Abstract:
A device and method for use in tactile communications adaptable for use by anyone able to recognize messages written in a language known to them. The devise uses a series of sequentially firing vibromechanical stimulators vibrating against the skin or other suitably tactile sensitive area of the wearer. The vibromechanical stimulators are arrange in a substantially two dimensional array over the skin and are then triggered individually and in sequence, following a set of patterns representative of the symbols in the language recognizable to the wearer to tactually convey the message. The wearer cognitively perceives the tactual stimulation as a line or lines drawn on the skin or suitably tactile sensitive area that resemble the symbols used to communicate between the message sender and the wearer.

Description:
CROSS REFERENCES TO RELATED CO-PENDING APPLICATIONS 
     The present application is a continuation-in-part application of U.S. patent application Ser. No. 08/548,003 filed Oct. 25, 1995, titled TACTILE COMMUNICATION DEVICE AND METHOD and both applications are wholly owned by the inventor now U.S. Pat. No. 5,719,561. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a communication device, in particular a tactile communication device, as a personal communication device for receiving messages and other useful information including navigational and orientation information. 
     BACKGROUND 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 information within a reasonable time period with acceptable accuracy. The primary audiovisual modes of communication have relied on the receiver&#39;s eyes and ears. 
     A lesser known and relatively uncommon mode of communication is tactile communication. As discussed 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. Tactile communications has not found use in the general population essentially 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 understanding the sense of touch. There is also a relative lack of sophistication of the sense of touch when compared with the acuity found for the senses of hearing and vision. By comparison, the sense of touch exhibits difficulty with localization and perception of a stimulus. Humans are able to see extremely fine patterns of surface asperity that nonetheless feels as smooth as glass. The relatively low level of sophistication of the sense of touch remains somewhat baffling in light of the myriad types of end organ receptors that provide the brain with tactile information about our environment 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. Stimulation of tactile end organs sends a stimulus along the neuron of that end organ to the sensory cortex of the human relaying the information typically carried by these nerves. There are a number of different types of end organ effectors 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, pressure, pain, heat, and cold. Mechanoreceptor end organs are present within the human body in muscles, tendons and joints and provide important information concerning 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 endings, Merkel&#39;s discs, Meissner&#39;s corpuscles, Pacinian corpuscles, and Ruffini&#39;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 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 predominantly supply light touch sensations. 
     Meissner&#39;s corpuscles are predominantly 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 the perception of light touch in these areas. The high density of Meissner&#39;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 discrimination. In contrast, Meissner&#39;s corpuscles are rare elsewhere in the thinner skin of the human body. Contrast the decrease in Meissner&#39;s corpuscles with a relative 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. Merkel&#39;s corpuscles predominantly give rise to vibratory sensing ability. As a consequence, Merkel&#39;s corpuscles have less sensitivity to location and two point 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 stimulus by propagating 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 stimuli 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&#39;s corpuscle, Meissner&#39;s corpuscle, and Ruffini&#39;s corpuscle generally share a higher degree 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 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 endings along the basement membrane of the cutaneous layer of the skin have little, if any, end organ structure to them and have fairly low thresholds for firing. Free nerve endings are also found to be fairly diffuse with the free end organs branching 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 endings 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 the main axis of the corpuscle perpendicular to the surface of the skin. This tiered arrangement, much like a stack of pancakes where each pancake represents a specialized epithelial cell and a nerve ending between the pancakes, is oriented in such a way as to be very sensitive to slight pressures applied along its major axis and relatively insensitive to pressures arriving from a lateral direction. This directionality of a Meissner corpuscle contributes to its greater ability to finally localize and discriminate from two different points accurately. Contrast a Meissner corpuscle with a Pacinian corpuscle which essentially is a laminated 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 lack of orientation there is less sensitivity to discriminate size and location of the pressure 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 associated with faster conduction velocities. 
     When a nerve threshold is reached, the nerve fires and conducts a signal stimulus along its length 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 part of the nerve in that it cannot respond to a continuing 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 have placed a car key in their hand. This level of perception is defined as stereognosis which is the appreciation of a form of an object by means of touch. With the perception 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 the fingertip and the high density of Meissner&#39;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 apparent when considering a subject&#39;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 scanning motion sets up a vibratory sensation to which Merkel&#39;s corpuscles may respond. The vibratory sensation builds up an image that is resolvable at dimensions 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: Mechanisms 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, Johnson et al. discuss the responses evoked by one and two point stimuli versus the neural mechanisms associated with tactile spatial resolution. The results demonstrate that there is a distinctly different mechanism 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 produce different 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 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 afferent fibers terminate in Merkel receptors and have high spatial resolving capacity. Contrast this with rapidly adapting (RA) afferents which terminate in Meissner corpuscles and have poor spatial resolving properties. Meissner corpuscles have relatively high density in the fingertips and palms of the hand and toes and sole of the feet. As noted above, this high density provides for substantially increased two point discrimination resolution, i.e., the ability of a subject to determine 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 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 discrimination threshold. 
