Abstract: A safety lock as taught herein comprises first and second members and is configured to lockably mount to an interlock switch. In one or more embodiments, the second member slidably couples to the first member and slides between a disengaged position that allows for mounting and an engaged position that engages a corresponding switch actuator opening in the interlock switch. In at least one embodiment, the second member projects through an opening in the first member into engagement. The first and second members may include corresponding lock openings, allowing the second member to be locked into the engaged position. In at least one embodiment, the first member conforms at least partially to the exterior of the interlock switch, e.g., it spans at least one exterior corner of the interlock switch. The first member may include an engagement finger to engage a corresponding switch actuator opening of the interlock switch.

Abstract: An active joining trim assembly allows the assembly's cover member to float on the abutting edge regions of adjacent safety mats. With this configuration, the joining trim assembly functions as an “active,” weight-responsive area. In at least one embodiment, the active joining trim assembly comprises a base member, a cover member, and one or more retaining members that clip or otherwise snap the base and cover members together. For example, in one embodiment, the underside of the cover member includes a clip retaining feature, the base member includes a central channel, and the retaining member(s) fasten or otherwise anchor to the clip retaining feature and flexibly clip onto the central channel in sliding, vertical engagement. Equivalently, the retaining member(s) anchor to the base member and flexibly clip onto the clip retaining feature of the cover member.

Abstract: A safety lock as taught herein comprises first and second members and is configured to lockably mount to an interlock switch. In one or more embodiments, the second member slidably couples to the first member and slides between a disengaged position that allows for mounting and an engaged position that engages a corresponding switch actuator opening in the interlock switch. In at least one embodiment, the second member projects through an opening in the first member into engagement. The first and second members may include corresponding lock openings, allowing the second member to be locked into the engaged position. In at least one embodiment, the first member conforms at least partially to the exterior of the interlock switch, e.g., it spans at least one exterior corner of the interlock switch. The first member may include an engagement finger to engage a corresponding switch actuator opening of the interlock switch.

Abstract: A pressure-sensitive mat system includes a mat with a recessed mat connector and a cable assembly that includes a cable connector that detachably mates to the mat connector. The cable connector is sized to the inset area of the mat connector and thus conforms to the dimensional envelope of the mat. Conforming to the mat's dimensional envelope minimizes tripping hazards, reduces the likelihood of cable damage, and permits the use of flush fitting edge trim strips that may be used to secure the mat to the floor. In one embodiment, the cable connector mounts to the mat connector via threaded fasteners. The use of threaded fasteners permits compressive connector engagement, which enhances inter-connector electrical contact integrity and permits the use of an interposed connector gasket that provides watertight sealing when the two connectors are compressively engaged. The connector(s) may include other features such as air vents to vent the mat interior.

Abstract: A presence sensing system provides one or more visible indicators useful for indicating a relative location of objects sensed within the scanning field of view. For example, the system may have an indicator array or an integrated display assembly in which individual indicators or indicator positions correspond to defined portions of the system's field of view. In this manner, the presence sensing system can indicate where one or more sensed objects lie within its field of view. The system may monitor or otherwise scan an angular field of view and may have an indicator array comprising a plurality of individual indicators, each one corresponding to a portion of the monitored area. With this configuration, the system selectively illuminates or otherwise activates those indicators in the array corresponding to the relative angles of detected objects within its field of view.

Abstract: A coupling system allows interconnection of multiple light curtains segments but prevents interconnecting dissimilar segment types. A first connector half mounts to a segment while a second connector half mounts to another segment, such that mating the two halves interconnects the two segments. The two mating sections of the connector or coupling system may be formed as matched mating blocks that are mounted in different orientations, depending upon whether they are attached to transmitter or receiver type light curtain segments. One or both mating sections may rotatably mount to its respective segment, thereby providing an articulated connection between the joined segments. In other implementation, one mating section may be formed as a reversible coupler, with the other mating section formed as a mating receptacle that may be conveniently keyed to accept only a particular orientation of coupler.

