Patent Publication Number: US-6713750-B2

Title: Visible light forklift alignment apparatus

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of systems and devices used to align or provide an indication to the operator of the location of the forks on a forklift relative to the access openings in a pallet or the like, such that the operator knows when the forks are at the correct height for entry into the access openings. More particularly, the invention relates to such systems which utilize visible light means to provide a visual indicator to the forklift operator. 
     Forklifts or similar load handling equipment are designed to handle pallets and the like by inserting a pair of forks or tines into access openings provided between opposing deck members or the pallet legs for a single deck pallet. The forks are mounted in parallel on a carriage which can be raised or lowered vertically, and usually also tilted slightly, with the forks extending typically a distance four feet forward from the carriage. The front of each fork is tapered or beveled to allow for a small margin of error during the insertion process. Because it is usually desirable to minimize the amount of floor space taken up by stored goods, warehouses are provided with high ceilings and forklifts are designed to raise loads many feet off the ground such that multiple pallets can be stored in a vertical column. Thus, even though the operator is seated on the forklift itself and is therefore a few feet above ground level, the load may need to be deposited onto or retrieved from a stack, rack or shelf many feet above the operator&#39;s head. Because of this, the operator cannot easily determine if the forks are at the optimum height prior to advancing forward to retrieve or deposit the load onto the stack, rack or shelf. Adding to the is problem is the fact that the load itself may block the operator&#39;s line of sight. Thus operators are forced to estimate the correct height of the forks, then slowly advance the forks forward to determine, either by striking the shelf or rack when depositing, or by striking the shelf, rack, pallet or the load itself when retrieving, that the forks are misaligned. This technique can result in damage to the pallets or loads and to the shelves or racks. 
     There have been attempts made to address the problem of fork misalignment, for instance by providing visual indicators or intelligent alignment systems. For example, Ohntrup et al. in U.S. Pat. No. 3,672,470, issued on Jun. 27, 1972, teaches the use of a photoelectric system wherein a light source and a light sensor is mounted onto the fork. The sensor is designed to detect the difference in reflected light from a solid object versus reflected light from the access openings in the pallet, such that when the latter is detected a visible light indicator is turned on for the operator to indicate that the forks are properly aligned. This system is susceptible to false readings due to ambient light conditions, since strong or weak warehouse illumination may alter the sensitivity of the sensor. Furthermore, Ohntrup et al. teaches mounting the light source and light sensor within or onto the fork itself, which is undesirable in that the light source and light sensor can be easily damaged form routine use of the forklift. An example of a visible light system is taught by Hansen in U.S. Pat. No. 3,854,820, issued Dec. 17, 1974, where a light source capable of producing a collimated beam of light is mounted laterally onto each side of the forklift carriage, with the light beam projected through prisms to produce a fan-shaped or diverging plane of light. As with the Ohntrup et al. device, the exposed mounting of the light source leaves it susceptible to damage. Another drawback to the Hansen device is that the visual indicators are located to the outside of each fork, such that only a small amount if any of the light falls onto the actual pallet to be removed, with most of the light striking the shelving or pallets to either side of the target pallet. Thus the operator is forced to interpret the visual information and must check the visual indicators to both sides of the forks to determine if they are properly aligned. Complicated forklift alignment systems using cameras and microprocessors are shown in U.S. Pat. No. 4,279,328, issued Jul. 21, 1981 to Ahlbom, and in U.S. Pat. No. 5,208,753, issued May 4, 1993 to Acuff. 
     It is an object of this invention to provide a relatively simple system for assuring proper alignment of forklift forks, where a visible light indicator is provided to the operator, the light indicator being a focused dot or other shape produced by a controlled beam striking an opaque object. It is a further object to provide such a system where the light source is mounted in a manner which makes it less susceptible to accidental damage. It is a further object to provide such a system where the visible light indicator is a visible laser beam which is preferably centrally oriented relative to the forks. It is a further object to provide such a system which incorporates various safety features to minimize or eliminate possible damage to people from inadvertent exposure to the beam from the light source, and in particular a laser beam, by incorporating vibration-responsive, height-responsive and distance-to-load-responsive actuation means. It is a further object to provide such a system which incorporates various safety features to minimize or eliminate possible damage to the system itself, such as from excessively high or low ambient temperatures, by incorporating temperature-responsive actuation means. 