     To evaluate this question, consider a device known as the Optacon developed by Bliss and noted in the paper “Summary of Optacon Related Cutaneous Experiment”. In the conference on cutaneous communication systems and devices, F. A. Geldard, editor of the  Psychonomic Society , 1974. The Optacon uses an array of 144 probes in a 12×12 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 approximately one millimeter. The Optacon takes visual representation of a letter or number as its input and extends the appropriate number of probes from the surface of the array to spatially correspond to the letter or number being visualized. For example, the letter “A” may use upwards of thirty probes simultaneously contacting the skin of a subject&#39;s fingertip with each probe no greater than approximately one millimeter from its nearest neighbor. Therefore, if the two point discrimination threshold is two millimeters, all thirty of the protruding probes from the array will be indistinguishable from each other and perceived as a single probe fairly broad in its size. 
     As demonstrated and discussed above, Meissner corpuscles are predominantly responsible for two point discrimination. Merkel discs, by contrast, are responsible for spatial resolution. However, to take advantage of Merkel&#39;s disc stimulation, the Optacon and similar devices such as U.S. Pat. No. 3,229,387 issued Jan. 18, 1966 to Linvill, use a plurality of probes in a fairly large array such as the 12×12 array of the Optacon. The array is used to scan across a page of letters and numbers while attached 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 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&#39;s fingertip. It is the combination of the changing sequence of simultaneously vibrating probes and the vibration of the probes that contributes to the subject perceptually identifying 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&#39;s fingertip, the subject would not resolve the pattern into any useful recognizable alphanumeric. And as noted above, it has been shown that the SAI fibers terminating in Merkel&#39;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 intended to replace one of the other sensory systems, most commonly 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 transducer generally has failed in attempts. Continued work in this area has led to the development of systems which electrically divide the speech spectrum into different 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 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. 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 simultaneously with the frequency ranges approximately a third of an octave in bandwidth spaced evening over the frequency range between 140 to 6,350 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 probes vibrating simultaneously 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 Stimulation 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 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 appropriate 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 minimum 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 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”, Homer,  Perception and Psychophysics , line 49 (6), pp. 51-62, 1991, the author identified tactile confusion for letters with a greater number of lines such as the letters M, W, B and K. Therefore, despite the spatial threshold being significantly less than the two point discrimination threshold, the difference of 0.9 millimeters versus approximately two millimeters for the overlaying skin of a fingertip, complexity of the spatial form remains an obstacle difficult to overcome. 
     Synthetic systems employ communicating with languages employing synthetic codes. Braille is the most useful, best known and longest lived example of the synthetic families of tactile codes. Braille uses a 2×3 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 2×3 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 scanning 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 discrimination 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 communication systems described above have been developed as devices to provide communication devices to subjects who are otherwise impaired with either visual or auditory abilities to communicate. Whether synthetic or analogic, these systems generally rely on Merkel&#39;s discs densely populating the fingertips to achieve spatial resolution thresholds low enough to communicate 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 “Apparent 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 vibrators sequentially fired over the surface of the subject&#39;s body. The authors describe one example where an intense sense of rotational motion was induced by successively firing six vibrators placed around a subject&#39;s chest. The authors further studied a subject&#39;s sensation of haptokinetic movement employing a device with two vibrators spaced at different distances, from 4 to 22 centimeters, along the length of the subject&#39;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 maximum 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 400 milliseconds (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 induced in subjects using a system slightly different than the previously described system as outlined in the journal article “The Cutaneous ‘Rabbit’: A Perceptual Illusion” by Geldard et al. in  Science , Vol. 176, pp. 178-179, Oct. 13, 1972. These authors used from two to five vibrators consisting 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 anywhere from 40 to 80 msec between each pulse. The vibrators were aligned in a linear array over a subject&#39;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 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 taps between the stimulus loci which is in contradistinction to the continuous vibrating 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 simultaneously to reproduce either a complex spatial 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&#39;s discs, Meissner&#39;s corpuscles or Pacinian corpuscles to relay the communication information from the vibromechanical device to the conscious awareness of the recipient. 