Abstract: A data reduction circuit serves as a post-processor for digitized waveform data, providing reduced data sets for subsequent processing. Preferably, the data reduction circuit receives one or more potentially long sequences of digital waveform data and provides as output sets of sequence numbers corresponding to transitions in the digitized waveforms. In this manner, a processor concerned with the location of waveform transitions is relieved from the burden of processing the sequences just to identify the transition points. In some embodiments, the data reduction circuit cooperates with a waveform digitizer that produces digitized sequences of comparator waveforms in a laser-based distance measuring circuit. Transition points in the digitized waveform correspond to return reflections of emitted laser pulses and may be used to identify laser pulse flight time.

Abstract: A mixed architecture light curtain system comprises a mix of flexibly and rigidly interconnected light curtain segments. For example, a number of light curtain segments may be rigidly interconnected in series at desired connection angles using one or more types of rigid connectors to form a set of rigidly connected segments. Another set of rigidly connected segments may be flexibly connected to this first set, or one or more individual segments may be flexibly connected in series with this first set. In general, a series of interconnected segments may be formed in any desired combination of rigidly and flexibly connected segments. In any such combination, differing types of rigid and flexible connectors may be used, such that rigidly and flexibly interconnected segments may be fixed at essentially any desired angle, offset, or relative spacing, allowing the mixed architecture light curtain to conform to complex and even disjointed protection zone shapes.

Abstract: A circuit generates a test signal useful in verifying the actual delay values of individual delay stages in a digital delay line. In general, the cumulative delay of the delay line defines a window in time having its zero point anchored to the beginning of the delay line. Successive delay stages correspond to successive time bins within the overall time window. The test signal shifts at a known, linear rate in time with respect to a reference signal, which is used to initiate a test cycle. The reference signal synchronizes sampling of the test signal to the beginning of the time window. Samples of the test signal are taken at sample points determined by the actual time delays in the successive delay stages. The observed distribution of test signal edges across the time window may be used to determine the actual delay intervals of the delay line.

Abstract: A clockless time-of-flight interval timer includes a tapped delay line register comprising N buffers that each contribute a substantially identical incremental time delay. A latched version of a START pulse associated with an output of transmitted energy from a laser is propagated through the tapped delay line. A DATA signal representing a detected pulse returned from a target is coupled to a block of four comparators each having a different signal threshold. The output of each comparator block is provided as input to one of four channel registers, each register comprising N D-type flipflops separately but synchronously triggerable by tapped incrementally delayed outputs from the N buffers. Channel register outputs are multiplexed and decoded and interfaced with a microprocessor. The microprocessor determines first signal time over threshold (FOT) information and total time over threshold (TOT) information from the channel registers.

Abstract: A modular articulated light curtain is formed by combining straight, curved, or angled modules with straight or angled couplers. Modules include an array of pitched light emitters or light detectors, and have rounded distal ends that mate, mechanically and electrically, with each other or with a coupler. Interconnection of adjacent modules is such that a constant pitch of light emitters or light detectors is maintained. The light curtain comprises an assembly of interconnected light emitting modules spaced-apart from interconnected light detecting modules. One end of each assembly is terminated, while the other assembly end has a cable end module that may include at least one light emitter or detector, and may include a visual indicator, and provides input/output electrical interface to the light curtain.

Abstract: A modular articulated light curtain is formed by combining straight, curved, or angled modules with straight or angled couplers. Modules include an array of pitched light emitters or light detectors, and have rounded distal ends that mate, mechanically and electrically, with each other or with a coupler. Interconnection of adjacent modules is such that a constant pitch of light emitters or light detectors is maintained. The light curtain comprises an assembly of interconnected light emitting modules spaced-apart from interconnected light detecting modules. One end of each assembly is terminated, while the other assembly end has a cable end module that may include at least one light emitter or detector, and may include a visual indicator, and provides input/output electrical interface to the light curtain.

Abstract: A trim structure for use with safetymats. The trim structure is of two-part construction and includes a rigid base which is fastened to a floor together with a cover formed of a resilient material. The top wall of the cover and the bottom wall of the base carry interlock structures which include releasable engagement members. In an assembled mode, the engagement members function to hold the cover on the base. The top wall is separated from the bottom wall to form a wireguide through which the cables or wires leading from the safetymat can be threaded. The trim structure can be easily disassembled by pulling the cover from the base to cause the engagement members to disengage.

