CN101888230A - Reflection-type optoelectronic switch and object detection method - Google Patents
Reflection-type optoelectronic switch and object detection method Download PDFInfo
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Abstract
The invention relates to a reflection-type optoelectronic switch which realizes favorable precision by simple and cheap structure by using a self-mixed type laser counter. The reflection-type optoelectronic switch comprises a semiconductor laser (1), a detection unit (an optoelectronic diode (2) and an current-voltage conversion amplifying part 5)), a period distinguishing part (7) and a judging part (8), wherein the detection unit is used for detecting electric signals comprising interference waveform generated by self-mixed effect of laser emitted by the semiconductor laser (1) and light returned by an object (10); the period distinguishing part (7) is used for distinguishing the frequency of periods of interference waveform on the basis of the value of reference period; and the judging part (8) is used for judging whether the object (10) is nearer or further than the reference distance according to the detection result of the period distinguishing part (7).
Description
Technical field
The present invention relates to reflection-type optoelectronic switch, the distance that particularly is measured to object is than the reference range of regulation still near reflection-type optoelectronic switch and object detection method far away.
Background technology
In the past, a kind of as reflection-type optoelectronic switch, known have the distance of mensuration from the optoelectronic switch to the object than the reference range of regulation still near distance setting reflection-type (Background Suppression far away, being designated hereinafter simply as BGS) optoelectronic switch is (for example, with reference to patent documentation 1, patent documentation 2).According to such BGS optoelectronic switch, can not measure background and only measure object.
On the other hand, distance meter as the interference of light that utilizes laser to send, the laser instrumentation device (for example, with reference to non-patent literature 1, non-patent literature 2, non-patent literature 3) of the back light of a kind of output light that utilizes laser and determination object in the interference (self-mixing effect) of semiconductor laser inside proposed.Figure 12 shows the compound resonator model of FP type (Fabry-Perot type) semiconductor laser.In Figure 12,101 is semiconductor laser, and 102 is the semiconducting crystal cleavage surface, and 103 is photodiode, and 104 is determination object.
If the oscillation wavelength of laser is λ, from being L to the distance of determination object 104 from the near cleavage surface 102 of determination object 104, when satisfying following condition of resonance, strengthen mutually from the laser in the back light resonator 101 of determination object, laser is exported increase slightly.
L＝qλ/2 ...(1)
In formula (1), q is an integer.Even the scattered light of determination object 104 is very faint, but, produces amplification, thereby can observe fully because the reflectivity that is showed in the resonator 101 of semiconductor laser increases.
Owing to big or small corresponding the launch frequency different laser of semiconductor laser with injection current, in the modulating oscillation frequency, do not need external modulator, can directly modulate by injection current.Relation between oscillation wavelength when Figure 13 demonstration changes the oscillation wavelength of semiconductor laser with certain certain ratio and the output waveform of photodiode 103.When satisfying formula (1) L=q λ/2, the phase difference of the laser in the back light resonator 101 is 0 ° (same-phase), and the laser in this moment back light resonator 101 be maximum enhancing mutually; If L=q λ/2+ λ/4 o'clock, phase difference is 180 ° (phase reversals), and the laser in this moment back light resonator 101 are that maximum weakens mutually.Therefore, if change the oscillation wavelength of semiconductor laser, laser is output as strong and weak alternate repetition and occurs, and at this moment, laser output is measured by the photodiode 103 that is arranged on resonator 101, obtains the stepped waveform as the some cycles as shown in Figure 13.Such waveform is commonly referred to as the interference ripple.
This stair-stepping waveform, promptly each interferes ripple to be called mould jump pulse (below be called MHP).MHP is different from the phenomenon that mould is jumped phenomenon.For example, be L1 in distance to determination object 104, when the number of MHP was 10, in the distance L 2 of half, the number of MHP was 5.That is, make in a certain special time in the oscillation wavelength variation of semiconductor laser, the number of MHP is ratio with the mensuration distance and changes.So, detect MHP by photodiode 103, measure the frequency of MHP, easily the instrumentation distance.
Utilize above-mentioned laser instrumentation device, can realize the BGS optoelectronic switch from mixed type.The BGS optoelectronic switch is as long as carry out object in closely still remote ON/OFF judgement by comparing with the reference range of regulation.Therefore, when the laser instrumentation device from mixed type uses as the BGS optoelectronic switch, as long as be long or short with respect to known reference cycle of the MHP of object when the position of reference range the average period of the MHP that judge to measure.With respect to the known reference cycle of the MHP of object when the position of reference range, the average period of the MHP that is measured to is under the long situation, ON is judged to be object in the distance nearer than reference range, again, the cycle of the MHP that is measured to, OFF was judged to be object in the distance more farther than reference range under the short situation.
Patent documentation 1 Japanese kokai publication sho 63-102135 communique
Patent documentation 2 Japanese kokai publication sho 63-187237 communiques
On the non-patent literature 1 field just, hillside plot is earnest, Chinese wistaria advances, East Sea branch of " utilizing the distance meter of the self-mixing effect of semiconductor laser " 1994 annual electrical relation association associating conference speech collection of thesis, 1994
Non-patent literature 2 hillside plots are earnest, and Chinese wistaria advances, Tianjin Tian Jisheng, last field just, " about the research of the small-sized distance meter of the self-mixing effect that utilizes semiconductor laser " is liked to know polytechnical university's research report, No. 31 B, p.35-42,1996
Non-patent literature 3 Guido Giuliani, Michele Norgia, Silvano Donati and Thierry Bosch, [Laser diode self-mixing technique for sensing applications], JOURNAL OF OPTICS A:PUREAND APPLIED OPTICS, p.283-294,2002
Invent problem to be solved
As mentioned above, utilize laser instrumentation device, can realize the BGS optoelectronic switch from mixed type.But the average period and the reference period of only trying to achieve MHP compare, and judge that precision can variation.Therefore, the inventor utilizes the method that proposes patent application 2007-015020 number, the number of times of obtaining the cycle of MHP distributes, obtain the typical value of the distribution of median or mode etc., distribute according to the typical value of the distribution in this cycle and the number of times in cycle and to calculate the distance of object, the distance and the reference range of calculating are compared, can improve the judgement precision.Then, in such method, need memory and computer, thereby cause the problem of the cost rising of BGS optoelectronic switch.
