Sensor assembly

A sensor assembly includes a housing and a plurality of lenses. The lenses are connected with a lens carrier by a plurality of releasable connector elements. A circuit board is disposed on the lens carrier. The circuit board has a black coating. A connector assembly connects the circuit board with an electrical conductor. The connector assembly includes a body portion and a flange portion. The flange portion engages a recess in the sensor housing to hold the body portion of the connector assembly against axial movement relative to the sensor housing. A retainer extends from a cover portion of the sensor housing into engagement with the flange portion of a connector assembly to hold the flange portion against rotation to thereby block unauthorized access to the interior of the sensor housing. A light detector is movable relative to a light source to enable the distance from the light source to a location from which reflected light is received by the detector to be adjusted.

BACKGROUND OF THE INVENTION

The present invention relates to a sensor assembly which may be utilized to detect objects at a location spaced from the sensor assembly.

A known sensor assembly has a light source or emitter from which light is transmitted to an object spaced from the sensor assembly. The light is reflected from the object back through a second lens to a detector.

Users of known sensor assemblies have tried to gain access to the interior of the sensor assemblies by engaging wrenching flats on electrical connectors for the sensor assemblies. This can result in unauthorized tampering with the sensor assemblies in a manner which is detrimental to the operation of the sensor assemblies.

The lenses in a sensor assembly should be easy to accurately position in the sensor assembly. In addition, the lenses in a sensor assembly should not become loose during use of the sensor assembly. It is also important to have the light source and light detector accurately positioned relative to each other and to the lenses.

From a commercial standpoint, it is necessary to minimize the cost of a sensor assembly. It is also desirable to make the sensor assembly compact so that it can be easily positioned in many different environments. There should be minimal reflection of light from components of a sensor assembly. The lenses in a sensor assembly should be protected from the environment in which the sensor assembly is utilized so that the operating qualities of the sensor assembly do not deteriorate with the passage of time.

SUMMARY OF THE INVENTION

The present invention relates to a new and improved sensor assembly. The sensor assembly includes a light source and a lens which directs light from the light source to a remote object. Light reflected from the remote object is transmitted through another lens to a light detector.

The lenses may advantageously be mounted on a lens carrier. The lens carrier is disposed in a housing. The lenses are advantageously connected with the lens carrier by a plurality of releasable connectors. The connectors may be disposed in engagement with the rim portions of the lenses and press the lenses into recesses formed in the lens carrier. The connectors may be of the snap-in type.

The sensor assembly may advantageously include a connector assembly which connects the sensor assembly with an electrical conductor. This tamper resistant electrical connector assembly may include a body portion and a flange portion. The flange portion may be movable to engage a recess in the sensor housing and retain the electrical connector assembly against movement along a central axis of body portion of the connector assembly. In order to resist unauthorized access to the interior of the sensor assembly, a retainer may engage the flange portion of the electrical connector assembly and hold the flange portion against movement out of engagement with the recess.

The light source and/or the light detector may be movable relative to a circuit board to adjust the distance at which light from the light source is reflected from an object back to the detector. The circuit board may be connected with the lens carrier. A black coating may advantageously be provided on a side of the circuit board facing toward the lenses.

The sensor assembly may include one or more of a plurality of features of the present invention. It should be understood that although the features may advantageously be used in combination with each other, the features may also be used separately.

DESCRIPTION OF SPECIFIC PREFERRED EMBODIMENTS OF THE INVENTION

General Description

A sensor assembly20, constructed in accordance with the present invention, is illustrated inFIGS. 1 and 2. The sensor assembly20includes a housing22. The housing22includes a flat, generally rectangular, front wall24and a flat, generally rectangular, rear wall26which extends parallel to the front wall24. A pair of rectangular parallel side walls28and30extend between the front wall24and rear wall26. Parallel rectangular upper and lower end walls32and34extend between the side walls28and30.

A cylindrical, externally threaded, mounting section36extends from the lower end wall34. It is contemplated that the mounting section36will be inserted through a circular opening in a base or support member. The mounting section36may be connected with the base or support member by an internally threaded member or nut.

In the illustrated embodiment of the invention, the housing22has a generally rectangular configuration. However, it is contemplated that the housing22could have a different configuration if desired. For example, the housing could have a cylindrical configuration.

The front wall24, side walls28and30, end walls32and34, and the mounting section36are integrally formed as one piece. In the illustrated embodiment of the invention, the housing22is molded of a polymeric material. The front wall24, side walls28and30, end walls32and34, and mounting section36are integrally molded as one piece. The rear wall26is molded separately from the remainder of the housing22and forms a cover for the housing.

In the illustrated embodiment of the sensor assembly20, the sensor assembly includes three lenses40,42and44(FIGS.2and4). The center lens42is associated with a light source or emitter48(FIG. 4) mounted on a rectangular circuit board50(FIGS. 2 and 4) disposed within the sensor housing22. Upper and lower light detectors54and56(FIG. 4) are disposed in the housing22in association with upper and lower lenses40and44.

