Device for communicating environmental information to a visually impaired person

An aid for a blind person (1), includes a distance sensor (3), which creates a distance image of an object (2). The distance information that is generated by the distance sensor (3) is transmitted to a tactile matrix (10), which is integrated into a guide stick (11). The blind person (1) obtains information about his or her environment by touching the tactile matrix (10).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for communicating environmental information to a visually impaired person, said device comprising an information transmitter and a playback device which converts information supplied by the information transmitter into a signal which can be perceived by the visually impaired person.

2. Description of the Related Art

Devices of this kind are generally known. With such devices it is possible for example to make the information displayed on a computer screen readable for a blind person. For this purpose a text displayed by the computer monitor is converted by a tactile matrix into a height profile which can be deciphered by touching by the blind person. A tactile matrix typically consists of a plurality of two-dimensionally arranged feeler pins which can be individually raised by an actuating device.

Outside their own residence and their accustomed environment blind people are reliant on orientation aids such as a white cane or guide dog. However, both aids only allow a limited degree of mobility. Moreover the blind person can find his or her bearings at close range, i.e. within a distance of about one meter, without further aids by means of his or her sense of touch. Beyond this distance range the blind person's current and real environment is revealed to him/her directly only by means of acoustic impressions.

SUMMARY OF THE INVENTION

Proceeding from this prior art the object underlying the invention is to create a device for communicating environmental information to a visually impaired person by means of which a visually impaired person's orientation ability and confidence in movement can be substantially improved.

This object is achieved by means of a device having the features of the independent claim. Advantageous embodiments and developments are set forth in the dependent claims.

The device for communicating environmental information to a visually impaired person comprises a distance sensor which can be attached to the body of the visually impaired person. The distance information supplied by the distance sensor is played back by way of a portable playback device.

Distance sensors can be manufactured as integrated components. A distance sensor of this kind can be worn without problems by a visually impaired person. Since the measurement range of a distance sensor extends far beyond the local area which the visually impaired person can register by means of touch, the range of perception of a visually impaired person is considerably extended by means of the device. The device therefore helps in considerably increasing the orientation ability and confidence in movement of a visually impaired person.

In a preferred embodiment the embodiment the distance sensor operates according to the principle of light transit time measurement. Distance sensors of this kind operate independently of daylight and of the optical properties of the reflecting objects. Furthermore distance sensors of said type have a great measuring accuracy of approximately one centimeter.

Functional elements specific to the distance sensor are preferably integrated at least partially into an optoelectronic semiconductor component. In this context a distance-sensor-specific functional element should be understood to mean all functional elements which serve to determine at least one measured variable that can be used for calculating distance. Functional elements serving to supply power to and to buffer an integrated semiconductor component are to be excluded therefrom, however. The functional elements specific to the distance sensor therefore include at any event those functional elements in which light is generated and received. If the functional elements specific to the distance sensor are integrated in a semiconductor component or a plurality of semiconductor components, small, lightweight distance sensors are produced which can be worn without difficulty on the body.

The distance sensor can be integrated into an item of headgear. In this case the visually impaired person can change the orientation of the visual field of the distance sensor by movements of the head.

In a preferred embodiment the distance information supplied by the distance sensor is played back via a portable feeler device. For this purpose the portable feeler device can embody variable height profiles which can easily be made out by touching by the visually impaired person. In this way even complex distance information can be communicated to a visually impaired person.

In a further preferred embodiment the distance sensor has a linear visual field. Furthermore a feeler surface of the feeler device is implemented so as to correspond to the beam fan of the distance sensor. The distance profile of an object in the visual field is then reproduced by means of a height step which is embodied on the feeler surface and follows the shape of the distance profile.

This embodiment offers the advantage that the distance information can be relayed easily and robustly to the visually impaired person, since the outlines of the objects which are situated within the visual field of the distance sensors are to a certain degree reproduced on the feeler surface. A movement of the object can also be registered in a simple manner, since in this case the height step moves on the feeler surface in accordance with the movement of the object.

