Abstract:
A mounting plate for a transmitting and receiving device. The transmitting and receiving devices are securably attached to the mounting plate so that adjustments are not necessary after the plate has been moved. The mounting plate has two mirror panels that reflect the signal generated by the transmitting device and two filtering plates for limiting the divergence of the beam of light to provide greater secured coverage of the area with only one transmitter and receiver.

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to the mounting and protection of light sensors and their respective beams. More particularly, the present invention is directed towards the rigid mounting of the sensor equipment, combined with the reflecting and blocking of the light beams to provide a more reliable, and usable sensor for product detection in inaccurate product ejection systems. 
     Sensors have been widely used in the detection of product for many years. Prior art sensor beams utilize long an narrow conical beams for sensing product ejection. In most cases the sensors are used in their original manufactured state and the beams are altered by lenses and covers. This prior art method requires the ejected product to pass through a relatively small target area. When the ejection process is inaccurate, the randomly tossed product is difficult to detect consistently. This is due to the normal ejection error that may result in a product ejection path when the error is greater than twice the size of the area of the product. 
     In addition to the problems associated with the product ejection area, the variable mounting of prior art sensors has to be adjusted for proper alignment with the product flow. The adjustable mounting causes problems because the sensors may be moved accidentally or intentionally which can cause the sensing units to become mis-aligned and fail to detect the product flow. 
     A further problem associated with the prior art is the production debris that may be ejected along with the actual product being produced. Production debris has been an ongoing problem to sensors and the buildup of this debris requires a periodic cleaning of the sensor lenses. In dusty or dirty production environments this debris has severely limited or prevented the use of sensors because the constant cleaning down time of the sensors results in lost production time. In addition to the cleaning problems associated with the production debris, other problems, such as false sensing can also be attributed to this debris. If a sensor is designed to detect small products by increasing the resolution of the sensor, then the debris particles can break the sensing beam and result in an inaccurate sensing signal. Consequently, a need remains for a device to overcome these problems. 
     Previous monitoring or detection systems include U.S. Pat. No. 4,605,850; issued to Anselment et al. on Aug. 12, 1986; U.S. Pat. No. 4,742,337, issued to Haag on May 3, 1988; U.S. Pat. No. 5,583,334, issued to Baumann on Dec. 10, 1996; and U.S. Pat. No. 5,812,058, issued to Sugimoto et al. on Sep. 22, 1998. These patents are hereby incorporated by reference. 
     U.S. Pat. No. 4,605,850, issued to Anselment et al on Aug. 12, 1986 discloses a LIGHT BARRIER APPARATUS FOR MONITORING DOORWAYS. This patent teaches a device that has a central mount with a transmitter and a receiver that are mounted on a dye-cast support element. The design has two deflecting mirrors mounted on adjustable universal joints within a housing to deflect a beam of light to the receiver. The principal object of this invention is to provide a light sensor apparatus that does not require the whole apparatus to be changed when the apparatus is defective. 
     U.S. Pat. No. 4,742,337, issued to Haag on May 3, 1988 discloses a LIGHT-CURTAIN AREA SECURITY SYSTEM. This specification teaches an area coverage security system that provides a “curtain” for detecting a break in the light. The device further teaches the use of a series of transmitting and receiving strips wherein the transmitters send a signal that is reflected off of a reflection strip to be received by a receiver. The device provides a means for timing the signal (see col. 5, lines 32-48) to determine when a alarm should be sent, and thus providing sensitivity to keep the occurrence of false alarms small. 
     U.S. Pat. No. 5,583,334, issued to Baumann on Dec. 10, 1996, discloses a METHOD AND APPARATUS FOR THE DETECTION OF DEFECTIVE LIGHT TRANSMITTERS AND/OR RECEIVERS OF A LIGHT GRID FOR DETECTING OBJECTS IN A SURVEILLANCE AREA. This disclosure teaches a device having multiple light transmitters and the same number of light receivers that are positioned opposite of the transmitters. The device provides for the transmission of light by the transmitters and the reception of light by the receivers, with the beam of lights from the transmitter diverging to contact more than one receiver. The apparatus is then able to analyze the received signals to determine if an element (transmitter or receiver) is not operating properly. 
