Sensor component stabilization

This application claims the benefit of U.S. Provisional Application Ser. No. 61/963,249, filed Nov. 26, 2013, the content of which provisional application is incorporated herein by reference.

The present disclosure relates to alignment of a sensor component, such as a transmitter, within a sensor housing. In certain conventional sensors of type having adjustable emitters, the emitters have barrels disposed in matching sockets, allowing the direction in which the emitters are pointed to be varied. The barrel of the emitter is typically held in place by screws balanced by springs only. Glue is used to maintain the alignment after the alignment adjustment is done. However, it has been observed that the alignment can undergo significant drift as the ambient temperature changes. It is thus desirable to device a sensor assembly and method to allow convenient adjustment of the emitter, or another adjustable component while maintaining the stability of the sensor.

In one example aspect of this disclosure, a method for stabilizing a sensor component includes: positioning a portion of the sensor component relative to a support with a plurality of retaining members in contact with the portion of the sensor component, the plurality of retaining members including at least a first one of the retaining members being a resilient biasing member and a second one of the retaining members being an adjustable retaining member; adjusting the adjustable retaining member to reposition the portion of the sensor component relative to the support and deform the resilient retaining member; immobilizing the portion of the sensor component relative to the support with an additional, rigid retaining member in contact with the portion of the sensor component; and filling a space between the portion of the sensor component and the support with a glue.

FIG. 1 illustrates a sensor according to an aspect of the present disclosure.

FIG. 2 illustrates another view of the sensor shown in FIG. 1 , with mounting assembly visible.

FIG. 3 is a more detailed view of the mounting assembly shown in FIG. 2 .

FIG. 4 is another view of the mounting assembly shown in FIG. 1 , with certain parts removed from the view to more clearly show the various retaining members for securing the barrel of the emitter.

FIG. 5 illustrates an emitter as an example of an adjustable component in a sensor according to an aspect of this disclosure.

FIG. 6 illustrates a portion of the body of the sensor shown in FIG. 1 , showing a cavity in the body for receiving the emitter.

FIG. 7 illustrates a view of the sensor shown in FIG. 1 , with the emitter and various retaining members isolated from the remainder of the sensor.

FIG. 8 is another view of the assembly shown in FIG. 7 , with the emitter rendered transparent to show additional retaining members not visible in the view shown in FIG. 7 .

FIG. 9 illustrates a retainer member according to an aspect of this disclosure.

The present disclosure relates to securing a sensor component, such as a transmitter, within a sensor housing with minimized alignment variability over a wide range of temperature variation, while facilitating ease of alignment adjustment. The disclosure is made with reference to an example device illustrated in the attached FIGS. 1-9 .

Referring to FIG. 1 , a sensor ( 100 ) has an emitter ( 110 ) for launching light pulses (such as laser pulses) toward an object, and a receiver ( 120 ) for receiving the light pulses reflected by the object. The emitter ( 110 ) and receiver ( 120 ) are both located in a housing ( 130 ), which can also have a display (not shown) located on one of the faces ( 132 ) of the housing ( 130 ) for displaying information such as object distance or calibration information. The sensor ( 100 ) also has a cable connector ( 140 ) for connecting the sensor ( 100 ) to external electronics. It is noted that it is not a requirement that the receiver is located in the same housing as the emitter.

Inside the housing ( 130 ), as shown in FIG. 2 , the emitter is mounted in a holder, or mounting assembly ( 210 ). The receiver includes a photoelectric module ( 220 ) for converting optical signals to electrical signals. As shown in FIG. 3 , the mounting assembly ( 210 ) secures the barrel ( 310 ) of the emitter and includes a body portion ( 320 ), which serves as a support, and cap ( 330 ). The cap ( 330 ) is bolted to the body portion ( 320 ) by one or more screws ( 332 ). A number of securing elements, or retaining members, such as set screws ( 340 , 350 , 360 ) and screw/spring assembly ( 370 ) are disposed in the mounting assembly ( 210 ) for maintaining the alignment of the emitter barrel ( 310 ). FIG. 4 shows, with the cap ( 330 ) removed from the view, the relationship between the barrel ( 310 ) and the securing elements ( 340 , 350 , 360 , 370 ).

As shown in FIG. 5 , the emitter barrel ( 310 ) has a bulbous portion ( 312 ) and cylindrical portion ( 314 ). As shown in FIG. 6 , the body portion ( 320 ) of the mounting assembly ( 210 ) defines a recess, including a concave portion 322 that the bulbous portion ( 312 ) of the barrel ( 310 ) fits into so that the barrel can be secured in the mounting assembly ( 210 ) while being tilted to adjust the alignment of the emitter ( 110 ).

