Patent Application
20080244970
The present invention relates to an improved apparatus and method for cutting vegetation. More particularly, the present invention relates to an apparatus and method for cutting lawns using laser light.
The vast majority of suburban houses and many urban houses in the United States have yards covered with grass. These grass yards or lawns must be mowed on a regular basis to keep the grass at a desirable height. Furthermore, commercial property, parks, golf courses and other maintained property is often covered with grass. Currently, most lawns and maintained properties are mowed using gasoline or electric powered lawn mowers, riding mowers or lawn tractors which include spinning steel blades. The owner, or someone hired by the owner, either pushes or rides the mowers across the lawn to cut the grass, which is a time consuming process. In addition, the use of gasoline powered lawnmowers uses a significant amount of fossil fuels and releases carbon dioxide and pollutants into the atmosphere.
Recently, lawn mowing devices have been developed which use lasers to cut grass. For example, U.S. Pat. No. 6,269,617 discloses a lawn cutting device in which a lawn tractor or lawn mower is fitted with an apparatus which uses lasers to cut the grass. While this design eliminates the rotating steel blade, it still requires the operator to push or ride the mower across the lawn which is a time consuming process.
U.S. Pat. Nos. 4,952,222 and 6,374,584 also disclose laser devices for cutting grass which include a mower which must be moved across the lawn by a person. In each of these prior art references, significant time and effort must be expended to cut the lawn.
A device is needed which will allow a land owner to automatically and effortlessly cut the grass on a lawn using lasers without having to utilize a lawn mower, riding mower or lawn tractor.
A device is also needed which will allow a land owner to cut the grass in a manner which causes less pollution and uses less energy.
The present invention overcomes the problems associated with prior devices used for cutting lawns. It is no longer necessary to push or ride a lawn mower across the lawn. The present invention utilizes rotating laser light from fixed locations on the lawn to cut the grass.
The laser lawn cutting system of the present invention will consist of an array or grid of laser heads distributed across a lawn. The laser heads may be permanently fixed above the surface of the lawn, or preferably mounted underneath the surface of the lawn and designed to rise up at the time of cutting. If mounted underneath the surface of the lawn, solenoids may be used to move the laser heads above the surface. Other mechanical devices, as would be within the skill of one of ordinary skill in the art to design, could also be used to cause the laser heads to move above the surface of the lawn.
A control box can be programmed to make the laser heads rise up and cut the lawn on a predetermined schedule. In addition or in the alternative, the system could be designed to be switched on and off manually. The laser heads can also be arranged in zones so that each zone is independently controlled by a control box. Both the programming and the arrangement of the laser heads in to zones which are independently controlled can be easily accomplished by one of ordinary skill in the art. Similar control systems are used in the lawn sprinkler art.
Preferably, the laser heads will be distributed across the lawn in a grid or matrix, such that the laser light generated by the rotating laser head sweeps across the lawn in overlapping arcs. Each laser head may rotate up to 360 degrees, or the amount of its rotation may be limited so that the laser light does not extend to objects, such as flowerbeds, trees or other vegetation, in an undesirable manner. In addition, the rotation of the heads can be adjusted so that the laser light does not extend beyond the boundaries of the property on which they are installed.
The laser light need only have enough power such that it cuts through a single or a small number of blades of grass. As the light continues to sweep, multiple sweeps of the same area will gradually cut more blades of grass further from the laser head until the desired range is obtained. In this way, the power of the laser can be held to the lowest possible level consistent with cutting a single blade of grass or a small number of blades at one time. The variability of the surface of the ground requires variable length beams, which are achieved by varying the power level of the lasers. Where the ground surface is uneven, lower power is used to prevent the laser light from scalping the lawn or cutting the grass too high. By localizing the laser light emitted from the laser heads, a more even cut length is possible. Instead of using lower power, a lens system could be used which allows for the adjustment of the length of the laser beam, or its effective range. Alternatively, the laser heads could be replaceable such that a laser head which generates a laser beam of an appropriate length may be selected for the localized requirements on the land area.
It is preferable that the lasers used are solid state, low power, low voltage and direct current, although other types of lasers and power sources are possible. If low voltage direct current is used, the commonly used 12 volt direct current can adequately power the laser heads. The beam created by the laser heads is preferably divergent, so that the intensity of the beam will drop rapidly with distance. The range of the cutting ability of the laser light could be, preferably, up to 12 to 20 feet in diameter, although any distance of cutting range could be used. Semiconductor laser diodes may be used which generate laser beams in the visible or infrared light spectrum.
Preferably, the laser heads will be mounted on a heat sink, which will absorb the heat generated by the laser. The heat can then slowly dissipate into the ground in the long interval before the next use.
To facilitate the safe operation of the system, motion sensors could be used to prevent or stop the generation of the laser beam when the motion sensor senses a predetermined amount of motion within or near the laser grid. With this feature, when an animal or person enters the lawn area covered by the matrix of laser heads, the system will prevent the generation of laser light. The motion detectors should, preferably, cover an area which extends beyond the property lines of the land which has the system installed. This would provide an early warning system that will safely result in laser shutdown before people or animals actually cross the property lines. In addition, rain sensors could be used to prevent the generation of a laser beam when it is raining.
The present invention may also be used to control insects. The laser light generated by the laser heads will be powerful enough to kill small flying insects such as mosquitoes and gnats. These insects frequently are found in the evening and at night flying just above a lawn or above a stationary body of water, such as a small pond. A laser head may be adapted such that it can kill these insects. The laser beam could be elevated a few inches above those used for cutting the lawn. Preferably, the beam of light would be wider and more diffuse than one designed to cut grass. The laser heads used for insect elimination could be combined with the ones for cutting grass or could be part of an independent plurality of laser heads. For example, when used over water, the insect elimination lasers will be used without the vegetation cutting lasers. In addition, the insect killing laser beams could be emitted much higher above the ground than the vegetation cutting lasers so that the laser light can sweep large areas above the land, well above the level of the top of the vegetation.
In another embodiment, the laser heads can be used to melt snow and ice on a surface, such as a driveway, walkway, patio, parking lot or other surface. The laser heads are arranged along the perimeter of a surface, with overlapping coverage. The laser heads can melt the snow as it falls, or after it accumulates on the surface. The resulting water would either drain away or be evaporated. To melt snow and ice, a power level lower than that used to cut grass would be possible. As with the grass cutting application, multiple passes would be used to melt the snow
To melt the snow and ice, the laser heads would be aimed such that a portion of the beam is directed downward, to sweep the surface itself which would keep the water from re-freezing.
When electrical current is sent from the power supply 34 to the solenoid 26, it is energized and the pin 24 moves upward. The laser 14 is energized and is caused to rotate by the motor 28 through shaft 30.
As shown in
