CN101888232B - 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 a current-voltage conversion amplifying part (5)) and a distance judgment processing unit (a filtering part (6), a counting 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); and the distance judgment processing unit is used for judging whether the object (10) is nearer or further than the preset reference distance according to the information of the interference waveform.
Description
Technical field
The present invention relates to reflection-type optoelectronic switch, particularly detect reflection-type optoelectronic switch and the object detecting method far away or near than the reference range of regulation with the distance of object.
Background technology
In the past, a kind of as reflection-type optoelectronic switch, known have the distance distance far away or near than the reference range of regulation of measuring from optoelectronic switch to object to set reflection-type (Background Suppression, 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, detection background inspected object only not.
On the other hand, distance meter as the interference of light that utilizes laser to send, a kind of output light of laser and back light of determination object of utilizing proposed at the laser instrumentation device (for example,, with reference to non-patent literature 1, non-patent literature 2, non-patent literature 3) of the interference (self-mixing effect) of semiconductor laser inside.Figure 14 shows the compound resonator model of FP type (Fabry-Perot type) semiconductor laser.In Figure 14,101 is semiconductor laser, and 102 is semiconducting crystal cleavage surface, and 103 is photodiode, and 104 is determination object.
If the oscillation wavelength of laser is λ, distance from the cleavage surface 102 close to determination object 104 to determination object 104 is L, during condition of resonance below meeting, from the laser in the back light resonator 101 of determination object, mutually strengthen, Laser output has increased slightly.
L＝qλ/2 ...(1)
In formula (1), q is integer.Even if the scattered light of determination object 104 is very faint, but because the reflectivity showing in the resonator 101 of semiconductor laser increases, produces amplification, thereby can observe fully.
Because the size of semiconductor laser and Injection Current is corresponding, launch the laser that frequency is different, in modulating oscillation frequency, do not need external modulator, can directly modulate by Injection Current.Oscillation wavelength when Figure 15 demonstration changes the oscillation wavelength of semiconductor laser with certain certain ratio and the relation between the output waveform of photodiode 103.When meeting formula (1) L=q λ/2, the phase difference of the laser in back light resonator 101 is 0 ° (same-phase), and now the laser in back light resonator 101 is maximum enhancing mutually; If L=q λ/2+ λ/4 o'clock, phase difference is 180 ° (phase reversals), and now the laser in back light resonator 101 is that maximum weakens mutually.Therefore, if change the oscillation wavelength of semiconductor laser, Laser output is that strong and weak alternate repetition occurs, now, Laser output is detected by the photodiode 103 that is arranged on resonator 101, obtains the stepped waveform of the some cycles as shown in Figure 15.Such waveform is commonly referred to as interference fringe.
This stair-stepping waveform, each interference fringe is called mould jump pulse (being called MHP below).MHP is different from the phenomenon that mould is jumped phenomenon.For example, in the distance to determination object 104, be L1, when the number of MHP is 10, in the distance L 2 of half, the number of MHP is 5.That is,, when making the oscillation wavelength variation of semiconductor laser in a certain special time, the number of MHP is ratio with mensuration distance and changes.So, by photodiode 103, detect MHP, measure the frequency of MHP, easily instrumentation distance.
Utilize the laser instrumentation device of above-mentioned Self-mixing, can realize BGS optoelectronic switch.As long as BGS optoelectronic switch, by comparing with the reference range of regulation, carries out object in closely still ON/OFF judgement at a distance.Therefore, when the laser instrumentation device of Self-mixing uses as BGS optoelectronic switch, as long as the average period of the MHP that judgement is measured the MHP when the position of reference range with respect to object the known reference cycle be long or short.The known reference cycle of MHP with respect to object when the position of reference range, the average period of the MHP being measured to is in long situation, ON is judged to be object in the position nearer than reference range, again, the cycle of the MHP being measured to is that in short situation, OFF is judged to be object in the position more farther than reference range.
Patent documentation 1 Japanese kokai publication sho 63-102135 communique
Patent documentation 2 Japanese kokai publication sho 63-187237 communiques
On non-patent literature 1, field just, hillside plot is earnest, Chinese wistaria enters, < < utilizes distance meter > > 1994 East Sea branches of the annual electrical relation association associating conference speech collection of thesis of the self-mixing effect of semiconductor laser, 1994
Non-patent literature 2 hillside plots are earnest, Chinese wistaria enters, Tianjin Tian Jisheng, upper field just, the research > > of < < about utilizing the small-sized distance of the self-mixing effect of semiconductor laser to count, Ai Zhi polytechnical university 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 the laser instrumentation device of Self-mixing, can realize BGS optoelectronic switch.But average period and the reference period of only trying to achieve MHP compare, judge that precision can variation.Therefore, the method that inventor utilizes patent application to propose for No. 2007-015020, the number of times of obtaining the cycle of MHP distributes, obtain the typical value of the distribution of median or mode etc., according to the number of times in the typical value of the distribution in this cycle and cycle, distribute and calculate the distance of object, the distance of calculating and reference range are compared, can improve judgement precision.Then, in such method, need memory and computer, thereby cause the problem of the cost rising of BGS optoelectronic switch.
