CA 0223~844 1998-04-23 W O 97/16035 PCTrUS96/17126 TACTILE COMMUNICATION DEVICE AND METHOD
Field of the Invention The present invention relates to a commllnic~tion device, in particular a tactile commllnic~tion device, as a personal commlmic~tion device for receiving Illessages.
5Background of the Invention Communication methods and devices have traditionally relied on audiovisual modes to convey the message from a source to a recipient. Audiovisual modes are capable of conveying considerable amounts of il~..,.aLion within a reasonable time period with acceptable accuracy. The primary audiovisual modes of commlmiç~tif~n10 have relied on the receiver's eyes and ears.
A lesser known and relatively uncommon mode of communication is tactile communication. As di~cllssed below in more detail, efforts to develop this mode of communication have been limited and typically geared towards improving the communication reception for people disabled or impaired in either hearing or vision.
15 Tactile communications has not found use in the general population ~ss~nti~lly because of the overwhelming reliance on audiovisual modes of communication.
Development of communication devices using the sense of touch in general have suffered because of a general lack of knowledge in the area of underst~n~lin~ the sense of touch. There is also a relative lack of sophistication of the sense of touch when 20 compared with the acuity found for the senses of hearing and vision. By comparison, the sense of touch exhibits difficulty with loç~li7~tion and perception of a stiml~ Humans are able to see e,.L-c...ely fine patterns of surface asperity that nonetheless feels as smooth as glass. The relatively low level of sophistication of the sense of touch .cm~ls somewhat baffling in light of the myriad types of end organ leceplol~ that provide the 25 brain with tactile i.~....~lion about our envilol~llc.-L obtained through the sense of touch.
~Within the human body, tactile conditions are monitored through an interaction of neuron end organ receptors within the skin and internal organs and musculoskeletal system of the human body. Stimlll~tion of tactile end organs sends a stimll~ along the 30 neuron of that end organ to the sensory cortex of the human relaying the i-~----aLion typically carried by these nerves. There are a llumber of di~elellL types of end organ SUBSTITUTE SI~EET (RULE 2~) CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 erre~;~ol~ within a human. The general areas of sensory modality detected by skin receptors fall in the categories of fine or light touch, coarse touch, vibratory, ~ ule, pain, heat, and cold. Mechanoreceptor end organs are present within the human body in muscles, tendons and joints and provide important information concerning 5 musculoskeletal positioning and movement. Consequently, the sense of touch can be distinguished by dividing into two general categories, the first being the exteroceptive sensory modality and the second category is the proprioceptive sensory modality. The general subject of this present invention will be concerned primarily with the exteroceptive tactile sensory modality.
The neuron end organ effectors in the exteroceptive modality are a diverse assortment of organelles. There are free nerve en~ling~, Merkel's discs, Meissner's corpuscles, pacinian corpuscles, and Ruffini's endings supplying tactile sensation to the skin. Free nerve endings predominate and are found generally throughout the entire skin surface area. Free nerve endings typically innervate the layers of the skin as 15 unmyelinated fibers carrying primarily pain as well as hot, cold and light touch. Free nerve endings with medium myelinated fibers are associated with hair follicles within the skin and predomin~ntly supply light touch sensations.
Meissner's corpuscles are predomin~ntly associated with the thicker skin of the palms and fingertips of a hand and the sole and toe tips of the feet and primarily provide 20 the perception of light touch in these areas. The high density of Meissner's corpuscles in the hands and feet is the underlying anatomic basis behind the relatively exquisitely sensitive tactile abilities associated with the hands and feet and two point disc. ;~ ion. In contrast, Meissner's corpuscles are rare elsewhere in the thinner skin of the human body. Contrast the decrease in Meissner's corpuscles with a relative 25 increase in the number of hair follicles and associated free nerve ending fibers that provide the light touch sensory modality to those areas of skin not associated with the palms or soles of the body. Consequently, the differences in light touch between the palms, soles and the skin of the rest of the body lies not only in the difference in neuron end organ effectors but also in whether the nerve fiber is myelinated or non-myelinated.
30 Merkel's corpuscles predomin~ntly give rise to vibratory sensing ability. As a consequence, Merkel's corpuscles have less sensitivity to location and two point CA 0223~844 1998-04-23 W O 97/16035 PCTrUS96/17126 discrimination but exquisitely sensitive to spatial resolution of complex surface patterns when the fingers are scanned over an object or the object moved over the fingers.
The quality of sensory ability is dependent on the ability of an end organ effector (or free nerve ending) to sense the presence of a stimulus, respond to that 5 stimulus by prop~g~tin~ a signal along the length of the neuron, recharge the neuron after its firing, and regain sensitivity to a stimulus following reception of the previous stimulus. These general areas of qualification of nerve function are threshold, conduction velocity, refraction, and adaptation. Non-myelinated fibers are generally slower to conduct, have higher periods of refractoriness and quickly adapt to external 10 stirnuli relative to myelinated fibers and the converse is true wherein the greater the degree of myelination the higher the conduction velocity, the shorter the period of refractoriness and the less susceptible to adaptation the nerve becomes. Additionally, the more sophisticated neuron end organs such as Pacinian corpuscle, Merkel's corpuscle, Meissner's corpuscle, and Ruffini's corpuscle generally share a higher degree 15 of sophistication as to structure and are associated with medium myelinated fibers.
Contrast this with heavily myelinated fibers used in the proprioceptive sensory modality where position sense, muscle force contraction and joint position are relatively refined and sophisticated allowing us to perform fairly complex fine motor athletic movement.
The heavily myelinated fibers having the highest rate of conduction, the shortest period 20 of refractoriness and the greatest resistance to adaptability.
