DE10018948B4 - Optoelectronic device - Google Patents

Optoelectronic device

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Publication number
DE10018948B4
DE10018948B4 DE2000118948 DE10018948A DE10018948B4 DE 10018948 B4 DE10018948 B4 DE 10018948B4 DE 2000118948 DE2000118948 DE 2000118948 DE 10018948 A DE10018948 A DE 10018948A DE 10018948 B4 DE10018948 B4 DE 10018948B4
Authority
DE
Germany
Prior art keywords
optoelectronic device
characterized
object
device according
distance
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
DE2000118948
Other languages
German (de)
Other versions
DE10018948A1 (en
Inventor
Martin Argast
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Leuze electronic GmbH and Co KG
Original Assignee
Leuze electronic GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to DE19918629 priority Critical
Priority to DE19918629.4 priority
Application filed by Leuze electronic GmbH and Co KG filed Critical Leuze electronic GmbH and Co KG
Priority to DE2000118948 priority patent/DE10018948B4/en
Publication of DE10018948A1 publication Critical patent/DE10018948A1/en
Application granted granted Critical
Publication of DE10018948B4 publication Critical patent/DE10018948B4/en
Application status is Expired - Fee Related legal-status Critical
Anticipated expiration legal-status Critical

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/497Means for monitoring or calibrating
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06Systems determining position data of a target
    • G01S17/08Systems determining position data of a target for measuring distance only
    • G01S17/32Systems determining position data of a target for measuring distance only using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves
    • G01S17/36Systems determining position data of a target for measuring distance only using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves with phase comparison between the received signal and the contemporaneously transmitted signal
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/491Details of non-pulse systems

Abstract

Optoelectronic device for detecting objects with a transmitter receiving light rays, a receiver receiving light rays and means for determining the distance of an object, by means of which the received signals at the output of the receiver (6) are fed back to the input of the transmitter (4), so that in the case of an object (2) arranged within a first distance range, the transmission power of the transmitter (4) is modulated at a frequency which is determined by the transit time of the transmitted light beams (3) to the object (2), characterized in that from the correspondingly modulated received signal a switching signal is derived which, in the case of an object (2) arranged in the first distance range, assumes the switching state "on" and otherwise the switching state "off", that for the detection of an object (2) in the near range, the distance of which lies within a second distance range, the compared to the first distance range h is at smaller distance values, the amplitude of the received signal is evaluated with at least one threshold value S 3 , and that object detection is present if the amplitude falls below the threshold value S 3 .