Summary of the invention
The present invention makes in order to solve above-mentioned problem, and its object is to utilize the laser instrumentation device of Self-mixing, with simple and cheap structure, realizes the good reflection-type optoelectronic switch of precision.
Reflection-type optoelectronic switch of the present invention, comprises: the semiconductor laser of Emission Lasers; The detecting unit of the electric signal that detection contains interference waveform, described interference waveform is because the laser of launching from this semiconductor laser and the self-mixing effect of back light from being positioned at the object in described semiconductor laser the place ahead produce; According to the information that is included in the described interference waveform in the output signal of this detecting unit, judge distance to described object than the reference range of regulation far away or near range estimation processing unit.
Again, in a configuration example of reflection-type optoelectronic switch of the present invention, range estimation processing unit comprises: counting unit, this counting unit is when using the cycle of the described interference waveform when described object is positioned at the position of described reference range as reference period, and the number of the described interference waveform that the output signal of described detecting unit is comprised is divided into the number of the short interference waveform of reference period described in the number of the interference waveform that reference period is long described in period ratio and period ratio and counts; Identifying unit, this identifying unit is when the number of the number of long interference waveform of the described cycle interference waveform shorter than the described cycle is many, judge that described object is in the position nearer than described reference range, when the number of the number of short interference waveform of the described cycle interference waveform longer than the described cycle is many, judge that described object is in the position far away than described reference range.
Again, in a configuration example of reflection-type optoelectronic switch of the present invention, described range estimation processing unit comprises: counting unit, this counting unit is using the half period of the described interference waveform when described object is positioned at the position of described reference range as benchmark during the half period, and the number of the described interference waveform that the output signal of described detecting unit is comprised is divided into the number of the number of the half period interference waveform longer than the described benchmark half period and the half period interference waveform shorter than the described benchmark half period and counts; Identifying unit, this identifying unit is when the number of the number of long interference waveform of the described half period interference waveform shorter than the described half period is many, judge that described object is in the position nearer than described reference range, when the number of the number of short interference waveform of the described half period interference waveform longer than the described half period is many, judge that described object is in the position far away than described reference range.
Again, in a configuration example of reflection-type optoelectronic switch of the present invention, described counting unit comprises: the rise detection unit that detects the rising of described interference waveform; Mensuration is from the timing unit that rises to the time of rising next time of described interference waveform; Comparing unit, when described comparing unit is longer than described reference period in the time of rising next time from rising to of described interference waveform, the number of the interference waveform that described in increase period ratio, reference period is long, the time of rising next time from rising to of interference waveform than described reference period in short-term, increase the number of the short interference waveform of reference period described in period ratio.
Again, in a configuration example of reflection-type optoelectronic switch of the present invention, described counting unit comprises: the decline detecting unit that detects the decline of described interference waveform; Mensuration is from the timing unit that drops to the time declining next time of described interference waveform; Comparing unit, when described comparing unit is longer than described reference period in the time declining next time from dropping to of described interference waveform, the number of the interference waveform that described in increase period ratio, reference period is long, the time declining next time from dropping to of interference waveform than described reference period in short-term, increase the number of the short interference waveform of reference period described in period ratio.
Again, in a configuration example of reflection-type optoelectronic switch of the present invention, described counting unit comprises: the rise detection unit that detects the rising of described interference waveform; Detect the decline detecting unit of the decline of described interference waveform; Mensuration is from the very first time determination unit that rises to the very first time of rising next time of described interference waveform; Mensuration is from the second timing unit that drops to the second time declining next time of described interference waveform; Comparing unit, when described comparing unit was grown than described reference period in the described very first time or described the second time is longer than described reference period, the number of the interference waveform that described in increase period ratio, reference period is long, in the described very first time, than described reference period, short or described the second time than described reference period in short-term, increases the number of the short interference waveform of reference period described in period ratio.
Again, in a configuration example of reflection-type optoelectronic switch of the present invention, described counting unit comprises: the rise detection unit that detects the rising of described interference waveform; Detect the decline detecting unit of the decline of described interference waveform; Mensuration is from the very first time determination unit that rises to the very first time declining next time of described interference waveform; Mensuration is from the second timing unit that drops to second time of rising next time of described interference waveform; Comparing unit, described comparing unit is when in the described very first time, than the described benchmark half period, long or described the second time is longer than the described benchmark half period, increase the number of the half period interference waveform longer than the described benchmark half period, the described very first time than the described benchmark half period short or described the second time than the described benchmark half period in short-term, increase the number of the half period interference waveform shorter than the described benchmark half period.
At object detecting method of the present invention, comprising: drive current is offered to the vibration step that semiconductor laser makes described semiconductor laser action again; The detecting step of the electric signal that detection contains interference waveform, described interference waveform produces due to the laser of launching from this semiconductor laser with from the self-mixing effect of back light that is positioned at the object in described semiconductor laser the place ahead; According to the information that is included in the described interference waveform in the output signal that this detecting step obtains, judge distance to described object than the reference range of regulation far away or near range estimation treatment step.