In a further preferred embodiment the visual field is extended in terms of surface area. In this case a height profile corresponding to the distance image is embodied on the feeler surface.

This embodiment thus provides the visually impaired person not just with the outline of the external contours of an object, but with a complete distance image. A disadvantage, however, is that the distance resolution is low, since the entire distance measurement range of the distance sensor has to be represented by means of the relatively short travel of the feeler pins.

The feeler device is preferably a tactile matrix which is integrated into a guide cane. In this way the visually impaired person has the feeler device constantly to hand when he or she reaches for the guide cane.

The device also enables information about the speed of objects in the visual field to be communicated. It is possible for example to cause areas of the feeler surface which reproduce a fast moving object to vibrate as a function of the speed of the object. In this way the visually impaired person is made aware of objects which are approaching him or her at speed.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a blind person1who is finding his bearings with the help of an aid device in the area of an object2. InFIG. 1said object2is a wall in which a passage is embodied. The aid device comprises a distance sensor3which is integrated into an item of headgear4of the blind person1. The headgear4can be, for example, a headband, cap or hat. The distance sensor3can also be worn on some other part of the body of the blind person1, however. For example, the distance sensor3can also be integrated into a pair of sunglasses.

The distance sensor3preferably operates on the basis of a light transit time measurement. With distance sensors of said type, which require no mechanically moving parts, a laser light illumination is modulated synchronously with the sensitivity of photosensitive receivers which are disposed on the surface of a semiconductor component either in the form of a row or in the form of a matrix. Various basic principles for distance sensors3of said type, including those referred to by the term PMD (=Photonic Mixing Device) or MDSI (=Multiple Double Short Time Integration), are known to the person skilled in the art. An advantage of light transit time measurement is that this can be performed with the aid of integrated semiconductor components. In that respect this results in small and lightweight distance sensors which can be worn without difficulty on the body.

In principle distance sensors having mechanical deflection units are also conceivable. Lightweight and robust deflection units can be created in particular with the aid of silicon micromechanics.

By inclining5or turning6his head the blind person1can direct a linear visual field7of the distance sensor1onto a spatial area of interest. In order to scan the visual field7the distance sensor3emits a beam fan8which comprises a plurality of sensor beams9which are distributed preferably uniformly over the angular extension of the linear visual field7. For example, 64 sensor beams can be distributed over an angle of vision of 100 degrees. The distance images recorded at a frequency of 10 Hz for example are reproduced with the aid of a tactile matrix10which is integrated into a guide cane11. The distance information contained in the distance images is transmitted preferably wirelessly between the distance sensor3and the tactile matrix10.

FIG. 2shows a plan view of the tactile matrix10integrated in the guide cane11. Arranged on a feeler surface12, the tactile matrix10has a plurality of feeler pins13which can be raised above the feeler surface12. Tactile matrices are known to the person skilled in the art and as such are not the subject matter of the invention.

The feeler surface12of the tactile matrix10is embodied so as to correspond to the beam fan8of the distance sensor3. The feeler surface12is therefore embodied preferably in the shape of a circular segment.

If an object2is situated in the visual field7of the distance sensor3, there is generated on the feeler surface12a height step which can be easily made out by touching by the blind person1and whose shape across the feeler surface12corresponds to the external contours of the object2.

FIGS. 3 to 6each show the outline of the object2that is situated in the visual field7and the associated display on the feeler surface12.

FIG. 3shows the representation, on the feeler surface12, of a wall14which is located immediately in front of the blind person1. Corresponding to the external contours of the wall14, the feeler pins13form an elevation15which is indicated inFIG. 3by the shaded area of the feeler surface12. In this case a height step16delimiting the elevation15moves across the feeler surface12as a function of the distance of the blind person1from the wall14. Because the height step16can easily be made out by touching by the blind person1, the blind person1receives information about the features of and distance from the wall14.