Again, be positioned at when object under the situation in the place nearer than reference range, the period profile of MHP is as the distribution 40 of Figure 14, towards the direction skew longer than reference period Th.Opposite, when object under the situation in the place far away than reference range, the period profile of MHP is shown in the distribution 41 of Figure 14, towards the direction skew shorter than reference period Th.Like this, the number Nshort of the MHP that number Nlong by the compare cycle MHP longer than reference period Th and period ratio reference period Th are short can judge the distance of object by simple and inexpensive structure.In this decision method, if Nlong＞Nshort sets up, then judge object in the place nearer than reference range, if Nlong＜Nshort sets up, judge that then object is in the place far away than reference range.
But, in the decision method that the number Nshort of the MHP that number Nlong and the period ratio reference period Th of the MHP that period ratio reference period Th is grown lack compares, for example interference such as outside light at random are also counted as MHP, perhaps the saltus step of signal causes that the MHP that can't be counted is arranged, thereby the cycle of the MHP that measures produces error sometimes, the error that therefore, judgement might be arranged when near the position of object reference range.
Summary of the invention
The present invention makes in order to solve above-mentioned problem, and its purpose is to utilize the laser instrumentation device from mixed type, realizes the reflection-type optoelectronic switch that precision is good with simple and cheap structure.
The present invention also aims to realize evaluated error that can calibration cycle and can judge the reflection-type optoelectronic switch of object distance accurately again.
The means of the usefulness of dealing with problems
The invention provides a kind of reflection-type optoelectronic switch, comprise: the semiconductor laser of emission laser; Make the laser driver of this semiconductor laser action; Detection contains the detecting unit of the electric signal of interference waveform, and described interference waveform is owing to the self-mixing effect of the laser of launching from this semiconductor laser with the back light of the object that is positioned at described semiconductor laser the place ahead produces; All measure the period measurement unit in the cycle of the described interference waveform in the output signal that is included in described detecting unit when importing interference waveform at every turn; Counting unit, the cycle of the described interference waveform with the position of described object at reference range the time is during as reference period, the number of times in the cycle of the interference waveform that described counting unit will be measured by described period measurement unit is divided into following four kinds: less than the times N 1 in cycle of first specified multiple of described reference period, more than or equal to first specified multiple of described reference period and less than the times N 2 in cycle of reference period, more than or equal to described reference period and less than the times N 3 in cycle of second specified multiple of reference period, with the times N 4 more than or equal to cycle of second specified multiple of described reference period, wherein first specified multiple is less than second specified multiple; Identifying unit, the more described times N 1 of this identifying unit, the size of N4 and number of times sum (N2+N3), when described times N 1 is maximum, judge that described object is in the position far away than described reference range, when times N 4 is maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2+N3) is maximum, the size of then more described times N 2 and N3, when described times N 2 is big, judge described object in the position far away, when described times N 3 is big, judge that then described object is in the position nearer than described reference range than described reference range.
A configuration example of the present invention again further comprises: pass through the number of times correcting unit that N2 '=N2-N1 calculates the corrected value N2 ' of described times N 2, the more described times N 1 of described identifying unit, the size of N4 and number of times sum (N2+N3), when described times N 1 is maximum, judge that described object is in the position far away than described reference range, when described times N 4 is maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2+N3) is maximum, the size of the corrected value N2 ' of more described number of times and times N 3 then, when described corrected value N2 ' is big, judge that described object is in the position far away than described reference range, when described times N 3 is big, judge that described object is in the position nearer than described reference range.
A configuration example of the present invention again further comprises: pass through the number of times correcting unit that N3 '=N3+N1 calculates the corrected value N3 ' of described times N 3, the more described times N 1 of described identifying unit, the size of N4 and number of times sum (N2+N3), when described times N 1 is maximum, judge that described object is in the position far away than described reference range, when described times N 4 is maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2+N3) is maximum, the size of the corrected value N3 ' of then more described times N 2 and number of times, when described times N 2 is big, judge that described object is in the position far away than described reference range, when described corrected value N3 ' is big, judge that described object is in the position nearer than described reference range.
Again, in a configuration example of reflection-type optoelectronic switch of the present invention, described laser driver drives described semiconductor laser, make comprise at least oscillation wavelength dull continuously increase during first duration of oscillation and comprise at least oscillation wavelength continuously dull minimizing during second duration of oscillation exist alternately; And further comprise: the normalization unit, described normalization unit is after the times N 1, N2, N3, the N4 that described counting unit are tried to achieve with the number of times in each duration of oscillation by each duration of oscillation respectively carry out normalization, to the times N after each normalization 1, N2, N3, N4, try to achieve respectively first duration of oscillation and second duration of oscillation number of times and N1 ", N2 ", N3 ", N4 "; With pass through N2 '=N2 "-N1 " calculate described times N 2 " the number of times correcting unit of corrected value N2 '; The more described times N 1 of described identifying unit "; N4 " and the size of number of times sum (N2 "+N3 "), when described times N 1 " when being maximum; judge that described object is in the position far away than described reference range; when described times N 4 " when being maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2 "+N3 ") when being maximum, then the corrected value N2 ' of more described number of times and times N 3 " size; when described corrected value N2 ' is big; judge that described object is in the position far away than described reference range; when described times N 3 " when big, judge that described object is in the position nearer than described reference range.