Threshold of a nerve fiber will depend in great part to the type of neuron end organ effector present on that nerve fiber. The threshold of firing will also depend on the type of stimulus being presented to the neuron end organ. Free nerve enciing~ along the basement membrane of the cutaneous layer of the skin have little, if any, end organ 25 structure to them and have fairly low thresholds for firing. Free nerve en(lin~ are also found to be fairly diffuse with the free end organs brz-nching a number of times and innervating a substantial area of skin in proportion to the size of the nerve fiber supplying that area. Consequently, the quality of signal received from free nerve en~lin~ has a generally diffuse character poorly localized when compared to light touch provided by a Meissner corpuscle. A Meissner corpuscle is arranged in a tiered fashion of epithelial cells within the corpuscle with t_e main axis of the corpuscle perpendicular CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 to the surface of the skin. This tiered arrangement, much like a stack of p~nr~k(:s where each p~nr~ke represents a specialized epithelial cell and a nerve ending between the p~nc~kes,is oriented in such a way as to be very sensitive to slight pres7uLes applied along its major axis and relatively insensitive to pressures arriving from a lateral S direction. This directionality of a Meissner corpuscle contributes to its greater ability to finally localize and discriminate from two dirr~ points accurately. Contrast a Meissner corpuscle with a Pacinian corpuscle which essentially is a l~min~te-1 body surrounding a single nerve ending. This lamellar construction with the nerve ending at its center provides increased sensibility to pressure from all directions but because of a 10 lack of orientation there is less sensitivity to discriminate size and location of the ples~7~ stimulus.
Conduction velocity is a measure of the speed with which a nerve will transmit to the sensory cortex of the brain the fact that a stimulus has arrived at the nerve end organ. Myelination provides for higher conduction velocities where more myelin is 15 associated with faster conduction velocities.
When a nerve threshold is reached, the nerve fires and conducts a signal stimulus along its len~th and must then recharge the nerve in order to be ready to respond to the next stimulus. The length of time that the nerve is discharged is known as the refractory period. The refractory period is a state of non-responsiveness on the 20 part of the nerve in that it cannot respond to a continlling external stimulus during this period.
Neuronal adaptation is that ability of the nerve to modify its level of sensitivity to changes in the environment. In effect, the neuron becomes used to the external stimulus and reestablishes a new level of response to stimuli.
Tactile communication not only relies on the ability to sense that a touch has in fact occurred but also determine the nature of the touch. The touch should convey useful information. An example might be placing a car key in the hands of a blindfolded subject. The subject should be able to tell you not only that their hand has in fact been touched but be able to discern from the pattern of the stimulus that you 30 have placed a car key in their hand. This level of pelc~;~lion is defined as stereognosis which is the appreciation of a form of an object by means of touch. With the perception CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 of a key, the subject is able to tactually feel a continuous surface and edge. In light of the anatomy and distribution of neuron end organs contributing to tactual perception, the spatial resolution is limited by the spacing of single nerve fibers in the immediately surrounding area adjacent to that single nerve fiber and its end organ. As in the case of S the fingertip and the high density of Meissner's corpuscles, the perception of a spatial form on the skin of the fingertip would depend on a neuronal image of the stimulus established by the density of the Meissner corpuscles. The greater the density, the greater the perceptual ability to perceive complexity and the greater the spatial resolution. The effect of this density pattern of neuron end organs becomes readily 10 a~ when considering a subject's ability to discriminate between two points. Our tactile ability to resolve a form spatially is enhanced if we then rub our fingers over the object, such as the key. This sc~nning motion sets up a vibratory sensation to which Merkel's corpuscles may respond. The vibratory sensation builds up an image that is resolvable at tiimen~ions less than a millimeter.
In the article titled "The Perception of Two Points is not the Spatial Resolution Threshold", K. O. Johnson et al., in Touch, Temperature, Pain and Health Diseases:
Mech~ni~m~ and Assessments, Progress and Pain Research and Management, Vol. 3, edited by J. Boivie et al., the authors discuss the tactual difference in perceiving a two point discrimination versus spatial pattern recognition thresholds. In their review, 20 Johnson et al. discuss the responses evoked by one and two point stimuli versus the neural mech~ni~m~ associated with tactile spatial resolution. The results demonstrate that there is a distinctly different mech~ni~m of response by a human subject when presented with a single probe, a double probe or a more complex vibratory pattern.
Furthermore, they are able to show that response to one and two point stimuli will 25 produce dirrel~lll sensations depending upon longitudinal or transverse orientations of the probes which would allow discrimination between one and two points stimuli on the basis of cues that may have had nothing to do with spatial resolution. Furthermore, they were able to demonstrate that the threshold of tactile spatial resolution has remained independent of the two point discrimination threshold. It has been shown that the 30 neurologic system responsible for tactile spatial pattern recognition at the limits of resolution is the slowly adapting type 1 (SAI) afferent fiber system. The individual SAI
CA 0223~844 l998-04-23 fibers termin~te in Merkel receptors and have high spatial resolving ca~aciLy.
Contrast this with rapidly adapting (RA) ~rrere..L~ which ~ in Meissner corpuscles and have poor spatial resolving ~lv~ ies. Meissner corpuscles have relatively high density in the fingertips and palms of the hand and toes and sole of the 5 feet. As noted above, this high density provides for substantially increased two point discrimination resolution, i.e., the ability of a subject to clet~rmine whether they are being touched by a single or two separate probes simultaneously. Contrast this with a plurality of probes that are in a spatially configured pattern, for instance the letter "A", such that if all of the probes come into contact with the skin surface of a fingertip 10 simultaneously, the question becomes will the subject be able to discern and resolve the spatial configuration of the multiple probes if the probes are spaced together less than the two point discrimination threshold or if the probes are spaced apart greater than the two point discrimin~tion threshold.