FIG. 4shows the representation of a corner17on the feeler surface12. In this case the elevation15is limited to a corner-shaped section of the feeler surface12.

By feeling the elevation15on the feeler surface12with his fingers, the blind person1can determine his distance from the corner17, which is for example the corner of a building, and give this a wide berth.

The details of the profiles of objects2can also be represented on the feeler surface12.

FIG. 5shows the representation of a rounded corner18on the feeler surface12. In this case the height step16of the elevation15is rounded corresponding to the external contours of the corner18.

FIG. 6, finally, shows the outline and the display of the object2represented perspectively inFIG. 1. The object depicted inFIG. 1comprises a passage19in a wall20. In this case the elevation15is restricted to two corner-shaped sections, with a depression21being located between the corner-shaped elevations15, said depression21indicating the passage19. By feeling the height profile embodied on the feeler surface12with his fingers, the blind person1receives information about the passage2which is located in front of him within the measurement range of the distance sensor3. The blind person1can therefore approach the passage19already from a distance which corresponds to the measurement range of the distance sensor3.

It should be noted that unobstructed areas can also be indicated by means of elevations in the same way as obstacles. In this case obstacles are indicated by means of a lowering of the feeler pins13.

A further variation relates to the embodiment of the visual field7.FIG. 7shows a modified aid device. The aid device illustrated inFIG. 7comprises a distance sensor22having a visual field23that is extended in terms of surface area. A tactile matrix24shown inFIG. 8is provided for the purpose of representing the distance image recorded by the distance sensor22. The feeler surface25of the tactile matrix is designed to correspond to the shape of the visual field23. A height profile which corresponds to the distance image recorded by means of the distance sensor22is generated on the feeler surface25. In this case the displacement of the feeler pins13is preferably proportional to the measured distance from the object2. If no object2is situated in the visual field23, the feeler pins13are retracted as far as possible. Conversely, if the object2is situated in close proximity to the blind person1, the feeler pins are raised as far as possible.

FIG. 9shows the display of the object2fromFIGS. 1 and 6on the feeler surface25. Said object2is the wall20with the passage19. In this case an elevation26which corresponds to the distance image of the wall20is embodied on the feeler surface25. The passage19is indicated by means of a depression27.

It should be noted that the tactile matrix10or24integrated into the guide cane11can offer both the representation of the outline of the external contours of an object2and the display of a distance image. This can be effected either by way of two separate feeler surfaces12and25or by way of a switchable feeler surface12or35.

It is furthermore possible to represent speed components of each pixel in the direction of the blind person1via the tactile matrices10and24. By direct and continuous recording of the distance image by means of the distance sensors3and22it is possible to calculate the speed of each pixel in the direction of the blind person1by comparison of two successive distance images. The speed information can be communicated to the blind person1for example by means of a speed-proportional vibration of the feeler pin13corresponding to the respective pixel. This makes the blind person aware of those objects2that are approaching him at speed. The display of the speed can modulate both the frequency and the amplitude of the vibration as a function of the speed. A vibration signal can also be communicated with the aid of a vibrator worn close to the body.

In a further modified embodiment the distance information is communicated to the blind person by way of an acoustic signal. For example, the immediate proximity of an obstacle can be indicated by means of a warning tone which is all the higher, the closer the blind person comes to the obstacle. In addition it is also conceivable, when an obstacle is approached, to output a spoken warning with the aid of a speech generator. The latter has the advantage that the warning will not be submerged in the ambient noise. The acoustic signal can be communicated inconspicuously by means of a hearing aid or a device which has the appearance of a hearing aid.

The aid devices described here facilitate the mobility of a blind person to a considerable degree. The perceptual capability of the blind person1equipped with the aid devices described here even partially exceeds that of a sighted person, for the aid devices described here operate even in complete darkness. The blind person1can therefore also find his bearings at nighttime. Furthermore reliable information about the distance and speed of objects2is communicated to the blind person1.