Again in a configuration example of reflection-type optoelectronic switch of the present invention, described laser driver drives described semiconductor laser, make comprise at least oscillation wavelength dull continuously increase during first duration of oscillation and comprise at least oscillation wavelength continuously dull minimizing during second duration of oscillation exist alternately; And further comprise: the normalization unit, described normalization unit is after the times N 1, N2, N3, the N4 that described counting unit are tried to achieve with the number of times in each duration of oscillation by each duration of oscillation respectively carry out normalization, for the times N after each normalization 1, N2, N3, N4, try to achieve respectively first duration of oscillation and second duration of oscillation number of times and N1 ", N2 ", N3 ", N4 "; With pass through N3 '=N3 "+N1 " calculate described times N 3 " the number of times correcting unit of corrected value N3 '; The more described times N 1 of described identifying unit "; N4 " and the size of number of times sum (N2 "+N3 "), when described times N 1 " when being maximum; judge that described object is in the position far away than described reference range; when described times N 4 " when being maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2 "+N3 ") when being maximum, then more described times N 2 " and the size of the corrected value N3 ' of number of times; when described times N 2 " when big, judge that described object is in the position far away than described reference range, when described corrected value N3 ' is big, judge that described object is in the position nearer than described reference range.
In the configuration example of reflection-type optoelectronic switch of the present invention, described first specified multiple is 0.5 again, and described second specified multiple is 1.5.
The invention provides a kind of object detecting method again, it comprises: drive current is offered semiconductor laser, drive the vibration step of described semiconductor laser action; Detection contains the detection step of the signal of telecommunication of interference waveform, and described interference waveform is owing to the self-mixing effect of the laser of launching from this semiconductor laser with the back light of the object that is positioned at described semiconductor laser the place ahead produces; All measure the period measurement step in the cycle that is included in the described interference waveform in the output signal that obtains by described detection step when importing interference waveform at every turn; Counting step, the cycle of the described interference waveform with the position of described object at described reference range the time is during as reference period, to divide into following four kinds by the number of times in cycle of the interference waveform of described period measurement step measurements: less than the times N 1 in cycle of first specified multiple of described reference period, more than or equal to first specified multiple of described reference period and less than the times N 2 in cycle of reference period, more than or equal to described reference period and less than the times N 3 in cycle of second specified multiple of reference period, with the times N 4 more than or equal to cycle of second specified multiple of described reference period, wherein first specified multiple is less than second specified multiple; Determination step, the size of more described times N 1, N4 and number of times sum (N2+N3), when described times N 1 is maximum, judge that described object is in the position far away than described reference range, when described times N 4 is maximum, judge that described object is more accurate apart near position than described, when described number of times sum (N2+N3) is maximum, the size of then more described times N 2 and N3, when described times N 2 is big, judge described object in the position far away, when described times N 3 is big, judge that described object is in the position nearer than described reference range than described reference range.
The invention effect
According to the present invention, the influence of the shortcoming of the mould jump pulse in the time of can eliminating period measurement and too much Interference Detection can judge correctly that the distance from the reflection-type optoelectronic switch to the object is near still far away than reference range.Again, in the present invention, period measurement unit and counting unit and identifying unit can be realized by simple structure, thereby can realize the good reflection-type optoelectronic switch of accuracy with simple and inexpensive structure.
Again, in the present invention, by the number of times correcting unit is set, the influence of too much Interference Detection in the time of can eliminating period measurement more effectively, thus improve judgement precision to the object distance.
Description of drawings
Fig. 1 is the block diagram of formation that shows the BGS optoelectronic switch of first embodiment of the invention.
Fig. 2 is the schematic diagram of an example showing that time of oscillation wavelength of the semiconductor laser of first embodiment of the invention changes.
Fig. 3 schematically shows the output voltage waveforms of current-voltage conversion enlarging section of first embodiment of the invention and the oscillogram of filter house output voltage waveforms.
Fig. 4 is the block diagram of formation of cycle difference portion that shows the BGS optoelectronic switch of first embodiment of the invention.
Fig. 5 is the oscillogram of output voltage waveforms of filter house that schematically shows the BGS optoelectronic switch of first embodiment of the invention.
Fig. 6 is the schematic diagram that the number of times in the cycle of the mould jump pulse when in the demonstration first embodiment of the invention waveform shortcoming taking place distributes.
Fig. 7 is the schematic diagram that the number of times in the cycle of the mould jump pulse the when cycle is divided into two according to noise in the demonstration first embodiment of the invention distributes.
Fig. 8 is the block diagram that shows the formation of the cycle difference portion of BGS optoelectronic switch in the second embodiment of the invention.
Fig. 9 is that display noise causes the mould jump pulse cycle to cut apart with waveform shortcoming and shows the schematic diagram that object does not have the number of times in the mould jump pulse cycle when static to distribute.
Figure 10 is the block diagram of formation of cycle difference portion that shows the BGS optoelectronic switch of four embodiment of the invention.
Figure 11 is the block diagram of formation that shows the BGS optoelectronic switch of fifth embodiment of the invention.
Figure 12 is the schematic diagram that shows the compound resonator model of the semiconductor laser in the existing laser instrumentation device.
Figure 13 is the schematic diagram of relation that shows the output waveform of the oscillation wavelength of semiconductor laser and built in light electric diode.
Figure 14 is the schematic diagram that shows the relation of object distance and the distribution of the number of times in mould jump pulse cycle.
Embodiment
[first execution mode]
Below, embodiments of the present invention are described with reference to the accompanying drawings.Fig. 1 is the block diagram that shows the structure of the BGS optoelectronic switch that relates to first embodiment of the invention.
