Communications – electrical: acoustic wave systems and devices – Echo systems – Distance or direction finding
Reexamination Certificate
1999-10-29
2001-10-02
Pihulic, Daniel T. (Department: 3662)
Communications, electrical: acoustic wave systems and devices
Echo systems
Distance or direction finding
Reexamination Certificate
active
06298010
ABSTRACT:
TECHNICAL FIELD
The invention relates to a device to aid the orientation of blind and partially sighted people, comprising
(a) at least one contactless distance measurement system, which generates a correcting variable depending on the distance between the device and an object measured by the distance measurement system, and
(b) at least one indicating device, to which the correcting variable of the distance measurement system is applied and which supplies an indication depending on the correcting variable.
BACKGROUND ART
Blind or partially sighted people usually use a mobility or long cane for orientation, with which objects in a distance up to 1.2 m can be detected. The orientation with such a long cane has several disadvantages. Especially the distance to the detectable objects is very short.
A number of devices for blind or partially sighted people is known which use contactless distance measurement systems to rectify the disadvantages of the long cane. Different versions of such a contactless distance measurement system are known. These devices comprise a transmitter which sends out a measurement beam and if the beam is reflected by an object a receiver detects the reflected beam. The distance between the device and the object is determined either via a time of flight measurement or by triangulation. The measurement beam can be electromagnetic (IR-radiation or laser beam) or sonic. The determined distance will be converted into a distance-dependent correcting variable which will be supplied to an indicator that displays the distance in a way that is adapted to the needs of the blind and partially sighted persons. Such indicators use either acoustic or vibronic signals.
The DE-A1-37 43 696 reveals a mobility aid that use a contactless distance measurement system. A transmitter sends out an IR-beam or a laser beam. If the beam is reflected by an obstacle a receiver detects the reflected beam and an acoustic signal will be generated. Transmitter and receiver are put in a device that is carried in front of the blind persons body. The measured distance to the obstacle is indicated by the pitch and the volume of the acoustic signal.
The DE-A1-35 44 047 describes a mobility aid that works with a contactless distance measurement system which measure the distance to an obstacle by a so called sonic echo pulse time of flight method. A miniaturized sonic echo pulse time of flight evaluation device is put on the long cane. The pulses which are reflected by an obstacle are detected by a receiver and analyzed. The measured distance is converted into an acoustic noticeable audio frequency. This results in a kind of musical sequence of sounds if the distance to the obstacle decreases.
By the DE-A1-44 02 764 an other mobility aid using a contactless distance measurement system is known. In one housing comprises a radar signal transmitter, a radar receiver and a unit to analyze which produces a control signal if there is a frequency difference between the send and the received signals reflected by the surrounding. The control signal is supplied to a signal generator who is built as a kind of tappet pestle that is moving electromagnetic. The mechanic effect occurs on the body of the person through the force of pressure depending on the control signal. The radar system and the tappet pestle are arranged in a headgear. Within a further development of the mobility aid a second radar system and a second tappet is provided. The second radar system is arranged in a belt.
By the DE-A1-25 11 935 a further mobility aid for partially sighted persons using a contactless distance measurement system is known. Here the measured distance (or any measured value) is indicated acoustically by variation of the pitch and volume or vibronic through the variation of the vibrational frequency, the force of vibration and the kind of vibration.
Through the DE-A1-195 22 601 a further mobility aid for partially sighted persons using a contactless distance measurement system is known. A primary unit of the device comprises a sonic transmitter and a sonic receiver. A second unit comprises a micro computer for the receiver signals and a electro-mechanic vibrator as indicator.
Further devices using contactless distance measurement as orientation aid for blind and partially sighted people which use similar acoustic or vibronic indications are described in DE-A1-41 40 976, DE-A1-29 32 659, DE-PS-23 30 940, DE-A1-28 16 530, DE-A1-31 33 645, DE-A1-195 05 402, DE-A1-40 438 and DE-A1-38 36 961.
It turned out that the display of the indication devices of the known mobility aids for blind people working with contactless distance measurements is not satisfying. The main reason therefore is the difficulty of interpretation of those acoustic or vibronic signals. The assignment of a acoustic or vibronic signal to a determined distance needs a lot of practice. While the user receives the actually measured signal there is no reference signal (e.g. distance zero) to compare with. Furthermore, acoustic signals bother blind persons because they use their hearing for orientation in and perception of the environment.
DISCLOSURE OF INVENTION
The object of the invention is to indicate a measured distance—in a device for orientation of blind or partially sighted people as described above—in a way that is easy and clear noticeable for the blind and partially sighted person.
According to the invention this object is achieved in that
(c) the indicating device comprises at least one tactile indicator, which is displaced continuously or quasi continuously along a tactile path as monotone function of the distance measured by the distance measurement system.
Thus the indication device delivers tactile indicator which represents the determined distance not through different tones or vibrations but through a displacement. In this way a “direct” indication of the distance occurs. The measured distance, namely the distance to an object will be transformed into a tactile distance, namely the displacement of the tactile indicator. This makes the interpretation of the indication device much easier.
The user feels the tactile path along which the tactile indicator is moving. The tactile path may be designed in such a manner that the user can feel the tactile path with one part of his body without displacing this part of his body. For example the tactile path can be covered by a part of the forearm or by a finger (e.g. the thumb). The tactile indicator is moving in relation to this part of the body. Thus the user feels the position of the tactile indicator and relates a distance to this position.
The displacement of the tactile indicator occurs in relation to the measured distance as monotone function, this means a small distance is shown as a small displacement and a longer distance is shown as a larger displacement. This also makes the interpretation much easier.
The displacement of the tactile indicator occurs continuously or quasi continuously. A quasi continuous displacement means that the displacement is stepwise.
As contactless distance measurement system which generates a correcting variable which is depending on the measured distance between the device and an object detected by the measurement system can be any kind of distance measurement system. The presented invention is not restricted to a specific design of the distance measurement system. Acoustical as well as optical systems can be used. Such distance measurement systems are known and will not be described in more detail here.
However, a laser distance measurement system is preferably used. The use of a laser beam to detect a distance has two substantial advantages. Based on the small divergence of the beam even fine structures e.g. ropes can be scanned by pointing the device in that direction.
Therefore the device has to be moved slightly to and fro. Furthermore the range is very high.
Thus through the device according to the invention the blind has the opportunity to orientate in an environment by the directional information namely by pointing in a direction with the device and the distanc
Konig Lutz
Ritz Maria
Woste Ludger
Mallinckrodt Robert R.
Mallinckrodt & Mallinchrodt
Pihulic Daniel T.
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