     U.S. Pat. No. 5,812,058, issued to Sugimoto et al., discloses a SECURITY SENSOR WITH BUILT-IN SIGHT. This invention teaches a security sensor having a receiver and a transmitter that are accommodated within a housing. See col. 3, lines 56-60. The security sensor is quipped with a sighting device in which the respective optical axes of the beam projector and receiver can easily and quickly be adjusted. The security device has an alarm whereby when the beam of light is broken, the receiver causes the alarm or warning display to so indicate. 
     In contrast to these patented systems, different manufacturing processes require different detection systems for varying product types. Some manufacturing production schemes require the product to be present during the operation and others may require the product to be absent. Thus, a sensor should also allow for detecting when a product is present and when a product is absent. The present invention provides a sensor mounting, reflecting, and protection device which satisfies the aforementioned needs. 
     SUMMARY OF THE INVENTION 
     A mounting plate for a light sensor with a reflective mirror, transmitting device and a receiving device. The reflective mirror, transmitting device, and receiving device are securably attached to the mounting plate of the invention so that aiming adjustments are not required. The permanent mounting of the transmitting device and the receiving device in alignment with the reflective mirror provide a stable environment that does not require realignment after the sensor has been moved. The mounting plate is designed with two mirrored panels that reflect the signal generated by the transmitting device and two filtering plates for limiting the divergence of the beam of light to provide greater secured coverage of the area with only one transmitter and receiver. 
     The present invention is particularly suited for mounting sensors that are used to monitor the absence of, or the presence of, product passing through the shaped sensing area. The present invention protects the sensors and reflectors from much of the manufacturing debris and thereby reducing the cleaning time normally associated with high production debris systems. The invention provides for fixed sensor and reflector alignments to eliminate user alignment of the system. 
     Accordingly, the present invention is directed to a sensor mounting device for the mounting of sensors, reflectors, debris guards, and beam masking to monitor product ejection with repeatability. 
     Yet another advantage of the present invention is directed towards a sensing device that can be mounted in any direction to accommodate many different types of machines and product detection. 
     A still further advantage of the present invention allows multiple devices to be mounted in a front to back configuration to obtain redundant sensing. The present invention may also be mounted in a side by side configuration to accommodate closely ejected multiple product systems where two or more parts ejected simultaneously. 
     One embodiment of the present invention includes a base that maintains alignment of the reflectors, sensors, and protective covers. 
     A further embodiment of the present invention adds debris guards to further protect the reflectors and sensors from debris. 
     Yet another embodiment of the present invention utilizes masks to block portions of the beam to de-sensitize standard sensor arrangements to eliminate small particle sensing. 
     Thus, the present invention utilizes reflected through-beam photoelectric sensing to detect product being ejected, poured, extruded, or otherwise expelled from equipment. The small particles, drops of oil or other debris that may be associated with the expelled product can be ignored by the sensor. The present invention accomplishes these advantages with a combination of mechanical and electrical connections mounted within a case that is not easily tampered with. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top schematic view of the light sensing apparatus of the present invention. 
     FIG. 2 is a side schematic view of the light sensing apparatus of the present invention. 
     FIG. 3 is a reflector end view of the light sensing apparatus of the present invention. 
     FIG. 4 is a cable end view of the light sensing apparatus of the present invention. 
     FIG. 5 is a top view of the cover of the light sensing apparatus of the present invention. 
     FIG. 6 is an end view of the reflector end mask of the present invention. 
     FIG. 7 is an end view of the sensor end mask of the present invention. 
     FIG. 8 is a side view of the reflector end mask and the sensor end mask mounted on the cover of the light sensing apparatus of the present invention. 