Again, in a configuration example of object detecting method of the present invention, described range estimation treatment step comprises: counting step, it is when using the cycle of the described interference waveform when described object is positioned at the position of described reference range as reference period, the number of the described interference waveform that the output signal obtaining at described detecting step is comprised, the number that is divided into the short interference waveform of reference period described in the number of the interference waveform that reference period is long described in period ratio and period ratio is counted; Determination step, when its number at the number of long interference waveform of the described cycle interference waveform shorter than the described cycle is many, judge that described object is in the position nearer than described reference range, when the number of the number of short interference waveform of the described cycle interference waveform longer than the described cycle is many, judge that described object is in the position far away than described reference range.
Again, in a configuration example of object detecting method of the present invention, described range estimation treatment step comprises: counting step, it is using the half period of the described interference waveform when described object is positioned at the position of described reference range as benchmark during the half period, the number of the described interference waveform that the output signal obtaining at described detecting step is comprised, the number that is divided into the number of the half period interference waveform longer than the described benchmark half period and the half period interference waveform shorter than the described benchmark half period is counted; Determination step, when its number at the number of long interference waveform of the described half period interference waveform shorter than the described half period is many, judge that described object is in the position nearer than described reference range, when the number of the number of short interference waveform of the described half period interference waveform longer than the described half period is many, judge that described object is in the position far away than described reference range.
Accompanying drawing explanation
Fig. 1 is the block diagram that shows the structure of the BGS optoelectronic switch that relates to first embodiment of the invention.
Fig. 2 is the figure of an example showing that time of oscillation wavelength of the semiconductor laser of first embodiment of the invention changes.
(A) of Fig. 3 shows that the current-voltage of first embodiment of the invention converts the schematic diagram of the output voltage waveforms of enlarging section, and (B) of Fig. 3 is the schematic diagram that shows the output voltage waveforms of filter house.
Fig. 4 is the figure that shows the distance of object and the relation of the number of times in the cycle of mould jump pulse distribution in first embodiment of the invention.
Fig. 5 is the block diagram of formation of the count section of the BGS optoelectronic switch that shows that the second execution mode of the present invention relates to.
Fig. 6 is the schematic diagram of output voltage waveforms of the filter house of explanation the second execution mode of the present invention.
Fig. 7 is the maximum schematic diagram of the output voltage waveforms of filter house constantly of triangular wave.
Fig. 8 is the schematic diagram of formation of the count section of the BGS optoelectronic switch that relates to of third embodiment of the invention.
Fig. 9 is the schematic diagram of output voltage waveforms of the filter house of third embodiment of the invention.
Figure 10 is the oscillogram that the problem of the count section of the BGS optoelectronic switch that relates to of explanation third embodiment of the invention is used.
What Figure 11 showed is in third embodiment of the invention, in mould jump pulse, to exist in the situation of DC bias voltage, the example that the number of times of the half period of mould jump pulse distributes.
Figure 12 is the minimum value schematic diagram of the output voltage waveforms of filter house constantly of triangular wave.
Figure 13 is the block diagram of formation that shows the BGS optoelectronic switch of fifth embodiment of the invention,
What Figure 14 showed is the compound resonator model of the semiconductor laser of existing laser instrumentation device.
Figure 15 shows the relation between the oscillation wavelength of semiconductor laser and the output waveform of built in light electric diode.
Embodiment
[the first execution mode]
Below, with reference to accompanying drawing explanation embodiments of the present invention.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 Lasers, the photodiode 2 that is the signal of telecommunication by the light output transform of semiconductor laser 1, the light that noise spectra of semiconductor lasers 1 is sent carries out light harvesting transmitting, and the back light of object 10 is carried out to the lens 3 that light harvesting incides semiconductor laser 1, drive the laser driver 4 of semiconductor laser 1, the current-voltage conversion enlarging section 5 that the output current of photodiode 2 is transformed to voltage and amplifies, from the output voltage of current-voltage conversion enlarging section 5, remove the filter house 6 of carrier wave, calculate the count section 7 of the number of the MHP containing in the output voltage of filter house 6, according to the count results of count section 7, judge that object 10 is than the near distance of reference range or the detection unit 8 of distance far away, the display part 9 that shows the result of determination of detection unit 8.
Photodiode 2 and current-voltage conversion enlarging section 5 form detecting unit, and filter house 6 and count section 7 and detection unit 8 form range estimation processing 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).
Laser driver 4 offers semiconductor laser 1 by using the triangular wave drive current that certain rate of change increases and decreases repeatedly along with the time as Injection Current.Like this, semiconductor laser 1 is driven to, and with being in proportion of Injection Current, second duration of oscillation that first duration of oscillation that oscillation wavelength increases continuously with certain rate of change and oscillation wavelength are reduced continuously with certain rate of change occurs alternately repeatedly.Fig. 2 is the figure changing the time of the oscillation wavelength of demonstration semiconductor laser 1.In Fig. 2, P1 was first duration of oscillation, and P2 was second duration of oscillation, and λ a is the minimum value of oscillation wavelength during each, and λ b is the maximum of oscillation wavelength during each, and Tt is triangle wave period.In the present embodiment, the maximum λ b of oscillation wavelength and the minimum value λ a of oscillation wavelength are respectively certain value conventionally, and their poor λ b-λ a is also generally certain value.