Description

  • The invention relates to an optoelectronic device according to the generic term of claim 1.
  • An optoelectronic device of this type is known from the EP 0 434 191 A2 known. This device is designed as a distance sensor and has a transmitter emitting light rays and a receiver, on which the received light rays reflected back from an object strike. The received signals thus present at the output of the receiver are fed back to an input of the transmitter via an inverter, whereby the transmission power of the transmitter is modulated at a frequency which is determined by the light propagation time from the transmitter to the object and back to the receiver. This frequency is detected to determine the object distance.
  • The DE 195 20 993 A1 relates to a method and a device for detecting the distance between a measuring device and an object, in which a light signal sent over a measuring section experiences a phase shift, which is converted into a frequency change in an oscillating circuit.
  • From the US 4,738,529 a device for determining the transit time of electromagnetic waves is known. The device has a pulse generator arranged in a feedback loop, which is triggered by pulses. Optionally, a measuring section or a reference section is integrated into the feedback loop for carrying out runtime measurements.
  • The DE 197 07 861 A1 relates to a reflection light scanner for detecting objects in a surveillance area with a transmitter emitting light rays and a receiver receiving light rays. The receiver has a near element and a far element, the received signals at the output of the near element and the far element being fed to an amplifier, the amplification factors of which can be set to adjust the scanning range that limits the monitoring range. The transmitted light beams are aimed at a test object for setting the scanning distance. For the received signals generated in the process, the amplification factors are automatically set to a ratio corresponding to the switching point of the reflection light sensor via an adjustable resistance element connected to the inputs of the amplifiers. The setting process can be activated via an externally operable signal line.
  • The DE 43 03 804 C2 relates to a device for distance measurement with a transmission light-emitting laser, the transmission light beam of which is amplitude-modulated with two predetermined modulation frequencies, and with a receiver and a phase detector for determining the phase difference of the transmission light beam and of the reception light beam reflected by an object. The modulations of the transmitted light beam are carried out at different times with the respective modulation frequencies. To determine the distance of an object to the facility, the object is measured with both modulation frequencies. The amounts of the modulation frequencies are alien numbers of the same order of magnitude. The modulation frequency is changed within predetermined intervals that are adapted to the speed of the objects relative to the device.
  • A major disadvantage of this Device is that the high demands on the phase measurement accuracy a high circuit complexity.
  • The invention is the object to create a device of the type mentioned in the introduction, the reliable detection of objects with little circuitry with almost any surface in a defined, the immediate vicinity of the device comprehensive range guaranteed.
  • To solve this task are the Features of claim 1 provided. Advantageous embodiments and appropriate further training the invention are described in the subclaims.
  • The optoelectronic device according to the invention is used for the detection of objects and has a transmitter receiving light rays, a receiver receiving light rays and means for determining the distance of an object, by means of which the received signals at the output of the receiver are fed back to the input of the transmitter, so that at an object arranged within a first distance range, the transmission power of the transmitter is modulated with a frequency that is determined by the transit time of the transmitted light beams to the object. A switching signal is derived from the correspondingly modulated received signal and assumes the switching state "on" and otherwise the switching state "off" for an object arranged in the first distance range. For the detection of an object in the near range, the distance of which lies within a second distance range, which is smaller than the first distance range, the amplitude of the received signal is evaluated with at least one threshold value S 3 , whereby an object detection exists if the amplitude exceeds the threshold value S 3 falls below.
  • If the object is within a certain first distance range, a resonant oscillation is generated, the period of which he or frequency provides a direct measure of the distance of the object. A binary switching signal is derived from the distance information obtained in this way by means of a threshold value, which indicates whether or not an object is in the first distance range.
  • It is advantageous that the frequency of the resonant vibration essentially only from the object distance depends but not the reflectivity the object surface, so that objects with almost any surface texture can be reliably detected are.
  • With one close to the device arranged object, its distance to the device can be so small that the resonant vibration due to damping subsides so quickly that distance determination is no longer possible possible is.