The illustrated embodiment of the sensor assembly20includes a pair of light detectors54and56associated with a pair of lenses40and44. However, a greater or lesser number of light detectors could be provided in association with a greater or lesser number of lenses. In addition, a plurality of light sources and associated lenses could be provided. For example, a single light source48and lens42could be provided in association with a single light detector54and lens40. Alternatively, a plurality of light sources and associated lenses could be provided in association with a plurality of light detectors and lenses.

The light source48is electrically energized to provide radiation which can be sensed by the light detectors54and56. By providing a pair of light detectors54and56, the sensor assembly20can be utilized to sense the distance of an object from the sensor assembly, that is, the sensor assembly20has depth perception. Of course, when depth perception or distance sensing is not required, the number of light detectors could be reduced.

It is contemplated that the light source48could provide many different types of radiation. Thus, the light source48could provide electromagnetic radiation anywhere within a wavelength range which includes the infrared range, visible, ultraviolet, and X-rays. Of course, the light source48could be utilized to provide a different type of radiation if desired.

In the illustrated embodiment of the invention, the light source48provides infrared radiation. Therefore, the detectors54and56are effective to detect the presence of infrared radiation. Of course, if the light source48provided a different type of radiation, the detectors54and56would be constructed to sense this radiation.

The housing22is advantageously formed of a material through which light having an infrared wavelength can be transmitted. Light in the visible spectrum is blocked by the material of the housing. In one specific embodiment of the invention, the housing22was molded of General Electric Lexan (trademark) polymeric material to which a die of color 21092 was added. The resulting housing is transparent to light in the infrared spectrum while being opaque to light in the visible spectrum.

Of course, if the light source40provided radiation other than infrared light, the housing22would be transparent to whatever radiation was provided by the light source48. For example, the light source48could be a source of light in the visible spectrum and at least the front wall24of the housing22would be transparent to light in the visible spectrum. Of course, if this was done, the detectors54and56would be effective to detect light in the visible spectrum.

In the illustrated embodiment of the invention, the lenses40,42and44, light source48and light detectors54and56are all enclosed within the housing22. This protects the lenses40,42and44, light source48, and light detectors54and56from contaminants in an environment in which the sensor assembly20is utilized. In the illustrated embodiment of the invention, the housing22is sealed so that contaminants from the environment around the housing can not enter the housing. However, if desired, at least the front wall24could be formed with openings to at least partially expose the lenses40,42and44.

When the sensor assembly20is to be utilized to detect the presence of objects at a location spaced from the sensor assembly, the light source48is electrically energized to provide radiation, specifically, infrared radiation. The infrared radiation is transmitted from the light source48through the center lens42and front wall24to the object to be sensed. Infrared light from the light source48is reflected from the object to be sensed through the front wall24to the upper and lower lenses40and44. The upper and lower lenses40and44direct the reflected infrared light to upper and lower light detectors54and56.

The upper and lower light detectors54and56provide output signals in response to the reflected infrared light. These output signals indicate the presence of the object at the location which is spaced from the sensor assembly20.

In the illustrated embodiment of the sensor assembly20, light emitting diodes are mounted on the circuit board50adjacent to a window60which is molded into the upper end wall32of the housing22. The window60is transparent to light in the visible spectrum. Therefore, light can be transmitted from the LEDs through the window60to an operator to provide a visible indication of the detection of an object.

It should be understood, that with the exception of the window60, the housing22has a black appearance to a person viewing the housing. This is because the housing22is formed of a material which is opaque to light in the visible spectrum while being transparent to infrared light.

Lens Carrier

In accordance with one of the features of the present invention, the lenses40,42and44are disposed on a lens carrier66(FIGS. 2,3,4,5and6). In addition, the circuit board50, light source48, and light detectors54and56are disposed on the lens carrier66. The lens carrier66facilitates accurate positioning of the lenses40-44, light source48and light detectors54and56relative to each other before they are inserted into the housing22.

The lens carrier66has a generally rectangular configuration (FIGS. 2 and 3) and supports the lenses40,42and44in the housing22(FIG.4). The lens carrier56includes a plurality of tubular sections70,72and74. The tubular sections70,72and74have parallel central axes76,78, and80(FIG. 4) which extend through the centers of the lenses40,42and44. The central axes76and80of the tubular sections70and74extend through the centers of the light detectors54and56. Similarly, the central axis78of the tubular section72extends through the center of the light source48.

The lens carrier66has a mounting section84(FIG. 3) disposed between the tubular sections70and72and offset to the right of the central axes76and78(FIG. 4) of the tubular sections70and72. A second mounting section86(FIG.3), having the same construction as the mounting section84, is disposed between the tubular sections72and74. The mounting section86is offset to the left (as viewed inFIG. 3) of the central axes78and80(FIG. 4) of the tubular sections72and74.