Laser scioptics 3 light harvestings that semiconductor laser 1 sends, incide object 10.Light scioptics 3 light harvestings that reflected by object 10, incide semiconductor laser 1.But the light harvesting of lens 3 not necessarily.Photodiode 2 is arranged near the inside of semiconductor laser 1 or its, and the light output transform of semiconductor laser 1 is electric current.Current-voltage conversion enlarging section 5 is transformed to the output current of photodiode 2 voltage and amplifies.
Filter house 6 has the function that extracts overlapped signal from modulating wave.(A) of Fig. 3 is the schematic diagram that shows the output voltage waveforms of current-voltage conversion enlarging section 5, and (B) of Fig. 3 is the schematic diagram that shows the output voltage waveforms of filter house 6.The waveform (carrier wave) that these accompanying drawings have represented to remove from being equivalent to the waveform (modulating wave) of (A) of Fig. 3 of the output of photodiode 2 semiconductor laser 1 of Fig. 2 extracts the process of MHP waveform (interference waveform) of Fig. 3 (B).
Count section 7 is respectively in the first duration of oscillation P1 and the second duration of oscillation P2, be included in the number of the MHP in the output voltage of filter house 6, especially object 10 regulation reference position time period ratio MHP known periods (below, be called reference period Th) the number Nshort of the number Nlong of long MHP and the short MHP of period ratio reference period, counts.
The spacing distance of each MHP is 0.5mm, and reference range is 200mm, and in the situation that triangle wave frequency is 1kHz, the number of the MHP of mensuration is distance [the mm]/0.5[mm with object 10].So when BGS optoelectronic switch is only the position of reference range, the number of MHP is 200[mm at object 10]/0.5[mm]=400[].Now, the reference period Th of MHP was 1/ (1000x2)/400=1.25[μ second].If the distance to object 10 is longer than reference range, the period ratio reference period Th=1.25[μ second of MHP] short, if shorter than reference range to the distance of object 10, the period ratio reference period Th=1.25[μ second of MHP] long.
If object 10 is in the place nearer than reference range, the period profile of MHP is as the distribution 40 of Fig. 4, towards the direction skew longer than reference period Th.Contrary, if object 10 in the place far away than reference range, the period profile of MHP is as the distribution 41 of Fig. 4, towards the direction skew shorter than reference period Th.
Detection unit 8 judges that according to the count results of count section 7 object 10 is in the local or far away place nearer than reference range.; the number Nshort of the MHP that the number Nlong of the MHP that detection unit 8 compare cycles are longer than reference period Th and period ratio reference period Th are short; when Nlong > Nshort sets up; judge that object 10 is in the place nearer than reference range; if Nlong < Nshort sets up, judge that so object 10 is in the place far away than reference range.
During the counting that detection unit 8 is counted in the number of 7 couples of MHP of each count section, (the first duration of oscillation P1 in present embodiment and the second duration of oscillation P2) carries out above-mentioned judgement.
Display part 9 shows the result of determination of detection unit 8.
As mentioned above, in the present embodiment, the number Nshort of the MHP that number Nlong that can be by the compare cycle MHP longer than reference period Th and period ratio reference period Th are short judges that the distance (the more precisely distance from semiconductor laser 1 to object 10) from BGS optoelectronic switch to object 10 positions is far away or near than reference range, therefore can realize with simple and cheap formation the good BGS optoelectronic switch of precision.
Again, count section 7 and detection unit 8 can be by possessing the computer of CPU, storage device and interface, and the program being stored in storage device realizes, and also can realize by hardware.
Again, in the present embodiment, although relatively be the number Nshort of the MHP that the number Nlong of the long MHP of period ratio reference period Th and period ratio reference period Th are short, but the number that also can compare the number of the half period MHP longer than half Th/2 of reference period (following, be called benchmark half period Th/2) and the half period MHP shorter than benchmark half period Th/2.Use the situation of benchmark half period Th/2 to narrate in the back.
[the second execution mode]
Below, the second execution mode of the present invention is described.Present embodiment is to carry out more specifically bright to the count section 7 of the first execution mode.Fig. 5 is the block diagram of formation of the count section of the BGS optoelectronic switch that shows that the second execution mode of the present invention relates to.
The count section 7 of present embodiment has rise detection portion 70, decline test section 71, timing portion 72,73 and comparing section 74.
Fig. 6 is for the figure of action of the count section 7 of present embodiment is described, and is to show that the output voltage waveforms of filter house 6 is the schematic diagram of the waveform of MHP.In Fig. 6, H1 is the threshold value for detection of the rising of MHP, and H2 is the threshold value for detection of the decline of MHP.