  • In order to also secure objects at close range According to the invention, the device can be detected both as a rangefinder operated as well as energetic button. Objects can also be operated in push button mode can be reliably recognized in the immediate vicinity of the device. The device according to the invention is preferably alternating while different phases A and B as an energetic button and once operated as a rangefinder.
  • In the operating mode as a rangefinder the distance of the object by evaluating the frequency of the resonant Vibration determined. The object distance can be determined if this is within the first distance range.
  • In the operating mode as more energetic The button is the amplitude of the inverted received signal with a Threshold value assessed, in which case the transmitter does not go through the received signal is modulated and therefore emits constant light. In this mode, objects in the close range are within a second Distance range detectable. This second distance range partially overlap in particular with the first distance range.
  • The optoelectronic device according to the invention is characterized by an extremely low Switching effort.
  • The invention is set out below explained using the drawings. Show it:
  • 1 : Schematic representation of the optical components of an optoelectronic device.
  • 2 : Block diagram of an optoelectronic device.
  • 3 : Pulse diagram for modulating the transmission power of the transmitter according to the optoelectronic device 2 ,
  • 4 : Schematic representation of the evaluation of the frequency of the modulated transmission power according to 3 ,
  • 5 : Block diagram of an embodiment of the optoelectronic device according to the invention.
  • 6 : First example of pulse diagrams for signal evaluation for the optoelectronic device according to 5 ,
  • 7 : Second example of pulse diagrams for signal evaluation for the device according to 5 ,
  • 8th : Characteristic of the transmission power of the transmitter of the optoelectronic device according to the invention.
  • 9 : Schematic representation of a first and second distance range, to which different operating modes of the optoelectronic device are assigned.
  • 10 : Third example of pulse diagrams for signal evaluation for the optoelectronic device according to 5 ,
  • 1 shows schematically the optical structure of an optoelectronic device 1 for the detection of objects 2 in a surveillance area. The device 1 has a transmitted light beam 3 emitting transmitter 4 and a received light beam 5 receiving recipient 6 on that in a common housing 7 are integrated. The transmitter 4 is from a laser diode, the receiver 6 formed by a photodiode.
  • The transmitter 4 and the recipient 6 are arranged one behind the other so that the transmitted and received light beams 5 run coaxially within the monitored area.
  • The transmitter 4 is at the center of a receiving optics 8th arranged over which the of the object 2 reflected transmitted light rays 3 as received light rays 5 to the recipient 6 are led.
  • The receiving optics 8th is in the front wall of the case 7 arranged. The transmitter 4 is for beam shaping of the transmitted light beams 3 a transmission optics 9 downstream.
  • If necessary, the monitoring area can be limited by a reflector or the like, not shown, on which the transmitted light beams 3 with free beam path of the optoelectronic device 1 incident.
  • 2 shows a block diagram of an embodiment of an optoelectronic device 1 , The one from the broadcaster 4 emitted light beams 3 are from an object 2 reflected and hit as received light rays 5 to the recipient 6 , This at the exit of the receiver 6 pending receive signal is via an inverter 10 , a resistance 11 and a coupling capacitor 12 on the transmitter 4 fed back. The inverter 10 is preferably formed by an amplifier which amplifies and inverts the received signal. The resistance 11 are two diodes switched in opposite directions 13 . 14 downstream, of which a feed line to a counter unit 15 leads. In the present exemplary embodiment, the counter unit has 15 also has a computer unit which forms an evaluation unit in which, in particular, analog signals can also be processed. To the counter unit 15 is also an oscillator 16 connected, which generates a periodic reset signal U r , which the counter unit 15 controls. In addition, the reset signal U r via a further capacitor 17 on the lead from the resistor 11 to the coupling capacitor 12 coupled.
  • To the outputs of the counter unit 15 are a binary switching output 18 as well as an analog output 19 connected.
  • The received light rays 5 generate in the receiver 6 a receive signal that is in the inverter 10 is inverted and amplified. The following limiter circuit consisting of the resistor 11 and the diodes 13 . 14 , limits the feedback signal U a to the diode threshold voltage. Via the coupling capacitor 12 the signal U a modulates the transmitter 4 , which was previously set to a medium transmission power, so that the transmitter 4 initially emitted uniform light.
  • 3 shows the diagram of the transmission power of the transmitter 4 , In the idle state, the transmission power is set to the average value P_qual by a DC voltage level. By noise voltages from the receiver 6 a change in transmission power is caused. This creates an alternating light component, which depends on the duration of the transmitted light beams 3 to the object 2 conditional delay time t 1 at the receiver 6 captured by the inverter 10 inverted and the transmitter 4 is modulated in the opposite direction. With sufficient object reflection, the amplitude of the signal U a increases until it passes through the diodes 13 . 14 is limited. The period of U a adjusts to the value 2t 1 . The value t 1 corresponds to the light propagation time of the transmitted light rays 3 to the object 2 and back to the device 1 , Thus, by the feedback of the received signal on the transmitter 4 generates a resonant vibration, the frequency of which provides a direct measure of the object distance. In order to guarantee a reliable oscillation of the oscillation, the switching edge of the reset signal U r is used, which is via the capacitor 17 one is coupled. By coupling through the capacitor 17 there is a short start pulse that triggers the feedback vibration.