     The perceptual phenomena described with the vibrotactile or haptokinetic movement and the rabbit affect appear to be independent of Meissner&#39;s corpuscles, Merkel&#39;s discs or Pacinian corpuscles since the vibromechanical stimulators 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 stimulator 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. 
     SUMMARY OF THE INVENTION 
     The present invention discloses a method and device for vibromechanical tactile communications adaptable for use by anyone able to recognize alphanumeric messages in a language, in other symbols known to them, or even in symbols or communications formats that are learned specifically for use with the present invention. The present invention uses a series of sequentially firing vibromechanical stimulators vibrating against a suitably tactile sensitive surface of the wearer, such as skin or buccal mucosa, to induce a phenomenon of illusion of linear continuity. This illusion of linear continuity, through vibromechanical stimulators tapping on the suitably tactile sensitive surface of the wearer, can be used to produce simple or complex pattern configurations perceived cognitively by the wearer of the device as line drawings or “tracings”, such as alphanumerics or other tactual patterns recognizable by the wearer, or perceived as an induction of motion. 
     Although the wearer is receiving discrete tappings on the surface area, the patterned vibratory stimuli are consciously perceived as the uninterrupted dragging of a blunt tipped stylet across the subject&#39;s tactile sensitive surface, i.e., a “tracing” across the surface. The closest somatosensory equivalent to this phenomenon is the tactile and cognitive sensation known as graphesthesia. In the present invention the plurality of vibromechanical stimulator are arrangeable in an array, or as a single line of multiple vibrators. Each vibromechanical stimulator in a two dimensional array is spaced apart from its nearest neighbors a distance that is still within the two point discrimination threshold distance for the suitably tactile sensitive surface area being stimulated. The vibromechanical stimulators in a linear arrangement do not need to be constrained within the two point discrimination distance. Each vibromechanical stimulator is triggered to vibrate individually and sequentially from one stimulator to the next successive stimulator for the pattern chosen to be conveyed. 
     One embodiment of the present invention is a tactile communications device (TCD) for use by a human wearing the device against a tactually sensitive surface of the human and receiving and converting communication elements of a data stream into a tactual message haptically or cognitively perceptible to the human. The device comprises a housing including a power source and a tactile stimulator array mountable within the housing. The array includes a plurality of vibromechanical stimulators 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 stimulators being connected to the power source. A control circuit is connected to the power source and to the tactile stimulator array for independently and sequentially controlling each vibromechanical stimulator. The control circuit preferably includes a receiver for receiving alphanumeric and/or other communication elements of the data stream, a tactual pattern storage circuit for storing a patterned sequence of turning on and off at least one vibromechanical stimulator of the plurality of vibromechanical stimulators corresponding to each tactual pattern stored, and a conversion circuit for converting the received communication elements of the data stream into a tactual data stream according to the corresponding tactual pattern. 
     As a consequence, for each alphanumeric and/or communication element within the data stream, beginning with the first datum, the corresponding tactual pattern is used to turn on and off a sequence of vibromechanical stimulators, one vibratory stimulator at a time, following the pattern sequence for each alphanumeric and/or communication element converted from the data stream. 
     The type of communication of information useful in a tactile communication device is limited only by a person&#39;s ability to perceive tactually. Virtually all forms of communications are transcribable to some form of a tactual pattern that is either associated with a previously learned symbol, such as alphanumerics, or is at least learnable, such as orienteering directions or navigational vectors. This type of communication may be stand alone or incorporated into other devices such as a watch, pager, or other devices that also traditionally communicate in audio or visual alphanumerics with the user. The use of the device of the present invention is not limited to humans. Realistically, the device of the present invention is useful for conveying any tactual message to any animal that has a tactually sensitive surface. The list of such animals includes most mammals. The animal must be capable of learning the association of the symbol or communications element, or elements, received to the response desired of the animal. For the purposes of this disclosure, the terms wearer, user and human should not be construed so narrowly as to limit the scope of these terms to just humans, but should be read to include any animal having a tactually sensitive surface. 