The rising of MHP, by the output voltage of filter house 6 and threshold value H1 are compared, detects in rise detection portion 70.Timing portion 72, according to the testing result of rise detection portion 70, measures the time tuu next time rising that rises to from MHP.Timing portion 72 carries out such mensuration at every turn when detecting the rising of MHP.
On the other hand, decline test section 71, by comparing output voltage and the threshold value H2 of filter house 6, detects the decline of MHP.Time detecting portion 73, according to the testing result of decline test section 71, measures the time tdd that decline to next time that drops to from MHP.Timing portion 73 carries out such mensuration at every turn when detecting the decline of MHP.
Comparing section 74 is the time tuu and the described reference period Th that rise to rising next time of MHP relatively, if time tuu is longer than reference period Th, the number Nlong of the MHP that period ratio reference period Th is long increases by 1, if the time, tuu was shorter than reference period, the number Nshort of the MHP that period ratio reference period Th is short increases by 1.Comparing section 74 is carried out such counting when each minute tuu.
Or comparing section 74 also can be utilized from MHP and drop to the time tdd that decline to next time, carries out following mensuration.; comparing section 74 compares drop to the time tdd and the reference period Th that decline next time from MHP; if time tdd is longer than reference period Th; the number Nlong of the long MHP of period ratio reference period Th is increased to 1; if the time, tdd was shorter than reference period, the number Nshort of the short MHP of period ratio reference period Th is increased to 1.Comparing section 74 is carried out such counting when each minute tdd.
As mentioned above, the number Nshort of the MHP that the number Nlong of the MHP that the comparing section 74 of present embodiment is can computing cycle longer than reference period Th and period ratio reference period Th are short.As illustrated in the first execution mode, count section 7 respectively each counting during (the first duration of oscillation P1 and the second duration of oscillation P2 are separately) MHP is counted.
Again, the in the situation that of comparing section tuu 74 service time, decline test section 71 and timing portion 73 not necessarily form.Again, in the situation of comparing section tdd service time, rise detection portion 70 and time detecting portion 72 not necessarily form.
Other of BGS optoelectronic switch form with in the first execution mode, illustrate identical.
In the present embodiment, if carry out the detection of rising (or decline) of MHP and Cycle Length relatively, so can simply form and realize count section 7.
But, in the present embodiment, also have following problem.; in the situation that the Self-mixing laser instrumentation device using as BGS optoelectronic switch; because the oscillation wavelength of semiconductor laser 1 is changed to triangular waveform; therefore cannot eliminate the impact that the transition on triangular wave summit is replied completely; because cycle of MHP may be than actual length or short by instrumentation; therefore cause the error of count results to produce, the possibility of result produces erroneous judgement to the distance of object 10.
; filter house 6 is removed the waveform (carrier wave) of semiconductor laser 1 from the output voltage waveforms (modulating wave) of current-voltage conversion enlarging section 5; MHP waveform shown in extraction Fig. 3 (B); but now; in the output of filter house 6, in the moment on the summit of triangular wave, there is the transition response waveform of needle pattern.Because this transition response waveform causes the instrumentation in MHP cycle to produce error.
Utilize Fig. 7 to describe this problem.In the example of Fig. 7, some PE shows the peaked moment of triangular wave.As shown in Fig. 3 (B), in the peaked moment of triangular wave, in the output of filter house 6, there is downward spike noise, therefore MHP becomes the waveform that is pulled to the direction that voltage is low as shown in Figure 7.Therefore, shorter than original value from the time tuu that rises to rising next time of MHP, longer than original value from the time tdd that drops to decline next time of MHP.If the action of count section 7 and detection unit 8 is carried out in the one-period of triangular wave, can improve the problems referred to above, but the in the situation that of there is DC bias voltage in MHP, due to the transition constantly of the maximum of triangular wave, reply the transition constantly with the minimum value of triangular wave and reply as different replying, therefore can exert an influence.
[the 3rd execution mode]
Below the 3rd execution mode of the present invention is described.Present embodiment is to adopting the situation of benchmark half period Th/2 to describe in the BGS optoelectronic switch of the first execution mode.Fig. 8 is the schematic diagram of formation of count section of the BGS optoelectronic switch of third embodiment of the invention.
The count section 7 of present embodiment has rise detection portion 70, decline test section 71, timing portion 75,76 and comparing section 77.
Fig. 9 is the figure of action of the count section 7 of explanation present embodiment, but also is to show that the output voltage waveforms of filter house 6 is the schematic diagram of the waveform of MHP.
The action of rise detection portion 70 and decline test section 71 is identical with the second execution mode.
Timing portion 75, according to the testing result of rise detection portion 70 and decline test section 71, measures the time tud that decline to next time that rises to from MHP.Timing portion 75 carries out such mensuration when detecting the rising of MHP at every turn and declining.
On the one hand, timing portion 76, according to the testing result of rise detection portion 70 and decline test section 71, measures the time tdu rising next time that drops to from MHP.Timing portion 76 carries out such mensuration when detecting the decline of MHP at every turn and rising.