The BGS optoelectronic switch of Fig. 1 has: the semiconductor laser 1 of emission laser, with the light output transform of semiconductor laser 1 is the photodiode 2 of the signal of telecommunication, the light that noise spectra of semiconductor lasers 1 is sent carries out the light harvesting emission, and the back light of object 10 carried out the lens 3 that light harvesting incides semiconductor laser 1, drive the laser driver 4 of semiconductor laser 1, the output current of photodiode 2 is transformed to voltage and amplified current-voltage transformation enlarging section 5, from the output voltage of current-voltage conversion enlarging section 5, remove the filter house 6 of carrier wave, measure the cycle of the MHP that comprises in the output voltage of filter house 6, and according to the cycle difference portion of the number of times in the cycle of MHP being distinguished based on the value of reference period 7, judge that according to the difference result of cycle difference portion 7 object 10 is than the near distance of reference range or the detection unit 8 of distance far away, shows the display part 9 of the result of determination of detection unit 8.
Photodiode 2 and current-voltage conversion enlarging section 5 constitute determination unit.Below, for convenience of explanation, suppose that semiconductor laser 1 uses and do not have mould to jump phenotype (VCSEL type, DFB laser class).
Cycle difference portion 7 measures the cycle of the MHP in the output voltage that is included in filter house 6, according to based on the value of the known periods of the MHP of object 10 when the reference range position of regulation (below, be called reference period Th) number of times in the cycle of MHP being distinguished.
Fig. 4 is the block diagram of the formation of display cycle difference portion 7.Cycle difference portion 7 comprises period measurement portion 70 and count section 71.Period measurement portion 70 comprises rise detection portion 72 and timing portion 73.
Fig. 5 is the figure of the action of explanation period measurement portion 70, and is to show that the output voltage waveforms of filter house 6 is the schematic diagram of the waveform of MHP.In Fig. 5, H1 is the threshold value that is used for detecting the rising of MHP.
The rising of MHP detects by comparing the output voltage and the threshold value H1 of filter house 6 in rise detection portion 72.Timing portion 73 measures the time tuu (that is the cycle of MHP) that rises next time that rises to from MHP based on the testing result of rise detection portion 72.Timing portion 73 carries out said determination when each rising to MHP detects.
The number of times difference of the period T of the MHP that count section 71 will be measured by period measurement portion 70 is following four kinds: less than 0.5 times of the reference period Th (times N 1 in the cycle of 0.5Th＞T), more than or equal to 0.5 times of reference period Th and less than the reference period Th (times N 2 in the cycle of 0.5Th≤T＜Th), more than or equal to reference period Th and less than 1.5 times of the reference period Th (times N 3 in the cycle of Th≤T＜1.5Th) and more than or equal to 1.5 times of the reference period Th (times N 4 in the cycle of 1.5Th≤T).
As mentioned above, the number of times in the cycle of 7 couples of MHP of cycle difference portion is distinguished.Cycle difference portion 7 (in the present embodiment, refers to respectively at first duration of oscillation P1 and second duration of oscillation P2) measure the cycle of MHP respectively between each test period, the number of times in cycle is distinguished.
Then, detection unit 8 judges that according to the measurement result of cycle difference portion 7 object 10 is near still far away than reference range.Detection unit 8 is the size of times N 1, N4 and the number of times sum (N2+N3) in the cycle of MHP relatively, if times N 1 is maximum, judge object 10 so in the position far away,, judge that so object 10 is in the position nearer than reference range if times N 4 is maximum than reference range.If number of times sum (N2+N3) is maximum, the size of detection unit 8 number of comparisons N2 and N3 then when times N 2 is bigger than times N 3, judges that object 10 is in the position far away than reference range, if times N 3 is bigger than times N 2, judge that object 10 is in the position nearer than reference range.
(in the present embodiment mode, respectively at first duration of oscillation P1 and second duration of oscillation P2) carries out above-mentioned judgement between the test period that detection unit 8 was measured and distinguished in the cycle of each 7 couples of MHP of cycle difference portion.
Fig. 6, Fig. 7 are the figure of resolution principle of explanation present embodiment, and Fig. 6 is the schematic diagram that shows that the number of times in the cycle of the MHP when producing the waveform shortcoming distributes, and Fig. 7 is the schematic diagram that the number of times in the cycle of the MHP when being divided into two because of noise the display cycle distributes.In Fig. 6, Fig. 7, T0 is the typical value (value of median or frequency of occurrences maximum etc.) of cycle times distribution a of the script of MHP.
If for example because the intensity of MHP is less, produce the words of the shortcoming (detect and omit) of MHP during period measurement, the cycle of MHP that then produces the place of shortcoming be about 2 times of cycle originally, and being distributed as with 2T0 by the cycle times of the MHP of this shortcoming generation is the normal distribution (b of Fig. 6) at center.The cycle times distribution a of the script of this number of times distribution b and MHP is similar figures.
On the other hand, if the noise mistake is detected as MHP during period measurement, then the cycle of MHP is divided into two parts with at random ratio.At this moment, as the result who noise is carried out superfluous counting, the cycle times that is divided into two-part MHP distributes and is be symmetrically distributed (c of Fig. 7) with respect to 0.5T0.
In the present embodiment, as mentioned above, the number of times in cycle of MHP is divided into 4 kinds, if the times N 1 less than cycle of 0.5 times of reference period Th is maximum, then this times N 1 is not caused by noise, and it is considered as the MHP cycle originally, and judges that object 10 is in the position far away than reference range.If the times N 4 more than or equal to cycle of 1.5 times of reference period Th is maximum, then this times N 4 is not that shortcoming by MHP causes, and it is considered as the script cycle of MHP, judges that object 10 is in the position nearer than reference range.Again, can't number of pass times N1 or N4 judge under the situation of distance of object 10, ignore times N 1 and N4, to more than or equal to 0.5 times of reference period Th and less than the times N 2 in cycle of reference period Th, with compare more than or equal to reference period Th and less than the size of the times N 3 in cycle of 1.5 times of reference period Th, thereby judge the distance of object 10.
Like this, in the present embodiment, can eliminate the shortcoming of MHP when measuring the cycle and the influence that superfluous noise measuring causes, 10 the distance (semiconductor laser 1 is to the distance of object 10 more precisely) of judging rightly from the BGS optoelectronic switch to object is far away still closely than reference range.