     Information other than alphanumerics or symbol data is also conveyable by the present invention. Consider a tactile position localization device (TPLD) housed in a suitable housing. By way of example, a pilot, deep sea diver, or even an astronaut, may wear a two dimensional array across their chest, leg, back, or elsewhere, and tactually receive spatial orientation information from their navigational instrumentation through an appropriate interface. The type of message received and conveyed to the wearer of a tactile array for representing spatial orientation information may incorporate any type of message format desired, as long as the format is taught to the wearer. For instance, consider a pilot wearing an array across his or her abdomen wherein the array “traces” a straight line across the pilot&#39;s abdomen sequentially using one tactile stimulator at a time. Through training, the pilot knows that when the line is traveling from left to right at about the level of the pilot&#39;s umbilicus, the pilot knows that the plane is flying upright and level with the horizon. Nose up or down, or turning inclinations would lead to corresponding changes in the line being “traced.” For nose up, the line would move above the pilot&#39;s umbilicus, and vice versa for nose down. During turns, the line would also bank in the same direction, and to the same degree, as the wings are banked. The pilot would even know when the plane is inverted, after having gone through half a roll, for the line is now moving right to left across the pilot&#39;s abdomen. 
     Another formatting example is the supplying of directional, or navigational, information, such as information telling a pilot which direction to fly. A specific example is an airplane&#39;s instrument landing system (ILS), usually providing visual guidance to the pilot on landing approaches. The tactile array could be programmed to receive data from the ILS and graphically represent that data tactually across the pilot&#39;s skin in the form a horizontal line to indicate the airplane&#39;s relative position to the glide path, and a vertical line to represent the airplane&#39;s relative position to the runway centerline. The array would “trace” a horizontal line, to be followed by a vertical line, and then repeat the process as quickly or as slowly as desired, updating the information from the ILS instrumentation as often as needed. In this fashion, the pilot may then fly the airplane to the lines being “traced” across their skin much as they would fly their airplane to the lines visually displayed on their cockpit ILS instruments. The pilot could feasibly land the plane without using, or relying on, any other cockpit instruments, or without visual cues through the cockpit windows. 
     Additional TCDs could be used with a TPLD to provide the pilot with additional alpha-numeric information such as their heading, wind speed, altitude, and angle-of-attack. An alternative to multiple TCDs is multiplexing data input into a large TPLD array, for example, an array having 100 or more individual stimulators in a rectangular or square grid placed across the pilot&#39;s chest and abdomen or back, wherein ILS glide slope and flight path could be given as horizontal and vertical lines, respectively, and other information, such as spatial orientation, altitude, angle of attack, and air speed could be given in smaller areas of unused corners of the array, with all the data being updated as often as desired by the pilot. 
     Another embodiment of the present invention is a tactile egovection device (TED) for use by a human wearing the device against the skin of the human. Egovection is a useful term for describing inducing a sense of motion in a person, where, in fact, the person is not moving at all relative to their surroundings. Such a phenomenon may be encountered in various pathological conditions, such as labyrinthitis, an inflammation of the semi-circular canals of the inner ear, that induce the sensation of spinning in a person. Egovection may also be artificially induced by tactually stimulating a persons body, circumferentially about a central axis, one vibromechanical stimulator at a time, according the present invention. 
     Such an embodiment comprises an array of a plurality of vibromechanical stimulators suitable for arrangement circumferentially axially around the person&#39;s head, neck, thorax, or abdomen. The axis may be in any one or all three axes. The plurality of vibromechanical stimulators are electrically connected to an electrical power source. A control circuit is electrically connected to the electrical power source and the tactile stimulator array for independently and sequentially controlling each vibratory stimulator. The control circuit includes a program for sequentially firing the plurality of stimulators, one stimulator at a time, in either direction around the circumference of the person and at variable rates of firing. 
     The present invention embodies a tactile communications method for receiving and converting a communications data stream into a message haptically perceptible to a human. The method comprises the steps of attaching a housing to the human with the housing including an electrical power source, then mounting a tactile stimulator array within the attachment housing, the stimulator array having a plurality of vibromechanical stimulators in a substantially two dimensional array. Next is positioning the tactile stimulator array abuttably over a tactually sensitive surface area of the human, connecting the plurality of vibromechanical stimulators electrically to the electrical power source, storing a tactual pattern for each alphanumeric and other symbol, controlling each vibratory stimulator independently and sequentially using the stored tactual pattern for each symbol, receiving electronically an alphanumeric and/or other symbol data stream, converting the received data stream into an tactual pattern data stream according to the corresponding stored tactual patterns, and turning on and off a sequence of vibromechanical stimulators, one vibratory stimulator at a time, according to the corresponding tactual pattern data stream for each alphanumeric or other symbol datum within the tactual pattern data stream, beginning with the first alphanumeric or other symbol datum, such that the sequence of vibrating stimulators on the tactually sensitive surface area is perceived tactually by the human as the communications message. The present method also includes a step for controlling the sequence of vibratory stimulator on and off times and intervibratory latency time periods. This method provides for a person to cognitively experience the complete or whole alphanumeric, or other symbol, message through the illusion of linear continuity phenomenon. 