Comparing section 77 compares by the time tud declining next time from rising to of MHP with from drop to the time tdu and the benchmark half period Th/2 that rise next time of MHP, when time tud is when than benchmark half period Th/2, long or time tdu is longer than benchmark half period Th/2, the number Nlong of the MHP that half period is longer than benchmark half period Th/2 increases by 1, if time tud is shorter or time tdu is shorter than benchmark half period Th/2 than benchmark half period Th/2, the number Nshort of the half period MHP shorter than benchmark half period Th/2 increases by 1.During some in each minute tud or tdu of comparing section 77, carry out such counting.
As mentioned above, the number Nshort of the MHP that the number Nlong of the MHP that the count section of present embodiment is can half period longer than benchmark half period Th/2 and half period are shorter than benchmark half period Th/2 counts.As described in the first execution mode, count section 7 respectively each counting during (the first duration of oscillation P1 and the second duration of oscillation P2 are separately) carry out the counting to MHP.
In present embodiment, the number Nshort of the MHP that the number Nlong of the MHP that the 8 comparison half periods of detection unit are longer than benchmark half period Th/2 and half period are shorter than benchmark half period Th/2, when Nlong > Nshort sets up, judge that object 10 is in the position nearer than reference range, when Nlong < Nshort sets up, can judge that object 10 is in the position far away than reference range.
Other of BGS optoelectronic switch form illustrated with the first execution mode identical.
In the present embodiment, except the effect of the second execution mode, because count value is 2 times, can improve counting precision, its result has improved the judgement precision of the distance of object 10.
But, in the present embodiment, there is problem below, in MHP, exist in the situation of DC bias voltage, be difficult to judge the distance of object 10.With Figure 10, Figure 11, this problem is described.What the example of Figure 10 showed is due to DC bias voltage, and the average voltage of MHP is than the high situation of value of original anticipation.As shown in figure 10, have DC bias voltage in MHP, the rising of MHP and decline can correctly not be divided into 1/2, therefore long than original value from the time tud that rises to decline next time of MHP, shorter than original value from the time tdu that drops to rising next time of MHP.
Therefore, as shown in figure 11, the distribution of the half period of MHP is the coincidence of two normal distributions of line symmetry with respect to benchmark half period Th/2.That is, the number Nshort of the number Nlong of the half period MHP longer than benchmark half period Th/2 and the half period MHP shorter than benchmark half period Th/2 is almost identical.Thereby because MHP count results produces error, result erroneous judgement is decided to be Nlong > Nshort, or sometimes erroneous judgement is decided to be Nlong < Nshort, thereby is difficult to the distance of object 10 correctly to be judged.
[the 4th execution mode]
Below four embodiment of the invention is described.Present embodiment is more specifically bright to the count section 7 of the first execution mode.Identical due to the formation of the count section 7 of present embodiment and the second execution mode, therefore adopts the symbol of Fig. 5 to describe.
The action of rise detection portion 70, decline test section 71 and timing portion 72,73, identical with the second execution mode.
The comparing section 74 of present embodiment is by rising to the time tuu till rise next time and comparing from the time tdd and the said reference cycle T h that drop to till decline to next time of MHP from MHP, in the situation that time tuu is longer than reference period Th than the long situation of reference period Th or time tdd, number Nlong to the long MHP of period ratio reference period Th increases by 1, in the situation that time tuu is shorter than reference period Th than the short situation of reference period Th or time tdd, the number Nshort of the short MHP of period ratio reference period Th is increased to 1.Comparing section 74 is carried out such counting when at every turn to some mensuration in time tuu, tdd.
As mentioned above, the number Nshort of the MHP that the number Nlong of the MHP that the count section 7 of present embodiment can be grown period ratio reference period Th and period ratio reference period Th are short counts.Illustrated in the first execution mode, count section 7 respectively each counting during (the first duration of oscillation P1 and the second duration of oscillation P2 are separately) MHP is counted.
Other of BGS optoelectronic switch form illustrated with the first execution mode identical.
In the present embodiment, except the effect of the 3rd execution mode, the impact on count results is replied in the transition that also can reduce triangular wave summit, can eliminate the problem of mentioning in the second execution mode.
As shown in Figure 7, due to the moment on triangular wave summit, MHP becomes the waveform that is pulled to the direction that voltage is low, shorter than original value from the time tuu rising to till rise next time of MHP, longer than original value from the time tdd that drops to decline next time of MHP.
On the other hand, in the example of Figure 12, some PE represents the moment of the minimum value of triangular wave.As shown in Fig. 3 (B), due to the minimum value at triangular wave time be engraved in filter house 6 output produce spike noise upwards, therefore MHP becomes the waveform that is pulled to the direction that voltage is high as shown in figure 12.Therefore, longer than original value from the time tuu that rises to rising next time of MHP, shorter than original value from the time tdd that drops to decline next time of MHP.
In arbitrary situation of Fig. 7, Figure 12, due to the impact that transition is replied, the number of the MHP that the number of the MHP that periodic quantity is longer than original value and periodic quantity are shorter than original value about equally.Thereupon, the number Nshort of the MHP that the number Nlong of the MHP that period ratio reference period Th is long and period ratio reference period Th are short increases identical number, or reduce identical number, therefore can offset the variation of replying the count results causing because of transition, the impact that count results is caused is replied in the transition that can reduce the summit of triangular wave.
