Abstract: A counter counts the run lengths of a binarized signal. A counting result correcting portion generates frequency distributions for run lengths for first run lengths, which are from a rising edge to a falling edge of the signal, and second run lengths, which are for a falling edge to a rising edge of the signal, calculates a total number of first run lengths of lengths that are no less than 0 times and less than 1 times a representative value for the first run lengths, calculates a total number of second run lengths of lengths that are no less than 0 times and less than 1 times a representative value for the second run lengths, calculates a total number of first run lengths, calculates a total number of second run lengths, and corrects the counting results.

Abstract: A velocity measuring device emitting a laser beam at a web; a photodiode converting an optical output of the laser into an electric signal; a laser driver operating the laser to alternate a first emitting interval wherein the oscillating wavelength increases and a second emitting interval wherein the oscillating wavelength decreases; a current-voltage converting/amplifying portion converting the electric current from the photodiode into a voltage; a filter portion removing a carrier wave from the output of the current-voltage converting/amplifying portion; a signal extracting portion calculating a number of interference waveforms in the output of the filter portion; and a calculator calculating the velocity of the web based on the result of the extracting portion. The laser driver operates so the absolute values for the rates of change, in respect to time, of the oscillating wavelengths during the first emitting interval and during the second emitting interval are different.

Abstract: To reduce the probability of incorrect determination to detect an object reliably. A reflective photoelectric sensor is provided with: a light projecting device for emitting light; a light receiving device for receiving the optical feedback of the light that is emitted from the light projecting device; a determining portion for determining whether or not an object exists in the direction in which the light is emitted from the light projecting device, based on the optical feedback; and a reflection preventing plate of a moth-eye structure, disposed at a position that is on the optical path of the light that is emitted from the light projecting device at a position that is more distant than the location wherein the object is anticipated to appear.

Abstract: A signal evaluating device comprises: a binarizing portion for binarizing an input signal; a run length measuring portion for measuring the run length of the input signal during the evaluating interval, using the output of the binarizing portion as the input; and evaluating means for calculating, from the measurement results of the run length measuring portion, a distribution wherein the noise frequency distribution included in the input signal during the evaluating interval is assumed to be a geometric distribution, and for evaluating whether or not the input signal is valid through comparing the calculated frequency to the run length frequency obtained from the measurement results by the run length measuring portion (probability calculating portion, noise frequency calculating portion, and validity evaluating portion).

Abstract: A signal evaluating device comprises: a binarizing portion for binarizing an input signal; a run length measuring portion for measuring the run length of the input signal during the evaluating interval, using the output of the binarizing means as the input; and a validity evaluating portion for evaluating whether or not the input signal is valid, from the degree of matching of a run length frequency distribution, obtained from the measurement results by the run length measuring portion, and a geometric distribution. The validity evaluating portion evaluates whether or not an input signal is valid through a ratio of the total frequency during the evaluation interval to Nsamp/2, or a ratio of the frequency of a class 1 during the evaluating interval to Nsamp/4, where Nsamp is the total of the sampling clocks for measuring the run length during the evaluating interval.

Abstract: A physical quantity sensor includes: a semiconductor laser which emits laser light to a measurement target; an oscillation wavelength modulating device that operates the semiconductor laser such that at least one of a first oscillation period and a second oscillation period alternately exists; a detector that detects an electrical signal including interference waveforms, the interference waveforms being caused by a self-coupling effect of the laser light and return light from the measurement target; a signal extracting device that measures each cycle of the interference waveforms whenever the interference waveform is input; a cycle correcting device that compares each cycle of the interference waveforms with a reference cycle to correct the cycles of the interference waveforms; and a calculating device that calculates at least one of displacement and velocity of the measurement target based on each of the cycles of the interference waveforms corrected by the cycle correcting device.

