1. Field of the Invention
The present invention is generally related to a safety device for a marine vessel and, more particularly, to a detector that senses the presence of a human being in the region of the marine propulsion device and deactivates the device to prevent injury to the human being.
2. Description of the Prior Art
Many different types of marine propulsion devices are well known to those skilled in the art. For example, outboard motors that are attached to the transom of a marine vessel, stern drive systems that extend in a rearward direction from the transom of a marine vessel, docking thrusters, and bow thrusters are well known to those skilled in the art. In addition to bow thrusters, certain types of docking thruster systems used in conjunction with marine vessels incorporate a plurality of propulsors that are responsive to the joystick manipulations of a marine vessel operator.
Many types of infrared sensors are well known to those skilled in the art. These types of sensors have been used in many applications where the presence of a human being is detected and the detection is used to activate or deactivate a device, such as a lighting system.
U.S. Pat. No. 6,142,841, which issued to Alexander et al on Nov. 7, 2000, discloses a water jet docking control system for a marine vessel. Several versions of the docking system are disclosed in this patent. Once system utilizes pressurized liquid at three or more positions of a marine vessel in order to selectively create thrust that moves the marine vessel into desired locations and according to chosen movements. Electrical embodiments of the system utilize one or more pairs of impellers to cause fluid to flow through the outlet conduits in order to provide thrust on the marine vessel. In one embodiment of the device, a cross thrust conduit is associated with the marine vessel to direct fluid flow in a direction perpendicular to a centerline of the marine vessel and a pair of outlet conduits are associated with the marine vessel to direct flows of fluid in directions which are neither parallel nor perpendicular to a centerline of the marine vessel.
U.S. Pat. No. 5,283,427, which issued to Phillips et al on Feb. 1, 1994, describes a night sight for a missile launcher comprising an image intensifier tube, a reticle, and an objective lens. The missile launcher night sight has an objective lens with a field of view of at least 22 degrees. The output image of the objective lens is intensified by a variable gain light intensifier tube and the output of the intensifier is viewed through an eyepiece. A reticle pattern etched on a glass substrate and filled with titanium dioxide is illuminated by adjustable brightness LED""s positioned at points on the periphery of the substrate. The reticle is disposed between the light intensifier and the eyepiece and substantially duplicates the function of reticles used in daysights.
U.S. Pat. No. 6,160,948, which issued to McGaffigan on Dec. 12, 2000, describes optical light pipes with laser light appearance. A simulated laser light system includes a light source which emits substantially parallel light rays and a prismatic element having a plurality of prismatic surfaces. The prismatic surfaces define a curved surface either on the inside or the outside of the prismatic element. The prismatic surfaces redirect the light rays emitted from the prismatic element in a plurality of plants which are perpendicular to a tangent to the curved surface. The simulated laser light system appears to emit light from a centerline of the prismatic element when the light is actually emitted from an exterior surface of the prismatic element.
U.S. Pat. No. 3,950,645, which issued to Rotstein et al on Apr. 13, 1976, describes an infrared detection tube. An imaging device comprises a cooling means for lowering the temperature of the device, a wafer of preselected infrared sensitive material, a layer of thin infrared transparent electrically conductive material deposited on one side of the wafer, a wire mosaic, the wire mosaic being in intimate contact with the remaining side of the wafer, opaque material filling a preselected area between the wires of the wire mosaic, and a silver paste interposed between the wafer and the tips of the wires of the wire mosaic. The resistance of the infrared sensitive wafer cooperates with a grid current flow and reduces the bias permitting flow of electrons according to infrared radiation impinging on the wafer.
U.S. Pat. No. 3,936,822, which issued to Hirschberg on Feb. 3, 1976, describes a method and apparatus for detecting weapon fire. The method and apparatus disclosed in this patent relates to the automatic detection of the firing of weapons, such as small arms, or the like. Radiant and acoustic energy produced upon occurrence of the firing of the weapon and emanating from the muzzle thereof are detected at known, substantially fixed, distances therefore. Directionally sensitive radiant and acoustic energy transducer means are directed toward the muzzle to receive the radiation and acoustic pressure waves therefrom may be located adjacent each other for convenience.
