A kind of pyroelectric sensorTechnical field
The present invention relates to a kind of human body detection sensor, in particular, relate to a kind of pyroelectric sensor.
Background technology
In pyroelectric sensor, the Main Function of optical filter is only to allow wavelength infrared ray (people about 10 μmThe Infrared wavelength that body sends) pass through, and light, sunlight and other radiation are filtered, with the interference that suppression is extraneous.Infrared senseAnswering source to be generally made up of two pyroelectricity elements in series or in parallel, the electrode of the two pyroelectricity element is contrary, and environment is carried on the backScape radiation almost has identical effect to two pyroelectricity elements so that it is the pyroelectric effect of generation is cancelled out each other, output letterNumber it is close to zero.In once having people's intrusion detection region, human infrared radiation is focused on by partial mirror, and by pyroelectricity elementReceiving, owing to angle is different, the heat that two panels pyroelectricity element receives is different, and pyroelectricity energy is the most different, it is impossible to support completelyDisappear, after treated processing of circuit, export control signal.Pyroelectric effect is similar to piezoelectric effect, refer to the change due to temperature andCause the phenomenon of plane of crystal electric charge.Pyroelectric infrared sensor is made up of ceramic oxide or piezolectric crystal unit, at elementElectrode is made on two surfaces, and when in the range of Sensor monitoring, temperature has the change of △ T, pyroelectric effect can be on two electrodesProduce electric charge △ Q, produce a faint voltage △ V the most between electrodes.Owing to its output impedance is high, in the sensorA field effect transistor is had to carry out impedance transformation.Electric charge △ Q produced by pyroelectric effect can be combined by the ion in air andDisappearing, i.e. when ambient temperature-stable is constant, △ T=O, sensor is without output.Human body or the bigger animal of volume have constantBody temperature, typically at 37 degree, so the infrared ray about specific wavelength 10 μm can be sent, when human body enter detection zone, because of human bodyTemperature and ambient temperature have difference, and the infrared ray about 10 μm of human-body emitting is assembled after being strengthened by Fresnel lens optical filterOn infrared induction source (pyroelectricity element), infrared induction source will lose charge balance when receiving human infrared radiation,Outwards discharge electric charge, and then produce △ T and △ T circuit to the periphery is exported.
And optical filter i.e. Nie Feier lens, presently, there are a problem, conventional body's induction apparatus uses list mostlyHead Fresnel Lenses, is susceptible to report by mistake situation about even not reporting, poor stability, and reliability is low.
Summary of the invention
In view of this, it is an object of the present invention to provide the pyroelectric sensor of a kind of bull Nie Feier lens.
In order to solve above-mentioned technical problem, the technical scheme is that
A kind of pyroelectric sensor, including housing and pyroelectricity element, when pyroelectricity element testing to biological thermal source, output hasPeople's signal, described housing is provided with at least 3 group Fresnel Lenses, and the optical axis of Fresnel Lenses intersects at optical axes crosspoint, optical axisLine place straight line for Fresnel Lenses central point Yu luminous point.By so arranging so that response accuracy improves, it is ensured that useEnvironment and service life.
Further, described Fresnel Lenses is shaped as arc.Arranged by arc, improve angular field of view.
Further, described Fresnel Lenses is set to 5 groups.By so arranging, farthest ensure that useEffect.
Further, four groups of Fresnel Lenses enclose and are located at the surrounding of another described Fresnel Lenses and are uniformly distributed and equidistantlyArrange.Ensure that the induction precision of each angle is identical.
A kind of pyroelectric sensor assembly, including the first pyroelectric sensor and the second pyroelectric sensor, described firstPyroelectric sensor and the second pyroelectric sensor are all identical with above-mentioned pyroelectric sensor structure, and described first pyroelectricity passesBeing also coupled to repeat circuit between sensor and the second pyroelectric sensor, described repeat circuit is configured with delay circuit, described in prolongTime circuit configure the first Preset Time, when described first pyroelectric sensor output have people's signal time, described repeat circuit time delayEnabling signal is exported to start described second pyroelectric sensor after first Preset Time.Owing to pyroelectric sensor can exist extremelyDistrict, when human body proximity, will trigger a signal, subsequently enter dead band, and now human body is regardless of whether the most close, also will notAgain trigger, so, can have a negative impact, and if arranging the second pyroelectric sensor and sense as the first pyroelectricityThe dead area compensation working sensor of device, so, it is possible to improve the precision under using, and too much electricity will not be wasted.