Abstract: An interface of the present invention includes a first inverter circuit that inverts a logic level of an input signal given to an external input terminal and outputs the inverted logic level, a second inverter circuit that outputs a potential in which a logic level of an output signal of the first inverter circuit is inverted, that is, a potential higher or lower than a logic of an input signal applied to the first inverter circuit by the amount of a predetermined potential, and a feedback path that positive feedbacks an output signal of the second inverter circuit to the external input terminal. The interface circuit of the invention positive-feedbacks a potential of the output signal of the second inverter circuit and shifts the potential of the external input terminal in a floating state to an H or L level potential.

Abstract: In a distance/speed meter, first and second semiconductor lasers emit parallel laser light beams to a measurement target. A first laser driver drives the first semiconductor laser such that the oscillation interval in which at least the oscillation wavelength monotonically increases repeatedly exists. A second laser driver drives the second semiconductor laser such that the oscillation wavelength increases/decreases inversely to the oscillation wavelength of the first semiconductor laser. First and second light-receiving devices convert optical outputs from the first and second semiconductor lasers into electrical signals. A counting unit counts the numbers of interference waveforms generated by the first and second laser light beams and return light beams of the first and second laser light beams.

Abstract: An interface of the present invention includes a first inverter circuit that inverts a logic level of an input signal given to an external input terminal and outputs the inverted logic level, a second inverter circuit that outputs a potential in which a logic level of an output signal of the first inverter circuit is inverted, that is, a potential higher or lower than a logic of an input signal applied to the first inverter circuit by the amount of a predetermined potential, and a feedback path that positive feedbacks an output signal of the second inverter circuit to the external input terminal. The interface circuit of the invention positive-feedbacks a potential of the output signal of the second inverter circuit and shifts the potential of the external input terminal in a floating state to an H or L level potential.

Abstract: The velocity calculating device includes a semiconductor laser for emitting a laser beam at a web that is the subject to be measured; a photodiode for converting into an electric signal the optical power of the semiconductor laser; a lens for focusing and emitting the beam from the semiconductor laser and for focusing the return light from the web and injecting it into the semiconductor laser; a laser driver for driving the semiconductor laser; a current-voltage converting/amplifying portion for converting the output current from the photodiode into a voltage and then amplifying; a filter portion for removing the carrier wave from the output voltage of the current-voltage converting/amplifying portion; a signal extracting portion for counting the number of interference waveforms included in the output voltage of the filter portion; and a calculating portion for calculating the velocity of the web based on the counting result of the signal extracting portion.

Abstract: A physical quantity sensor has a semiconductor laser, a laser driver for providing, to the semiconductor laser, a driving electric current that is a waveform wherein the maximum portions and minimum portions of a triangle wave have been rounded; detecting means (a photodiode and a current-voltage converting amplifier) for detecting an electric signal that includes an interference waveform that is produced by the self-coupling effect between a laser beam that is emitted from the semiconductor laser and a return beam from a measurement object; and measuring means (a filter circuit, a counting device, and a calculating device) for calculating a physical quantity for the measurement object from interference waveform information.

Abstract: An interface of the present invention includes a first inverter circuit that inverts a logic level of an input signal given to an external input terminal and outputs the inverted logic level, a second inverter circuit that outputs a potential in which a logic level of an output signal of the first inverter circuit is inverted, that is, a potential higher or lower than a logic of an input signal applied to the first inverter circuit by the amount of a predetermined potential, and a feedback path that positive feedbacks an output signal of the second inverter circuit to the external input terminal. The interface circuit of the invention positive-feedbacks a potential of the output signal of the second inverter circuit and shifts the potential of the external input terminal in a floating state to an H or L level potential.

Abstract: An interface of the present invention includes a first inverter circuit that inverts a logic level of an input signal given to an external input terminal and outputs the inverted logic level, a second inverter circuit that outputs a potential in which a logic level of an output signal of the first inverter circuit is inverted, that is, a potential higher or lower than a logic of an input signal applied to the first inverter circuit by the amount of a predetermined potential, and a feedback path that positive feedbacks an output signal of the second inverter circuit to the external input terminal The interface circuit of the invention positive-feedbacks a potential of the output signal of the second inverter circuit and shifts the potential of the external input terminal in a floating state to an H or L level potential.