     It is an object of the present invention to provide a method and device for tactile communications useful for persons who are sighted and have hearing, as well as, for persons visually impaired and/or hearing impaired. The device of the present invention is anticipated to accurately convey a message to the wearer of the device even while the wearer is engaged in other activity, such as sporting activities, driving or flying. 
     It is an additional object of the present invention to provide a method and device capable of accurate and timely tactile communications in many, if not all, the known written languages as well as in complex symbols and codes mutually known between the 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 apparent when reference is made to the following description, taken in conjunction with the accompanying drawings, and are in no way intended to limit the scope of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 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 in block diagram and the array component partially sectioned for clarity; 
     FIG. 2 is a bottom plan view of the housing of the embodiment depicted in FIG. 1; 
     FIG. 3 is a cross-sectional view taken at the line  3 — 3  in FIG. 2; 
     FIG. 4 is a perspective view of the embodiment of FIG. 1 as an embodiment of the invention to be worn on a wearer&#39;s skin; 
     FIG. 5 is an additional perspective view of the embodiment of FIG. 1; 
     FIG. 6 is a bottom plan view of an additional embodiment of the present invention; 
     FIG. 7 is a bottom plan view of another additional embodiment of the present invention; 
     FIGS.  8 ( a ) through  8 ( k ) are representative examples of how an embodiment of the present invention functions to generate numeric tactile communications; 
     FIGS.  9 ( a ) through  9 ( d ) are representative examples of how another embodiment of the present invention functions to generate non-alphanumeric tactile communications in addition to alphanumeric. 
     FIGS.  10 ( a ) through  10 ( b ) illustrate the placement of tactile stimulators on and around a wearer&#39;s chest and torso. 
     FIGS.  11 ( a ) through  11 ( c ) illustrate the placement of a tactile stimulator array on or around the head of a wearer. 
     FIGS.  12 ( a ) through  12 ( c ) show the placement of multiple stimulator arrays around the head of the wearer. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 depicts an embodiment of the present invention as a tactile communication device  30  which includes a control module  32 , a stimulator array  34 , a power source  36 , and a housing  38 . Tactile communication device  30  is an electromechanical device capable of receiving messages from an internal source transmitted to tactile communication device  30  from a remote device and then delivering the message to the user of tactile communication device  30  as a tactually sensed and cognitively perceived message. 
     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 communications. As a receiver, data receiver  40  will receive messages in the form of a data stream. The data stream itself may include analog, digital or combinations of these forms or other forms. Data receiver  40  is electronically connected 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 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 . 
     Stimulator array  34  includes a plurality of vibromechanical stimulators such as an array of electrical solenoids  46 . Suitable alternative vibromechanical stimulators 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 vibromechanical stimulator may protrude and retract a tactile effector portion of each vibromechanical stimulator. 
     One embodiment of the two dimensional array of housing face apertures  60  in housing face  58  is depicted in FIG.  2 . There are depicted eighteen housing face apertures  60  arranged in three columns of five and a single column of three housing face apertures  60 . 
     FIG. 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 effector is in a retracted position and upon energizing solenoid  46 , solenoid piston  62  will be forced out aperture  60  through housing face  58 . 
     Tactile communication device  30  is depicted in FIG. 4 using a band  64  to attach housing  38  to the skin of a wearer such as a forearm  66  much like wearing a watch. As depicted, the orientation is to place housing face  58  against the surface of the wearer&#39;s skin. In this orientation, the vibromechanical stimulators will come into contact with the surface of the wearer&#39;s skin when the stimulators are energized. An example is depicted in FIG. 5 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&#39;s skin or other suitably tactile sensitive surface, projection of any of the solenoid pistons  62  impinge against the wearer&#39;s skin and convey a tactual stimulation to the wearer. 