Cycle difference portion 7 and detection unit 8 can be realized by computer with CPU, storage device and interface and the program that is stored in the storage device, also can realize by hardware.In the present embodiment, cycle, difference cycle and the number of comparisons size of only measuring MHP can realize, therefore can simply constitute difference performance period portion 7 and detection unit 8.
[second execution mode]
Below, second embodiment of the invention is described.In the present embodiment, the whole formation of BGS optoelectronic switch is identical with first execution mode, so adopt the symbol of Fig. 1 to describe.
Fig. 8 is the block diagram of formation of cycle difference portion 7 that shows the BGS optoelectronic switch of second embodiment of the invention.Cycle difference portion 7 formations with respect to first execution mode of present embodiment have increased number of times correction unit 74.The action of period measurement portion 70 and count section 71 is identical with first execution mode.
Number of times correction unit 74 calculates more than or equal to 0.5 times of reference period Th and less than the corrected value N2 ' of the times N 2 in cycle of reference period Th with more than or equal to reference period Th and less than the corrected value N3 ' of the times N 3 in cycle of 1.5 times of reference period Th according to following formula.
N2’＝N2-N1 (2)
N3’＝N3+N1 (3)
Then, number of times correction unit 74 times N 1, N2, N3, N4 that count section 71 is tried to achieve and corrected value N2 ', the N3 ' that self tries to achieve are notified to detection unit 8.Identical with first execution mode, cycle difference portion 7 is distinguished the MHP cycle between each test period respectively, the corrected value of calculation times.Again, number of times correction unit 74, but also some among calculated correction value N2 ', the N3 '.
Then, the times N 1 in the cycle of the detection unit 8 comparison MHP of present embodiment and the size of N4 and number of times sum (N2+N3) if times N 1 is maximum, judge that then object 10 is in the place far away than reference range, if times N 4 is maximum, judge that then object 10 is in the place nearer than reference range.Again, detection unit 8 is under the situation of maximum in number of times sum (N2+N3), the size of number of comparisons corrected value N2 ' and times N 3, when corrected value N2 ' is bigger than times N 3, judge that object 10 is in the place far away than reference range, when times N 3 is bigger than corrected value N2 ', judge that object 10 is in the place nearer than reference range.Detection unit 8 carries out above-mentioned judgement between each test period.
Again, in number of times correction unit 74 calculated correction value N3 ', detection unit 8 carries out following judgement.That is, detection unit 8 is the times N 1 in the cycle of MHP and the size of N4 and number of times sum (N2+N3) relatively, if times N 1 be maximum, judges object 10 in the place far away than reference range, if times N 4 be a maximum, judgement object 10 is in the place nearer than reference range.Again, detection unit 8 is under the situation of maximum in number of times sum (N2+N3), the size of number of comparisons N2 ' and number of times corrected value N3 ', when times N 2 is bigger than number of times corrected value N3 ', judge that object 10 is in the place far away than reference range, when number of times corrected value N3 ' is bigger than times N 2, judge that object 10 is in the place nearer than reference range.
Other of BGS optoelectronic switch constitute with first execution mode in illustrated identical.
As the result of the superfluous counting of noise when the period measurement, be divided into two-part MHP cycle number of times distribution c as shown in Figure 7, morely overlapping with MHP cycle times distribution a originally.Therefore, in the present embodiment, as formula (2) to more than or equal to 0.5 times of reference period Th and proofread and correct less than the times N 2 in cycle of reference period Th, as formula (3) to proofreading and correct more than or equal to reference period Th and less than the times N 3 in cycle of 1.5 times of reference period Th.
Like this, in the present embodiment, can be more effective the influence of the noise measuring of surplus during the removal period measurement, compare with first execution mode, further improved judgement precision to the distance of object 10.
[the 3rd execution mode]
Below, third embodiment of the invention is described.In embodiment of the present invention,, adopt the symbol of Fig. 1, Fig. 4 to describe because the formation of BGS optoelectronic switch is identical with first execution mode.
The action of the period measurement portion 70 of cycle difference portion 7 is identical with first execution mode.
The count section 71 of present embodiment is identical with first execution mode, the number of times of the period T of the MHP that is measured by period measurement portion 70 is following four kinds by distinguishing: less than 0.5 times of the reference period Th (times N 1 of 0.5Th＞T), more than or equal to 0.5 times of reference period Th and less than the reference period Th (times N 2 in the cycle of 0.5Th≤T＜Th), more than or equal to reference period Th and less than 1.5 times of the reference period Th (times N 3 in the cycle of Th≤T＜1.5Th) and more than or equal to 1.5 times of the reference period Th (times N 4 in the cycle of 1.5Th≤T).
Identical with first execution mode, detection unit 8 is the size of times N 1, N4 and the number of times sum (N2+N3) in the cycle of MHP relatively, if times N 1 is maximum, judge that so object 10 is in the position far away than reference range, if times N 4 is maximum, judge that so object 10 is in the position nearer than reference range.If number of times sum (N2+N3) is maximum, then detection unit 8 is a benchmark with the integral multiple cycle nTh (n is the integer more than 2) of reference period Th, to be added on the times N 2 near the cycle nTh and less than the number of times of the period T of cycle nTh, be added on the N3 with near the of cycle nTh and more than or equal to the number of times of the period T of cycle nTh.Then, times N 2 after detection unit 8 relatively adds and the size of N3 if times N 2, is judged object 10 greater than times N 3 in the place far away than reference range, if times N 3 is bigger than times N 2, judge that object 10 is in the place nearer than reference range.
Other of BGS optoelectronic switch constitute and illustrated identical of first execution mode.
Present embodiment has illustrated the bearing calibration under the situation that the MHP shortcoming takes place when measuring the cycle of MHP, the measurement result of period measurement portion 70 is at N3＜N2＜effective when (N3+N4) setting up.