To evaluate this question, consider a device known as the Optacon developed by 15 Bliss and noted in the paper "Summary of Optacon Related Cutaneous Experiment". In the conference on cutaneous comrnunication systems and devices, F. A. Geldard, editor of the Psychonomic Society, 1974. The Optacon uses an array of 144 probes in a 12 x 12 pattern. The array measures approximately one to one and one-half centimeters on each side. Consequently, the distance between one probe and its nearest partner is 20 approximately one mil~imeter. The Optacon takes visual representation of a letter or number as its input and extends the ~ lol.liate number of probes from the surface of the array to spatially correspond to the letter or number being vi~ li7~?-1 For example, the letter "A" may use upwards of thirty probes simultaneously contacting the skin of a subject's fingertip with each probe no greater than approximately one millimeter from 25 its nearest neighbor. Therefore, if the two point discrimin~tion threshold is two millimeters, all thirty of the protruding probes from the array will be incli~tin~uishable from each other and perceived as a single probe fairly broad in its size.
As cl~m-~n~trated and discussed above, Meissner corpuscles are predominz~ntly responsible for two point ~ rimin~t;on. Merkel discs, by contrast, are responsible for 30 spatial resolution. However, to take advantage of Merkel's disc stim~ tion, the Optacon and similar devices such as U.S. Patent No. 3,229,387 issued January 18, 1966 CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 to Linvill, use a plurality of probes in a fairly large array such as the 12 x 12 array of the Optacon. The array is used to scan across a page of letters and numbers while ~tt~r.he-1 to a fingertip surface and the letters and numbers through protruding vibrating probes are then felt to scan across the fingertip much as a ticker tape output scans across a 5 marquee. For example, the Optacon slides across the letter "A" and the letter "A" is felt to slide across the fingertip of the wearer of the Optacon. Sequential numbers of probes in the pattern "A" protrude from the surface of the array and vibrate at a set frequency.
Depending upon the size of the letter there may be upwards of thirty or forty probes simultaneously vibrating against the surface of the subject's fingertip. It is the 10 combination of the ch~nging sequence of simultaneously vibrating probes and the vibration of the probes that contributes to the subject perceptually id~lliryillg the spatial resolution of the letter. If the letter were to not scan but remain static with the thirty or so probes arranged in a letter but vibrating against the subject's fingertip, the subject would not resolve the pattern into any useful recognizable ~lph~nl-meric. And as noted 15 above, it has been shown that the SAI fibers terrnin~tin~ in Merkel's discs contribute to the spatial resolution perceived by a subject using a device similar to the Optacon.
Tactile stimulators may be generally divided into two groups: The synthetic systems and the analogic systems. These systems are devices in which the cutaneous sensory system is inten~lefl to replace one of the other sensory systems, most commonly 20 vision or hearing. Examples of analogic audio systems are cochlear implants that convert sounds such as speech into tactile sensations felt by a subject at a site designed to be used by the device. The ability to transmit speech to the skin using a single vibrating trsln~ rer generally has failed in attempts. Continl~cl work in this area has led to the development of systems which electrically divide the speech spectrum into 25 dirr~....l frequency bands. These various bands may also be modified in terms of time delay schemes and positioning to more closely accommodate the direction of the actual sound source.
Other audio tactile aids are known as vocoders. A number of vocoder devices have been tested and an evaluation of two multichannel tactile aids can be found in the 30 paper "Evaluation of Two Multichannel Tactile Aids for the Hearing Impaired",Weisenberger et al. in the Journal of Acoustical Society of America, Vol. 86 (5), pp.
CA 0223~844 1998-04-23 1764-1775, November 1989. The two vocoder devices described used 16 element linear vibratory arrays displaying activity in 16 overlapping frequency channels. The 16 elements vibrated ~imllltAneously with the frequency ranges approximately a third of an octave in bandwidth spaced evening over the frequency range between 140 to 6,350 5 Hz. Accuracy of communicating with these vocoders was limited with subjects being able to identify only 70% of a 250 word test list even when combined with lip-reading.
All of these analogic systems replacing hearing use multiple vibrotactile probesvibrating ~imllltAneously at frequencies approximAting those of actual speech. These systems have proven difficult to incorporate and accurately rely on.
Visual analogic systems are represented by such devices as the Optacon or a tactile vision information system (TVIS) as described in "Effective Tactile StimlllAtion Pulse Characteristics on Sensation Threshold and Power Consumption", Nuziata et al., Annals of Biomedical Engineering, Vol. 17, pp. 423-35, 1989. The authors describe the basic function of the TVIS as the acquisition of an optical image with a video camera 15 and the transformation of the image or some portion of the image into a vibratory pattern on a specific region of skin. Like the Optacon, the TVIS uses a vibratory tactile array coupled with app~ iate electronic frequency filtering in order to create a spatial analog of the visual scene being picked up by the video camera. Each vibrator used a base frequency of 250 Hz. The choice of 250 Hz was dependent on the minimllnn 20 threshold for tactile sensation using Pacinian corpuscles that are the most responsive end organ receptors in the vicinity of 250 Hz stimulation frequencies. Both the Optacon and the TVIS use multiple vibrating probes in a spatial pattern to create the vibrotactile message discerned by the subject using the device.