     FIGS. 6 and 7 represent two additional embodiments of many possible embodiments 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 stimulators used. For example, as depicted in FIG. 6, there are twenty-one housing face apertures 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 asymmetric aperture  70  within the complete array or alternatively using aperture  70  and its corresponding vibromechanical stimulator to provide an asymmetric stimulus that may carry additional meaning. An example might be triggering the vibromechanical stimulator through aperture  70  to indicate that the tactile communication device is about to begin a message transmission, or switch from alphabet to numeric or even possibly denote when the next character to be delivered is a known complex pattern alerting the wearer to pay a heightened level of attention to the next character so as to discern its true nature. Further use of an asymmetric aperture such as aperture  70  will be discussed below. 
     FIG. 7 depicts an embodiment using twenty-one apertures in a housing face aperture array  72  having the shape of an hourglass in its two dimensional configuration. This particular arrangement depicted by aperture array  72  was arrived at through studies to determine the most efficient two dimensional array pattern for being able to trace all the letters of the English 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 dimensional arrays available to the present invention. Although not disclosed, additional two dimensional patterns have been studied and useful arrays have been constructed from patterns employing as few as nine vibromechanical stimulators to as many as thirty. Arrays utilizing from fifteen to twenty-three vibromechanical stimulators have demonstrated the greatest practicality in terms of highest efficiency at the lowest cost and still providing accurate rendition of the received message. 
     FIGS.  8 ( a ) through  8 ( k ) depict the sequential firing of an array of eighteen (18) vibromechanical stimulators using the array pattern shown in FIG.  8 ( a ) to generate the numbers 0 through 9. This particular array is convenient for generating letters as well as numbers. FIGS.  8 ( b ) through  8 ( k ) depict which numbered stimulator firing sequence is used to produce each of the numbers. 
     FIGS.  9 ( a ) through  9 ( d ) depict a large array  100  using a 14 by 21 vibromechanical stimulator array totaling 294 stimulators beginning with a first stimulator  102  numbered as “1” on the array face and, for convenience, each of the corner stimulators also bearing their appropriate sequential number on the array face. Such a large array is useful for tactually conveying non-alphanumeric information, such as spatial orientation and navigational headings information, as well as alphanumerics. This type of information is not standardized, as is alphanumeric information, and as a consequence the format for tactually conveying this information relies on choosing a format for presentation then teaching that format to the user of the device. With this type of open ended formatting, many different and useful formats may be chosen and adapted for tactually conveying useful information to a wearer of the present invention. Examples of orientation and navigational information are those data receivable from flight instrumentation, global positioning satellites, diving instruments and the like. 
     In operation, tactile communication device  30  is powered by an internal power source  36  preferably a power source capable of delivering intermittent high peak current suitable for energizing the vibromechanical stimulators chosen and additionally providing sustained low current power suitable for radio receivers and integrated circuits both digital and analogic. 
     Data receiver  40  comprises an appropriate radio receiver including an antenna for reception of a radio signal bearing the message to be communicated 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 data receiver  40  is reception of commands for both altering programs as well as the symbol patterns that are stored in pattern memory module  42 . The most common 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 appropriate symbol matching 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. In addition, other symbol sets may be used that would be useful to communicate with other animals including mammals besides humans, such as, primates, dogs, and horses. Each symbol set could be customized to each animal using the tactile communications device of the present invention. Each animal using the tactile communications device would need specific training as to the the meaning of each symbol received. Stored with each symbol will be the digital or 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  and the appropriate symbol pattern is then conveyed over memory data transfer bus  54 . Conversion module  44  then compares 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 appropriate pattern for the digital or analogic data received, sequentially fires a sequence of vibromechanical stimulators, firing one and then the next individually, until the alphanumeric pattern and/or symbol has been traced over the suitably tactile sensitive area of the wearer. As shown in FIG. 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 FIGS. 8 a  through  k . The particular sequence of sequential firing of vibromechanical stimulators depicted in FIG. 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 FIG.  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&#39;s perception but will be necessarily inverted if one were to look directly at aperture array  60 . FIG.  8 ( b ) depicts one of the possible sequences for generating the number “1” by sequentially firing the vibromechanical stimulators associated with apertures labeled 1, 2, 3, 4 and 5. The pattern that is traced begins with firing the vibromechanical stimulator associated with aperture 1 individually and then sequentially followed by vibromechanical stimulator at aperture number 2, then at 3, then at 4, and finishing at 5. In FIG.  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 FIG.  8 ( d ) of 1, 6, 9, 14, 10, 7, 12, 18, 13, 8 and 5. The numbers “5”, “6” and “7” as depicted in FIGS.  8 ( f ), ( g ) and ( h ), continue the linear sequential firing of vibromechanical stimulators through those apertures as shown in each of these three figures. 