     FIG. 9 is an electrical schematic of the sensing apparatus of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 1 of the drawings, a reflective-light, product-detection, sensing apparatus  10  consists of a mounting base  12 , which positions a conventional light source emitter  14  in a first bin  16 , and a photoelectric light receiver sensor  18  in a second bin  20 . The light emitter  14  and the receiver  18  are rigidly mounted by mounting connectors  15  to the base  12  for proper alignment. Additional support for the light emitter  14  and receiver  18  are provided by the close tolerances within the bins  16  and  20  which hold the light emitter  14  and the receiver  18  tightly in position. This configuration allows the light sensing apparatus  10  to be transported without disturbing the positioning of the emitter  14  or the receiver  18 . Therefore, the light sensing apparatus  10  may be transported without requiring re-calibration. 
     The light sensing apparatus  10  utilizes an emitter  14  to generate a beam of light  20 . The beam  20  travels from the emitter  14  to a first light reflector  22 . The beam  20  is reflected from the first light reflector  22  to the second light reflector  24  where it is redirected back to the first light reflector  22 . The beam  20  is reflected between the first light reflector  22  and the second light reflector  24  to adequately cover the detection area  32  for the size of product being detected. The beam  20  is reflected at an angle so that the reflected beam  20  is directed into the receiver  18 . If the beam  20  is not blocked or broken, a continuous signal will be provided at the receiver  18 . If the beam  20  is broken, the signal will stop which can alert the user. The signal may also be inverted to allow for a product absence detector as further described herein. 
     The base  12  is also known as a rigid mounting surface  12 . The base  12  is manufactured from a heavy duty cast aluminum to provide a rigid mounting surface for the detectors, and provide a tamper and impact resistant housing for the detector  10 . The base  12  provides a solid foundation for mounting the light source  14 , the light sensor  18 , and the light reflectors  22  and  24 . The solid foundation of the base  12  allows the light source  14 , light sensor  18 , and light reflectors  22  and  24  to be permanently positioned for proper operation. The base  12 , which is typically an inch to two inches high allows the apparatus  10  to be attached to pre-existing machines or assembly lines to determine when a product is being delivered. The base  12  also includes a device mounting location  49  for mounting the apparatus  10  near a product ejection area. 
     Drain holes  13  in the base  12  casting are provided to avoid a build up of oil or cleaner in the base  12 . These drain holes  13  allow for cleaner to be sprayed onto the light reflectors  22  and  24  without disassembling the device  10 . Once the cleaner has been sprayed onto the light reflectors  22  and  24 , the cleaner will drain off of the light reflectors  22  and  24  and may drain through the drain holes  13  and out of the device  10 . This allows for easy cleaning of the device  10  without a significant cost of time to the user. 
     A printed circuit board  42  is mounted to the base  12 , by a 3 point system  43  to help eliminate stress on the circuit board  42  during rough handling or in impact situations. The board  42  is enclosed inside the base  12  behind an internal protective cover  40 . This cover also protects all of the internal connections between the light source  14 , light receiver  18 , and the connecting cable  44 . The light source  14 , light receiver  18 , and the light reflectors  22  and  24  are firmly mounted and held in alignment by the aluminum base  12  and no alignment adjustments are needed or provided with the device  10 . 
     The light emitter  14  and the receiver  18  are conventional units as widely used in the prior art. For purposes of this application, the light emitter  14  is also known as a light source  14 , and the receiver sensor  18  is also known as a light receiver  18 . The light receiver  18  generates and controls an output signal that may be monitored for detecting a change in the status of the light beam  20  being received by the light receiver  18 . 
     The mounting connectors  15  hold the light emitter  14  and the light receiver  18  in position on the base  12 . The mounting connectors  15  may be any type of connection that is appropriate for mounting items to the base  12 . Known mounting connectors  15  that are appropriate for the present invention include pins, screws, welds, rivets, glue, bolts, zip ties, and other secure methods that are conventionally known in the art of connectors. 