Again, the in the situation that of present embodiment, even if there is DC bias voltage in MHP, due to the next time tuu rising of rising to of MHP with from the time tdd declining next time that drops to of MHP, there is no variation, the impact of the DC bias voltage of MHP can be eliminated, thereby the problem illustrating in the 3rd execution mode can be eliminated.
[the 5th execution mode]
In the first～four execution mode, from the output signal of the photodiode as light-receiving device, extract MHP waveform out, but also can with photodiode, not extract MHP waveform out.Figure 13 is the block diagram of formation that shows the BGS optoelectronic switch of fifth embodiment of the invention, marks identical symbol in the formation identical with Fig. 1.The BGS optoelectronic switch of present embodiment replaces photodiode 2 and the current-voltage conversion enlarging section 5 of the first～four execution mode with voltage detection department 11.
Voltage detection department 11 detects the also voltage between terminals of amplification semiconductor laser 1, i.e. voltage between anode-cathode.Due to the laser of semiconductor laser 1 transmitting with from the back light of object 10, produce while interfering, in the voltage between terminals of semiconductor laser 1, occur MHP waveform.Thereby can extract MHP waveform from the voltage between terminals of semiconductor laser 1.
Filter house 6 and first～four execution mode is identical, has the function that extracts overlapped signal from modulating wave, extracts MHP waveform from the output voltage of voltage detection department 11.
Action and first～four's of semiconductor laser 1, laser driver 4, count section 7, detection unit 8 and display part 9 execution mode is identical.
Like this, in the present embodiment, do not use photodiode can extract MHP waveform out, and the parts of comparing the first～four execution mode BGS optoelectronic switch also can cut down, thereby can reduce the expense of BGS optoelectronic switch.
Utilizability in industry
The present invention can be applicable to reflection-type optoelectronic switch.
Claims (8)
1. a reflection-type optoelectronic switch, is characterized in that, comprises:
The semiconductor laser of lase;
The detecting unit of the electric signal that detection contains interference waveform, described interference waveform is because the laser of launching from this semiconductor laser and the self-mixing effect of back light that is positioned at the object in described semiconductor laser the place ahead produce;
According to the information that is included in the described interference waveform in the output signal of this detecting unit, judge distance to described object than the reference range of regulation far away or near range estimation processing unit wherein, described range estimation processing unit comprises:
Counting unit, this counting unit is when using the cycle of the described interference waveform when described object is positioned at the position of described reference range as reference period, and the number of the described interference waveform that the output signal of described detecting unit is comprised is divided into the number of the short interference waveform of reference period described in the number of the interference waveform that reference period is long described in period ratio and period ratio and counts;
Identifying unit, this identifying unit is when the number of the number of the long interference waveform of reference period described in the described period ratio interference waveform shorter than reference period described in described period ratio is many, judge that described object is in the position nearer than described reference range, when the number of the number of the short interference waveform of reference period described in the described period ratio interference waveform longer than reference period described in described period ratio is many, judge that described object is in the position far away than described reference range.
2. a reflection-type optoelectronic switch, is characterized in that, comprises:
The semiconductor laser of lase;
The detecting unit of the electric signal that detection contains interference waveform, described interference waveform is because the laser of launching from this semiconductor laser and the self-mixing effect of back light that is positioned at the object in described semiconductor laser the place ahead produce;
According to the information that is included in the described interference waveform in the output signal of this detecting unit, judge distance to described object than the reference range of regulation far away or near range estimation processing unit, wherein, described range estimation processing unit comprises:
Counting unit, this counting unit is using the half period of the described interference waveform when described object is positioned at the position of described reference range as benchmark during the half period, and the number of the described interference waveform that the output signal of described detecting unit is comprised is divided into the number of the number of the half period interference waveform longer than the described benchmark half period and the half period interference waveform shorter than the described benchmark half period and counts;
Identifying unit, this identifying unit is when the number of number interference waveform shorter than the described benchmark half period than the described half period of the interference waveform longer than the described benchmark half period of described half period is many, judge that described object is in the position nearer than described reference range, when the number of the number of the interference waveform shorter than the described benchmark half period of the described half period interference waveform longer than the described benchmark half period than the described half period is many, judge that described object is in the position far away than described reference range.
3. reflection-type optoelectronic switch as claimed in claim 1, is characterized in that,
Described counting unit comprises:
Detect the rise detection unit of the rising of described interference waveform;
Mensuration is from the timing unit that rises to the time of rising next time of described interference waveform;
Comparing unit, when this comparing unit is longer than described reference period in the time of rising next time from rising to of described interference waveform, the number of the interference waveform that described in increase period ratio, reference period is long, the time of rising next time from rising to of interference waveform than described reference period in short-term, increase the number of the short interference waveform of reference period described in period ratio.