Again, also using under the situation of the present embodiment and second execution mode, needing to use corrected value N2 '.This corrected value N2 ' and times N 3 are carried out above-mentioned adding.
[the 4th execution mode]
In first～the 3rd execution mode, the possibility of erroneous judgement is not arranged if object 10 has static.This be because, if being positioned at the object 10 in semiconductor laser the place ahead moved to the direction near the BGS optoelectronic switch in the duration of oscillation, then the number of MHP increases (cycle of MHP shortens) in first duration of oscillation P1, and the number of MHP reduces (cycle of MHP is elongated) in second duration of oscillation P2 simultaneously.
Fig. 9 has shown that noise causes the cycle of MHP to cut apart and the waveform shortcoming, and has shown that object 10 does not have the number of times in the cycle of the MHP under the static situation to distribute.If suppose that cutting apart with the frequency proportions of waveform shortcoming of MHP cycle that noise causes is roughly the same at first duration of oscillation P1 and second duration of oscillation P2, owing to after number of times normalization, judge, therefore, can judge correctly also that from the BGS optoelectronic switch to object distance till 10 (more correctly say so from semiconductor laser 1 to object 10 till distance) is far away still nearer than reference range even object 10 moves.
In the present embodiment, the integral body of BGS optoelectronic switch constitutes and first execution mode identical, and the symbol of employing Fig. 1 describes.
Figure 10 is the block diagram of formation of cycle difference portion 7 of the BGS optoelectronic switch of four embodiment of the invention.The cycle difference portion 7 of present embodiment compares with the formation of first execution mode, has increased normalization portion 75 and number of times correction unit 76.The action of period measurement portion 70 and count section 71 and first execution mode identical.
In the present embodiment, the times N 1 that count section 71 is tried to achieve in first duration of oscillation P1, N2, N3, N4 are respectively as N1 (P1), N2 (P1), N3 (P1), N4 (P1), and the times N 1 that count section 71 is tried to achieve in second duration of oscillation P2, N2, N3, N4 are respectively as N1 (P2), N2 (P2), N3 (P2), N4 (P2).
As following formula, after normalization portion 75 carries out normalization with the number of times in each duration of oscillation to times N 1, N2, N3, N4 in each duration of oscillation, obtain the number of times sum N1 of first duration of oscillation P1 and second duration of oscillation P2 respectively for the times N after the normalization 1, N2, N3, N4 ", N2 ", N3 ", N4 ".
N1”＝{N1(P1)
/(N1(P1)+N2(P1)+N3(P1)+N4(P1))}
+{N1(P2)
/(N1(P2)+N2(P2)+N3(P2)+N4(P2))} (4)
N2”＝{N2(P1)
/(N1(P1)+N2(P1)+N3(P1)+N4(P1))}
+{N2(P2)
/(N1(P2)+N2(P2)+N3(P2)+N4(P2))} (5)
N3”＝{N3(P1)
/(N1(P1)+N2(P1)+N3(P1)+N4(P1))}
+{N3(P2)
/(N1(P2)+N2(P2)+N3(P2)+N4(P2))} (6)
N4”＝{N4(P1)
/(N1(P1)+N2(P1)+N3(P1)+N4(P1))}
+{N4(P2)
/(N1(P2)+N2(P2)+N3(P2)+N4(P2))} (7)
The number of times correction unit 76 following times N 2 that calculate like that " corrected value N2 ' and times N 3 " corrected value N3 '.
N2’＝N2”-N1” (8)
N3’＝N3”+N1” (9)
Then, number of times correction unit 76 times N 1 that normalization portion 75 is tried to achieve ", N2 ", N3 ", N4 " and the corrected value N2 ' and the N3 ' that self try to achieve be notified to detection unit 8.In the present embodiment and since try to achieve first duration of oscillation P1 and second duration of oscillation P2 and, cycle difference portion 7 moved in each cycle of oscillation (triangular wave cycle).Again, number of times correction unit 76 calculates some the getting final product among corrected value N2 ', the N3 '.
Then, the detection unit 8 of present embodiment is the times N 1 in the cycle of MHP relatively " and N4 " and the size of number of times sum (N2 "+N3 "), if times N 1 " be maximum; judge that then object 10 is in the place far away than reference range; if times N 4 " and be maximum, judge that then object 10 is in the place nearer than reference range.Again, under number of times sum (N2 "+N3 ") is maximum situation, detection unit 8 number of comparisons corrected value N2 ' and times N 3 " size; when corrected value N2 ' than times N 3 " big the time, judge that object 10 is in the place far away than reference range, when times N 3 " bigger than corrected value N2 ' time, judge that object 10 is in the place nearer than reference range.Detection unit 8 carries out above-mentioned judgement in each cycle of oscillation (triangular wave cycle).
Again, in number of times correction unit 76 calculated correction value N3 ', detection unit 8 carries out following judgement.Promptly, detection unit 8 is the times N 1 in the cycle of MHP relatively " and N4 " and the size of number of times sum (N2 "+N3 "), if times N 1 " be maximum, judge that then object 10 is in the place far away than reference range; if times N 4 " and be maximum, judge that then object 10 is in the place nearer than reference range.Again, detection unit 8 is under number of times sum (N2 "+N3 ") is maximum situation, number of comparisons N2 " and the size of the corrected value N3 ' of number of times; when times N 2 " bigger than the corrected value N3 ' of number of times the time, judge that object 10 is in the place far away than reference range, when the corrected value N3 ' of number of times than times N 2 " big the time, judge that then object 10 is in the place nearer than reference range.
Other of BGS optoelectronic switch constitute and illustrated identical of first execution mode.
In the present embodiment, identical with second execution mode, the influence of the noise measuring of surplus in the time of can effectively removing period measurement even object 10 has moved, also can correctly be judged the distance of object 10.