  • The feedback of the received signal via the inverter 10 , the resistance 11 and the coupling capacitor 12 thus forms an oscillatory circuit into which the transmitted and received light beams 5 formed measuring path is included. The values of resistance 11 and the coupling capacitor 12 , which serves to eliminate the signal components of the signal U a caused by constant light components, are selected so that they do not impair the frequency of the resonant oscillation initiated. Except for the effects of component-related transit times, the frequency of the vibration is therefore only due to the light transit times of the transmitted light beams 3 and received light beams 5 determined, so that a direct measure of the object distance is obtained by determining the frequency of the vibration. The counter unit is used to determine this frequency 15 used.
  • 4 shows the diagram of the counter reading of the counter unit 15 , With each edge of the reset signal U r , the counter of the counter unit 15 reset. The periods of the output signal U a are counted during half the period t 2 of the reset signal U r . The counter status is compared with two threshold values S 1 and S 2 before being reset by the next reset signal. Since the transmitter frequency that is set depends on the object distance, a large object distance necessitating a small transmission frequency, the maximum object distance is set by the threshold value S 2 . If the threshold value S 2 is exceeded, an object becomes 2 recognized and the corresponding switching output 18 set. A minimum object distance can be detected with the threshold value S 1 . Falling below the threshold value S 2 means that the object 2 too far away or too little reflection.
  • By specifying the threshold values S 1 and S 2 is the distance of an object 2 detectable within a first distance range. The switching output takes 18 the switching state corresponding to an object detection "on" if the object is 2 is within this first range. In addition to this binary switching signal, the determined distance value can be sent directly as an analog signal via the analog output 19 be issued.
  • 5 shows a block diagram of an embodiment of the optoelectronic device according to the invention 1 , In this case, the feedback of the inverter takes place 10 inverted received signal on the transmitter 4 about unifying resistance 11 upstream coupling capacitor 12 ' , The signal U e before the coupling capacitor 12 ' , which still contains signal components caused by constant light, and the signal U a after the coupling capacitor 12 ' , in which these signal components are filtered out, are sent to the counter unit via separate inputs 15 entered.
  • In the oscillator 16 are in contrast to the embodiment according to 1 In addition to the periodic reset signal U r , a periodic additional reset signal U r1 is also generated, each via a diode 13 ' . 14 ' on the transmitter 4 coupled and into the counter unit 15 can be entered. The diodes 13 ' . 14 ' serve to limit the transmission power.
  • Otherwise, the circuit arrangement has one the embodiment  according to 2  corresponding structure on.
  • How out 5 can be seen, two phases A and B are predetermined by the reset signal U r , in within which the device 1 is operated in different operating modes.
  • During phases A, the transmit power of the transmitter 4 not modulated so that it emits constant light. In these phases, the device 1 operated as an energetic button, in which the amplitude of the inverted received signal U e is evaluated with a threshold value S 3 . Here is the device 1 in the in 9 shown, a second distance-forming static area, in which objects 2 are detectable in the extremely close range.
  • During phases B, the transmission power of the transmitter 4 modulated by feedback of the received signal, so that according to the embodiment according to 2 a distance measurement is carried out. Within these phases B, the object distance can be determined within the first distance range, which in 9 is designated with the resonance range. This first distance range is limited to a lower limit distance.
  • This is based on the fact that for very short object distances, the delay times t 1 caused by the light propagation times become so short that the signal U a required for feedback is damped too much by circuit capacitances and the vibration triggered by U r decays.
  • In the embodiment according to 5 the reset signal U r is designed so that the signal U a in phase A via the diodes 13 ' . 14 ' is short-circuited. U a then has the value of a diode threshold voltage and causes the transmission power to reach its maximum value P_max. Is an object at close range 2 is present by the recipient 6 a signal registered and after the inverter 10 the signal U e results which falls below the threshold value S 3 . At the end of phase A is in the counter unit 15 the comparator output state determined with the threshold value S 3 is queried and, if the value is undershot, as a recognized object 2 rated and at the switching output 18 output. The switching edge of the reset signal U r (transition from phase A to B) triggers the oscillation of the signal U a and, with sufficient object reflection and sufficient object distance, reaches the resonance condition. In the counter unit 15 the periods of the signal Ua are counted and evaluated at the end of phase B using the threshold values S 1 and S 2 . If the threshold S 2 is not reached, the switching states at the switching output 18 defined by the result of the evaluation of U e during phase A. Otherwise, the switching outputs 18 determined by the result of the evaluation of phase B.