     The first bin  16  is snapped in association with the connectors  15  to properly align the light source  14  within the base  12 . The second bin  20  is similarly snapped to properly align the light receiver  18  within the base  12 . The proper position of the light source  14  and the light receiver  18  is determined by the number of reflections  28  used in the application and the distance between the reflectors  22  and  24  in the base  12 . This determination is standard for light transmission systems and thus, will not be described in further detail. Once the proper position has been determined, the light source  14  and the light receiver  18  can be permanently mounted to the base  12  without requiring further adjustment or re-alignment of the device  10  during operation. 
     The double strength reflectors  22  and  24  are permanently attached on a unique adhesive-based, shock-resistant mounting where the alignment of the reflectors  22  and  24  has been machined directly into the base  12 . The reflectors  22  and  24  are mounted to lower holding peaks  23  by an elastic adhesive substance  25 . This mounting configuration provides a series of peaks  23  and cylinders  21  which hold the elastic adhesive substance  25  such as glue or some other type of mounting substance. The elastic adhesive  25  holds the light reflectors  22  and  24  in place on the cylinders  21  and the peaks  23 . This mounting configuration protects the light reflectors  22  and  24  from breaking during transportation and use of the apparatus  10 . An additional advantage of this mounting configuration allows for the reflectors to work even if the reflectors break during transportation or use of the apparatus  10 . Because the light reflectors  22  and  24  are supported in multiple locations, an individual break or crack in the light reflectors  22  and  24  will not affect the angle of reflection of the light due to the support provided by other locations. 
     The first light reflector  22  is used to reflect the light beam  20  from the light source  14  towards the light receiver  18  to form a detection area  32 . The second light reflector  24  redirects the light beam  20  back towards the first light reflector  22 . In this manner, the light beam  20  travels between the first light reflector  22  and the second light reflector  24  to cover the opening of the light detection area  32 . The path across the detection area is called a reflection  28 . The path from the light source  14  to the first reflector  22  is also called a reflection  28 , as is the path from the first reflector  22  into the light receiver  18 . 
     A reflection  28  is one segment of the path traveled by the light beam  20  between the light source  16  and the light receiver  18 . By increasing or decreasing the number of reflections  28  in the path of the light beam  20 , the sensitivity of the light sensor  10  to various sizes of objects may be adjusted. As the number of reflections  28  is increased, the open area  30  between the reflections  28  is decreased and smaller products may be detected. Conversely, as the number of reflections  28  is decreased, the open area  30  is increased and the associated size of the product that will be detected is increased. The maximum number of reflections  28  is limited by the strength of the light emitter  16 , the efficiency of the light reflectors  22  and  24 , the sensitivity of the light sensor  18 , and the clarity of the air or other background medium associated with an empty product detection area  32 . 
     The number of reflections  28  is controlled by the angle positioning of the light source  14  and the light receiver  18  to the light reflectors  22  and  24 . Additional adjustments may be made when determining the size of the device  10  by adjusting the distance between the light reflectors  22  and  24 . An alternative embodiment of the sensor  10  would locate the light source  14  and light receiver  18  on opposite sides of the detection area  32  so that an odd number of reflections  28  could be used to cover the detection area  32 . Thus, a light sensor  10  could be constructed with three reflections  28 , where the first reflection  28  travels from the light source to the first reflector  22 , the second reflection  28  travels from the first reflector  22  to the second reflector  24 , and the third reflection  28  travels from the second reflector  24  to the light receiver  18 . 
     The product detection area  32  is shaped to allow for a mounting location in proximity to said a product ejection area on a machine or supply line. The product detection area  32  may be a circle, square, rectangle, polygon, oval or any other shape that allows for the product to pass through an opening where the light beam  20  may be directed between the light source  16  and the light receiver  18 . 