Abstract: An optical sensing array and method of operation for controlling the acceptance angle of light beams which are iteratively strobed in side-by-side channels between light transmitters and light receivers. In one embodiment, the light beams in at least a pair of channels are directed along axes which are intentionally mispointed or squinted. A control circuit measures the amplitudes of signals produced responsive to light being received by the light receivers and compares the ratio of those amplitudes to the ratio of predetermined high and low amplitude values which provide a threshold window. When the ratio of the signal amplitudes exceeds the ratio of the window threshold values, an output signal is produced indicative of an unsafe operating condition. The control circuit further maintains the gain of the signals from the light receivers to stay within the range of the predetermined window threshold values.

Abstract: An optical sensing array and method of operation for controlling the acceptance angle of light beams which are iteratively strobed in side-by-side channels between light transmitters and light receivers. The light beams in at least a pair of channels are directed along axes which are intentionally mispointed or squinted. A control circuit measures the amplitudes of signals produced responsive to light being received by the light receivers and compares the ratio of those amplitudes to the ratio of predetermined high and low amplitude values which provide a threshold window. When the ratio of the signal amplitudes exceeds the ratio of the window threshold values, an output signal is produced indicative of an unsafe operating condition. The control circuit further maintains the gain of the signals from the light receivers to stay within the range of the predetermined window threshold values.

Abstract: A light curtain system and method of operation includes a control circuit having visible light indicators positioned adjacent channels of individual light beams established across a guard zone. The light beams are transmitted along a plurality of parallel channels between a transmitter bar and receive bar. The control circuit operates to sense when one or more beams are blocked by the intrusion of an opaque object. The circuit responds by operating visible light LEDs which are positioned adjacent the channels of the blocked beams. The visible light provides continuous feedback to the machine operator as to the condition of the guard zone. The visible light indicators are also used to facilitate alignment of the transmitter and receiver bars.

Abstract: A method of operation of a light curtain system for sensing the intrusion of objects into detection planes which define a protected zone. A group of light beams are strobed from one transmitter in a first direction across a zone to a receiver, and another group of light beams are strobed from another transmitter across the zone to another receiver. Light beams within each group which intersect a desired entry area are deactivated for penetration of a permitted object, and other beams in the groups are enabled to detect intrusion into the objects in portions of the zone which lie around the entry area.

Abstract: A light curtain system for sensing the intrusion of objects into detection planes which define a protected zone. A plurality of light curtain segments are provided with each segment including spaced-apart transmitter and receiver heads. The transmitter and receiver heads are each connected in series by flexible cables which form a part of a control circuit. The series-connected segments permit the detection planes to be aligned in predetermined angular orientations as required by the particular application.

Abstract: A light curtain system and method of operation which detects the intrusion of objects into a protected zone. The system is characterized in having an inherent self-checking mode of operation by logic circuits which analyze data signals from both the LED light transmitters and phototransistor receiver circuits. A shutdown signal is generated if the logic circuit determines that light is not received in a selected channel at the time that the LED is strobing light exclusively for that channel. The system further provides a relatively simple and inexpensive method of selecting and amplifying the LED transmitters and PT receivers. In the circuit each PT acts as a switch which selects itself, and a single amplifier is employed for a plurality of the channels. The circuit further provides for the concatenation of groups of amplifier/PT circuits into a longer chain using a single diode.

Abstract: A light monitoring arrangement, specifically one for monitoring relatively high frequency light pulses and producing corresponding electrical output pulses, is disclosed herein. This arrangement includes circuitry which has the tendency to become electrically saturated if the light pulses being monitored reach or exceed a certain minimum intensity level. This in turn distorts the electrical output pulses in a way which causes these pulses to merge with one another. However, the arrangement disclosed herein also includes circuitry for preventing this from occurring even if the light pulses do reach or exceed circuit saturating intensity levels.