  • 6 shows the diagram of the waveforms in the embodiment 5 , In the example shown, an object delivers 2 sufficient reception signals in the resonance range so that the oscillation of the signal U a can be evaluated. In phase A, the signal level U e is determined by the intensity of the reflected light, and if the threshold value S 3 is undershot, the object becomes 2 recognized and a message at the switching output 18 output.
  • 7 shows a modification of the signal evaluation according to 6 , A total of three different phases A, B and C are defined by means of the reset signal U r and the additional reset signal U r1 , a different signal evaluation taking place in each of the phases. In phase C, the reset signal U r1 is keyed to negative values, causing the diodes 13 ' . 14 ' Become conductive, short-circuit the signal U a and thus set the transmission power to a minimum value. Phase C thus essentially forms a pause in which the transmitter 4 is almost completely switched off. The evaluations in phases A, B correspond to the exemplary embodiment according to 6 , In phase A, the diodes 13 ' . 14 ' conductive by the reset signal U r and the laser power jumps to the maximum value. During phase B, in which U r and U r1 assume the value 0, an oscillation U a with an amplitude corresponding to the diode threshold voltage can form. The particular advantage of this signal sequence is that the reset voltage phases A and B can be designed significantly shorter than phase C, thereby reducing the average transmission power and thus the load on the laser diode. Compliance with the laser class with regard to eye safety can thus be better maintained, or the permissible maximum laser power can be increased and used to extend the distance range. In the embodiment according to 7 is the object 2 in the close range, so that the resonant vibration decays quickly during phase B. The switching states of the switching output 18 are therefore determined in this case by the evaluation during phases A.
  • 8th shows the laser characteristic of the transmitter 4 with the typical power values in phases A, B and C. The average laser power is kept at an average value by a monitor control circuit. The maximum laser power is reached during phase A.
  • 9 schematically shows the first distance range within which the device 1 works as a rangefinder and the second range, within which the device 1 works as an energetic button. The static area (second distance area) begins just before the device 1 (5 ... 20mm) and, depending on the reflection of the object, extends up to a few meters and is defined by the fact that in this area the signal U e can be evaluated using the threshold value S 3 .
  • The resonance range (first distance range) has an overlap with the static range and extends to larger distances depending on the object reflectivity, for example with triple reflectors up to 100 ... 200mm. In this area, an off evaluation with the threshold values S 1 and S 2 and output of a switching signal at the switching output 18 or an output of a distance-proportional measured value at the analog output 19 respectively. The overlapping of the distance areas ensures a complete detection area that is difficult to reach with conventional distance sensors based on the time-of-flight principle.
  • 10 shows the arrangement of two devices 1 and 1' at the opposite ends of the surveillance area. The transmitted light beams 3 a device 1 or 1' are from the recipient 6 the other device 1' or 1 registered. The output signal of the inverter 10 then modulates the transmitter 4 , whose transmitted light rays 3 as received light rays 5 to the recipient 6 the opposite device 1' or 1 reach. In this light barrier arrangement, the transmission beams serve to align the device 1 , In addition, the otherwise necessary synchronization of the receiver is omitted 6 through active feedback. This arrangement is particularly suitable for large distances with high ambient light pollution. The frequency of the resonant vibration is calculated approximately according to the formula: f (Mhz) = 500 / (6.6ns · s (m) + t V (Ns)) where t V (ns) is the circuit delay time and s is the distance between the devices 1 and 1' is.
  • In an alternative embodiment, the monitoring area is delimited by a reflector, which is the device 1 at the other end of the surveillance area. The reflector is at a distance from the device 1 that is within the first range.
  • With a free beam path, the transmitted light beams hit 3 on the reflector and become a device 1 reflected back. The distance of the reflector is detected by evaluating the resonant vibration generated thereby.
  • 1
    Optoelectronic contraption
    1'
    Optoelectronic contraption
    2
    object
    3
    Transmitted light beams
    4
    Channel
    5
    Receiving light rays
    6
    receiver
    7
    casing
    8th
    receiving optics
    9
    transmission optics
    10
    inverter
    11
    resistance
    12
    coupling capacitor
    12 '
    coupling capacitor
    13
    diode
    13 '
    diode
    14
    diode
    14 '
    diode
    15
    counter unit
    16
    oscillator
    17
    capacitor
    18
    switching output
    19
    analog output