While an analogic system such as the Optacon, where the device uses multiple 25 simultaneous vibrotactile probes to create a complex spatial form, confusion and difficulty with perception has been studied. In the paper "The Effects of Complexity on the Perception of Vibrotactile Patterns", Horner, Perception and Psychophysics, line 49 (6), pp. 51-62, 1991, the author i~lentifie-l tactile confusion for letters with a greater number of lines such as the letters M, W, B and K. Therefore, despite the spatial 30 threshold being significantly less than the two point discrimin~tion threshold, the difference of .9 millimeters versus approximately two millimeters for the overlaying CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 .
skin of a fingertip, complexity of the spatial form remains an obstacle difficult to overcome.
Synthetic systems employ co.. l.. icating with languages employing synthetic codes. Braille is the most useful, best known and longest lived example of the synthetic 5 families of tactile codes. Braille uses a 2 x 3 array to form unique patterns discernible as the alphabet. Consequently, the tactile experience does not resemble either the visual or auditory experience associated with the letter for which the pattern stands. In the simplest of terms, synthetic systems require that the user of the system learn the additional language set employed by the synthetic system.
Translation of Braille into a vibrotactile device would necessarily require an array 2 x 3 and be capable of simultaneously vibrating up to all six of the probes. As with the Optacon, to achieve the smaller sizes and utilize the lower threshold associated with spatial resolution of complex forms, the Braille patterns would necessarily need to be scanned across the skin surface, preferably the tip of a finger. Consequently, a device useful for tactually displaying Braille figures would need an array having substantially greater than six vibromechanical probes. Without the sc~nning capability, a device incorporating Braille as the underlying interpretive language would use a minimum of six vibromechanical probes, each requiring spacing between probes to be greater than the two point discrimin~tion threshold. This minimum spacing is necessary to allow the subject wearing the device to discern between two or more probes, since Braille characters require anywhere from one to six simultaneously vibrating probes.
The collllllullication systems described above have been developed as devices toprovide collllllunication devices to subjects who are otherwise impaired with either visual or auditory abilities to collllllullicate. Whether synthetic or analogic, these systems generally rely on Merkel's discs densely populating the fingertips to achieve spatial resolution thresholds low enough to coll-~nunicate complex spatial forms such as letters and numbers.
There exist other tactile phenomena that are not well understood. An example of such a tactile phenomenon is described in the paper "Ap~c;llt Haptic Movement" by Sherrick et al. in Perceptions and Psychophysics, Vol. 1, pp. 175-180, 1966, wherein the author describes the induction of a sense of movement produced by stationary CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 vibrators sequentially fired over the surface of the subject's body. The authors describe one example where an intense sense of rotational motion was in~ cecl by ~llccec~ively firing six vibrators placed around a subject's chest. The authors further studied a subject's sensation of haptokinetic movement employing a device with two vibrators 5 spaced at different distances from 4 to 22 centimeters along the length of the subject's leg. The subject was allowed to control the duration of the two vibrotactile bursts as well as the interval of time between the onset of the two vibrotactile bursts. In this way, the subject was able to adjust the sequential firing of the two vibrators to achieve a m~hllu.ll perception of haptic movement between the two vibrators. For each trial run, the vibrators were vibrated at 150 Hz for burst durations ranging from 25 to 400milli~econds (msec) which equates to from 4 to 60 vibrations per burst. The interval between burst onsets ranged from 75 to 400 msec.
A different tactile phenomenon was infll~cecl in subjects using a system slightly different than the previously described system as outlined in the journal article "The 15 Cutaneous 'Rabbit': A Perceptual Illusion" by Geldard et al. in Science, Vol. 176, pp.
178-179, October 13, 1972. These authors used from two to five vibrators con~i~tin~ of a short length of Lucite rod about 0.6 centimeters in diameter with a rounded tip rigidly mounted on Clevite bimorph benders and driven by a pulse generator generating a square wave pulse 2 msec in duration. Each vibrator received five pulses separated 20 anywhere from 40 to 80 msec between each pulse. The vibrators were aligned in a linear array over a subject's forearm and upper arm on an average spacing of approximately ten centimeters with a range from two centimeters to 35 centimeters.
The phenomenon experienced by the subjects in the test was the sensation of a smooth progression of jumps, or taps, on the arm between the successively firing vibrators. It 25 was described as if a tiny rabbit were hopping from one vibrator to the next. If the number of vibrator taps is increased for each vibrator then the hops become shorter and closer together and the opposite effect is also noted. The authors distinguished this rabbit effect from the vibrotactile movement described above by Sherrick et al. on the basis that the rabbit effect gives a discontinuous hopping sensation described as discreet =30 taps between the stimulus loci which is in contr~ tinction to the continuous vibrating CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 gouging sensation in the skin between loci experiencing the vibrotactile or haptokinetic movement illusion.
The devices that attempt to replace vision or hearing do so by relying on a plurality of vibrators firing ~iml-lt~neously to reproduce either a complex spatial S arrangement such as a letter or number or to recreate the vibrations associated with speech. These systems consume a considerable amount of power to fire the plurality of vibrator arrays simultaneously and are dependent on their interaction with Merkel's discs, Meissner's corpuscles or Pacinian corpuscles to relay the communication information from the vibromechanical device to the conscious awareness of the 1 0 recipient.
The perceptual phenomena described with the vibrotactile or haptokinetic movement and the rabbit affect appear to be independent of Meissner's corpuscles, Merkel's discs or Pacinian corpuscles since the vibromechanical ~timlll~tors are placed independent of, and in fact can be varied in their distance between each locus and still create the illusion of movement between the ~tim~ tor loci. These phenomena appear to be more a function of perception at the sensory cortex level as the stimuli are reconstructed in real time and perceived at a conscious awareness level by the subject.
Therefore, these phenomena appear to be independent of two point discrimination and spatial resolution thresholds.