     SUMMARY OF THE INVENTION 
     The invention is in general an apparatus, device or system for providing a visual indication to a forklift operator of proper vertical alignment of the forks or tines of the forklift relative to the access openings designed to receive the forks of a pallet or like device for supporting a load, which may consist of a single or multiple objects, boxes or the like, even where the proper alignment occurs many feet above the operator&#39;s head. The system comprises in general means to produce a relatively focused or controlled beam of visible light, preferably produced by a laser, where the beam is forwardly directly between the forks in a generally horizontal plane common to the forks themselves, such that the height of the forks is indicated by the height and location of the visible indicator, a dot or the like, produced by the beam when it strikes an object, such as a pallet, shelf or rack, or the load on the pallet, or by it disappearing into the void created by the pallet access opening. By raising or lowering the fork carriage such that the light beam strikes the middle support or a midpoint in the central leg of a single-deck member pallet, or by observing when the light indicator or spot produced by the beam disappears as it is directed into the access opening of the pallet, the operator is provided a visual indication that the forks are properly oriented relative to the pallet. Conversely, if the spot produced by the beam appears on the load, the shelf or the upper or lower portion of the pallet, the operator knows that the forks are improperly aligned and can raise or lower them accordingly before moving forward to insert the forks into the pallet. 
     The apparatus is mounted onto the carriage to which the forks are mounted in a manner such that the beam is emitted at a height equal to the vertical midpoint of the forks and at some point between the forks, preferably at the lateral midpoint between the forks, whereby the apparatus itself is raised or lowered correspondingly with the forks. The forward extension of the apparatus is minimized such that it does not extend forward beyond the vertical brace stop members, where the combination of the vertical brace stop members and the forks themselves are relatively L-shaped, or beyond the forward side of the carriage where the carriage itself acts as the vertical component limiting load movement in the rearward horizontal direction. Preferably, the apparatus comprises a vertically elongated battery housing containing one or more rechargeable batteries with a laser housing containing the laser producing components affixed to the bottom of the battery housing. Brackets are joined at the upper and lower ends of the battery housing for securing the apparatus by mechanical fasteners to the carriage of the fork lift. 
     Preferably, the apparatus is equipped with one or more safety features to reduce or prevent danger to personnel and to the beam producing means. The apparatus may comprise vibration-responsive actuation means, whereby the beam producing means is not operational unless the forklift is in motion or vibrations from the forklift motor are sensed. The apparatus may comprise height-responsive actuation means, whereby the beam producing means is not operational unless the apparatus is raised above a predetermined minimal distance from the floor. The apparatus may comprise distance-to-load-responsive actuation means, whereby the beam producing means is not operational unless the apparatus is closer than a predetermined maximum distance from the load, or within a predetermined maximum and minimum distance from the load. The apparatus may comprise temperature-responsive actuation means, whereby the beam producing means is only operational at temperatures below a predetermined maximum temperature, at temperatures above a predetermined minimum temperature, or within the range between the maximum and minimum temperatures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of an embodiment of the apparatus. 
     FIG. 2 is a front view of the same embodiment of the apparatus, with a portion partially exposed to reveal the battery. 
     FIG. 3 is an exposed side view of the light beam emitting means, also illustrating the vibration-responsive actuation means, the height-responsive actuation means, the load-to-distance-responsive actuation means and the temperature-responsive actuation means. 
     FIG. 4 is a perspective view of the apparatus shown as mounted onto the carriage of a forklift. 
     FIG. 5 is a representative side view showing the elevated forks properly aligned with a pallet. 