Claims (18)

  1. Optoelectronic device for detecting objects with a transmitter receiving light rays, a receiver receiving light rays and means for determining the distance of an object, by means of which the at the output of the receiver ( 6 ) pending reception signals on the input of the transmitter ( 4 ) are fed back, so that in the case of an object arranged within a first distance range ( 2 ) the transmission power of the transmitter ( 4 ) is modulated with a frequency that is determined by the transit time of the transmitted light beams ( 3 ) to the object ( 2 ) is determined, characterized in that a switching signal is derived from the correspondingly modulated received signal, which for an object arranged in the first distance range ( 2 ) assumes the switching state "on" and otherwise the switching state "off" that for the detection of an object ( 2 ) in the near range, the distance of which lies within a second range, which is smaller than the first range, the amplitude of the received signal is assessed with at least one threshold value S 3 , and that an object detection is present if the amplitude falls below the threshold value S 3 ,
  2. Optoelectronic device according to claim 1, characterized in that the switching signal via a switching output ( 18 ) can be output.
  3. Optoelectronic device according to claim 1 or 2, characterized in that the means for Determining the distance of an object an inverter ( 10 ), to which a coupling capacitor ( 12 . 12 ' ) is subordinate.
  4. Optoelectronic device according to one of claims 1 to 3, characterized in that the transmission power of the transmitter ( 4 ) is limited by a limiter circuit.
  5. Optoelectronic device according to claim 4, characterized in that the limiter circuit has a resistor ( 11 ) and two diodes ( 13 . 14 respectively. 13 ' . 14 ' ) having.
  6. Optoelectronic device according to one of claims 1 to 5, characterized in that a periodic reset signal U r is provided to activate an oscillation causing the modulation of the transmission power, which is in an oscillator ( 16 ) is generated.
  7. Optoelectronic device according to one of claims 1 to 6, characterized in that for determining the frequency with which the transmission power is modulated, a counter unit ( 15 ) is provided, by means of which the periods of the oscillation causing the modulation of the transmission power are counted within a predetermined time interval.
  8. Optoelectronic device according to claim 7, characterized in that the counter unit ( 15 ) is driven by the reset signal U r .
  9. Optoelectronic device according to one of claims 7 or 8, characterized in that the counter reading of the counter unit ( 15 ) is compared with a threshold value S 2 , the. Switching output ( 18 ) assumes the switching state "on" if the counter reading exceeds the threshold value S 2 .
  10. Optoelectronic device according to one of claims 7 to 9, characterized in that the counter reading of the counter unit ( 15 ) with a threshold value S 1 (S 1 > S 2 ), which is a minimum distance of the object ( 2 ) which limits the first distance range towards small distance values.
  11. Optoelectronic device according to one of claims 1 to 10, characterized in that the first distance range partially overlaps with the second distance range.
  12. Optoelectronic device according to one of claims 1 to 11, characterized in that for object detection alternately during a first phase A with constant light emitting transmitter ( 4 ) the amplitude of the inverted received signal is evaluated with the threshold value S 3 and during a second phase B the period of the received signal modulated due to the vibration is determined.
  13. Optoelectronic device according to claim 12, characterized in that the clock of the phases A and B is predetermined by the reference signal U r .
  14. Optoelectronic device according to Claim 13, characterized in that the oscillation causing the modulation of the transmission power is initiated with the falling edge of the reference signal U r .
  15. Optoelectronic device according to one of claims 12 to 14, characterized in that the switching states at the switching output ( 18 ) are defined by the result of the evaluation during phase A if the counter reading of the counter unit ( 15 ) does not reach the threshold value S 2 , and that otherwise the switching states of the switching output ( 16 ) are determined by the result of the evaluation during phase B.
  16. Optoelectronic device according to one of Claims 12 to 15, characterized in that phases A and B are followed by a third phase C, within which the transmission power of the transmitter ( 4 ) is set to a minimum value.
  17. Optoelectronic device according to claim 16, characterized in that a periodic additional reference signal U r1 is provided for generating the phases A, B and C in addition to the reference signal U r , where in phase C with the falling edge of the additional reference signal U r 1 is activated.
  18. Optoelectronic device according to one of claims 1 to 17, characterized in that the monitoring area, within the objects ( 2 ) can be detected, is limited by a reflector which is detected with a free beam path within the first distance range.
DE2000118948 1999-04-23 2000-04-17 Optoelectronic device Expired - Fee Related DE10018948B4 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DE19918629 1999-04-23
DE19918629.4 1999-04-23
DE2000118948 DE10018948B4 (en) 1999-04-23 2000-04-17 Optoelectronic device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2000118948 DE10018948B4 (en) 1999-04-23 2000-04-17 Optoelectronic device

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DE10018948B4 true DE10018948B4 (en) 2004-02-05

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DE10329043B4 (en) * 2003-06-27 2007-07-26 Leuze Electronic Gmbh & Co Kg Method for determining distances
JP4009862B2 (en) * 2003-09-30 2007-11-21 オムロン株式会社 Multi-axis photoelectric sensor
DE10346813B4 (en) 2003-10-06 2013-08-29 I F M Electronic Gmbh An optoelectronic sensor and method for detecting an object in a surveillance area
DE102009029668A1 (en) * 2009-09-22 2011-03-24 Balluff Gmbh Optical sensor device and method for operating an optical sensor device
EP2450722A1 (en) * 2010-11-09 2012-05-09 Pepperl & Fuchs GmbH Device and method to determine the duration of a test radiation
DE102012102056B4 (en) 2011-04-27 2014-10-02 Leuze Electronic Gmbh & Co. Kg Optical sensor

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