Abstract: A self-calibrating photoelectric control system for use in a checkstand to control the starting and stopping of a conveyer belt utilized to move products closer to a checkout clerk. The self-calibrating photoelectric control system including a light source for emitting a light beam having an intensity, a photoelectric sensor for receiving light from the light source and for generating an output signal when the received light is equal to or greater than a light-state threshold of the photoelectric sensor; and a calibration circuit for automatically calibrating the sensitivity of the photoelectric control system to partial beam breaks after occurrence of any one of a plurality of predefined events. The calibration circuit is operative for performing a calibration process which adjusts the intensity of the light beam emitted by the light source such that the intensity is slightly greater than the light-state threshold of the photoelectric sensor.

Abstract: A programmable photoelectric sensor and a system for programming/controlling the photoelectric sensor and for monitoring the performance of the photoelectric sensor. The system includes a processor coupled to the photoelectric sensor, which is operative for generating at least one graphical user interface and for programming/adjusting the operation of the photoelectric sensor; and a display device coupled to the processor for displaying the graphical user interface. The processor programs/adjusts the operation of the photoelectric sensor in accordance with selections of an operator utilizing icons displayed on the graphical user interface.

Abstract: A photoelectric sensing circuit for adjusting the hysteresis of a photosensor. The photoelectric sensing circuit includes a photosensor capable of receiving light and generating an output signal indicating the amount of light incident on said photosensor. The photosensor generates a first output signal when the level of received light is above a first predetermined level, and a second output signal when the level of received light is below a second predetermined level. The circuit further includes a variable light source for generating and emitting the light incident on the photosensor and a power source coupled to the light source. The power source has a variable output level for controlling the intensity of the light emitted by the light source. Finally, the photoelectric sensing circuit also includes a control circuit coupled to the variable power source for varying the output level of the power source.

Abstract: The disclosed invention is a photoelectric sensor that is capable of resolving difficult low contrast sensing tasks by adjustment of the sensor's light source intensity, so as to prevent dark state saturation and extend the overall dynamic range of the sensor. The photosensor utilizes an enhanced dynamic (EDR.TM.) control circuit that combines the light source and offset adjustment of the DC amplifier circuit in a closed loop configuration. This connection provides an automatic reduction in the light source intensity as required to avoid saturation. Further, this is accomplished without sacrificing amplifier gain, so that the dynamic operating range of the photosensor is extended to include proper operation at very bright light levels. The EDR control circuit also includes an indicator circuit that is connected to the light intensity control circuit.

Abstract: A photoelectric sensing system, the adjustment of which is facilitated by the incorporation therein of a contrast indicator with a display in the form of an array of light emitting diodes (LEDs) controlled by a driver circuit which is arranged for successive illumination of the LEDs, preferably on a one-to-one basis. This bargraph type instrument is also effective in photoelectric sensing tasks involving variations of the detected light between "light" and "dark" at a rapid rate, in which case the range of LEDs between these two extremes appears dimly lit at a steady glow.

Abstract: A start/stop control arrangement for material handling systems, particularly automated checkout systems in retail stores. From a beam sensing device at the delivery end of the incoming conveyor a control is derived not only for stopping the conveyor in response to the detection of the arrival at that end of a product but also a time control for automatically stopping the conveyor in response to no such product being detected by that device for a predetermined time. The arrangement may be incorporated in the amplifier unit which serves to amplify the output of the beam of the beam sensing device. Alternatively, and as shown herein, the arrangement may be implemented by a plug-in accessory module designed to be interposed between two cooperating plug-in modules--one of them mounting the above sensor amplifier--which provide for the first of these two controls only. Provisions are also made for double-using the arrangement for the start/stop control of the conveyor outgoing from the checkout stand.