camera device is known from <figref idrefs="f0002">FIG. 2</figref> visible, it also being possible at the same time the compound is represented with a PC. With intraoral camera device 30 indicates that the targeting is true and an image of the patient's tooth can be taken. The intra-oral camera device has a PC 32 and an image pickup device 34th In known manner, a computer monitor 36 is connected as a display device of the PC 32nd The image pickup device 34 detects the multicoat color and shape information of the patient's tooth. This computer monitor 36 is displayed, which just acquired the image capture device, so what is targeted by the camera. Depending on the setting, also a stored image on the monitor can show. At the same time can be over the PC 32 and / or on the hardware of the image pickup device 34, the analysis of the image to be made.

p0035It can be carried out analyzes to determine whether the image pickup device 34 is targeted correctly adjusted to the object of interest. If desired, other functions can also be performed, for example, the identification of colors from a color schema table. According to the invention, the image pickup device 34, the target setting means to assist the operator to. This can be directed in the right way 34 the image recording device.

p0036In the <figref idrefs="f0003">Figures 3 and 4</figref> schematically appropriate image acquisition and target setting means are shown.

p0037Typically, the correct target setting depends on the angle that has a camera at a subject. According to the present camera angle is analyzed to determine whether the angle in question is correct or not. From the<figref idrefs="f0003">Figures 3 and 4</figref> is one camera 44 can be seen, which is oriented on a tooth surface 46th The tooth surface 46 is typically convex, with explanation's sake, the proportions are exaggerated. An incisor has, for example in the central region on a plane, but structured surface, which is then curved to the side flanks, ie mesial or distal direction. In an alignment of a camera different hues or "shades" would be for the considered areas arise, so that the restoration result would be distorted. To prevent this, it is inventively provided that Zieleinstelleinrichtung 26 (<figref idrefs="f0001">Fig. 1</figref>) to use.

p0038For this purpose, according to <figref idrefs="f0003">FIGS. 3 and 4</figref> the point light source 48 is aligned to the tooth surface 46th The point light source 48 is mounted in the embodiment shown, on the camera 44, in such a way that it is the optical axis 49 closely adjacent to, but spaced therefrom.

p0039To compensate for this divergence, the light source 48 is mounted on the camera at a small angle of for example 1 to 10 ° with respect to the optical axis 49th The orientation is chosen such that at a predetermined distance between camera 44 and the tooth surface 46 of incidence of the optical axis 49 coincides with the light spot generated by the light source 48th It is understood that this also a distance determination is made, at the same time easier to frame the image pickup device 12 in the camera 44th

p0040To make such a focus, and thus the distance down visually to the operator, for example, the dentist, clearly, it is in accordance <figref idrefs="f0003">Fig. 4</figref> provided to work with two light sources 48 and 50th With proper spacing dial the light spots of the two light sources 48 and 50 coincide, in which case at the same time there the optical axis 49 the generated double-light spot passes, namely preferably centrally.

p0041It is also possible to use a short tube or other suitable spacer which defines the distance from the start. Also, it is possible to perform a light measurement by the camera 44, which measures the brightness of the light spot generated with maximum brightness and indicating that the target position is carried out.

p0042Out <figref idrefs="f0003">Fig. 4</figref> It can be seen that both light sources 48 and 50 in the same but mirror symmetrical to each other, are arranged angle to the camera. It is understood that instead, any other number may be provided distributed by suitable light sources, for example, a circle around the camera.

p0043Out <figref idrefs="f0004">Fig. 5</figref> is a scheme according to the nature of a flow chart can be seen, showing the necessary steps for the inventive method. According to the function block 62, a camera is aligned with a patient's tooth, to take a picture of the tooth. In step 64 summary information is provided about what is being captured by the camera. According to step 66, a point light source, for example a laser diode, focused on the patients teeth, for example the integrated light source 48 or 50 is in accordance with<figref idrefs="f0003">FIGS. 3 and Fig. 4</figref>, It is understood that instead basically an external light source may be directed to the patient's tooth.

p0044In step 36 it is found on the destination setting means 26, when the camera is goal oriented substantially.

p0045As can be seen from step 70, will be displayed if the camera is properly aimed. For example, use an audible or visual indication means may be provided for indicating to the operator that the camera is properly aimed. As illustrated in step 72, then the image of the patient's tooth can be added, for example, automatically if previously indicated in step 70 for a period of time that the camera is properly aimed.

p0046Of these steps, the steps 62 and 66 are typically made by the user, while the stone's throw 64, 66, 70 and 72 in the preferred embodiment automatically, so computerized, take place.