[the 5th embodiment]
In first～the 4th embodiment,, still also can not use photodiode to extract the MHP waveform out from as extracting the MHP waveform the photodiode output signals of light-receiving device out.Figure 11 is the block diagram of formation of the BGS optoelectronic switch of fifth embodiment of the invention, and the formation same with Fig. 1 adopts identical symbol.In the BGS optoelectronic switch of present embodiment, photodiode 2 and current-voltage conversion enlarging section 5 that working voltage test section 11 substitutes in first～the 4th execution mode.
Action and first～the 4th execution mode of semiconductor laser 1, laser driver 4, cycle difference portion 7, detection unit 8 and display part 9 identical.
Like this, in the present embodiment, can not use photodiode to extract the MHP waveform out, compare, can reduce the number of components of BGS optoelectronic switch, can reduce the cost of making the BGS optoelectronic switch with first～the 4th execution mode.
The present invention is applicable to reflection-type optoelectronic switch.
Claims (12)
1. a reflection-type optoelectronic switch is characterized in that, comprises:
The semiconductor laser of emission laser;
Make the laser driver of this semiconductor laser action;
Detection contains the detecting unit of the electric signal of interference waveform, and described interference waveform is owing to the self-mixing effect of the laser of launching from this semiconductor laser with the back light of the object that is positioned at described semiconductor laser the place ahead produces;
All measure the period measurement unit in the cycle of the described interference waveform in the output signal that is included in described detecting unit when importing interference waveform at every turn;
Counting unit, the cycle of the described interference waveform with the position of described object at reference range the time is during as reference period, the number of times in the cycle of the interference waveform that described counting unit will be measured by described period measurement unit is divided into following four kinds: less than the times N 1 in cycle of first specified multiple of described reference period, more than or equal to first specified multiple of described reference period and less than the times N 2 in cycle of reference period, more than or equal to described reference period and less than the times N 3 in cycle of second specified multiple of reference period, with the times N 4 more than or equal to cycle of second specified multiple of described reference period, wherein first specified multiple is less than second specified multiple;
Identifying unit, the more described times N 1 of this identifying unit, the size of N4 and number of times sum (N2+N3), when described times N 1 is maximum, judge that described object is in the position far away than described reference range, when times N 4 is maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2+N3) is maximum, the size of then more described times N 2 and N3, when described times N 2 is big, judge described object in the position far away, when described times N 3 is big, judge that then described object is in the position nearer than described reference range than described reference range.
2. reflection-type optoelectronic switch as claimed in claim 1 is characterized in that it further comprises:
Pass through the number of times correcting unit that N2 '=N2-N1 calculates the corrected value N2 ' of described times N 2,
The more described times N 1 of described identifying unit, the size of N4 and number of times sum (N2+N3), when described times N 1 is maximum, judge that described object is in the position far away than described reference range, when described times N 4 is maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2+N3) is maximum, the size of the corrected value N2 ' of more described number of times and times N 3 then, when described corrected value N2 ' is big, judge that described object is in the position far away than described reference range, when described times N 3 is big, judge that described object is in the position nearer than described reference range.
3. reflection-type optoelectronic switch as claimed in claim 1 is characterized in that it further comprises:
Pass through the number of times correcting unit that N3 '=N3+N1 calculates the corrected value N3 ' of described times N 3,
The more described times N 1 of described identifying unit, the size of N4 and number of times sum (N2+N3), when described times N 1 is maximum, judge that described object is in the position far away than described reference range, when described times N 4 is maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2+N3) is maximum, the size of the corrected value N3 ' of then more described times N 2 and number of times, when described times N 2 is big, judge that described object is in the position far away than described reference range, when described corrected value N3 ' is big, judge that described object is in the position nearer than described reference range.
4. reflection-type optoelectronic switch as claimed in claim 1 is characterized in that,
Described laser driver drives described semiconductor laser, make comprise at least oscillation wavelength dull continuously increase during first duration of oscillation and comprise at least oscillation wavelength continuously dull minimizing during second duration of oscillation exist alternately;
And further comprise:
The normalization unit, described normalization unit is after the times N 1, N2, N3, the N4 that described counting unit are tried to achieve with the number of times in each duration of oscillation by each duration of oscillation respectively carry out normalization, to the times N after each normalization 1, N2, N3, N4, try to achieve respectively first duration of oscillation and second duration of oscillation number of times and N1 ", N2 ", N3 ", N4 "; With
Pass through N2 '=N2 "-N1 " calculate described times N 2 " the number of times correcting unit of corrected value N2 ';
The more described times N 1 of described identifying unit "; N4 " and the size of number of times sum (N2 "+N3 "), when described times N 1 " when being maximum; judge that described object is in the position far away than described reference range; when described times N 4 " when being maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2 "+N3 ") when being maximum, then the corrected value N2 ' of more described number of times and times N 3 " size; when described corrected value N2 ' is big; judge that described object is in the position far away than described reference range; when described times N 3 " when big, judge that described object is in the position nearer than described reference range.
5. reflection-type optoelectronic switch as claimed in claim 1 is characterized in that,
Described laser driver drives described semiconductor laser, make comprise at least oscillation wavelength dull continuously increase during first duration of oscillation and comprise at least oscillation wavelength continuously dull minimizing during second duration of oscillation exist alternately;
And further comprise:
The normalization unit, described normalization unit is after the times N 1, N2, N3, the N4 that described counting unit are tried to achieve with the number of times in each duration of oscillation by each duration of oscillation respectively carry out normalization, for the times N after each normalization 1, N2, N3, N4, try to achieve respectively first duration of oscillation and second duration of oscillation number of times and N1 ", N2 ", N3 ", N4 "; With
Pass through N3 '=N3 "+N1 " calculate described times N 3 " the number of times correcting unit of corrected value N3 ';
The more described times N 1 of described identifying unit "; N4 " and the size of number of times sum (N2 "+N3 "), when described times N 1 " when being maximum; judge that described object is in the position far away than described reference range; when described times N 4 " when being maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2 "+N3 ") when being maximum, then more described times N 2 " and the size of the corrected value N3 ' of number of times; when described times N 2 " when big, judge that described object is in the position far away than described reference range, when described corrected value N3 ' is big, judge that described object is in the position nearer than described reference range.