The lens carrier66is connected to the housing22by fasteners90and92(FIG. 2) which extend through openings in the mounting sections84and86into openings in ribs formed on the side walls28and30(FIG. 2) of the housing22. Although only a single rib96on the side wall28for receiving the fastener92is illustrated inFIG. 2, it should be understood that a similar rib is formed on the side wall30of the housing22and has an opening to receive the fastener90. The fasteners90and92cooperate with the mounting sections84and86and the ribs96to accurately position and securely retain the lens carrier66in the housing22.

The mounting sections84and86(FIG. 3) cooperate with the ribs96in the housing22to enable the lens carrier66to be inserted into a rectangular chamber100(FIG. 2) in the housing22only when the lenses40,42and44are leading so that the lenses are disposed adjacent to the front wall24in the manner illustrated in FIG.4. The tubular sections70,72and74have rear end walls104,106and108(FIG. 3) which enable light to be transmitted between the lenses40,42and44and the light source48and light detectors54and56mounted on the circuit board50(FIG.4). Thus, the end walls70and74have central slots112and114(FIG. 3) which are aligned with the upper and lower light detectors54and56(FIG.4). Similarly, the end wall106has a central opening118(FIG. 3) which is aligned with the light source48. It should be understood that the openings112,114and118could have a different configuration if desired.

In the illustrated embodiment of the invention, the lens carrier66is integrally formed as one piece. The lens carrier66may be integrally molded of a polymeric material which blocks the transmission of infrared radiation. This results in infrared light and in visible light being blocked by the lens carrier. However, if desired, the lens carrier66could be formed of a different material.

Generally cylindrical tubes122,124and126(FIG. 2) of flock paper line cylindrical chambers in the tubular sections70,72and74(FIG.4). The tubes122,124and126have black inner surfaces128,130and132with a velvety texture. This enables the tubes122,124and126(FIG. 4) to absorb stray rays of light. It is contemplated that the tubes122,124and126could be formed of material other than flock paper if desired. In fact, the tubes122,124and126could be omitted if desired and the sides of the interior surfaces of the tubular sections70,72and74of the lens carrier66could be coated with a black material which has a rough or velvety surface and which absorbs light.

The tubes122,124and126extend between the lenses40,42and44and the end walls104,106and108of the tubular sections70,72and74(FIGS. 3,4,5, and6). Thus, the end of the tube124(FIG. 5) closest to the front wall24(FIG. 4) of the housing22is disposed in abutting engagement with the lens42(FIGS.5and6). The opposite end of the tube124is disposed in abutting engagement with the end wall106of the tubular section72. Although only the relationship between the flock paper tube124and the tubular section72of the lens carrier66is illustrated inFIGS. 5 and 6, it should be understood that the tubes122and126in the tubular sections70and74(FIG. 4) are also disposed in engaged with their associated lenses40and44and housing end walls104and108(FIG.3).

The lens carrier66has a plurality of arcuate shields134,136,138,140,142and144(FIGS. 3 and 4) which block the transmission of light between the tubular sections70,72and74of the lens carrier. The shields134-144are disposed in abutting engagement with an inner side surface148(FIG. 4) of the front wall24. Therefore, the shields134-144are effective to block the direct transmission of light between the tubular sections70,72and74of the lens carrier66.

The lens carrier66supports the lenses40,42and44. The lenses40,42and44are positioned in abutting engagement with the inner side surface148of the front wall24by the lens carrier66. However, if desired, the lens carrier66could be constructed so as to position the lenses40,42and44in a spaced apart relationship with the front wall24of the housing22.

The front wall24of the housing22extends across and protects the lenses40,42and44. The smooth, flat front wall24of the housing20is relatively easy to clean. The lenses40,42and44are protected from dust, dirt and other contaminants in the environment in which the sensor assembly20is used.

It is preferred to utilize the lens carrier66to position the lenses40,42and44relative to each other while the lens carrier66is outside of the housing22. The lens carrier66and lenses40,42and44can then be inserted into the housing22as a unit with the lenses accurately positioned relative to each other. However, if desired, the lens carrier66could be omitted. If this was done, the housing22would be constructed so as to have supporting surfaces for engaging the lenses40,42and44. It is preferred to completely enclose the lenses40,42and44in the sealed housing22. However, if desired, openings could be provided in the front wall24to expose the lenses40,42and44.

Lens Connectors

In accordance with another one of the features of the present invention, lens connectors156are provided to releasably connect the lenses40,42and44with the lens carrier66. The lens connectors156enable the lenses40,42and44to be quickly and accurately positioned relative to the lens carrier66. The lens connectors156also enable a lens40,42or44to be easily connected with and subsequently disconnected from the lens carrier66.