     The light source  14 , light receiver  18 , the light reflectors  22  and  24 , the circuit board  42 , and other internal components are protected by an external protective cover  50 . Attached to the cover  50  are splashguards  52  and  54  to further protect the components of the sensor  10 . The components include the light source  14 , light receiver  18 , and reflectors  22  and  24 . The splashguards  52  and  54  protect the components from an impact and/or contact from the product and/or debris associated with the manufacturing process or environment. The outside cover assembly  50  is made from an attractive brushed stainless steel and appropriately marked with a use warning. Other materials such as plastics, natural products, metals, or other items may be used which are suitable for the mounting location of the light sensing apparatus  10 . 
     The reflective light sensing apparatus  10  utilizes an external product guide  34  that is mounted to the guide mounting location  36  on the cover  50 . The guide  34  directs the product that is being detected into, through, and out of the detection area  32 . The external product guide  34  is shown in FIGS. 6-8 as mounted on the cover  50  of the apparatus  10 . 
     FIGS. 5-8 of the drawings show the mounting of the splashguards  52  and  54  which are also known as the first mask  52  and second mask  54 . The splashguards  52  and  54  are constructing with masking holes  53  to form a first mask  52  and second mask  54  for controlling and shaping the beam  20 . FIG. 5 shows a top view of the cover  50  with the first mask  52  and the second mask  54  mounted to the mask mounting locations  56 . FIG. 6 is a front view of the first mask  52  that is used in coordination with the first reflector  22 . FIG. 7 is a front view of the second mask  54  that is used in co-ordination with the second reflector  24 . The masks  52  and  54  are positioned in front of the light reflectors  22  and  24  to block the secondary light that is not a part of the direct beam  20 . The masks  52  and  54  allow the receiver  18  to be more sensitive to a break in the beam  20  by reducing the loss in sensitivity that is associated with stray secondary light contacting the light receiver  18 . 
     As shown in FIG. 9 of the drawings, a simplified electrical schematic of the wiring diagram for the sensing device  10  allows for a DC type source or sink style of electrical signal to be connect to the device  10 . An alternative embodiment of the present invention may also use an alternating current style of sensors. However, the alternating current style of sensors will not generate the sourcing and sinking signals that the direct current style of device  10  will provide. In the preferred embodiment, the device  10  will utilize direct current power supplies and sensors and this embodiment will be further described herein. The device  10  is connected to a power supply so that the device  10  will supply both sinking and sourcing signals to accommodate most controls. These signals can be used at the same time should the need arise. The device  10  provides dual sensing-signal outputs in the form of a sourcing signal output and a sinking signal output. An input voltage  64  is connected to provide power to the light source  14  and the light receiver  18 . The switch contacts  66  and  68  within the receiver  18  can be set in two different switching positions by a selector switch  19 . The first switching position provides for the contact to be closed when a light signal is detected. The second switching position provides for the contacts to be open when a light signal is detected. This method of providing an output signal is common in the prior art and will not be described in further detail. The first output from the light receiver  18  may be connected to provide power to a sourcing signal load  60  so that the sourcing load  60  may receive power when the sourcing receiver switch  66  is closed. A second output from the light receiver  18  may be connected to provide power to a sinking signal load  62  so that the sinking load  62  may dump power when the sinking receiver switch  68  is closed. Separate wire pairs for sinking and sourcing signals are supplied for maximum flexibility of custom installations to a broad range of external components. 
     The final installation of the apparatus  10  is made easy by the absence of the alignment requirements of other sensor devices. The apparatus  10  is assembled into one rigid unit and does not require an alignment adjustment to the photoelectric sensors. A 10-foot connector cable  44  is sealably attached to the detector  10  and the other end is stripped, tinned, and color-coded, ready for connection to the monitoring equipment. The conductor seal is maintained by means of a liquid tight strain relief compression fitting. 
     Two indicator lights  46  and  48  are provided for the sensors. The first indicator light  48  shows that power is being supplied to the light source  14 . The second indicator light  46  is used to show the status of the detector  18  as receiving the light beam  20 . These indicators  46  and  48  are visible from a distance and make supervision of the detector simple. 