4. reflection-type optoelectronic switch as claimed in claim 1, is characterized in that,
Described counting unit comprises:
Detect the decline detecting unit of the decline of described interference waveform;
Mensuration is from the timing unit that drops to the time declining next time of described interference waveform;
Comparing unit, when this comparing unit is longer than described reference period in the time declining next time from dropping to of described interference waveform, the number of the interference waveform that described in increase period ratio, reference period is long, the time declining next time from dropping to of interference waveform than described reference period in short-term, increase the number of the short interference waveform of reference period described in period ratio.
5. reflection-type optoelectronic switch as claimed in claim 1, is characterized in that,
Described counting unit comprises:
Detect the rise detection unit of the rising of described interference waveform;
Detect the decline detecting unit of the decline of described interference waveform;
Mensuration is from the very first time determination unit that rises to the very first time of rising next time of described interference waveform;
Mensuration is from the second timing unit that drops to the second time declining next time of described interference waveform;
Comparing unit, when this comparing unit was grown than described reference period in the described very first time or described the second time is longer than described reference period, the number of the interference waveform that described in increase period ratio, reference period is long, in the described very first time, than described reference period, short or described the second time than described reference period in short-term, increases the number of the short interference waveform of reference period described in period ratio.
6. reflection-type optoelectronic switch as claimed in claim 2, is characterized in that,
Described counting unit comprises:
Detect the rise detection unit of the rising of described interference waveform;
Detect the decline detecting unit of the decline of described interference waveform;
Mensuration is from the very first time determination unit that rises to the very first time declining next time of described interference waveform;
Mensuration is from the second timing unit that drops to second time of rising next time of described interference waveform;
Comparing unit, this comparing unit is when in the described very first time, than the described benchmark half period, long or described the second time is longer than the described benchmark half period, increase the number of the half period interference waveform longer than the described benchmark half period, the described very first time than the described benchmark half period short or described the second time than the described benchmark half period in short-term, increase the number of the half period interference waveform shorter than the described benchmark half period.
7. an object detecting method, detects the distance of object than the far away or near object detecting method of reference range of regulation, it is characterized in that, comprising:
Drive current is offered to the vibration step that semiconductor laser makes described semiconductor laser action;
The detecting step of the electric signal that detection contains interference waveform, described interference waveform is because the laser of launching from described semiconductor laser and the self-mixing effect of back light that is positioned at the object in described semiconductor laser the place ahead produce;
According to the information that is included in the described interference waveform in the output signal being obtained by described detecting step, judgement is to the reference range still near range estimation treatment step far away of the distance ratio regulation of described object, wherein
Described range estimation treatment step comprises:
Counting step, the cycle of its described interference waveform when described object being positioned to the position of described reference range is during as reference period, and the number of the described interference waveform that the output signal obtaining at described detecting step is comprised is divided into the number of the short interference waveform of reference period described in the number of the interference waveform that reference period is long described in period ratio and period ratio and counts;
Determination step, when its number at the number of the long interference waveform of reference period described in the described period ratio interference waveform shorter than reference period described in described period ratio is many, judge that described object is in the position nearer than described reference range, when the number of the number of the short interference waveform of reference period described in the described period ratio interference waveform longer than reference period described in described period ratio is many, judge that described object is in the position far away than described reference range.
8. an object detecting method, detects the distance of object than the far away or near object detecting method of reference range of regulation, it is characterized in that, comprising:
Drive current is offered to the vibration step that semiconductor laser makes described semiconductor laser action;
The detecting step of the electric signal that detection contains interference waveform, described interference waveform is because the laser of launching from described semiconductor laser and the self-mixing effect of back light that is positioned at the object in described semiconductor laser the place ahead produce;
According to the information that is included in the described interference waveform in the output signal being obtained by described detecting step, judgement is to the reference range still near range estimation treatment step far away of the distance ratio regulation of described object, and wherein, described range estimation treatment step comprises:
Counting step, the half period of its described interference waveform when described object being positioned to the position of described reference range is as benchmark during the half period, and the number of the described interference waveform that the output signal obtaining at described detecting step is comprised is divided into the number of the number of the half period interference waveform longer than the described benchmark half period and the half period interference waveform shorter than the described benchmark half period and counts;
Determination step, when its number at number interference waveform shorter than the described benchmark half period than the described half period of the interference waveform longer than the described benchmark half period of described half period is many, judge that described object is in the position nearer than described reference range, when the number of the number of the interference waveform shorter than the described benchmark half period of the described half period interference waveform longer than the described benchmark half period than the described half period is many, judge that described object is in the position far away than described reference range.
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| CN200910141026.7A CN101888232B (en) | 2009-05-11 | 2009-05-11 | Reflection-type optoelectronic switch and object detection method |
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| CN200910141026.7A CN101888232B (en) | 2009-05-11 | 2009-05-11 | Reflection-type optoelectronic switch and object detection method |
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| CN108225543B (en) * | 2018-03-28 | 2019-06-25 | 中国科学院长春光学精密机械与物理研究所 | A kind of the orthogonal detection vibration measurement device and method of self-mixed interference |
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