초록 ▼

A method and a device for indicating the presence of an object in a measuring zone (E), and for objects having a measurable cross-sectional shape, also the extent of the object along a reference line (R). The method and device makes use of lines (A, B) of radiation emitters (11) and radiation receiv

A method and a device for indicating the presence of an object in a measuring zone (E), and for objects having a measurable cross-sectional shape, also the extent of the object along a reference line (R). The method and device makes use of lines (A, B) of radiation emitters (11) and radiation receivers (12) located on opposite sides of the object, the receivers being fewer than the emitters. Created between the emitters and the receivers is a network of intersecting radiation paths in the measuring zone. An electronic unit (20) establishes which intersections (P 1 ) of the radiation paths are screened-off by the object. The invention is useful for indicating the presence of objects with arbitrary cross-section when it is desired to determine a lower limit for the size an indicated object shall have, and to determine a diameter measurement, in particular in the saw mill industry.

대표청구항 ▼

1. A method of indicating the presence of an object in a measuring zone E, and of measuring with a degree of accuracy depending on the cross-sectional shape of the object, the extent of the object along a reference line R located in the measuring zone comprising: positioning plural groups of stat

1. A method of indicating the presence of an object in a measuring zone E, and of measuring with a degree of accuracy depending on the cross-sectional shape of the object, the extent of the object along a reference line R located in the measuring zone comprising: positioning plural groups of stationary radiation emitters and receivers on opposing sides of said measuring zone so that radiation paths between them intersect in the measuring zone, each group including at least one emitter and at least one receiver; sucessively actuating and deactivating said emitters in a scanning sweep; successively interrogating one group of receivers after another at the same pace as the emitters are activated and deactivated, each group of receivers comprising at least one receiver; each activated emitter emitting radiation along diverging paths toward a plurality of receivers on the opposite side, and each activated receiver receiving radiation along converging paths from a plurality of emitters on the opposite side, whereby a network of radiation paths is created in the measuring zone having intersections with fixed predetermined locations; determining with electronic computer means which intersections are occupied by the object and the extent of the object along the reference line to establish with said degree of accuracy two uninterrupted intersections on the reference line between which a length of screened-off intersections lies; and repeating the scanning sweep and successive interrogation of receivers as desired in a plurality of cross-sectional planes relative to the object as the latter is transported at right angles to the planes past the emitters and receivers. 2. The method of claim 1, and further employing a plurality of reference lines subtending a selected angle, such as 90°. 3. The method of claim 1 wherein the extent of a scanning sweep is established on the basis of a previous scanning sweep on the same object, and is smaller than the maximum scanning sweep. 4. A device for indicating the presence of an object (10) in a measuring zone (E) and, with a degree of accuracy depending on the cross-sectional shape of the object, of the extent of the object along a reference line (R) located in the measuring zone, comprising: a carrier means for the object, a plurality of radiation emitters and receivers located so that radiation paths between them intersect in the measuring zone, and an electronic unit connected to said emitters and receivers and adapted to establish an indication result on the basis of radiation paths screened-off by the object, wherein on each of at least two opposite sides of said carrier means and at an invariable spacing therefrom, a plurality of receivers is provided at predetermined spacing, and between at least some pairs of neighbouring receivers at least two emitters are provided at smaller spacings, said emitters and receivers being located as to create in the measuring zone a network of inter-connecting radiation paths with a plurality of intersections (P 1, P 2 ), the emitters being adapted to emit, upon activation by the electronic unit, radiation along diverging paths towards a plurality of receivers on the opposite side and subsequently to be deactivated, the receivers being adapted to receive, upon activation by the electronic unit, radiation along converging paths from a plurality of emitters on the opposite side, and subsequently to be deactivated, and the electronic unit being programmable with the locations of said intersections and sequentially activating and deactivating the emitters one after the other, and at the same pace, the receivers in sequence one group after the other, each group comprising one or more receivers, said electronic unit being employed to determine on the basis of interrupted radiation paths which intersections are occupied by the object, and therefrom to conclude on the presence of an object of predetermined minimum magnitude in the measuring zone and, with said degree of accuracy, on the extent of the object along the reference line. 5. The device of claim 4, wherein the emitters and receivers on each side of the carrier means are arranged in lines (A, B) parallel with said reference line, equidistant therefrom and lying in the measured cross-sectional plane of the object. 6. The device of claim 4, wherein for the increase of the resolving power of the device, said receiver groups comprise two or more receivers (12'). 7. The device according to claim 4, wherein the location of the emitters and receivers on one side of the carrier means are positioned relative to the emitters and receivers on the opposite side, e.g. by half the receiver spacing. 8. The device according to claim 4, wherein the number of emitters and receivers on one side of the carrier means is greater than on the opposite side. 9. The device according to claim 4, wherein in order to prevent deterioration of measuring results in marginal zones of said lines, the number of emitters between a marginal pair of receivers on at least one side of said carrier means is smaller than the number between other pairs of receivers. 10. The device according to claim 4, and further comprising a module including one receiver and all the emitters between two receivers, said module defining a unit which can be used together with other equal units to form a measuring ramp (A', B'). 11. A method of indicating the presence of an object in a measuring zone using a plurality of stationary radiation emitters and receivers positioned on at least two opposite sides flanking the measuring zone so that the radiation paths between them intersect in the measuring zone, comprising controlling the emitters and receivers with an electronic unit by activating said receivers and said emitters in a scanning sweep manner by activating said emitters individually seriatim and said receivers in predetermined groups of one or more seratim, sensing screening-off of separate radiation paths by the object with said electronic unit by creating a network of said radiation paths which meet in a network of predetermined location intersections, storing the locations of said intersections, and determining a dimension of the object along a line in the measuring zone based on said intersections screened off and not screened off by said object. 12. A method of indicating the presence of an object in a measuring zone using a plurality of stationary radiation emitters and receivers positioned on at least two opposite sides flanking the measuring zone so that the radiation paths between them intersect in the measuring zone, comprising controlling the emitters and receivers with an electronic unit, sensing screening-off of separate radiation paths by the object with said electronic unit by creating a network of said radiation paths which meet in a network of predetermined location intersections, storing the locations of said intersections in said electronic unit, determining a dimension of the object along a line in the measuring zone based on said intersections screened off and not screened off by said object, said object being known to decrease in size along said line in the measuring zone at successive locations along its length, moving the object through the measuring zone in the direction of its length, and controlling the emitters and receivers at each measurement along its length starting from the previous measurement, whereby the speed of each measurement is speeded compared to what it would be if each measurement were made based on all of said predetermined location intersections. 13. The method of claim 11, further comprising providing said receivers in smaller number than said emitters, whereby each receiver receives radiation from a plurality of said emitters. 14. The method of claim 11, further comprising spacing said emitters and said receivers respectively each along its respective side flanking said measuring zone at predetermined spacings. 15. The method of claim 12, further comprising activating said receivers and said emitters in a scanning sweep manner by activating said emitters individually seriatim and said receivers in predetermined groups seriatim. 16. The method of claim 13, and further comprising spacing said emitters and said receivers respectively each along its respective side so as to flank said measuring zone at predetermined spacings. 17. The method of claim 13, and further comprising activating said receivers and said emitters in a scanning sweep by activating said emitters individually seriatim and said receivers in predetermined groups seriatim.