     FIG. 6 is a partial side view of an alternative embodiment of the apparatus, illustrating a vertically adjustable bracket member. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the drawings, the invention will now be described in detail with regard for the best mode and the preferred embodiment. In general, the invention is an apparatus adapted to be mounted onto the forklift carriage of a forklift such that a relatively focused beam of light is projected forward between the forks to provide a generally concise visual indication to the operator of the exact vertical position of the forks. 
     As shown in FIGS. 1,  2  and  4 , the invention comprises a light beam emitting means  10  which is mounted onto the carriage  98  of a forklift or similar piece of equipment, the carriage  98  being the vertically movable panel member or cross beams onto which the forks  99  are mounted. The forks  99  extend forward in a parallel configuration, and are adapted to fit into the access openings of a pallet  101  designed to carry a load  102 . With the forks  99  inserted into the pallet  101 , the pallet  101  can be raised from a shelf or stack for transport. The forks  99  are inserted by raising or lowering the carriage  98  to the proper height relative to the pallet  101  and then advancing the forklift forward. The forks  99  fit between the legs of a single deck pallet or between the upper and lower deck members of the two deck pallet. The forks  99  are typically L-shaped, each with a horizontal forward-extending member  97  and vertical load stop member  96 , or a portion of the carriage  98  itself may act as the load stop member. Such constructions for forklifts are well known in the industry. 
     The light beam emitting means  10  may comprise any suitable apparatus for producing a collimated or focused beam of light  100  in the visible spectrum, such as standard light bulbs or LED&#39;s in combination with focusing lenses or mirrors, but is preferably comprised of a laser module  11  which produces a controlled light beam  100  in a manner such that the beam  100  results in the appearance of a dot or similar controlled shape on any opaque object in the path of the light beam  100 . For example, laser modules  11  containing a diode and focusing lens arrangement producing a beam  100  with wavelength between 670 to 635 nm are suitable, the laser module  11  creating a visible red dot when an object is struck. Other colors may be produced used different wavelength ranges. Such laser modules  11  are well known in the industry. The laser module  11  is mounted within a laser housing  21 , such as a generally rectangular plastic or metal box, which is positioned such that the beam  100  is emitted horizontally on the same plane containing the vertical midline of the forks  99 , and most preferably centrally between the two forks  99  such that the beam  100  indicates the midpoint between the forks  99 . The laser housing  12  is most preferably mounted onto the carriage  98  such that it does not extend in the forward direction beyond the forward side of the vertical load stop members  96  or the forward side of the carriage  98  where it is the load stop. In this manner the forward side of the laser housing  12  does not contact the pallet  101  even when the forks  99  are fully inserted into the pallet  101 , thereby protecting the laser module  11  and other components from damage. 
     The laser housing  12  may be adjoined to the bottom of a battery housing  21  which is adapted to contain a battery  22  for powering the laser beam emitting means  10 , with the battery  22  preferably being a rechargeable battery of a type well known in the industry, such as a rechargeable nickel metal hydride battery having an average life of 40 hours before recharging. The battery housing  21  as shown is a generally elongated rectangular member to which is attached mounting means  30  for connecting the apparatus to the forklift carriage  98 . Preferably, the battery housing is less than 1.5 inches deep, as most fork vertical load stop members  96  are at least 1.5 inches deep. As shown in FIGS. 1 and 2, the mounting means  30  may comprise an upper bracket member  31  adapted to receive a mechanical fastener  34 , such as a threaded bolt, and a lower bracket member  32  having a hook-like configuration which can be abutted against the underside of the carriage  98 , with the length of the battery housing  21  determined by the vertical dimension of the carriage  98 . Alternatively, the mounting means  30  may comprise an adjustable bracket member  33  mounted to the back of the battery housing  21 , where the adjustable bracket member  33  has adjustment means such as a vertical slot adapted to receive a mechanical fastener  34 , where the position of the adjustable bracket member  33  relative to the battery housing  21  may be changed to accommodate different carriage  98  vertical dimensions, as shown in FIG.  6 . 