The specific lens connectors156disclosed herein for connecting the lenses40,42and44with the lens carrier66, are resiliently deflectable snap-in type connectors. However, it is contemplated that the lens connectors156could have a different construction if desired. For example, the lens connectors156could have thread convolutions which engage thread convolutions on the lens carrier66to retain the lenses40,42and44in place. Alternatively, the lens connectors156could be formed by a plurality of fasteners which are connected with the lens carrier66by a threaded connections or by snap-in connections.

The specific lens connectors156disclosed herein are resilient fingers which are integrally formed as one piece with the lens carrier66. The resilient lens connectors156are deflectable by the lenses40,42and44to enable the lenses to snap into place on the lens carrier. However, the lens connectors156could be integrally formed as one piece with the lenses40,42and44if desired.

In order to provide the sensor assembly20with a relatively compact construction, the lenses40,42and44are all formed with a noncircular configuration. Thus, the lens42(FIG. 7) has a rim portion160which extends around the lens42. The rim portion160includes a plurality of linear side sections162and164. The side sections162and164extend parallel to each other. Although a pair of parallel side sections162and164are provided on the rim portion160, it is contemplated that the rim portion could be provided with a greater or lesser number of linear side sections. If a greater number of linear side sections are provided, the side sections could be skewed relative to each other.

The rim portion160of the lens42also includes a plurality of arcuate sections166and168. The arcuate sections166and168have centers of curvature which are coincident with the center of the lens42. Although the lens42has an oval configuration, it should be understood that the lens42could have a rectangular configuration if desired. For example, the arcuate sections166and168could at least be partially replaced by linear sections. This would have the effect of reducing the vertical extent (as viewed inFIGS. 1 and 4) of the sensor assembly20.

The rim portion160forms a rib or flange which extends outward from a main portion172of the lens42. The main portion172of the lens42has convex inner and outer side surfaces174and176(FIGS. 5,6and8). The outer side surface174of the lens42has a smaller radius of curvature than the inner side surface176. The inner side surface176is almost flat and, if desired, may be flat.

The rim portion160is releasably engaged by the lens connectors156to hold the lens42against movement relative to the lens carrier66. Thus, the lens connector156ofFIG. 8has a retainer surface180which presses the arcuate section166of the rim portion160of the lens42firmly against an end of the lens carrier66. The lens connector156continuously applies force to press the lens42against the lens carrier66. In the illustrated embodiment of the invention, there are four lens connectors156for each lens40,42and44. However, a larger or smaller number of lens connectors156could be provided for each lens40,42and44if desired.

The lens carrier66is formed with a recess184having a configuration and size which is the same as the configuration and size of the main portion172of the lens42. The main portion172of the lens42is telescopically received in the recess184in the lens carrier66. This enables the lens connectors156to hold the main portion172of the lens42in the recess184. The recess184has linear side surface portions and arcuate side surface portions. This enables the linear side sections162and164of the rim portion160to cooperate with corresponding side surfaces of the recess184in the lens carrier66to hold the lens42against rotational movement relative to the lens carrier66. Although only the lens carrier recess184for the lens42is illustrated inFIGS. 8 and 9, it should be understood that the lens carrier66has a separate recess for each of the lenses40,42and44.

In the illustrated embodiment of the invention, the lens connectors156engage the arcuate sections166and168of the rim portion160of the lens42to hold the lens42in the recess184(seeFIG. 5) in the lens carrier66. The linear side sections162and164(FIGS. 6 and 7) of the lens42cooperate with the recess184to hold the lens against rotation relative to the recess. However, additional lens connectors156could be provided to engage the linear side sections162and164of the lens42if desired.

In the illustrated embodiment of the invention, the lens connectors156are integrally formed as one piece with the lens carrier66and are resiliently deflected by the rim portion160of the lens42when the lens is snapped into the recess184. Thus, the arcuate section166of the rim portion160of the lens42engages a cam surface192(FIG. 8) on the lens connector to resiliently deflect the lens connector toward the left (as viewed in FIG.8). As this occurs, the lens42moves downward into the recess184. As the lens42moves downward (as viewed inFIG. 8) into the recess184, the resiliently deflected lens connector156snaps back to the position shown in FIG.8. As this occurs, the retainer surface180on the connector156engages the arcuate section166of the rim portion160to press the lens42firmly against the lens carrier66and to hold the lens42in the lens carrier.

In the illustrated embodiment of the invention, the lens connectors156engage the arcuate sections166and168of the lens42(FIGS. 5,7and8). The lens connectors156do not engage the linear side sections162and164of the lens42(FIGS.6and9). However, if desired, lens connectors156could be provided to engage the linear side sections162and164of the rim portion160of the lens.

The illustrated lens connectors156have a relatively short arcuate extent (seeFIGS. 2,3and5) along the arcuate sections166and168of the rim portion160. If desired, the extent of the lens connectors along the rim portions160could be increased to increase the extent of engagement of the lens connectors with the rim portion of the lens.

