The present invention relates to measurement systems for power tools, and more specifically, to digital measurement systems for a tool such as, for example, a miter saw.
Miter saws are typically used for cutting workpieces. To calculate the length of the workpiece to be cut, a user typically uses a conventional tape measure or a ruler to mark the workpiece at the desired cutting length. The user then places the workpiece on the miter saw and aligns the marking line on the workpiece with the cutting blade. The user begins the cutting process once the marking line and cutting blade are aligned. The miter saw is powered on and the workpiece is cut. The user may then repeat the process by powering off the miter saw and manually measuring and marking the workpiece, or another workpiece, and aligning the marking line on the workpiece with the cutting blade.
The measuring process, as one might see, is time consuming and tedious. Miter saws may be used in the construction of large structures such as houses and buildings. A user in such a context is required to cut a large quantity of material, most with varying lengths. However, with the current way of measuring the workpiece, the user is severely limited in the number of workpieces that can be cut within a particular timeframe.
Miter saws may also be used for small wood working projects, such as constructing furniture or picture frames. In such a context, the dimensions of the workpiece must be extremely accurate. However, a user in this context typically does not have the level of skill required to manually measure, align, and cut a workpiece at consistent level of accuracy. As a result, the user often spends additional, and unnecessary, time re-cutting or re-measuring the workpiece, to achieve the desired level of accuracy.
These and other problems are addressed by the present invention, as summarized below.
According to one embodiment of the present invention, the measurement device is coupled with a power tool comprising a rotatable member about an axis, where a shaft is coupled with the rotatable member along the axis. A disk is coupled to a first end of the shaft, and a detecting device is disposed adjacent to the disk, wherein the detecting device provides an output as the disk rotates.
According to another embodiment of the present invention, the measurement device is coupled with a power tool and comprises a roller rotatable about an axis, where a shaft is fixably coupled with the roller along the axis. The shaft has a first end and a second end, where the first end is coupled with a disk. A mounting bracket is coupled with the first end and the second end of the shaft, where the mounting bracket further comprises a first portion and a second portion, where the first portion is reciprocably coupled with the second portion. A detecting device is coupled with the first portion of the mounting bracket and disposed adjacent to the disk, wherein the detecting device provides an output as a portion of a workpiece actuates the disk of the detecting device.
According to another embodiment of the present invention, the measurement device is coupled with a power tool and comprises a roller rotatable about an axis with a shaft fixably coupled with the roller along the axis. The shaft has a first end and a second end, where a disk is coupled with the first end of the shaft. The disk has at least one aperture and in one aspect has a plurality of spaced apertures formed therein that are disposed around a circumference of the disk. In another aspect, the apertures are evenly spaced from each other. A mounting bracket is coupled to the shaft. The mounting bracket has a first portion and a second portion coupled together by a biasing member. The first portion is also coupled with the first end and the second end of the shaft. A detecting device is coupled with the first portion of the mounting bracket, where the detecting device further comprises at least one light emitting source and at least one sensor, with the disk disposed therebetween. The detecting device generates an electrical pulse each time the at least one aperture passes between the detecting device as the disk is rotated by a workpiece.
According to another aspect of the present invention, the measurement device is coupled with a power tool and comprises a housing that is coupled with a digital display system. Disposed in the housing is a roll tape and a detecting device, where the detecting device generates an electrical signal as the roll tape is displaced by a workpiece.
According to another aspect of the present invention, the measurement device is coupled with a power tool and comprises a housing disposed on a fence coupled with a digital display system. A roll tape, with a series of spaced apertures, and a detecting device are disposed in the housing. In one aspect, the apertures are evenly spaced from each other. The detecting device comprises at least one light emitting source and at least one sensor with at least a portion of the roll tape disposed therebetween. When the roll tape is displaced by a workpiece, such that an aperture passes between the detecting device, an electrical pulse is generated and transmitted to the display system.
The invention is described with reference to the drawings in which like elements are referred to by like numerals. The relationship and function of the various elements of this invention are better understood by the following description. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. The embodiments described below are by way of example only, and the invention is not limited to the embodiments illustrated in the drawings.