     The apparatus  10  is attached to the equipment to be monitored using at least two of the four mounting holes  49 . The apparatus  10  should be mounted in such a manner as to allow the product to pass through the detecting area  32  when expelled from the manufacturing process. Movement and oscillation of the detector  10  are of no importance as long as the detector will not migrate into the moving parts of the monitored equipment, or shift enough to prevent the product from passing through the detection area  32 . 
     Light and dark operation is important if your manufacturing equipment does not use a timing signal for a cycle. This is usually the case in extrusions, pouring, monitoring overflows, or any continuous process that is not cyclic. In these cases the process begins and remains constant until the equipment is deliberately stopped. To select the proper operation mode for your equipment you must decide if absence of product or presence of product causes your equipment to fail. To change between light and dark operation modes a rotary selector switch  19  is provided on the photoelectric receiver  18 . 
     Any number of external problems could cause signal loss from the detector including a broken or loose connection, a transformer failure, or cut connections coming from the detector after the equipment is started. If the proper operation mode has not been selected your equipment will continue to run with the detector disabled. Using the light and dark operating modes properly will prevent this from happening. 
     When the selector switch  19  is set to the first position, the apparatus  10  is operating in the light operated mode. On power up the receiver will see light and will close the switches  66  and  68  to turn on the output to the sinking and sourcing signal wires. When product passes into the detection area  32 , the product blocks a significant amount of the light beam  20  and the signals are turned off until the product exits the detection area  32 . 
     When the selector switch  19  is set to the second position, the apparatus  10  is operating in the dark operated mode. On power up the receiver  18  will see light and will not turn on the sinking and sourcing signals. When product passes into the detection area  32  it blocks a significant amount of the light beam  20  and the signals are turned on until the product exits the detection area  32 . 
     The apparatus  10  can be rotated and tilted to any angle to suit the ejection path of the product. In some cases it may be advantageous to rotate or tilt the detector  10  for a wider profile of a thin part. This can make a normally undetectable product detectable. 
     In addition, the devices can be mounted in a front to back configuration to obtain redundant sensing. By placing a first sensor so that its detection area is located in alignment with a second sensor&#39;s detection area, a product may be made to pass through both the first and second sensor detection areas. This will allow for the first sensor to send a first signal and a second sensor to send a second signal so that a redundant signal is obtained by the sensor system. This type of mounting provides a series relationship for the sensors. The present invention may also be mounted in a side by side, or parallel, configuration to accommodate closely ejected multiple product systems where two or more parts ejected simultaneously. 
     A gain adjustment  17  is provided on the receiver  19 . Adjustments are set to obtain a balance between part size and the pollutants associated with an operating environment. Increasing the gain will allow for the detection of smaller product profiles but will make the detector more sensitive to environmental conditions. Decreasing the gain will increase the required product profile and decrease the environmental sensitivity. In most cases adjustments are not needed to the gain adjustment  17 . 
     By creating a detection area  32  for the product to pass through the variation of the product ejection path is not as critical. Most manufacturing system&#39;s ejection path consistency can be extremely poor. The present device  10  will allow the product to be detected as long as it passes through the detection area  32 . In extreme cases where product occasionally is ejected poorly and does not pass through the detection area  32 , accessory entry guides can be mounted in the accessory mounting holes to help ‘funnel’ the product into the detection area  32 . 
     The detector  10  should be positioned to allow the average ejection path of the product to pass through the center of the detection area  32 . The detector  10  should be placed as close to the ejection point as possible without incurring damage from moving parts of the equipment. This will allow the detector  10  to signal the condition of the product as early as possible in the cycle. In fast moving equipment this can reduce the effects of an occasional slow ejection of product. Fasten the detector in place using at least two of the four tapped mounting holes  49  provided. As long as the detector  10  does not move enough to allow the product to miss the detection area  32  the mounting will work. 
     Thus, although there have been described particular embodiments of the present invention of a new and useful Mounting Bracket for Product Sensor, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.