     With the laser module  11  properly aligned with the forks  99 , the projected light beam  100  provides a visual indicator to the forklift operator of the height of the forks  99  relative to the object upon which the beam  100  impinges. As shown in FIG. 5, with the forks  99  at the correct height, a centrally mounted beam  100  will either strike the center leg or support of a pallet  101 , or where no center leg or support is present will disappear into the access opening of the pallet  101 , thereby indicating to the operator that the forks  99  are correctly positioned for insertion. Conversely, if the forks  99  are not at the proper height, the light beam  100  will impinge on the upper or lower deck members of the pallet  101 , or on the load  102  or a shelf or support rack. The position of the visible dot on these objects indicates to the operator whether the forks  99  need to be raised or lowered. 
     In the preferred embodiment of the invention, the apparatus is provided with one or more actuation means  40 ,  50 ,  60  and  70  to control the operational state of the laser module  11  at any given moment, as shown representationally in FIG.  3 . The purpose of these actuation means  40 ,  50 ,  60 ,  70  is to prolong battery life, to provide a safety margin to persons in the vicinity of the apparatus, and to preclude damage to the laser module  11  from operation in excessively high ambient temperatures. To this end, one or more actuation means  40 ,  50 ,  60 ,  70  are provided in circuit between the battery  22  and the laser module  11  through connector wires  23 , in known manner to act as switches to either enable or prevent completion of the electrical circuit. 
     Vibration-responsive actuation means  40  is a switch of a type known in the industry which provides for an open circuit only when sufficient vibration is sensed, such as from the operation or the forklift motor or movement of the forklift. When there are no or insufficient vibrations sensed, the circuit is closed and the laser module  11  will not operate. This precludes the need for an actuation switch or button which must be manually activated and deactivated, thereby saving battery life and ensuring that the laser beam  100  is produced only when the forklift is operational. Height-responsive actuation means  50  is a switch of a type known in the industry, such as for example a photosensor or sonar range finding system, which provides for an open circuit only when the laser module  11  is raised a predetermined minimal distance from the ground. This not only saves battery life, but also prevents accidental aiming of the beam  100  into a person&#39;s eyes. Thus for example, the minimum height for actuation could be set at seven feet, such that the laser module  11  is nonoperational at any lower height. Distance-to-load-responsive actuation means  70  is a switch of known type in the industry, which may be similar in operation to the height-responsive actuation means  50 , which provides for an open circuit only when the laser module  11  is positioned closer than a maximum distance from the load  101  or pallet  100 , or within a predetermined maximum and minimum distance range. Thus for example, the maximum distance may be set at ten feet, such that the laser module is inoperable until the laser module is less than this distance from the load  101 , and the minimum distance may be set at one foot, such that the laser module  11  turns off when the forks  99  are inserted into the pallet  101 . Temperature-responsive actuation means  60  is a switch of a type known in the industry, such as a thermostat, which provides for an open circuit only when the ambient temperature is below a predetermined maximum temperature, above a predetermined minimum temperature, or within the range between a predetermined maximum temperature and a predetermined minium temperature. Operation of laser modules  11  in high temperature conditions or low temperature conditions can be detrimental to the laser module  11 , so the maximum temperature may be set at 45 degrees C., for example, such that the laser module  11  will only operate at temperatures below this setting, and the minimal temperature may be set at 0 degrees C., for example, such that the laser module  11  will operate only at temperatures above this setting. Any or all of these actuation means  40 ,  50 ,  60 ,  70  may be incorporated into the invention, along with time delay circuits such that the actuation or non-actuation is not immediate when one of the conditions is encountered. 
     It is understood that certain equivalents and substitutions for elements set forth above may be obvious to those skilled in the art, and thus the true scope and definition of the invention is to be as set forth in the following claims.