For a proper fit e.g. of a hearing device it has always been considered vital to obtain good data of the ear canal. In case of hearing instruments for hard of hearing patients the data needs to cover a significant part of the canal and preferably beyond the “second bend”. Traditionally, data has been obtained with a silicon ear impression and this process is well-established. Being a manual and quite difficult process, alternative technologies have been searched for a long time and currently the focus is on direct scanning of the ear. An intermediate stage is scanning of ear impressions for computer-based in-the-ear (ITE) shell or behind-the-ear (BTE) mold production.
The pursuit of direct ear scanning is still ongoing and there are several approaches being studied. A number of problems remain to be solved, one being the way to insert the scanning head (probe) into the ear canal without hurting the patient, changing the shape of the canal or impacting the data acquisition. This is one of the subjects of the present invention.
In this respect in WO 02/091920 A1 the insertion of a scanning probe into an ear canal is proposed. Therefore, this prior art document is highly relevant and interesting, but does not give any contribution to the above mentioned problem.
In WO 02/16867 A1 a 360° probe-shaped non-contact scanning device is described. It also includes the post-processing of the data to obtain high-precision 3D data for individual ear canal shapes. But again nothing in this prior art document is addressing the issue relating to bends within the ear canal and insertion depth control.
In WO 02/16865 A2 a calibration method for ear scanning probes in order to achieve needed precision is described. The invention itself again does not touch the topic of the present invention.
There are several still open issues and real problems pursuing replacement of traditional ear impression taking by “direct ear scanning” one way or another. Most approaches involve the use of light (LED, laser, etc.); some propose video, ultrasound, computer tomography and even MRI (magnetic resonance imaging). Challenges relate to issues like: resolution, physical reference points, ear canal skin surface condition, post-processing of 3D information and touchless insertion/extraction of probes. The latter problem has not really been solved by any significant patent documents or publications to date and remains an obstacle in obtaining good 3D data of the undistorted ear canal. In addition, there are problems like skin scratches during insertion and extraction and even more severe: harm to the tympanic membrane, which is both very unpleasant and bears the risk of a distorted tympanic membrane function (e.g. conductive hearing loss).
Besides the described problem in relation particularly to insertion into the ear canal, this of course is a general problem in relation to the insertion of any kind of scanning probes, sensors, video heads, tubes like cannulas or catheters etc. into orifices, canals, tubes and the like of the human or animal body. Besides the ear canal this could be e.g. the intestinal tract, the gullet, etc.