There does not as yet exist a vibromechanical tactile communication device capable of universal use that can receive and convey information to the wearer conveniently or accurately.
Sllmm~ry of the ~nvention The present invention discloses a method and device for vibromechanical tactile cn"~",~ ications adaptable for use by anyone able to recognize alph~nl-meric messages in a language or in other symbols known to them. The present invention uses a series of sequentially firing vibromechanical stimlll~tors vibrating against a suitably tactile sensitive surface of the wearer, such as skin or buccal mucosa, to induce a phenomenon of illusion of linear co~ y. This illusion of linear Colllilluily, through vibromechanical stimulators tapping on the suitably tactile sensitive surface of the wearer, can be used to produce simple or complex pattern configurations perceived CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 cognitively by the wearer of the device as line drawings, such as ~lrh~nllmerics or other symbols recognizable by the wearer. Although the wearer is receiving discrete tappings on the surface area, the ps~tterned vibratory stimuli are consciously perceived as the u~l~;d dragging of a blunt tipped stylet across the subject's skin. The closest 5 somatosensory equivalent to this phenomenon is the tactile and cognitive sensation known as graph~sthç~i~ In the present invention the electromechanical vibrators are arranged in an array. Each vibrator in the array is spaced apart from its nearest neighbors a distance still within the two point discrimination threshold distance for the suitably tactile sensitive surface area being stim~ t~1 Each vibromechanical 10 stim~ tor is triggered to vibrate individually and sequentially from one stim~ tor to the next successive ~timlll~tor for the pattern chosen to be conveyed in the message.
An embodiment of the present invention is a tactile communications device for use by a human wearing the device against the skin of the human and receiving and converting a communications data stream into a message haptically or cognitively15 perceptible to the human. The device comprises a housing including an electrical power source, a tactile stim~ t~r array mountable within the housing and having a plurality of vibromechanical stimlll~tors positionable in a substantially two dimensional array, the array being abuttably positionable over a suitable tactile sensitive surface area of the human and the plurality of vibromechanical stimnl~tors being electrically connected to 20 the electrical power source, a control circuit electrically connected to the electrical power source and the tactile stimulator array for independently and sequentiallycontrolling each vibratory ~tim,ll~tor~ the control circuit including a communications receiver for electronically receiving a digital alph~nnmeric and other symbol communications data stream, an analog pattern storage circuit for storing a p~tt~med 25 sequence of turning on and off at least one vibratory stimlll~tor of the plurality of vibromechanical stimlll~tors corresponding to each alphanumeric and symbol stored, and a collv~;l.,ion circuit for collv~.ling the received digital alph~nllmeric and other symbol coll--llul~ications data stream into an analog data stream according to the corresponding analog pattern such that for each ~lrh~nllmeric and symbol datum within 30 the analog data stream, beginning with the first datum, the co.l~onding analog pattern is used to turn on and off a sequence of vibromechanical stimlll~tors~ one vibratory CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 stim~ tor at a time, following the pattern sequence for each ~lph~mlmeric datum converted from the digital data stream.
The present invention embodies a tactilé colllnlullications method for receivingand converting a coll-,llu,lications data stream into a message haptically perceptible to a S hllm~n, the method comprising the steps of ~tt~hin~ a housing to the human, the housing including an electrical power source, mounting a tactile stimulator array within the ~tt~(~hment housing, the stim~ tcr array having a plurality of vibromechanical stimulators in a subst~nti~lly two dimensional array, positioning the tactile stiml-l~tQr array abuttably over a surface area of the skin of the human, connecting the plurality of 10 vibromechanical stimulators electrically to the electrical power source, storing an analog pattern for each alph~numeric and other symbol, conkolling each vibratorystimulator independently and sequentially using the stored analog pattern for each symbol, receiving electronically a digital alph~numeric and other symbol data stream, converting the received digital data stream into an analog data stream according to the 15 corresponding stored analog patterns, turning on and off a sequence of vibromechanical stimlll~tors, one vibratory stimulator at a time, according to the corresponding stored analog pattern for each alphanumeric datum within the analog data stream, beginning with the first alphzmllmeric datum such that the sequence of vibrating stimulators on the skin is perceived tactually by the human as the communications message, and 20 controlling the sequence of vibratory stimulator on and off times and intervibratory latency time periods such that the illusion of linear continuity phenomenon and the complete or whole alphzlnl-nneric and other symbol message is cognitively experienced after the entire sequence for the alph~nllmeric is given.
It is an object of the present invention to provide a method and device for tactile 25 communications useful for persons who are sighted and have hezlring as well as for persons blind and or deaf. The device of the present invention is anticipated toaccurately convey a message to the wearer of the device even while the wearer isengaged in other activity, such as driving or flying.
- It is an additional object of the present invention to provide a method and device capable of accurate and timely tactile co~ ications in many, if not all, the known CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 written languages as well as in complex symbols and codes mutually known betweenthe sender of the message and the wearer of the device.
The above and other objects and advantages of the present invention will become more readily a~ l when reference is made to the following description, S taken in conjunction with the accolll~ly.llg drawings, and are in no way int~n-lecl to limit the scope of the present invention.
Rrief nescription of the nrawi~
Figure 1 is a side elevational view of an embodiment of the present invention with the outer housing depicted in phantom for better clarity, the electronic components 10 in block diagram and the array component partially sectioned for clarity;
Figure 2 is a bottom plan view of the housing of the embodiment depicted in Figure l;
Figure 3iS a cross-sectional view taken at the line 3-3 in Figure 2;
Figure 4 is a perspective view of the embodiment of Figure 1 as an embodiment 15 of the invention to be worn on a wearer's skin;
Figure 5is an additional perspective view of the embodiment of Figure l;
Figure 6 is a bottom plan view of an additional embodiment of the present invention;
Figure 7 is a bottom plan view of another additional embodiment of the present 20 invention; and Figures 8 a through k are representative examples of how an embodiment of the present invention functions to generate tactile communications.