Further, a kind of pyroelectric sensor assembly, described repeat circuit also includes edge triggered flip flop, works as repeat circuitWhen output has people's signal, described in described edge triggered flip flop collection, there is people's signal.
The technology of the present invention effect major embodiment is in the following areas: the accuracy of detection of solution and the problem in dead band, improves and makesBy life-span and detecting effect.
Accompanying drawing explanation
Fig. 1: present configuration schematic diagram；
Fig. 2: circuit theory diagrams of the present invention.
Reference: 100, housing；200, pyroelectricity element；210, Fresnel Lenses；1, the first pyroelectric sensor；2、Second pyroelectric sensor；11, edge triggered flip flop；12, delay circuit.
Detailed description of the invention
Below in conjunction with accompanying drawing, the detailed description of the invention of the present invention is described in further detail, so that technical solution of the present invention is moreShould be readily appreciated that and grasp.
With reference to shown in Fig. 1, a kind of pyroelectric sensor, including housing 100 and pyroelectricity element 200, when pyroelectricity element200 outputs when biological thermal source being detected have people's signal, and described housing 100 is provided with at least 3 group Fresnel Lenses 210, Fei NieYou intersect at optical axes crosspoint by the optical axis of lens 210, and optical axis is the line place straight line of Fresnel Lenses 210 central point and luminous point.By so arranging so that response accuracy improves, it is ensured that use environment and service life.Described Fresnel Lenses 210 is shaped asArc.Arranged by arc, improve angular field of view.Described Fresnel Lenses 210 is set to 5 groups.By so arranging,Big degree ensure that using effect.Four groups of Fresnel Lenses 210 enclose that to be located at the surrounding of another described Fresnel Lenses 210 uniformDistribution and spaced set.Ensure that the induction precision of each angle is identical.
With reference to shown in Fig. 2, a kind of pyroelectric sensor assembly, including the first pyroelectric sensor 1 and the second pyroelectricity biographySensor 2, described first pyroelectric sensor 1 is all identical with above-mentioned pyroelectric sensor structure with the second pyroelectric sensor 2,Being also coupled to repeat circuit between described first pyroelectric sensor 1 and the second pyroelectric sensor 2, described repeat circuit configuresDelay circuit 12, described delay circuit 12 is had to configure the first Preset Time, when described first pyroelectric sensor 1 output has people to believeNumber time, after described repeat circuit time delay the first Preset Time export enabling signal to start described second pyroelectric sensor 2.ByDead band can be there is in pyroelectric sensor, when human body proximity, a signal will be triggered, subsequently enter dead band, now human bodyRegardless of whether the most close, also will not again trigger, so, can have a negative impact, and if arranging the second pyroelectricitySensor 2 is as the dead area compensation working sensor of the first pyroelectric sensor 1, so, it is possible to improve under usingPrecision, and too much electricity will not be wasted.
Further, a kind of pyroelectric sensor assembly, described repeat circuit also includes edge triggered flip flop 11, central relayRoad output is when having people's signal, described edge triggered flip flop 11 gather described in have people's signal.Edge triggered flip flop 11 can be touched by edgePower Generation Road realizes, and designs, if the first pyroelectric sensor 1 is high level according to the triggering mode of the first pyroelectric sensor 1Trigger, then edge triggered flip flop 11 should be rising edge and triggers circuit, and delay circuit 12 can be realized by 555 enumerators,Can also realize by the way of crystal oscillator linkage counter, relatively simple, and so, the most such as: Dead Time is setIt it is 30 seconds.Human body starts timing after entering induction apparatus area triggering warning system, has people to enter and will not trigger sensing in 30 secondsAlarm device.5 seconds the most on triggering, another pyroelectric sensor triggered, and at Dead Time, the second pyroelectric sensor 2 entersRow judges, is that result is more accurate.
Certainly, being more than the representative instance of the present invention, in addition, the present invention can also have other multiple to be embodied asThe technical scheme that mode, all employing equivalents or equivalent transformation are formed, within all falling within the scope of protection of present invention.