U.S. Pat. No. 5,018,872, which issued to Suszynski et al on May 28, 1991, describes a probe assembly for an infrared thermometer. The probe assembly is adapted for insertion into a patient""s ear canal and facilitates a rapid measurement of the patient""s body temperature with very high accuracy. The probe assembly includes a plastic outer tube sized to fit snugly in the patient""s ear canal, with an elongated heat sink and an infrared sensor located within the tube.
U.S. Patent No. 6,100,803, which issued to Chang on Aug. 8, 2000, describes an infrared illuminative warning detector. The detector includes a base seat formed with at least four perforations for two light shades and two detector heads to insert in. A bulb in installed in each light shade. An infrared detector is disposed in each detector head for detecting alien article within a detection range and lighting up the bulb. Each light shade and detector head is disposed with at least one shifting mechanism for freely changing operation position. The light shades and the detector heads on the base seat are able to detect in different directions at the same time to provide a warning and illumination function in the case of intrusion of alien article.
U.S. Pat. No. 5,987,205, which issued to Moseley et al on Nov. 16, 1999, describes an infrared energy transmissive member and radiation receiver. The infrared energy transmissive member is used for conducing infrared energy from a first end of the infrared energy transmissive member to a second end disposed adjacent an infrared responsive circuit component of an infrared receiver. The member comprises a flexible hollow plastic tube. Preferably, the plastic tube comprises an ester based polyurethane tube and has a malleable rod disposed in the hollow plastic tube to allow the hollow plastic tube to be bent into a claimed configuration. The infrared responsive circuit component may control a fluorescent lamp dimming circuit or a window treatment control circuit, thereby allowing remote control of the lamp or window treatment.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
A safety device for a marine vessel, made in accordance with the present invention, comprises an electrical device, such as an electrical marine propulsion device, and an infrared sensor having an output signal representing a change in heat intensity within a viewing angle of the infrared sensor. It should be understood that the electrical device can be an electrically driven propulsor, such as a bow thruster for a marine vessel, or any other marine propulsion device that has an electrical element that can be deactivated for the purpose of deactivating the marine propulsion device. As an example, a conventional outboard motor incorporating an ignition system which is electrical is an electrical device within the meaning of the description of the present invention. The outboard motor can be deactivated, for example, by deactivating the ignition system.
The present invention further comprises a tube having a central cavity, the central cavity having a first end and a second end. The infrared sensor is disposed at the first end of the central cavity to receive infrared signals passing along a line of sight defined by the tube in a direction through the central cavity from the second end of the central cavity toward the first end. The viewing angle of the infrared sensor is defined by a length of the tube and a diameter of the tube. The tube is attached to the marine vessel to direct the line of sight in a generally downward direction toward a surface of water proximate the marine vessel to detect a change in heat intensity in a region proximate the surface of water and proximate the marine vessel. A preferred embodiment of the present invention further comprises an alarm circuit that is connected in signal communication with the infrared sensor and an electrical communication with the electrical device. The alarm circuit is configured to deactivate the electrical device in response to receipt of the output signal from the infrared sensor.
The magnitude of the length of the tube in a preferred embodiment of the present invention, is at least three times the magnitude of the diameter of the tube. More specifically, one embodiment of the present invention that has been empirically tested comprises a tube whose length is four times the magnitude of its diameter.
The alarm circuit can have an audible alarm output that is sounded in response to receipt of the output signal from the infrared sensor. The electrical device can be an electric motor with a propulsor attached to an output shaft of the electric motor or, as described above, it can be any marine propulsion device or system that incorporates an electric component that can be affected for the purpose of deactivating the electrical device.
In a particularly preferred embodiment of the present invention, the tube is opaque and the central cavity is circular in cross section. The infrared sensor in a preferred embodiment of the present invention comprises two infrared sensing elements that are associated with each other in a differential arrangement.