FIG. 6 also shows an additional securing element, which in this case is a spring ( 380 ) disposed in the body portion ( 320 ) of the mounting assembly ( 210 ). As shown in FIGS. 7 and 8 (with the barrel ( 310 ) rendered as transparent in FIG. 8 to show all securing elements), the spring ( 380 ) and screw ( 350 ) secures the barrel ( 310 ) vertically at the cylindrical portion ( 314 ) but allows the vertical position of the cylindrical portion ( 314 ) to be adjusted by turning the screw ( 350 ). Similarly, the screw ( 340 ) and screw/spring assembly ( 370 ) secures the barrel ( 310 ) horizontally at the cylindrical portion ( 314 ).

As shown in FIG. 9 , the screw/spring assembly ( 370 ) includes a screw ( 372 ) and spring ( 374 ). The screw ( 372 ) has a threaded portion ( 372 a ) and a rod portion ( 372 b ), which as a smaller diameter than the threaded portion ( 372 a ), such that the rod portion ( 372 b ) fits inside the spring ( 374 ). When the screw ( 372 ) is retracted from the barrel ( 310 ), the screw ( 340 ) and screw/spring assembly ( 370 ) secures the barrel ( 310 ) horizontally at the cylindrical portion ( 314 ) but allows the horizontal position of the cylindrical portion ( 314 ) to be adjusted by turning the screw ( 340 ). When the screw ( 372 ) is advanced so that the end ( 372 c ) of the screw is in firm contact with the cylindrical portion ( 314 ) of the barrel ( 310 ), the position of the cylindrical portion ( 314 ) of the barrel ( 310 ) is fixed, preferably not only horizontally but also vertically.

In addition, a screw ( 360 ) can be used to fix the position of the bulbous portion ( 312 ) of the barrel ( 310 ), as shown in FIGS. 3, 4, 7 and 8 . Alternatively, the body portion ( 320 ) of the mounting assembly ( 210 ) can be sized relative to the barrel ( 310 ) such that the bulbous portion ( 312 ) of the barrel ( 310 ) can be securely retained between the body portion ( 320 ) and the cap ( 330 ) by tightening the screws ( 332 ). The cap ( 330 ) can also define a concave surface substantially matching a portion of the surface of the bulbous portion ( 312 ), so that the bulbous portion ( 312 ) is substantially continuous surface-to-surface contact with the body portion ( 320 ) and cap ( 330 ) of the mounting assembly ( 210 ).

In another example configuration, a screw/spring assembly of the kind shown in FIG. 9 can be used instead of the spring ( 380 ) so that the vertical position of the cylindrical portion ( 314 ) of the barrel ( 310 ) can be adjusted and fixed.

Furthermore, the space between the barrel ( 310 ) and the mounting assembly is filled with glue (such as an epoxy), after the alignment of the barrel ( 310 ) has been adjusted and fixed, to further maintain the alignment.

The barrel and mounting assembly components are all metal in this example.

With the mounting assembly described above, especially with the feature of the screw/spring assembly, the alignment of the emitter barrel (or any other device for which alignment needs to be ensured) can be conveniently adjusted with the barrel held between screws and springs, i.e., with the screw in the screw/spring assembly in a refracted position. Once the adjustment is complete, the screw in the screw/spring assembly is tightened so that the barrel is securely held in place by at least two screws. The glue is then added to fill the space surrounding the barrel and further maintain the alignment.

In conventional sensors of this type, the barrel of the emitter is typically held in place by screws balanced by springs only. Glue is used to maintain the alignment after the alignment adjustment is done. However, it has been observed that the alignment can undergo significant drift as the ambient temperature changes. With the device described above, the alignment is fixed by screws after allowing adjustment. Improved alignment stability against temperature change is achieved while retaining the convenience of adjustment. Even with the metal screws, it is expected that the emitter barrel and other component will move around with varying ambient temperatures. The desired result is that even though the parts move around, they return to the same location when the temperature returns to the starting point. It has been found that glue does not return consistently to the original starting point but the metal nearly does. It is believed that this difference in behavior is attributable to the disordered molecular structure of the glue not being repeatable under varying temperature conditions, whereas the ordered nature of the molecules of metals exhibit the desired behavior where they do come to turn their original starting point naturally. One useful purpose of using the glue is to take up any void volume so that the barrel will not shift with shock loading or vibrations since the mechanical connections could be compromised under these conditions.