     Numbers such as “4”, “8” and “9” are depicted in FIGS.  8 ( e ),  8 ( i ) and  8 ( j ), and involve more complex patterns. For example, the number “4” in FIG.  8 ( e ) uses sequential firing of two linear patterns. 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 stimulator associated with aperture 11 is used at two different times during the pattern tracing. 
     FIG.  8 ( i ) depicts a firing sequence useful for the number “8” beginning with aperture 16, then going through the sequence 15, 14, 9, 6, 1, 2, 3, 7, 11 and returning 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 stimulator at aperture 16 has been used three times and the three stimulators at apertures 3, 7 and 11 were used twice. 
     The pattern trace for the number “9” as shown in FIG.  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 FIG.  8 ( g ). The pattern in FIG.  8 ( j ) was chosen, as were the patterns for “4” and “8” in FIGS.  8 ( e ) and  8 ( i ), because these patterns more closely approximate how these numbers are actually written. Recognition and accuracy have been shown to improve when construction of the patterns 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 strict representation. An example of a useful alternative pattern may be found in FIG.  8 ( k ) where only two vibromechanical stimulators are employed to convey the number zero as depicted in FIG.  8 ( k ). The number zero is traced by beginning with the vibromechanical stimulator at aperture 5, then jumping to 14 and then firing number 5 for a second time. It is understood that the wearer of the tactile communication device would necessarily need to know that this particular pattern represented the number zero. One obvious alternative is to program a stimulator sequence firing sufficient to draw out a zero. 
     FIG.  9 ( a ) depicts an example wherein a pilot is tactually receiving spatial orientation information in the form of an artificial horizon tactually “played” across array  100 . In the example depicted, the airplane&#39;s artificial horizon information is conveyed to the controlling portion of array  100  and is used to sequentially fire a series of vibromechanical stimulators one at time, beginning with a stimulator  104 , progressing in the direction of the arrow, and ending with a stimulator  106 . The sequence shown, with the array mounted over the pilots abdomen, would play across the wearer&#39;s skin left to right. All of the stimulators involved in the message have been blackened to more clearly indicate, pictorially, the message conveyed by the device. In this example, the artificial horizon “traced” across the array would convey a message of level upright flight to the pilot. 
     FIG.  9 ( b ) extends the example of FIG.  9 ( a ) depicting new information from the airplane&#39;s artificial horizon tactually “played” across array  100 . In this example, the horizon information is used to sequentially fire a series of vibromechanical stimulators one at a time, beginning with a stimulator  108 , and progressing in the direction of the arrow ending with a stimulator  106 . The artificial horizon tactually communicated in this example conveys a message of nose-up and right bank, i.e., an upright climbing right turn. 
     FIGS.  9 ( c ) and  9 ( d ) taken together depict an example for communicating navigational heading information received from a airplane&#39;s landing approach instruments, as well as, an alphanumeric message, a form of multiplexing of tactual information receivable from different sources sent to the wearer of the array. In FIG.  9 ( c ), the airplane&#39;s heading in relation to the runway and glide slope are depicted. The two “lines” tactually drawn sequentially are comprised of horizontal line for the glide slope represented by the sequential firing of vibromechanical stimulators beginning with a stimulator  112 , moving in the direction of the arrow and ending with a stimulator  114 . The alignment with the runway is represented by the sequential firing of vibromechanical stimulators beginning with a stimulator  116 , moving in the direction of the arrow and ending with a stimulator  118 . Sequential firing of the stimulators for glide slope from left to right, like the example given above, represents upright flight. Sequential firing of the stimulators for runway align from top to bottom could represent descent of the airplane at that moment from information received from the rate of descent instrument. Sequential firing from bottom to top could represent ascent. In the example depicted, the pilot is tactually receiving navigational information that the airplane is descending on the glide slope and in line with the runway. 
     Additionally, an alphanumeric message is tactually communicated to the wearer using a corner of large array  100  and represented by the sequential firing of stimulators beginning with a stimulator  120  and ending with a stimulator  122 . In the given example, the number “six” has been “traced”. Other corners of large array  100  may be used simultaneously as additional tactual communicators, tactually conveying information from any number of sources. 
