摘要:
A detector for detecting passing magnetic articles including a magnetic-field-to-voltage transducer having an output at which an analog voltage Vsig is generated, with the Vsig voltage being commensurate to the strength of the ambient magnetic field and having at least one peak. An analog-to-digital converter coupled to the output of the transducer is operative to convert to a corresponding digital signal at least a portion of the Vsig voltage, which portion includes the peak and a circuit coupled to the analog-to-digital converter is operative to generate an output signal indicative of the occurrence of the times t.sub.xpk when the difference between Vsig and said peak of Vsig has exceeded a predetermined amount.
摘要:
A Hall-effect sensor is presented which is adapted to sense a ferromagnetic object, including an integrated circuit chip having a planar Hall element which is positioned in, parallel to, and defines a sensor plane having a front side and a back side, and which element is normal to and centered on a sensor axis, and a magnet structure having an N pole and an S pole, the magnet structure being positioned behind the sensor plane and positioned so that an S pole and an N pole are adjacent each other and both are adjacent the element.
摘要:
In a proximity-detector, a Hall transducer produces a signal Vsig. Two counters, P-counter and N-counter count pulses from a clock and produce count signals respectively to two DACs, PDAC and NDAC. The DACs output signals track and hold, respectively, the positive pulses and negative pulses in Vsig. These output signals are compared with Vsig to produce a proximity-detector binary output voltage Vout that becomes high when a tracking voltage V.sub.DAC-P produced by PDAC rises to each peak positive voltage V.sub.pk in Vsig, and that becomes low when a tracking voltage V.sub.DAC-P falls to each peak negative voltage in Vsig. The peak V.sub.DAC-P is held until Vsig drops by a fixed amount below V.sub.pk to produce an output pulse that resets the counter connected to PDAC at a time shortly following the actual peak in Vsig. Similarly, the peak V.sub.DAC-N is held until Vsig rises a fixed amount above V.sub.DAC-N to produce an output pulse that resets the counter connected to NDAC. The N-counter is reset at t.sub.npk by the negative-peak indicating signal V.sub.Ncomp and is enabled at t.sub.ppk by the positive-peak indicating signal V.sub.Pcomp, while the P-counter reset by the positive peak indicating signal V.sub.Pcomp and enabled by V.sub.Ncomp. This proximity detector detects articles passing at rates down to zero.
摘要:
A magnetic-field-to-voltage transducer includes a Hall element and a digitally gain-controlled Hall-voltage amplifier that produces an analog voltage Vsig having excursions of one polarity corresponding to the passing of magnetic articles. Vsig is applied to the input of a signal-manipulating circuit that generates a proximity- detector binary output voltage, Vout, having transitions of one direction each time a predetermined point is reached in Vsig. A digitally gain-controlled gain amplifier is connected to the Hall element. A comparator circuit generates a binary signal Vbig (or V.sub.toobig) that changes from one to another binary level each time that Vsig exceeds a DC target voltage, V.sub.TG. The AGC circuit senses and counts gain counter excursions of one polarity in Vsig, and produces a binary count output signal at the input of the gain amplifier at each of the counted excursions in Vsig, incrementally changing the transducer gain in the direction to bring the peaks in Vsig to just below the target value T.sub.TG. This AGC feature prevents saturating the amplifier and quickly renders a Vsig of essentially constant amplitude so that either the peak excursion values or predetermined threshold levels in Vsig, at which transitions in the proximity detector output voltage Vout are caused to occur, provide greater accuracy and stability in the correlation between detection-approach and -withdrawal distances and transitions in Vout.
摘要:
A magnetic-field-to-voltage transducer includes a Hall element and a digitally gain-controlled Hall-voltage amplifier that produces an analog voltage Vsig having excursions of one polarity corresponding to the passing of magnetic articles. Vsig is applied to the input of a peak-referenced-threshold signal detector that generates a binary proximity-detector output voltage, Vout, having transitions of one direction upon approaches of gear teeth down to zero speed. A digitally gain-controlled amplifier is connected to the Hall element. A comparator circuit generates a binary signal Vbig (or Vtoobig) that changes from one to another binary level each time that Vsig exceeds a DC target voltage, VTG. The AGC circuit incrementally changes the transducer gain in the direction to bring the peaks in Vsig to just below the target value TTG. Reference voltages VP2 and VN2 are generated that are equal respectively to the most recent peak positive and negative going excursion in Vsig. DC off-set-limit voltages VA and VB are provided that are respectively above and below the center of the dynamic voltage range of the detector, and the entire signal Vsig at the output of the amplifier is biased in a negative direction when the median value, Vos, of Vsig is greater than VA and moving the entire signal Vsig in a less positive direction when Vos is less than VB to keep Vos within the range from VB to VA.
摘要:
A Hall transducer produces a signal Vsig. Threshold voltages V.sub.Pth and V.sub.Nth are generated at the beginning, t.sub.update, of each of a succession of update time intervals, of 64 pulses in Vsig, to be fixed percentages respectively of the peak to peak voltage in Vsig. A proximity-detector binary output voltage is high when Vsig exceeds threshold voltage V.sub.Pth and low when Vsig is below threshold voltage V.sub.Nth. Signals V.sub.Pold and V.sub.Nold, generated by first and second DACs, are equal to the first positive and negative peaks in Vsig after each time t.sub.update initiating the start of a successive interval. Signals V.sub.Pnew and V.sub.Nnew, simultaneously generated by third and fourth DACs, are equal to the greatest positive and negative peak voltages in Vsig during the interval ending at t.sub.update. Counters present their count to the first and second DACs that count pulses from a clock for tracking and holding +/- peaks in Vsig. After each time t.sub.update, a pulse in a signal Vupdt is generated if at time t.sub.update V.sub.Nnew lies outside the range. V.sub.Nold -v to V.sub.Nold +v of if V.sub.Nnew lies outside the range V.sub.Nold -v to V.sub.Nold +v, where v is an incremental DC bias voltage. Vupdt resets the counters so that during the succeeding update time interval the threshold voltages V.sub.Pth and V.sub.Nth have the fixed percentages of the updated threshold voltages V.sub.Pnew -V.sub.Nnew.
摘要翻译:霍尔传感器产生信号Vsig。 阈值电压VPth和VNth在Vsig中的64个脉冲的连续更新时间间隔的每一个的开始时产生,分别为Vsig中峰峰值电压的固定百分比。 当Vsig超过阈值电压VPth时,接近检测器二进制输出电压为高电平,当Vsig低于阈值电压VNth时,接近检测器二进制输出电压为高电平。 由第一和第二DAC产生的信号VPold和VNold等于每次启动连续间隔开始后的Vsig中的第一个正和负峰值。 由第三和第四DAC同时产生的信号VPnew和VNnew等于在tupdate结束的间隔期间的Vsig中最大的正和负峰值电压。 计数器将其计数器显示给第一和第二DAC,它们计数来自时钟的脉冲,用于跟踪Vsig中的+/-峰。 在每次tupdate之后,如果在tupdate VNnew处于该范围之外,则产生信号Vupdt中的脉冲。 如果VNnew位于VNold- + Z v到VNold ++ Z v的范围之外,则VNold- + Z v至VNold ++ Z v,其中+ Z v是增量DC偏置电压。 Vupdt复位计数器,使得在成功更新时间间隔期间,阈值电压VPth和VNth具有更新的阈值电压VPnew-VNnew的固定百分比。