Although only the lens connectors156for the lens42are illustrated inFIGS. 8 and 9, it should be understood that the lens connectors156all have the same construction and cooperate with rim portions160of the lenses40,42and44in the same manner. Although only the lens carrier recess184for the lens42is illustrated inFIGS. 8 and 9, it should be understood that the lens carrier66is provided with a separate recess184for each of the lenses40,42and44. Of course, if a greater or lesser number of lenses was utilized in the sensor assembly a greater or lesser number of recesses184would be provided in the lens carrier66.

Only the lens42is illustrated in FIG.7. It should be understood that the lenses40,42and44all have the same construction. The lenses40,42and44are molded from a suitable polymeric material. If desired, the lens connectors156could be integrally molded as one piece with the lenses40,42and44. If this was done, the lens connectors would extend axially from the rim portions160of the lenses40,42and44into engagement with the lens carrier66.

The lens connectors156and lens carrier recesses184cooperate with the lenses40,42and44to firmly and securely hold the lenses40,42and44in the sensor assembly20. The lens carrier recesses184hold the lenses40,42and44against rotation about central axes of the lenses and against sidewise movement. The lens connectors156continuously press the lenses40,42and44into the lens carrier recesses184to prevent rattling of the lenses. Therefore, the lens carrier66and lens connectors156cooperate with the lenses40,42and44to ensure that the focal length of the optical system in the sensor assembly20is maintained.

Connector Assembly

An electrical connector assembly200(FIG. 4) is utilized to connect the sensor assembly20with an electrical conductor. In accordance with another feature of the invention, the connector assembly200impedes access to the interior of the sensor housing22. To this end, the electrical connector assembly200is free of externally accessible elements, such as wrenching flats, which can be engaged to disconnect the electrical connector assembly from the housing22. In addition, the connector assembly200is relatively simple in construction, easy to install and thereby tends to minimize the cost of the sensor assembly20.

The connector assembly200(FIG. 4) includes a plurality of terminals or prongs204which are connected with the circuit board50by electrical conductors208. Although the illustrated electrical conductors208are flexible insulated wires, it is contemplated that suitable sheet metal terminals could be utilized in an interconnected between the connector assembly200and the circuit board56if desired.

The connector assembly200includes a generally cylindrical body portion210and a flange portion212. The body portion210of the connector assembly200is telescopically received in the mounting section36. A pair of coaxial O-rings216and218extend around the body portion at axially spaced apart locations along the body portion.

To maintain a desired axial spacing between the O-rings216and218, the O-rings are disposed in axially spaced apart grooves220and222in the body portion210of the connector assembly200. The O-rings216and218sealingly engage an inner side surface of the mounting section36. The O-rings216and218seal the cylindrical opening in the mounting section36so that contaminants can not enter the housing22.

A cylindrical socket chamber228(FIG. 4) is provided on the outer end portion of the connector assembly200to telescopically receive a connector secured to an electrical conductor. The connector secured to the electrical conductor (not shown) has suitable sockets which are engaged by the terminals204and206. Of course, the connector assembly200could be provided with sockets which are engaged by terminals on the connector which is connected with the electrical conductor if desired.

In accordance with one of the features of the invention, the connector assembly200is retained in the sensor housing22by engagement of the flange portion212with a recess or slot230formed in the housing22. The body portion210is rotatably received in a cylindrical opening232(FIGS.4and10). The opening232extends through the lower end wall34and through the mounting section36.

The longitudinally extending recess230(FIG. 10) has a central axis which extends perpendicular to a central axis236of the opening232. The recess230is offset to one side, that is, toward the side wall28, from the opening232. The recess230has an axial extent which is greater than the length of the flange portion212(FIG.11).

When the connector assembly200is to be positioned in the housing22, the cylindrical body portion210of the connector assembly is axially aligned with the opening232(FIG.10). At this time, an index corner240on the rectangular flange portion212(FIG. 10) is aligned with an arcuate positioning surface242on the inside of the housing22. The positioning surface242cooperates with the index corner240on the flange portion212so that the connector assembly200can be inserted into the housing in only one orientation.

As the connector assembly200is moved into the housing22, the body portion210moves into the opening232. As the connector assembly200continues to move along the central axis236of the opening232, the flange portion212moves into abutting engagement with the lower end wall34of the housing22(FIG.11). When this occurs, the connector assembly200is accurately positioned relative to the housing22. The O-rings216and218(FIGS. 4 and 10) on the body portion210of the connector assembly are disposed in sealing engagement with the cylindrical inner side surface of the opening232extending through the mounting section36.

The connector assembly200is then rotated in a counterclockwise direction (as viewed inFIG. 11) to the position illustrated in FIG.12. As this occurs, a corner portion246of the flange portion212moves into the recess or slot230. Once the corner portion246has entered the slot230, the connector assembly200is held against axial movement by the housing22. Therefore, if an axially upward (as viewed inFIG. 4) force is applied against the connector assembly200, engagement of the corner portion246with the recess or slot230(FIG. 12) in the housing22blocks axially upward (as viewed inFIG. 4) movement of the connector assembly200.