P~tzliled Description of the Invention Figure 1 depicts an embodiment of the present invention as a tactile 25 co~ ~ication device 30 which includes a control module 32, a ~tim~ tor array 34, a power source 36, and a housing 38. Tactile con~ ~ication device 30 is an electromechanical device capable of receiving messages from an intern~l source transmitted to tactile communication device 30 from a remote device and then delivering the message to the user of tactile coll..llullication device 30 as a tactually 30 sensed and cognitively perceived message.
CA 0223~844 l998-04-23 Control module 32 includes a data receiver 40, a pattern memory module 42 and a conversion module 44. Data receiver 40 comprises an electronic data reception capability preferably as radio frequency electronic co~ .ications. As a receiver, data receiver 40 will receive messages in the form of a data stream. The data stream itself 5 may include analog, digital or combinations of these forms or other forms. Data receiver 40 is electronically conn~cte~l to pattern memory module 42 via a memory data transfer bus 54. Data receiver 40 is also electronically connected to conversion module 44 through a message data transfer bus 52. Pattern memory module 42 is electronically connected to conversion module 44 through a memory data transfer bus 54. Data 10 receiver 40 is electronically connected to pattern memory module 42 through a memory rewrite transfer bus 56.
Power source 36 delivers electrical energy through electrical connectors 50. As depicted, power to stimulator array 34 is received through a plurality of electrical connections 48 between control module 32 and stimulator array 34.
Simulator array 34 includes a plurality of vibromechanical stimulators such as an array of electrical solenoids 46. Suitable alternative vibromcrh~nical stim~ tors are available such as bimorph ceramics and piezoelectric materials. Stimulator array 34 is constructed to present a two dimensional array of vibromechanical stimulators across a housing face 58 having corresponding housing face apertures 60 through which each 20 vibromechanical stimulator may protrude and retract a tactile effector portion of each vibromechanical stiml-l~tor.
One embodiment of the two dimensional array of housing face apertures 60 in housing face 58 is depicted in Figure 2. There are depicted eighteen housing face apertures 60 arranged in three columns of five and a single column of three housing face 25 apertures 60.
Figure 3 depicts an example of a vibromechanical stimulator with a tactile effector portion as a solenoid 46 with its electrical connection 48 and a solenoid piston 62. As shown, solenoid piston 62 acting as a tactile ~rre~;lol is in a retracted position - and upon energizing solenoid 46, solenoid piston 62 will be forced out aperture 60 30 through housing face 58.
CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 Tactile co~ lunication device 30 is depicted in Figure 4 using a band 64 to attach housing 38 to the skin of a wearer such as a forealll. 66 much like wearing a watch. As depicted, the orientation is to place housing face 58 against the surface of the wearer's skin. In this orientation, the vibromechanical stimulators will come into 5 contact with the surface of the wearer's skin when the stim~ tors are energized. An example is depicted in Figure S where one of the solenoid pistons 62 projects through its corresponding housing face aperture 60 and extends beyond the boundary of housing face 58 surface. As worn against a wearer's skin or other suitably tactile sensitive surface, projection of any of the solenoid pistons 62 impinge against the wearer's skin 10 and convey a tactual stimulation to the wearer.
Figures 6 and 7 l~leselll two additional embodiments of many possible embo-liment~ for number and the two dimensional positioning of housing face apertures. The present invention anticipates that many different two dimensional arrays are available both in spatial orientation and in total numbers of vibromechanical lS stimulators used. For example, as depicted in Figure 6, there are twenty-one housing face ap~ s with twenty in a housing face aperture array 68 that is four columns of five apertures. There is an additional aperture 70 placed to the side of aperture array 68 as an asymmetric configuration providing this embodiment with an aperture array capable of employing the asyrnmetric aperture 70 within the complete array or 20 alternatively using aperture 70 and its corresponding vibromechanical stimulator to provide an asymmetric stimulus that may carry additional me~ning An example might be triggering the vibromechanical stimulator through aperture 70 to indicate that the tactile communication device is about to begin a message tr~n~mi~ion, or switch from alphabet to mlnneric or even possibly denote when the next character to be delivered is a known complex pattern alerting the wearer to pay a heightf?ne-l level of attention to the next character so as to discern its true nature. Further use of an asymmetric aperture such as a~GlLu.~ 70 will be discussed below.
Figure 7 depicts an embodiment using twenty-one a~Lu,es in a housing face aperture array 72 having the shape of an hourglass in its two ~1imen~ional configuration.
30 This particular arrangement depicted by aperture array 72 was arrived at through studies to determine the most efficient two ~1imen~ional array pattern for being able to CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 trace all the letters of the Fnpli~h alphabet and the complement of arabic numerals as discussed below. Depiction of these three aperture arrays in no way should be construed as a limitation in the actual number of useful two ~limen~ional arraysavailable to the present invention. Although not disclosed, additional two ~1imen~ional 5 patterns have been studied and useful arrays have been constructed from patterns employing as few as nine vibromechanical stim~ tors to as many as thirty. Arrays~ltili7in~ from fifteen to twenty-three vibromechanical stim~ tors have demonstrated the greatest practicality in terms of highest efficiency at the lowest cost and still providing accurate rendition of the received message.