p0047The target setting is preferred so that a limited segment of the captured image is evaluated. This is described in detail in<figref idrefs="f0005">Fig. 6</figref> shown. In step 82, it is stated that the image recording device is at a particular interest intraoral object, ie usually to be detected tooth aligned. The image information is then - as is noted in step 84 - detected, wherein a predetermined or pre-selected segment is determined, which represents a small portion of the entire image. The surface of the respective cutout, for example, less than 10%, include, in particular less than 1% of the entire image.

p0048The segment size depends on the light spot and its size and shape, which is generated by the light source 48 and 50 on the tooth. According to the invention, it is in any case provided that the segment captures the entire light spot.

p0049In an advantageous embodiment, the section is now divided into subdivisions, as shown below based on <figref idrefs="f0006">Fig. 7</figref> is explained in more detail.

p0050Instead of the fairly inexpensive laser diode, it is also possible to use a laser which can produce a sharply defined light spot or light point. However, a laser is much more expensive and brings invention only a very small additional benefit, so that expensive light sources are preferred contrast.

p0051As is made clear in step 86, the image information of the cut will be assessed to determine whether the camera is correctly aligned on the intraoral object. For example, image information regarding the color, shape and brightness of the light spot generated by the point light source can be evaluated in order to determine this.

p0052From steps in <figref idrefs="f0005">Fig. 6</figref> are the steps 84 and 86 are typically the steps that are performed by the computer is implemented by the operator during step 82nd

p0053Out <figref idrefs="f0006">Fig. 7</figref> It can be seen the manner in which the image information is evaluated. In an advantageous embodiment a grid of 3 x 3 grid is generated fields as well as in<figref idrefs="f0007">Fig. 8</figref> is shown. In this respect (step 92) dividing the segment in step 94 in subdivisions after selecting a particular camera image section for analysis. The determination can be carried out automatically here, but possibly also by an adjustment by the operator. Preferably, each sub-segment contains an equal number of pixels, for example 20 pixels, it being understood that any other divisions can be made.

p0054In step 96, the image information of subdivisions now be captured. This includes the light parameters of each sub-section, which are then comparatively evaluated in step 98th In step 100 it is then determined whether any of the subdivisions is the desired portion, indicating the center of the tooth.

p0055Although the inventive method based here is described on an image capture of a complete tooth is understood that instead captured a portion of a tooth and a corresponding assessment can be made.

p0056In order to evaluate and identify the subdivisions example brightness characteristics of two sub-outs can be compared against each other. The alignment is then defined as the center, when the brightness of these diametrically opposed subdivisions matches. This works when the light spot 48 and 50 generated by the light source, a symmetrical distribution of brightness, for example, according to a Gaussian curve having.

p0057It is also possible to compare the absolute brightness of the central Unterausschnits with the brightness of a further outwardly located below the cutout. In any other way, the symmetry of the brightness can be assessed, which can be detected, whether the horizontal-lateral and vertical-lateral subdivisions each have the same brightness.

p0058Out <figref idrefs="f0007">Fig. 8</figref> is seen schematically the manner in which a camera view 102 having an image of a tooth 104, can be evaluated. Light from a point light source can be directed onto the tooth 104 to form a light spot 106 on the tooth 104th The grid (section 108) is a segment that is selected for the evaluation of light characteristics of the light produced by the pinpoint Lichquelle when the light falls on the tooth 104th

p0059Below is <figref idrefs="f0007">Fig. 8</figref> an enlargement of the section 108 and the light spot 106 shown. The grid (segment 108) is according to the invention divided into a plurality of fields (109 subdivisions). This segment may have a shape and size that is selected so that it is suitable for the typical shape and size of the light spot 106th A precise alignment is only achieved when the light spot of the light source in the central field of the grid (segment 108). It is understood that typical camera distances are used and the size of the light spot thus produced can be determined empirically. Examples of intraoral camera systems are illustratively shown in the documents P 101 20 717.4 and P 101 26 887.4 to which this fully incorporated by reference.

p0060From the <figref idrefs="f0008 f0009 f0010">Figures 9 to 11</figref> is an inventive camera in a schematic view seen. Each point light source 206 is formed in this embodiment by five side by side arranged in series diodes 204, which are laterally formed next to the lens 202 of the camera. It is understood that instead a single laser diode 204 can be realized.<figref idrefs="f0010">Fig. 11</figref> additionally shows a short distance pipe with a ring 208, which is suitable for contact with the patient or the patient's tooth is formed and sets the distance between the camera and the tooth. It is understood, however, that such a distance ring is not required according to the invention.