In the illustrated embodiment of the invention, the slot or recess230(FIG. 12) is formed by an elongated retainer section250of the housing22. The retainer section250is integrally formed as one piece with the lower end wall34and side wall28of the housing22. If desired, the recess230and retainer section250could be formed in a different manner and could have a different configuration.

It is contemplated that the recess or slot230could be formed in the housing22in a manner other than by the provision of the elongated retainer section250. For example, a relatively small overhanging shelf could be provided adjacent to the lower end wall34of the housing22. Although only a single retainer section250is provided in the illustrated embodiment of the invention, it is contemplated that a pair of recesses or slots230could be provided in the housing22to engage opposite corners on the flange portion212of the connector assembly200.

In order to prevent removal of the connector assembly200once the sensor assembly20has been assembled, the retainer flange or finger254is provided to block clockwise (as viewed inFIGS. 12 and 13) rotational movement of the connector assembly200. In the illustrated embodiment of the invention, the rear wall26of the housing22is formed on a cover portion258. After all of the components of the sensor assembly20have been positioned in the housing22, the cover portion258is moved downward (as viewed inFIG. 12) into engagement with the main portion of the housing. The cover portion258is then secured in place by a suitable adhesive. Securing of the cover portion258in place is facilitated by a plurality of pins262which extend from the cover portion and are received in suitable sockets formed in the housing22at the corners of the housing.

Once the cover portion258has been secured in place, as shown inFIG. 13, a generally L-shaped recess266(FIG. 12) defined by the retainer flange254engages a corner portion268of the flange portion212(FIG. 13) to hold the connector assembly20against clockwise rotation relative to the housing22. Thus, the flange254engages the corner portion268and blocks rotational movement of the corner portion268into alignment with the retainer section250. Therefore, the corner portion246of the flange portion212remains in the recess230.

In the illustrated embodiment of the invention, the flange portion212of the connector assembly (FIG. 10) is integrally formed as one piece with the body portion210of the connector assembly. Thus, both the flange portion212and body portion210of the connector assembly200are integrally molded from a suitable polymeric material. It is contemplated that the same polymeric material and pigment which is utilized to form the housing22may also be utilized to form the connector assembly210.

The flange portion212may be formed separately from the body portion210. If this is done, the flange portion212may be fixedly connected with the body portion210. Both the body portion210and the flange portion212would rotate together between the position shown in FIG.11and the position shown in FIG.12.

Alternatively, the flange portion212may be rotatably connected with the body portion210of the connector assembly200. This would enable the flange portion212to be rotated relative to the housing22while the body portion212of the connector assembly200remains stationary relative to the housing. If the flange portion212is formed separately from the body portion210of the connector assembly200, the flange and body portions could be formed of different materials. For example, the flange portion212could be formed of metal while the body portion210is formed of a polymeric material.

The illustrated connector assembly200has a generally square flange portion212(FIG.10). However, it is contemplated that the flange portion210could have a different configuration if desired. For example, the flange portion212could have a generally ovoid configuration with a circular portion which is connected with the body portion210and an outwardly projecting arm portion. The outwardly projecting arm portion may be received in the recess230to hold the connector assembly200against axial movement relative to the housing22. Alternatively, the flange portion212could be formed with a pair of outwardly extending arms which would be received in recesses in the housing22disposed at opposite sides of the opening232.

Circuit Board

The circuit board50(FIGS. 2 and 4) is mounted on the lens carrier66. Thus, the circuit board50is mounted on a rearwardly facing end portion of the lens carrier66opposite from the lenses40,42and44. The circuit board50is fixedly connected to the lens carrier66by a plurality of fasteners280(FIG.2).

By mounting the lenses40,42and44on the rightwardly (as viewed inFIG. 2) facing end portion of the lens carrier66and the circuit board50on the leftwardly facing (as viewed inFIG. 2) end portion of the lens carrier66prior to insertion of the lens carrier into the housing22, fabrication of the sensor assembly20is facilitated. Thus, the lens carrier66, tubes122,124and126(FIG.2), lenses40,42, and44, and circuit board50are all interconnected while the lens carrier56is spaced from the housing22. These components are then inserted into the housing22as a unitary module.

Although it is preferred to mount the circuit board50on the lens carrier66in the manner illustrated inFIG. 4, it is contemplated that the circuit board50could be mounted in the housing separately from the lens carrier if desired. For example, the circuit board50could be connected with the cover portion258of the housing22. Alternatively, the circuit board50could be connected with suitable mounting lugs mounted on the side walls28and30and/or end walls32and34of the housing22.