In operation, tactile c~ ~ication device 30 is powered by an intPrn~l power source 36 preferably a power source capable of delivering intermittent high peak current suitable for energi_ing the vibromechanical stimlll~tors chosen and additionallyproviding sustained low current power suitable for radio receivers and integrated circuits both digital and analogic.
Data receiver 40 comprises an a~plo~l;ate radio receiver including an ~ntenn~
for reception of a radio signal bearing the message to be cornmunicated to the wearer of the device. The message may be in the form of digital or analog data streams and data receiver 40 will be set up accordingly. An additional mode of operation for datareceiver 40iS reception of commzlnti~ for both altering programs as well as the symbol patterns that are stored in pattern memory module 42. The preferable and most comrnon patterns stored will be those consisting of the alphabet from A to Z and the set of arabic numerals. The symbol pattern is stored in pattern memory module 42 so that the a~propliate symbol m~trhing the symbol sent in the data stream to the data receiver 40 may be sent by pattern module 42 over memory data transfer bus 54 to conversion module 44. The present invention anticipates that other symbol sets may be utilized by the present invention, for example, coded symbol sets where an encryption and de-encryption scheme is shared between the source of the encoded message and the wearer of the device, the Cyrillic alphabet, the Greek alphabet and even, but not limited to, - Chinese and Japanese characters. Stored with each symbol will be the digital or 30 analogic equivalent set forth as the message is received by data receiver 40. The data stream is then conveyed to conversion module 44 over the received data transfer bus 52 CA 0223~844 1998-04-23 and the ~plop,;ate symbol pattern is then conveyed over memory data transfer bus 54.
Conversion module 44 then CO111~ ,S the digital or analogic data stream to the digital or analogic equivalent of patterns representing each of the symbols received from pattern memory module 42.
Conversion module 44, using the a~propl;ate pattern for the digital or analogic data received, sequentially fires a sequence of vibromechanical stim~ tors, firing one and then the next individually, until the ~lph~nllmeric pattern and/or symbol has been traced over the suitably tactile sensitive area of the wearer. As shown in Figure 1, conversion module 44 uses solenoid electrical connections 48 to energize the plurality of solenoids 46 used in stimulator array 34. An example of a sequential firing of these solenoids 46 for tracing the Arabic numerals zero through nine is depicted in Figures 8, a through k. The particular sequence of sequential firing of vibromechanical stimulators depicted in Figure 8 is not the only sequence of patterns available to the present invention. The present invention anticipates many different firing sequences for creating patterns for any of the alphabet, number or symbols available to any of the written languages. The present invention also anticipates the use of artificial languages and codes that may be used to communicate with the use of the present invention.As depicted in Figure 8(a), each element in housing face aperture array 60 in housing face 58 has been sequentially numbered from one to eighteen. As used, tactile communication device 30 is inverted over the skin of a wearer such that the pattern traced on the skin will be normal to the person's perception but will be necessarily inverted if one were to look directly at aperture array 60. Figure 8(b) depicts one of the possible sequences for generating the nurnber " 1 " by sequentially firing the vibromechanical stimlll~tQrs associated with apertures labeled 1, 2, 3, 4 and 5. The pattern that is traced begins with firing the vibromechanical stimulator associated with a~ ; 1 individually and then sequentially followed by vibromechanical tim~ tor at Lule number 2, then at 3, then at 4, and fini~hin~ at 5. In Figure 8(c), the number "2" is traceable using the following firing sequence of 2, 6, 9, 15, 11, 7, 4, 5, 8, 13, and ending with aperture 18. The number "3" has the firing sequence shown in Figure 8(d) of 1, 6, 9, 14, 10, 7, 12, 18, 13, 8 and 5. The numbers "5", "6" and "7" as depicted in CA 0223~844 1998-04-23 W O 97/1603S PCT~US96/17126 Figure 8(f), (g) and (h), continue the linear sequential firing of vibromechanical stim~ tr rs through those apertures as shown in each of these three figures.
Numbers such as "4", "8" and "9" are depicted in Figures 8(e), 8(i) and 8(j), and involve more complex p~ttern~ For example, the number "4" in Figure 8(e) uses - 5 sequential firing of two linear p~tt~rn~ The first sequential firing begins with 1 and continues with 2, 3, 7, 11 and ends with 16. The number "4" pattern is then completed with the second sequence firing beginning with 9, then 10, 11, 12, and ending with 13.
Note that the vibromechanical stimlll~tor associated with aperture 11 is used at two different times during the pattern kacing.
Figure 8(i) depicts a firing sequence useful for the number "8" be~inninp~ with aperture 16, then going through the sequence 15, 14, 9, 6, 1, 2, 3, 7, 1 1 and lc~L~ g to 16. Firing 16 a third time, the sequence then continues through 17, 18, 13, 8, 5, 4, 3, 7, 11, and finally back to 16. As is seen, the vibromechanical stiml-l~tor at aperture 16 has been used three times and the three stimulators at apertures 3, 7 and 11 were used twice.
The pattern kace for the number "9" as shown in Figure 8(j) begins at aperture 14 and progresses through apertures 9, 6, 1, 2, 3, 7, 11, 16, 15, and then 14 again. 14 then fires again after its slight delay and the sequence finishes through 15, 16, 17, ending at 18. The number "9" might just as easily have been generated in a linear fashion, for example by inverting the "6" pattern in Figure 8(g). The pattern in Figure 8(j) was chosen, as were the patterns for "4" and "8" in Figures 8(e) and 8(i), because these patterns more closely approximate how these nurnbers are actually written.Recognition and accuracy have been shown to improve when conskuction of the p~ttern~ can follow the actual tracings one might use to create the numbers on paper.
