Abstract: A fault pre-warning device for use in tufting machines has a switching strip (11) over which the carpet web is guided in such a way that the switching strip (11) is acted on by a defined force in the switching direction. On the occurrence of excessive tension in one or more of the warp threads the switching strip (11) initiates a switching process.

Abstract: Light barrier apparatus arranged in a housing comprises at least one photoelectric converter, at least one front lens arranged in a wall of the housing, an electronic circuit connected to the photoelectronic converter(s), power supply lines leading from power supply terminals to the electronic circuit, and also, in the case of a receiver or a transmitter/receiver signal lines and signal terminals. The housing is subdivided into first and second housing parts (11, 12) which are pivotably connected together by an articulated coupling (15). The first housing part (11) contains, at least in large part, the electronic circuit including the power supply lines, power supply terminals and, if present, the signal lines and signal terminals. The second housing part contains at most a part of the electronic circuit, the electronic converter and also the front lens.

Abstract: A photoelectronic apparatus, in which a photoelectric convertor (the operational convertor) receives a beam of light and produces an output signal proportional to the intensity of the light received, is protected against the effects of unwanted light by providing an auxiliary photoelectric convertor arranged in the vicinity of the operational convertor. The auxiliary convertor detects the presence of unwanted light and its output is subtracted from that of the operational convertor and the resultant signal is then examined to distinguish between events occuring in the light beam and events simulated by the unwanted light.

Abstract: Closing and opening movements are effected by a reversible motor M. The motor M receives its power from a supply U via a feed circuit which includes switch contacts r.sub.1, r.sub.2 controlled by a relay R. The arrangement is such that a closing movement takes place when the relay is energized and an opening movement when the relay is deenergized. To select these two movements there is provided a selector switch S in the feed circuit which has two operative positions and an intermediate neutral position. The excitation winding of the relay R is included in a monitoring circuit in parallel with a strip-like safety switch SL. The strip-like safety switch SL is positioned in the path of the closing movement and has two strip-like contact bands 1, 2 which are pressed together if an object should become trapped in the path of the closing movement. If this occurs the excitation winding of the relay is short circuited and it automatically reverses the motor to convert the closing movement into an opening movement.

Abstract: Light barrier apparatus generally features a light transmitter for projecting light across a region to be monitored to a light receiver. The light transmitter and receiver units can either be separate or can be combined in a single housing and used in conjunction with a retro-reflector for returning light from the sender to the receiver.In any of these arrangements the light transmitter and/or sender units incorporate photoelectric converter components 11, 12 and optical projection components 13, 14 together with electronic processing elements which enable interruption of the light barrier to be detected. The present arrangement features a housing 17 including at least one sealed chamber 15, 15', 15" containing solely the optical and photoelectric converter elements. These chambers are thus sealed against the ingress of contamination and moisture. The remaining elements of the electronic processing circuit are housed separately in a further chamber 16.

Abstract: A transmitting lens and a receiving lens are arranged alongside each other on one narrow side of a shallow housing so that a pencil beam of light transmitted by the transmitting lens and reflected by a separate reflector is received by the receiving lens and concentrated onto a photoelectric converter. Interruption of the pencil beam of light results in interruption of the output signal from the photoelectric converter and is detected and used to actuate an alarm signaller located within the housing. The alarm signaller, which is preferably a buzzer, is connected with the housing to form a single constructional unit. The optics and electronics are conveniently mounted on a circuit board which is conveniently located within the housing and secured by a resilient cushion.

Abstract: An optical apparatus for use in conjunction with spherically shaped concave mirrors for substantially eliminating aberrations in the reflections from such mirror. The mirror cooperates with a light source or a light receiver placed in the vicinity of but off-set relative to the natural focal point of the mirror. A plane parallel, transparent plate is placed between the mirror and the light source or receiver and it has a size so as to intercept light rays between the mirror and the light source or receiver and which respectively result in or are caused by light beams oriented parallel to the optical axis of the mirror. Use of the invention for additionally correcting astigmatism and chromatic aberrations caused by spherical mirrors is disclosed. Also disclosed is the use of the invention in connection with large spherical mirrors forming part of light curtain arrangements.

Abstract: A light barrier system for monitoring the presence or absence of an obstacle in the monitored area and for simultaneously monitoring itself to detect contamination of the system. A photo-converter emits signals indicative of the light intensity of a light barrier beam and the signal is applied to a first, obstacle switch which is normally open but which closes at a relatively high level of darkness, i.e. when an obstacle is present. A converter signal is also applied to a second, contamination switch which is normally open but which closes at a lesser degree of darkness than the first switch so that both switches can be simultaneously closed. The outputs of the switches when closed are applied to relays to switch the relays between alternative position to indicate (a) the presence of an obstacle in the light curtain area and (b) the contamination of the light curtain system irrespective of whether or not an obstacle is present.

Abstract: An electrooptical scanning device which can detect the relative position of register mark applied to a moving web, either serially on a single track or in two parallel, side-by-side tracks which extend in the direction of movement of the web. Light from a light source positioned some distance above the web is split into three light beams and the light beams are reflected downwardly towards the web. Lenses are positioned to receive and direct the light beam at an oblique angle onto the marks on the track or tracks. The lenses are aligned with the tracks and the light beam passing through a given lens is directed to the opposite track to illuminate three positions, two on the first track and one position on the second track. Light impinging on the web at these positions is scattered.

Abstract: A light curtain for scanning rectangular openings with an oscillating light beam originating in a corner of the opening. A photo-detector is placed in the same corner. Retroreflectors, such as triple reflectors are placed on adjacent sides of the opening which are opposite the light source for reflecting light back to the photo-sensor. Above a critical reflection angle for the retroreflector, a plane mirror is provided which directs light from the source to the retroreflector on the adjacent side so that light impinging on the mirror at an angle exceeding the critical angle is received by the adjacent retroreflector at an angle that is within the critical angle. Consequently, such light is reflected via the plane mirror back to the photo-sensor. The light can be modulated to facilitate the monitoring of the area encompassed by the opening.

Abstract: Bottle color identification apparatus with a light beam passing through the bottle, in which the light beam passing through the bottle is supplied to a spectral decomposition arrangement which emits a signal characteristic of the bottle color.A special application of the invention is the sorting of returnable bottles having the same size and shape but different colors.

Abstract: A light barrier system is provided which includes a light transmitter, a light receiver to receive the light beam transmitted over a predetermined path, an indicator unit which is connected to the light receiver and produces a signal when an obstacle is detected in the path, and a power unit supplying the light transmitter, light receiver and indicator unit. The power unit consists essentially only of a rectifier. A pulsed light source is employed, operated by the discharge of a capacitor in the rectifier output.

Abstract: A reading device for optically detectable digital codes with two different light-reflecting types of fields. It comprises: a scanning beam arrangement having a timing raster with two different light-reflecting types of serially-numbered fields, means for conducting part of the scanning beam via said timing raster and the rest onto the code fields, a timing signal photoelectric cell receiving the light reflected back by the timing raster, a coding signal photoelectric cell receiving the light reflected back from the code field, and an evaluation electronic system connected to the outputs of the photoelectric cells for determining the length of the code fields in units of the timing raster in the scanning direction. Each code field length is associated with a number of timing fields varying between two predetermined limits.