Abstract: A laser driver (4) causes a semiconductor laser (1) to operate such that a first oscillation period of monotonically increasing the oscillation wavelength and a second oscillation period of monotonically decreasing the oscillation wavelength alternately exist. A photodiode (2) converts laser light emitted from the semiconductor laser (1) and return light from a measurement target (12) into electrical signals. A counting unit (13) counts the number of interference waveform components obtained from an output signal from the photodiode (2) in each of the first oscillation period and the second oscillation period. A computing device (9) calculates the distance to the measurement target (12) and the velocity of the measurement target (12) from a shortest Lasing wavelength and a longest Lasing wavelength in a period during which the counting unit (13) counts the number of interference waveform components and the counting result obtained by the counting unit (13).

Abstract: The counting device includes: a signal counter that counts the number of half cycles of input signals during given counting periods; a signal half cycle measurement unit that measures the half cycles; a frequency distribution generator that generates a frequency distribution of the half cycles; a representative value calculator configured to calculate a representative value of a distribution of the half cycles; a correction value calculator configured to calculate a total number Ns and a total number Nwn so as to correct the number of the half cycles, wherein Ns represents the total of the number of the half cycles that are less than 0.5 times the represent value, and Nwn represents the total of the number of the half cycles that are equal to or greater than 2n and less than (2n+2) times the representative value.

Abstract: A tension/speed measuring device comprises a laser driver for driving the oscillation of a semiconductor laser, and a counter for counting interference waveforms included in the output of a photodiode for converting the output of the semiconductor laser into an electrical signal. The counter measures the periods of interference waveforms during a measuring interval, where a frequency distribution for the periods of the interference waveforms during the measuring interval is generated from the measuring results, where a class value wherein the product of the class value and the frequency is a maximum is used as a representative value D0 at the periods of the interference waveform, to calculate a total Ns of the frequencies of the classes that are less than 0.5 times the representative value T0 and to calculate a total Nwn of the frequencies of the classes that are equal to or greater than (n+0.5) times the representative value T0 and less than (n+1.

Abstract: In a distance/speed meter, first and second semiconductor lasers emit parallel laser light beams to a measurement target. A first laser driver drives the first semiconductor laser such that the oscillation interval in which at least the oscillation wavelength monotonically increases repeatedly exists. A second laser driver drives the second semiconductor laser such that the oscillation wavelength increases/decreases inversely to the oscillation wavelength of the first semiconductor laser. First and second light-receiving devices convert optical outputs from the first and second semiconductor lasers into electrical signals. A counting unit counts the numbers of interference waveforms generated by the first and second laser light beams and return light beams of the first and second laser light beams.

Abstract: An amplitude computing apparatus includes: a mean or median value computing unit configured to compute a mean or median value of a distribution of an input signal that changes sinusoidally; a mode value computing unit configured to compute a mode value of the distribution of the input signal; and an amplitude computing unit configured to compute a difference between the mean or median value and the mode value as an amplitude of the input signal.

Abstract: An interface of the present invention includes a first inverter circuit that inverts a logic level of an input signal given to an external input terminal and outputs the inverted logic level, a second inverter circuit that outputs a potential in which a logic level of an output signal of the first inverter circuit is inverted, that is, a potential higher or lower than a logic of an input signal applied to the first inverter circuit by the amount of a predetermined potential, and a feedback path that positive-feedbacks an output signal of the second inverter circuit to the external input terminal. The interface circuit of the invention positive-feedbacks a potential of the output signal of the second inverter circuit and shifts the potential of the external input terminal in a floating state to an H or L level potential.

Abstract: To reduce the probability of incorrect determination to detect an object reliably. A reflective photoelectric sensor is provided with: a light projecting device for emitting light; a light receiving device for receiving the optical feedback of the light that is emitted from the light projecting device; a determining portion for determining whether or not an object exists in the direction in which the light is emitted from the light projecting device, based on the optical feedback; and a reflection preventing plate of a moth-eye structure, disposed at a position that is on the optical path of the light that is emitted from the light projecting device at a position that is more distant than the location wherein the object is anticipated to appear.