As should be understood, the present invention is not necessarily limited to such a skict repres.ont~tion. An example of a useful alternative pattern may be found in , Figure 8(k) where only two vibromechanical stimulators are employed to convey the number zero as depicted in Figure 8(k). The number zero is kaced by beginnin~ with the vibromechanical stim~ tor at aperture 5, then jumping to 14 and then firing number 30 5 for a second time. It is understood that the wearer of the tactile conllullication device would necessarily need to know that this particular pattern represented the CA 0223~844 1998-04-23 W O 97tl6035 PCTrUS96/17126 nurnber zero. One obvious ~lt~rn~tive is to program a stim~ tor sequence firing sufficient to draw out a zero.
As noted above, the illusion of linear collLhluily of the present invention wherein letters, numbers and other complex symbols are cognitively recognizable from tactile S patterns generated by a two ~1imen~ional array of vibromechanical stim~ tors is accomplished by spacing the vibromechanical ~timlll~tors within the two point discrimin~tion threshold for the tactile sensitive area to be stimnl~tecl and using the vibromechanical stim~ tQrs one stimulator at a time in sequence. If two or more stimlll~tors are used .~imnlt~neously, the illusion of linear collLinuily would not be 10 created because the two or more simultaneously firing vibromechanical stimulators would not be perceived as individual or discrete vibromechanical stimulators but as a single point. The present invention does not use a sc~nnin~ technique of firing multiple vibromeçh~nical stimlll~tors to scan a letter, number or complex pattern across the tactile sensitive area and therefore spatial resolution of a letter, number or complex 15 symbol is not needed with the present invention. A number of vibromech~niczllstimulators are available to those skilled in the art and include solenoids, bimorph ceramics and piezoelectric crystals and ceramics.
In a number of studies using solenoids as the vibromechanical stimnl~tQrs, several variables were det~rmine~ to be influential in creating the illusion of linear 20 conlinuily and a wearer's ability to cognitively reCQgnize letters, numbers and complex symbols. These variable parameters were: the total number of vibrations for eachsolenoid used to generate a character, the delay time between a solenoid firing and the next solenoid to fire, the duty time for the solenoid, and the delay time between the end of creating of one character to the beginning of the creation of the next character.
25 Appropriate electronic circuits for generating and delivering electrical pulses to solenoids were developed and are f~mili~r to those skilled in the art. Components used include a suitable power source, a receiver, a pulse generator, a set of patterns programmed within a memory buffer and a control circuit for colllLpal;llg the received message components with the pattern set in memory and generating a sequence of 30 pulses deliverable to the a~l~fiate sequence of solenoids to tactually convey the CA 0223~844 1998-04-23 W O 97/16035 PCT~US96/17126 pattern of the message. Electronic circuits capable of modifying the above parameters were chosen.
Studies using a device for conveying arabic numeral was used to ~let~rmine a useful range of values for the variable parameters discussed above. The range of total - 5 number of vibrations per solenoid was from two to fifteen vibrations with five as the preferred number of vibrations. The solenoid duty time was tested having two variables and using a square wave pulse: the actual solenoid on time in milli~econds and the solenoid off time in milliseconds. A useful range for solenoid on time was from two to twenty milliseconds. A useful range for solenoid off time was from two to ten milli~econds. The prerel.~d solenoid duty time was fifty percent with a solenoid on time of ten milli~econds and a solenoid off time of ten milliseconds. Therefore the entire solenoid duty cycle time is preferably twenty milliseconds with a range from four to thirty milliseconds. This equates to a vibration frequency range of from 33 Hz to 250 Hz with a preferable frequency of 50 Hz.
The character delay setting is that programmable period between completion of the sequence for one letter, number or complex symbol to the onset of inscribing the next letter, number or complex symbol. Studies have shown this range to be substantially broad with a delay period as short as ten msec to greater than three seconds. There does not appear to be any physical limitation to this delay. Rather, a 20 cognitive perception of a character becomes the functional limitation. The subject should be able to discern the character being inscribed at a cognitive level prior to the onset of the next character to be delivered. The parameter reduces to the functionability of the subject to cognitively understand what is being delivered tactually before receiving the next character. This character delay setting becomes a functional speed 25 setting for the subject wearer and generally ~lçterrnines how fast a message will be delivered to the subject. This control parameter is therefore subject to individual ~ ,rele,lce. The wearer should be able to control the speed with which a message is delivered.
As discussed above, for Figure 6, aperture 70 with its associated 30 vibromechanical stim~ tor was initially described as an asymmetrically placed aperture for anticipated purposes of prol~ g that a condition previous may change. Use of a CA 0223~844 1998-04-23 ~ro,l,~LeL vibromech~nic~l stim~ tfr was useful in studies in order to assist some subjects having difficulty with some letters, numbers or other complex characters.
Study revealed that for some subjects there were a few symbols, only a few in total number, where the subject had difficulty in accurately perceiving the tactually conveyed 5 symbol. When the subject was p~ulll~Lt;d just prior to delivery of the difficult letter, number of complex character, the subject was then quickly placed on notice that the next character would be one of these few. This type of plo~ Lillg substantially increased both speed of delivery of messages as well as accuracy. As noted above, the use of a prompter is also ideal for circumstances where the subject wearer is to be 10 notified that there will be a change in the message. For instance, switching from letters to numbers or to complex characters that have been encoded with alternative me~nin~.
Additionally, relatively simple changes in state are communicated quickly, such as distinguishing a.m. from p.m. when receiving a time message.
The foregoing description is considered as illustrative only of the principles of 15 the invention, and since numerous modifications and changes will readily occur to those skilled in the art, it is not desire to limit the invention to the exact construction and operation shown and described. Accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the present invention.