Communications: electrical – Continuously variable indicating – With meter reading
Reexamination Certificate
1997-12-31
2001-12-04
Zimmerman, Brian (Department: 2635)
Communications: electrical
Continuously variable indicating
With meter reading
C340S870030, C340S407100
Reexamination Certificate
active
06326901
ABSTRACT:
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'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'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 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'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'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's corpuscles are rare elsewhere in the thinner skin of the human body. Contrast the decrease in Meissner'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's corpuscles predominantly give rise to vibratory sensing ability. As a consequence, Merkel'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's corpuscle, Meissner's corpuscle, and Ruffini'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 Pacin
Oppenheimer Wolff & Donnelly LLP
Zimmerman Brian
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