Geometrical instruments – Straight-line light ray type – Alignment device
Reexamination Certificate
1999-07-19
2001-03-06
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Straight-line light ray type
Alignment device
C033S290000
Reexamination Certificate
active
06195901
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to laser beam projectors, and more particularly to a method and device for controlling and delivering power to a laser and communicating information from said laser to a remotely positioned sensor assembly. The invention has particular application for making measurements as well as machine control, such as with earth moving and construction equipment
A common use of laser beam projectors in the construction industry is for ensuring that a trench or surface is of the proper and constant depth. The laser beam projector is placed at a fixed, known height, and an array of sensors senses the impingement of the laser beam. Depending on which sensors are impinged, the height of the receiver equipment relative to the laser beam projector can be determined.
While laser beam projectors come in a variety of different forms, this invention relates primarily to laser beam projectors which are capable of rotating. When the projector is in a rotation mode, the sensors in the sensor assembly do not continuously detect the laser beam, but rather only detect the laser beam for a brief instant when the rotating laser beam sweeps past the sensors. Rotating the laser beam, instead of keeping it constantly pointed in one direction, enables the sensors to move laterally with respect to the projector without the need for realignment of the laser beam projector with respect to the sensors. Because the rotating laser beam only impinges the sensors for a brief instant, the power of the signal detected by the sensors is much less than if the beam were not rotating, but instead continuously pointed at the sensors. The reduction in power of the detected signals makes it more difficult for the sensors to detect the signal and to filter the signal out from other radiation sources detected by the sensors, such as ambient sunlight. The distance from the projector which the sensor can effectively operate is therefore reduced when the laser beam is rotated.
In certain applications, the distance between the laser beam projector and the sensor may be quite large, which may lead to additional difficulties besides the relative weakness of the signal detected by the sensor. One difficulty relates to the requirement of keeping the laser beam level. If the laser beam is not level, the sensor will yield a height measurement that has an error component which increases with increasing distance from the laser. The height error may not be acceptable for various applications. One mechanism for eliminating the condition of a non-level laser beam projector is to mount the laser on a gimbal which allows the laser to generally swing freely so that the laser beam assumes a true vertical orientation. Providing power to the gimbaled laser, however, often hinders its free movement. In the past, to overcome the hindrance of the power feed mechanism to the free movement of the laser has typically required complex and expensive designs of the power feed mechanism.
Large distances between the laser beam projector and the sensor assembly may also make it difficult for people working near the sensor to know the status of the laser beam projector. For example, if the projector is bumped or otherwise knocked from its level position, this fact may not be readily apparent to people in the vicinity of the sensor if the projector is far away. An off level projector leads to the problems discussed above. Other conditions of the projector may also be important to know for those working away from the projector.
In light of the foregoing, a need can be seen for a laser which overcomes the difficulties associated with a laser beam projector stationed a large distance from the sensor unit.
SUMMARY OF THE INVENTION
The present invention is intended to provide a rotating laser beam projector and related methods which overcome the difficulties in the prior art. According to one aspect of the present invention, a laser beam projector includes a power controller having a microcontroller coupled to a laser power circuit. The microcontroller determines whether the laser beam emitted by the projector is rotating or stationary and controls the laser power circuit. When the laser beam is rotating, the laser power circuit delivers a first level of continuous power to the laser. When the laser beam is stationary, the laser power circuit delivers a second level of continuous power to the laser which is less than the first level of power.
According to another aspect of the present invention, a laser beam projector includes a bridge for delivering electrical power to a pendulum-supported device from a stationary source. A first conductor is affixed to the stationary source and a second conductor is electrically coupled to the pendulum supported device. At least one wire is bonded, such as by ball-and-stitch bonding, from the first conductor to the second conductor across a gap defined therebetween. The pendulum supported device may be a laser.
Another aspect of the present invention includes a method of communicating messages from a laser beam projector to a remotely positioned sensor assembly. The method includes the steps of rotating the laser beam emitted by the projector at a first speed when no message is to be communicated and rotating the laser beam at a second speed different from the first speed when a message is to be communicated. The emitted laser beam is detected at a remote sensor assembly which measures the frequency of detection of the laser beam. The measured frequency of detection is interpreted as receipt of the message when the frequency of detection is substantially equal to the second rotation speed of the laser beam.
The present invention overcomes the difficulties associated with operating the laser beam projectors and the sensor assembly with a large distance separation. The laser beam projector power controller overcomes the problem of a reduction in the usable operating distance of the laser beam projector when it is rotating. The laser beam projector power controller accomplishes this without having to reclassify the laser to a different power rating. The classification of a laser which is rotating will be different from the classification of a stationary laser because the stationary laser's power will be more concentrated. By altering the power delivered to the laser based on its state of rotation or non-rotation, the laser beam projector power controller delivers the maximum power to the laser at all times without the laser being reclassified to a higher power rating. The additional safety precautions which must be taken for a higher classification of laser can therefore be avoided without any concomitant loss in the safety of the projector.
The ability to alter the speed of rotation of the laser beam projector further facilitates a large spacing between the projector and sensor by allowing the projector to communicate messages to the sensor. People working in the vicinity of the sensor can therefore be more effectively informed of important status conditions of the projector, such as an off-level or low battery condition.
The bridge alleviates the difficulty of providing power to the laser without interfering with the leveling of the laser. The problems associated with an off-level controller are thus overcome in a simple and efficient fashion. These and other benefits, results, and objects of the present invention will be apparent to one skilled in the art, in light of the following specification when read in conjunction with the accompanying drawings.
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patent
Fulton Christopher W.
Laser Alignment, Inc.
Van Dyke Gardner, Linn & Burkhart, LLP
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