In accordance with one of the features of the present invention, the position of the light source48, upper light detector54and lower light detector56(FIGS. 2 and 4) can be adjusted relative to each other. By adjusting the positions of the light source48, upper light detector54and lower light detector56relative to each other, the location of an object from which infrared red light from the light source48is reflected back to the light detectors54and56can be adjusted. This enables the effective operating range of the sensor assembly20to be adjusted.

In the illustrated embodiment of the invention, the light detectors54and56are movably mounted on the circuit board50to enable their positions to be adjusted relative to the light source48. However, it is contemplated that the light source48could also be movably mounted on the circuit board50to enable the position of the light source to also be adjusted.

To facilitate positioning of the light source54relative to the circuit board50, the upper lens40and the light source48, the upper light detector54is mounted on a daughter board or carriage286(FIGS.4and14). The daughter board or carrier286is received in a slot288formed in a main or mother board290. The daughter board286and mother board290are part of the circuit board50.

The slot288(FIGS. 2 and 4) in the main or mother board290is aligned with the slot112(FIGS. 2 and 3) formed in the rear end wall104of the tubular section70of the lens carrier66. The slot288in the mother or main board290is slightly wider than the slot112in the rear end wall104of the tubular section70of the lens carrier (FIGS. 2,14and15). This enables the carriage or daughter board286to be supported by the end wall104of the lens carrier66as the carriage or daughter board is moved along the slot288in the main or mother board290(FIG.15).

Thus, once the circuit board50has been fixedly connected with the lens carrier66, the carriage286on which the light detector254is mounted is moved along the slot288in the mother board290. During this movement, the carriage286engages the rear end wall104(FIGS. 3 and 15) of the tubular section70of the lens carrier66to support the carriage. At this time, the light detector54is aligned with and disposed in the slot112in the rear end wall104of the tubular section70(FIG.14).

Once it has been determined that the light detector54has a desired position relative to the mother or main board290, the carriage286is fixedly connected to the mother or main board. This may be accomplished by soldering a pair of wires296and298(FIG.15), which extend across the carriage286, to both the carriage and the mother or main board290.

By having the position of the light detector54adjustable relative to the light source48, the light detector is effective to detect light reflected from an object at a predetermined distance from the sensor assembly20. Thus, the closer the light detector54is to the light sensor48, the greater is the distance at which light will be reflected from an object to the upper light detector54. Similarly, the further the upper light detector54is from the light source48, the smaller is the distance at which light from the light source48will be reflected from an object to the upper light detector54. Since the effective operating range of the sensor assembly20is determined by the distance at which light from the light source48is reflected from an object back to the light detectors54and56, accurate positioning of the light detectors54and56relative to the light source48is important.

Although only the upper light source54is illustrated inFIGS. 14 and 15, it should be understood that the lower light source56(FIG. 4) is mounted on a carriage or daughter board304having the same construction as the carriage286. The carriage304is movable along a slot306in the mother or main board290to position the light detector56relative to the light source48. The light detector56detects light which is reflected from an object and transmitted through the lens44to the light detector. The light detector56is aligned with the slot114(FIG. 3) in the rear end wall108of the tubular section74of the lens carrier66. Suitable fasteners, corresponding to the wires296and298, are provided to secure the carriage or daughter board304to the main or mother board290. In the embodiment of the invention illustrated inFIGS. 14 and 15, the carriage286is moved along the slot288in the mother or main board290to a desired position. The wires296and298are then fixedly connected with the carriage or daughter board286and the main or mother board290to hold the carriage in the desired position.

In the embodiment of the invention illustrated inFIGS. 16 and 17, a drive mechanism is connected with the carriage to enable the position of the light detector to be adjusted. Since the embodiment of the invention illustrated inFIGS. 16 and 17is generally similar to the embodiment of the invention illustrated inFIGS. 14 and 15, similar numerals will be utilized to designate similar components, the suffix letter “a” being added to the numerals ofFIGS. 16 and 17to avoid confusion.

A light detector54a(FIG. 16) is mounted on a carriage or daughter board286a. The carriage or daughter board286ais movable relative to a mother or main board290aby a drive mechanism320. The drive mechanism320includes a screw322which is rotatably supported by a pair of support elements324and326. The support elements324and326are fixedly connected to the mother or main board290aand hold the screw322against axial movement relative to the mother or main board290a.

A generally U-shaped bracket330is fixedly connected to the carriage or daughter board286a. The bracket330has upstanding (as viewed inFIG. 16) sections334and336which are engaged by an external thread on the screw322. Therefore, upon rotation of the screw322, the bracket330and carriage286aare moved along a slot288aformed in the mother or main board290a.

The longitudinally extending slot288ain the mother or main board290ais aligned with a longitudinally extending slot112ain an end wall104aof the tubular section70aof the lens carrier66a. The slot288ain the main or mother board290ais wider than the slot112ain the end wall104aof the lens carrier66a(FIG.17). Therefore, the end wall104aof the lens carrier66ais effective to support the carriage or daughter board286aas it is moved along the slot288ain the main or mother board290aby operation of the drive mechanism320. Although only the drive mechanism320for moving the carriage286ahas been illustrated inFIGS. 16 and 17, it should be understood that a similar drive mechanism is provided to move a light detector corresponding to the light detector56ofFIG. 4, relative to the circuit board50aand a light source corresponding to the light source48of FIG.4.