6. as each described reflection-type optoelectronic switch in the claim 1～5, it is characterized in that described first specified multiple is 0.5, described second specified multiple is 1.5.
7. object detecting method, its distance that detects object is far still nearer than the reference range of regulation, it is characterized in that, comprises:
Drive current is offered semiconductor laser, drive the vibration step of described semiconductor laser action;
Detection contains the detection step of the signal of telecommunication of interference waveform, and described interference waveform is owing to the self-mixing effect of the laser of launching from this semiconductor laser with the back light of the object that is positioned at described semiconductor laser the place ahead produces;
All measure the period measurement step in the cycle that is included in the described interference waveform in the output signal that obtains by described detection step when importing interference waveform at every turn;
Counting step, the cycle of the described interference waveform with the position of described object at described reference range the time is during as reference period, to divide into following four kinds by the number of times in cycle of the interference waveform of described period measurement step measurements: less than the times N 1 in cycle of first specified multiple of described reference period, more than or equal to first specified multiple of described reference period and less than the times N 2 in cycle of reference period, more than or equal to described reference period and less than the times N 3 in cycle of second specified multiple of reference period, with the times N 4 more than or equal to cycle of second specified multiple of described reference period, wherein first specified multiple is less than second specified multiple;
Determination step, the size of more described times N 1, N4 and number of times sum (N2+N3), when described times N 1 is maximum, judge that described object is in the position far away than described reference range, when described times N 4 is maximum, judge that described object is more accurate apart near position than described, when described number of times sum (N2+N3) is maximum, the size of then more described times N 2 and N3, when described times N 2 is big, judge described object in the position far away, when described times N 3 is big, judge that described object is in the position nearer than described reference range than described reference range.
8. object detecting method as claimed in claim 7 is characterized in that it further comprises:
Pass through the number of times aligning step that N2 '=N2-N1 calculates the corrected value N2 ' of described times N 2;
The more described times N 1 of described determination step, the size of N4 and number of times sum (N2+N3), when times N 1 is maximum, judge that described object is in the position far away than described reference range, when times N 4 is maximum, judge that described object is in the position nearer than described reference range, when number of times sum (N2+N3) is maximum, the size of the corrected value N2 ' of more described number of times and times N 3 then, when described corrected value N2 ' is big, judge that described object is in the position far away than described reference range, when described times N 3 is big, judge that described object is in the position nearer than described reference range.
9. object detecting method as claimed in claim 7 is characterized in that it further comprises:
Pass through the number of times aligning step that N3 '=N3+N1 calculates the corrected value N3 ' of described times N 3,
The more described times N 1 of described determination step, the size of N4 and number of times sum (N2+N3), when times N 1 is maximum, judge that described object is in the position far away than described reference range, when described times N 4 is maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2+N3) is maximum, the size of the corrected value N3 ' of then more described times N 2 and number of times, when described times N 2 is big, judge that described object is in the position far away than described reference range, when described corrected value N3 ' is big, judge that described object is in the position nearer than described reference range.
10. object detecting method as claimed in claim 7 is characterized in that,
Described vibration step make the action of described semiconductor laser so that comprise at least oscillation wavelength dull continuously increase during first duration of oscillation and comprise at least oscillation wavelength continuously dull minimizing during second duration of oscillation exist alternately;
And further comprise:
The normalization step, after with the number of times in each duration of oscillation times N 1, N2, N3, the N4 that is obtained by described counting step being carried out normalization by each duration of oscillation respectively, for the times N after each normalization 1, N2, N3, N4, try to achieve respectively first duration of oscillation and second duration of oscillation number of times and N1 ", N2 ", N3 ", N4 "; With
Pass through N2 '=N2 "-N1 " calculate described times N 2 " the number of times aligning step of corrected value N2 ';
The more described times N 1 of described determination step "; N4 " and the size of number of times sum (N2 "+N3 "), when times N 1 " when being maximum; judge that described object is in the position far away than described reference range; when described times N 4 " when being maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2 "+N3 ") when being maximum, then the corrected value N2 ' of more described number of times and times N 3 " size; when described corrected value N2 ' is big; judge that described object is in the position far away than described reference range; when described times N 3 " when big, judge that described object is in the described position nearer than reference range.
11. object detecting method as claimed in claim 7 is characterized in that,
Described vibration step make the action of described semiconductor laser so that comprise at least oscillation wavelength dull continuously increase during first duration of oscillation and comprise at least oscillation wavelength continuously dull minimizing during second duration of oscillation exist alternately;
And further comprise:
The normalization step, after with the number of times in each duration of oscillation times N 1, N2, N3, the N4 that is obtained by described counting step being carried out normalization by each duration of oscillation respectively, for the times N after each normalization 1, N2, N3, N4, try to achieve respectively first duration of oscillation and second duration of oscillation number of times and N1 ", N2 ", N3 ", N4 "; With
Pass through N3 '=N3 "+N1 " calculate described times N 3 " the number of times aligning step of corrected value N3 ';
The more described times N 1 of described determination step "; N4 " and the size of number of times sum (N2 "+N3 "), when described times N 1 " when being maximum; judge that described object is in the position far away than described reference range; when described times N 4 " when being maximum, judge that described object is in the position nearer than described reference range, when described number of times sum (N2 "+N3 ") when being maximum, then more described times N 2 " and the size of the corrected value N3 ' of number of times; when described times N 2 " when big, judge that described object is in the position far away than reference range, when described corrected value N3 ' is big, judge that described object is in the position nearer than described reference range.
12., it is characterized in that described first specified multiple is 0.5 as each described object detecting method in the claim 7～11, described second specified multiple is 1.5.
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