Turning now to the drawings and referring to
In one embodiment of the digital measurement system, a measurement device 20 and a digital display 22 are coupled with the tool. Desirably, one embodiment of measurement device 20 is coupled with the fence while the digital display 22 may be conveniently located on a portion of the miter saw 10 for viewing by the user. The measurement device 20, as illustrated in
A disk 38 is axially fixed adjacent the first end 34 of the shaft 32 with a fastener 40. It can be appreciated that the disk 38 may have, for example, a rectangular, square, or a triangular shape. As shown in
Referring back to
As illustrated in
Furthermore, the detecting device 44 and the disk 38 may be coupled below the rotatable member 24, as shown in
In this embodiment, the second portion 54 of the mounting bracket 50 is fixedly coupled with the fence 18 of the miter saw 10. The first portion 52 of the base 50 is orientated and adjusted with respect to the second portion 54 of the base such that a portion of the rotatable member 24 extends beyond the fence 18, such as to contact a workpiece 30, if present. The position of the measurement device 20 may be moved relative to the fence 18. For example, the measurement device 20 may be moved to a position closer to the saw blade 16 along the fence 18.
In another embodiment of the digital measurement system, the measurement device 20 is coupled with the base 12 of the miter saw 10, as illustrated in
In operation, a user selects to cut a desired workpiece 30 to a certain length “L.” The user places the workpiece 30 in a position adjacent to the fence 18 of the miter saw 10. The force of the workpiece 30, indicated as “F” in
In either embodiment, the rotation of the rotatable member 24 is translated to the disk 38 via the shaft 32. As the disk 38 rotates, the apertures 42 of the disk 38 similarly rotate. As an aperture 42 passes between the detecting device 44, the sensor 48 detects the light produced from the light emitting source 46 that passes through the aligned aperture 42. Each time the sensor 48 detects the light, the sensor 48 generates and sends a signal to the digital display 22. The digital display 22 calculates the distance traveled by the workpiece 30 with respect to the rotatable member 24. This process is repeated each time an aperture 42 comes into alignment with the light emitting source 46 and the sensor 48. The apertures 42 are spaced from each other and, desirably, are equally spaced from each other. As will be appreciated from the description below, the arc or distance between the adjacent apertures 42 may affect the numerical significance of the display. For example, a greater number of apertures 42 may result in a smaller distance between adjacent apertures 42. Accordingly, the numerical significance will increase as compared to a lesser number of apertures 42.
Accordingly, one equation to calculate the distance traveled, LT, for a disk 38 having N number of apertures 42, and with a rotatable member 24 with a radius of R is:
where T is the number of times the sensor 48 detected an aperture 42 that passed through the detecting device 44 and y is the offset between the saw blade 16 and the outer diameter of the rotatable member 24, In the alternative, T may represent the number of times the sensor disposed on the disk 38 detects the light emitted from the light emitting source 46 or the number of times the light is reflected from a reflector disposed on the disk 38 is detected by a sensor. The offset, y, will either be added to the length of travel or subtracted, depending from which direction the workpiece 30 is traveling.
Once the distance traveled LT, is equal to the desired length, L, the user may then power on the miter saw 10 and cut the workpiece 30. A visual or audible indicator may provide a signal to the user once the workpiece is in a position where its length, LT, is equal to L. The digital display system 22 would allow for the input of the desired length, L, and once reached, the display screen of the display system 22 provide a visual indication such as flashing or changing to a different color or any other suitable visual indication. Alternatively, a buzzer, chime, or other auditory indicator may be activated to alert the user once the desired length, L, has been reached.
Once the workpiece 30 is cut into a desired length, L, the user may reset the digital display 22 and continue to measure a second workpiece to a desired length. Once LT, is equal to L, which may or may not be the same length as the first workpiece, the user may then cut the workpiece 30. These steps may be repeated and it is not necessary for the user to reset the digital display 22 each time. The digital display 22 may be designed to display the distance traveled LT, in U.S. or metric units, and may have other capabilities, such as calculating the total length cut with a price per linear foot calculation.
In yet another embodiment of the digital measurement system and the measurement device 20, as illustrated in
In operation, and similar to the first two embodiments of the measurement device 20, a workpiece 30 is placed adjacent to the fence 18 of the miter saw 10 and the stopper 76 of the tape measurement device 62. The digital display 22 is reset and the workpiece 30 is moved along the fence 18. The movement of the workpiece 30 also extends the stopper 76 that is coupled with the tape 72. As the tape 72 passes between the detecting device 44, the sensor 48 sends a signal to the digital display 22 each time the sensor 48 detects a light from the light emitting source 46. The digital display 22 records the number of signals sent by the sensor 48 and converts the signals into a linear length traveled by the workpiece 30, using an equation similar to the equation described above. An example of one equation would be:
L
T=((N−1)*D−y),
where N is the number of apertures detected, D is the distance between apertures, and y is the offset value. As described with respect to the first and second embodiments, once a desired length is achieved, a user may power on the miter saw 10 and cut the workpiece 30. This process may be repeated with different desired lengths and may not be necessary to power off the miter saw 10 between the cuts.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated by the appended claims.