     FIG.  9 ( d ) depicts glide slope information represented by the sequential firing of vibromechanical stimulators beginning with a stimulator  124 , moving in the direction of the arrow and ending with a stimulator  126 . The alignment with the runway is represented by the sequential firing of vibromechanical stimulators beginning with a stimulator  128 , moving in the direction of the arrow and ending with a stimulator  130 . In the example depicted, the pilot is tactually receiving navigational information that the airplane is upright, descending, but above the glide slope, and is left of the runway. Another alphanumeric element is tactually transmitted in the lower corner of array  100  using the number four as the example and represented by the sequential firing of stimulators beginning with a stimulator  132 , progressing sequentially to a stimulator  134 , then finishing from a stimulator  136  and ending with a stimulator  138 , “tracing” a number four. 
     As noted above, the illusion of linear continuity of the present invention wherein letters, numbers and other complex symbols are cognitively recognizable from tactile patterns generated by a two dimensional array of vibromechanical stimulators. This illusion is accomplished by spacing the vibromechanical stimulators within the two point discrimination threshold for the tactile sensitive area to be stimulated and using the vibromechanical stimulators one stimulator at a time in sequence. If two or more stimulators are used simultaneously, the illusion of linear continuity would not be 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 scanning technique of firing multiple vibromechanical stimulators to scan a letter, number or complex pattern across the tactile sensitive area and therefore spatial resolution of a letter, number or complex symbol is not needed with the present invention. A number of vibromechanical stimulators are available to those skilled in the art and include solenoids, bimorph ceramics and piezoelectric crystals and ceramics. 
     Referring to our FIGS. 10 and 11, there are shown various placements for the vibromechanical stimulators of the present invention. More specifically. FIGS.  10 ( a ) and  10 ( b ) illustrate two different methodologies for positioning of vibromechanical stimulators on the chest and torso of a wearer. In FIG.  10 ( a ), Housing  38  is held in place by the use of a chest strap  152 . By such positioning to this tactually sensitive area of the body, the navigation information discussed above could be appropriately communicated. Further, multiple actuator housing  38  can be spaced apart from one another as shown in FIG.  10 ( b ). In this configuration. the signals can easily cover large areas of the skin. 
     Similarly, the housing  38  could be positioned in various locations on the user&#39;s head. For example, as shown in FIG.  11 ( a ), housing  38  is positioned on the forehead through the use of a head strap  150 . This attachment mechanism is modified slightly in FIG.  11 ( b ) to include an overhead strap  154 , thus positioning housing  38  on an upper portion of the forehead. Alternatively, in FIG.  11 ( c ), housing  38  is positioned on the top of the head again using cross strap  154 . 
     As with the stimulators placed on the chest and torso of a wearer, multiple stimulators could be spaced apart on the head. Three such examples are shown in FIGS.  12 ( a ),  12 ( b ) and  12 ( c ), using overhead strap  154  and headband  150 . 
     In a number of studies using solenoids as the vibromechanical stimulators, several variables were determined to be influential in creating the illusion of linear continuity and a wearer&#39;s ability to cognitively recognize letters, numbers, and complex symbols. These variable parameters were: the total number of vibrations for each solenoid 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. Appropriate electronic control circuits for generating and delivering electrical pulses to solenoids were developed and are familiar 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 comparing the received message components with the pattern set in memory and generating a sequence of pulses deliverable to the appropriate sequence of solenoids to tactually convey the pattern of the message. Electronic circuits capable of modifying the above parameters were chosen. 
     Studies using a device for conveying arabic numerals were also conducted to determine a useful range of values for the parameter variables discussed above. The range of total 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 milliseconds 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 milliseconds. The preferred solenoid duty time was fifty percent with a solenoid on time of ten milliseconds 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, reference frame or complex symbol to the onset of inscribing the next letter, number, reference frame or complex symbol. Studies have shown this range to be substantially broad with a delay period as short as ten msecs to greater than three seconds. There does not appear to be any physical limitation to this delay. Rather, a 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 function level of the subject to cognitively understand what is being delivered tactually before receiving the next character. This character delay setting becomes a functional speed setting for the subject wearer and generally determines how fast a message will be delivered to the subject. This control parameter is therefore subject to individual preference. The wearer should be able to control the speed with which a message is delivered. 
     As discussed above, for FIG. 6, aperture  70  with its associated vibromechanical stimulator was initially described as an asymmetrically placed aperture for anticipated purposes of prompting that a condition previous may change. Use of a prompter vibromechanical stimulator 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 symbol. When the subject was prompted just prior to delivery of the difficult letter, number or complex character, the subject was quickly placed on notice that the next character would be one of these few. This type of prompting 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 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 meanings. 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 the invention, and since numerous modifications and changes will readily occur to those skilled in the art, it is not a 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.