Geometrical instruments – Straight-line light ray type – Alignment device
Reexamination Certificate
2002-06-21
2004-07-20
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Straight-line light ray type
Alignment device
C033S290000, C033SDIG002, C033S291000
Reexamination Certificate
active
06763595
ABSTRACT:
TECHNICAL FIELD
This invention relates to laser alignment devices.
BACKGROUND
Portable devices capable of indicating level, plumb and square alignment have been useful in the construction and carpentry trades for some time. The advent of laser technology has seen the use of portable laser emitting devices capable indicating level and plumb, as well as level, plumb and square alignments simultaneously. Such devices typically require some sort of tilt-compensation mechanism or self-leveling mechanism, to avoid the introduction of error when operated from a non-level surface. However, even with a tilt-compensation or self-leveling mechanism, such tools typically can only accurately indicate level and plumb within a range of inclinations of the tool relative to level. To avoid a user inadvertently relying on an erroneous indication of alignment, some tools provide an indication to the user, when the user is attempting to use the tool outside of a predefined range of inclinations, for example, by ceasing projection of alignment beams or causing the alignment beams to blink. Although level and plumb alignments may be inaccurate when the tool is inclined beyond a certain range, it may still be possible to achieve an accurate square alignment using the laser beams.
In some prior art tools, alignment is indicated with beams that form points of light or “spots” on a surface against which they are projected. In some prior art tools, an invisible “line” can be imagined between two or more opposing and aligned spots to provide an alignment line. Other tools indicated alignment with beams that form the image of a straight line on the surface against which they are projected, that is, they project linear alignment beams.
SUMMARY
The present invention provides apparatus and a method for projecting alignment lines. In general, in one aspect, the invention features an apparatus for projecting an indication of alignment, including a housing, a projection unit pendulously suspended in the housing to project output beams to indicate level, plumb and square and a damper to dampen pendular motion of the projection means. The apparatus further includes an error indicator to indicate when the housing is inclined such that the accuracy of the level and plumb directions are compromised, and an override to deactivate the error indicator, whereby the output beams can be used at least to indicate square.
Implementations of the invention may include one or more of the following. The projection unit can include at least one laser diode to emit a laser beam, a first and a second collimator to form a first and a second collimated beam, and a first and a second optical element to convert the first and second collimated beam into a first and a second linear output beam. The first and second linear output beams are projected from the housing in different but generally perpendicularly related directions, and can be used to indicate level, plumb and square alignment.
The error indicator can suspend projection of the output beams from the projection unit. The error indicator can indicate that the housing is inclined such that the accuracy of the level and plumb directions are compromised, when the housing is inclined in any direction in the range of approximately plus or minus 4 to 9 degrees from horizontal. In another implementation, the error indicator can indicate the housing is inclined such that the accuracy of the level and plumb directions are compromised, when the housing is inclined in any direction more than approximately 9 degrees from horizontal. The override can include digital circuitry to deactivate the error indicator in response to a user input.
Each collimator can include a focus lens, and in one embodiment each focus lens can be an aspheric lens. Each optical element can include a rod lens, or alternatively a cylinder lens. The damper can include a magnet mounted in the housing below the projection unit and a damping plate rigidly suspended from the projection unit, such that the damping plate is positioned above the magnet with a gap maintained therebetween sufficiently small that eddy currents are generated in the damping plate by motion thereof above the magnet. The apparatus can further include at least one battery to provide power to at least one laser diode of the projection unit.
A user interface configured to receive a user input can also be included in the apparatus. In response to a first user input, the projection unit can project a first output beam that can be used to indicate level. In response to a second user input, the projection unit can project a second output beam having a generally perpendicular relationship to the first output beam, whereby the second output beam can be used indicate plumb. In response to a third user input, the projection unit can project simultaneously the first and second output beams, whereby together the output beams can be used to indicate simultaneously level, plumb and square. In response to a fourth user input, the override can be employed to deactivate the error indicator, and the projection unit can project simultaneously the first and second output beams, whereby the output beams together can be used to at least indicate square.
In general, in another aspect, the invention features an apparatus for projecting an indication of alignment including a housing and a projection unit pendulously suspended in the housing to project linear output beams. The projection unit includes two laser diodes configured and arranged to emit two laser beams, two collimators configured and arranged to form the two laser beams into a first and second collimated beam, and an optical element configured and arranged to convert the first and second collimated beams into a first and a second linear output beam. The first and second linear output beams are projected from the housing in different but generally perpendicularly related directions, and can be used to simultaneously indicate level, plumb and square. The optical element includes a first and second lens to convert the first and second collimated beams into the first and second linear output beams, and a mount to mount the first and second lens to the projection unit.
For each lens, the mount includes a member in which the lens can be mounted and a base. The member also includes openings through which connectors can be positioned. The openings allow the member to be laterally displaced once the connectors are in position, to align the lens such that the linear output beam is symmetrically projected from the housing. The base is configured to attach to the member by the connectors. At least one connector includes a longitudinal adjustment mechanism to adjust the position of the lens such that the output beam is substantially straight. The base is mounted onto a support protruding from the projection unit and rotatable about the support to achieve true vertical in relation to the projection unit for the first lens and true horizontal in relation to the projection unit for the second lens.
The apparatus further includes a damper configured and arranged to dampen pendular motion of the projection unit.
Implementations of the invention may include one or more of the following. An error indicator can be configured and arranged to indicate when the housing is inclined such that the accuracy of the level and plumb directions are compromised. An override device can be configured and arranged to deactivate the error indicator, so that the output beams can be used as alignment lines to at least indicate square directions.
The error indicator can suspend projection of the linear output beams from the projection unit. The error indicator can indicate the housing is inclined such that the accuracy of the level and plumb directions are compromised, when the housing is inclined in any direction in the range of approximately plus or minus 4 to 9 degrees from horizontal. In another embodiment, the error indicator can indicate the housing is inclined such that the accuracy of the level and plumb directions are compromised, when the ho
Fish & Richardson P.C.
Fulton Christopher W.
Hoolahan Amanda J
PLS - Pacific Laser Systems
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