In the embodiment of the invention illustrated inFIGS. 14 and 15, the carriage286and detector54are moved to a desired position relative to the light source48and then fixedly secured in that position by the wires296and298. In the embodiment of the invention illustrated inFIGS. 16 and 17, the carriage286aand light source54aare moved to a desired position relative to a light source corresponding to the light source48ofFIG. 4, by operating the drive mechanism320. It is contemplated that the drive mechanism320could be locked so that once the position of the carriage286aand light source54ahas been adjusted, their positions can not be readily changed. Alternatively, the drive mechanism320may be accessible from outside of the sensor assembly so that a user could adjust the position of the carriage286aand light source54a.

Black Coating

Portions of the circuit board50are exposed to the interior of the tubular sections70,72and74(FIGS. 2 and 4) of the lens carrier66. In addition, wiring extends through openings between opposite sides of the circuit board50. These openings, which may be referred to as vias, and the surface area of the circuit board50may result in an increase in the magnitude of background light within the sensor assembly20. This background light may tend to impair the operating characteristics of the sensor assembly.

In order to minimize unwanted background light, a black coating344(FIG. 18) is applied to a side346of the circuit board50which faces towards the lenses40,42and44. The black coating344extends across openings or vias348which extend between the front side346of the circuit board50and a rear side352of the circuit board50. A circuit component, such as a wire354, extends through the opening348. It should be understood that the wire354should be considered as merely being representative of many different circuit components and/or mountings for circuit components, which may extend through openings in the circuit board50.

The black coating344extends across the front end portion of the opening348to block transmittal of light through the opening. In addition, the black coating344blocks light from passing through laminations which form the circuit board50. The black coating344also reduces stray light reflections within the sensor assembly20.

The black coating344advantageously has an irregular surface which faces towards the lenses40-44in order to enhance the light absorbing characteristics of the black coating. The black coating may be formed by a non-reflective layer of black paint which may be referred to as flat black paint. Alternatively, the coating344could be formed with a velvety surface similar to the surface of flock paper.

In one specific instance, the light absorbing black coating344was an epoxy paint. However, it is contemplated that the black coating344could be formed of other materials if desired. For example, the black coating344could be formed by a black layer which is secured to the circuit board50by a suitable adhesive.

The black coating344has been illustrated inFIG. 18as being applied to the main or mother board290. It is also contemplated that the black coating344will extend across the sides of the carriages286and304(FIG. 4) which face toward the lenses40,42and44. It is believed that it may be advantageous to extend the flat black coating to the side surfaces of the slots288and306along which the carriages286and304are movable. Thus, the black coating344would cover not only the side of the mother board or main section290which faces toward the lenses40-44but could also cover the sides of the carriages or daughter boards286and304which face toward the lenses and the sides of the slots288and306and/or the sides of the carriages286and304which extend between the front side346and rear side352of the circuit board50.

Conclusion

The present invention relates to a new and improved sensor assembly20. The sensor assembly20includes a light source48and a lens42which directs light from the light source to a remote object. Light reflected from the remote object is transmitted through another lens40to a light detector54.

The lenses40and42may advantageously be mounted on a lens carrier66. The lens carrier66is disposed in a housing22. The lenses40and42are advantageously connected with the lens carrier66by a plurality of releasable connectors156. The connectors156may be disposed in engagement with the rim portions160of the lenses40and42and press the lenses into recesses184formed in the lens carrier66. The connectors156may be of the snap-in type.

The sensor assembly20may advantageously include a connector assembly200which connects the sensor assembly with an electrical conductor. This tamper resistant electrical connector assembly200may include a body portion210and a flange portion212. The flange portion212may be movable to engage a recess230in the sensor housing22and retain the electrical connector assembly200against movement along a central axis of body portion of the connector assembly. In order to resist unauthorized access to the interior of the sensor assembly, a retainer254may engage the flange portion212of the electrical connector assembly and hold the flange portion212against movement out of engagement with the recess.

The light source48and/or the light detector54may be movable relative to a circuit board50to adjust the distance at which light from the light source is reflected from an object back to the detector. The circuit board50may be connected with the lens carrier66. A black coating344may advantageously be provided on a side of the circuit board50facing toward the lenses.

The sensor assembly20may include one or more of a plurality of features of the present invention. It should be understood that although the features may advantageously be used in combination with each other, the features may also be used separately. For example, the lens connectors156may be used in combination with or separately from the electrical connector assembly200. Similarly, the lens carrier66may be used separately or in combination with the lens connectors156and/or electrical connector assembly200.