Embodiment
Below in conjunction with accompanying drawing, the invention will be further described:
With reference to Fig. 1, it is the electrical block diagram of a kind of motorbus of the present invention vision dead zone obstacle detector.Front end, rear end, outer left side and outside right side at motorbus respectively arrange at least one ultrasonic sensor, and ultrasonic sensor is for detecting obstacles thing.The number of the ultrasonic sensor arranging can arrange according to the body dimensions of motorbus, for example, at the front end of motorbus, is fixed with the first ultrasonic sensor, in the rear end of motorbus, is fixed with the second ultrasonic sensor; Wherein, the first ultrasonic sensor is positioned on the longitudinal centre line of front end face of motorbus, and its height is overhead between 1 meter to 1.5 meters; The second ultrasonic sensor is positioned on the longitudinal centre line of motorbus rear end face, and its height is overhead between 1 meter to 1.5 meters.Outer left side and outside right side at motorbus are respectively provided with 3 ultrasonic sensors, wherein, be positioned at 3 ultrasonic sensors of outer left side of motorbus in same level height (height is overhead between 1 meter to 1.5 meters), and be laterally evenly arranged on the outer left side of motorbus; Be positioned at 3 ultrasonic sensors on outside right side of motorbus in same level height (height is overhead between 1 meter to 1.5 meters), and be laterally evenly arranged on the outside right side of motorbus.Each ultrasound wave comprises a transmitting terminal (for outwards launching ultrasound wave), a receiving end (for receiving the ultrasound wave reflecting).In the embodiment of the present invention, the receiving end of each ultrasonic sensor and transmitting terminal are towards motorbus vehicle body outside.
In the embodiment of the present invention, each ultrasonic sensor adopts T/R-40 serial universal ultrasound wave transmitting/receiving sensor, and it is comprised of transmitting terminal (or claiming ripple transmitter), receiving end (or claiming ripple receiver) and control section.If the piezoelectric ceramic piece that is 40KHz to transmitting terminal interior resonance frequency (twin crystal oscillator) applies 40KHz HF voltage, piezoelectric ceramic piece just extends according to added high frequency polarity of voltage and shortens, so send the ultrasound wave of 40KHz frequency, its ultrasound wave is propagated (density degree can be modulated by control circuit) with density form, returns to receiving end after running into barrier.Receiving end is the principle of utilizing the piezoelectric effect that pressure transducer adopts, on piezoelectric element, exerts pressure, and makes piezoelectric element generation strain, and producing one side is "+" utmost point, and another side is the 40KHz sinusoidal signal of "-" utmost point.This sinusoidal signal, through amplifying after processing, is outwards exported through the signal output part of ultrasonic sensor.
In conjunction with Fig. 1, signal output part at each ultrasonic sensor is provided with a corresponding ultrasonic signal treatment circuit, each ultrasonic signal treatment circuit comprises voltage comparator, triode and voice guard, in each ultrasonic signal treatment circuit, the signal output part that the in-phase input end of voltage comparator is electrically connected to corresponding ultrasonic sensor (refers to ultrasound wave, the inverting input of voltage comparator is used for accessing reference voltage signal, and the output terminal of voltage comparator is electrically connected to the base stage of triode.The amplitude of reference voltage signal is setting value, and for example, for when barrier is positioned at front 1 meter of of ultrasonic sensor, ultrasonic sensor signal output part is the magnitude of voltage of the sinusoidal signal of output outwards.In the embodiment of the present invention, voltage comparator adopts LT311 type voltage comparator, this voltage comparator is for the magnitude of voltage of the voltage magnitude of comparison reference voltage signal and the sinusoidal signal of ultrasonic sensor signal output part output, and for according to comparative result, outwards export corresponding low and high level signal.When the input voltage of the in-phase input end of voltage comparator is greater than the input voltage of inverting input, the output terminal of voltage comparator output high level signal; Otherwise,, the output terminal output low level signal of voltage comparator.
The aerial velocity of propagation of ultrasound wave is v, and according to transmitting ultrasound wave and the hyperacoustic mistiming △ t of reception, just can calculate launching site apart from the distance S of barrier, that is: S=v △ t/2, known according to analyzing: mistiming △ t and S in above formula are closely related, sound wave amplitude can reduce along with the increase of S simultaneously, energy reduces thereupon, because ultrasonic sensor can utilize piezoelectric effect, the mechanical vibration that act on above it are converted to corresponding electric signal again, play the effect of energy conversion, when v and S mono-timing, ultrasonic sensor can be exported the voltage signal of amplitude and specific, the amplitude of this voltage signal is exactly the amplitude (S is 1 meter) of voltage comparator inverting input reference voltage.Reference voltage signal can directly generate through divider resistance dividing potential drop.In addition, according to above-mentioned principle, when barrier is less than 1 meter to the distance of ultrasonic sensor, the amplitude of the output voltage of ultrasonic sensor signal output part is greater than the amplitude of reference voltage, the output terminal output high level signal of voltage comparator; Otherwise, the output terminal output low level signal of voltage comparator.
In conjunction with Fig. 1, the grounded emitter of triode, the collector of triode is electrically connected to direct supply after serial connection voice guard.Triode is NPN triode.Triode plays the effect of a switch, and when the signal of voltage comparator output is low level signal, base current is 0, and transistor collector electric current is 0, and now, triode is in cut-off state, and voice guard is not worked; When the signal of voltage comparator output is high level signal, base current is larger, to such an extent as to triode is saturated, and at this moment, voice guard is switched on, the alarm signal of can sounding.Voice guard is positioned on driver's operation bench and (is for example positioned on panel board), is convenient to driver and hears audible alarm, and in the embodiment of the present invention, audible alarm adopts voice alarm device.
In the embodiment of the present invention, for example also comprise, for the power module (using car battery) of direct supply is provided to each ultrasonic sensor, each ultrasonic signal treatment circuit.Power end at ultrasonic sensor transmitting terminal is provided with hand push button, and this hand push button is positioned on pilothouse operation bench and (is for example positioned on panel board).Like this, driver can judge whether to open this motorbus vision dead zone obstacle detector (realizing by pressing hand push button) according to road conditions.
A specific embodiment of the present invention below:
With reference to Fig. 2, it is the ultrasonic sensor transmitting terminal electrical block diagram of a kind of motorbus vision dead zone obstacle detector of the embodiment of the present invention.In this ultrasonic sensor transmitting terminal circuit, the positive pole of direct supply U is in parallel with the first capacitor C 1 after serial connection hand push button S, the positive pole of direct supply U is electrically connected to the common node of one end of the first divider resistance R1 and one end of the second divider resistance R2 after serial connection hand push button S, the negative electricity of direct supply U connects the emitter of the first triode VT1, the common node of the anode of the emitter of the second triode VT2 and the first voltage stabilizing diode VD1, one end of T-40-16 ultrasonic transducer is electrically connected to the common node of the negative electrode of the first voltage stabilizing diode VD1 and the base stage of the first triode VT1, the other end of T-40-16 ultrasonic transducer is electrically connected to the other end of the second divider resistance R2, and the common node of the collector of the second triode VT2, the collector of the first triode VT1 is electrically connected to the other end of the first divider resistance R1, and the common node of the base stage of the second triode VT2.The first triode VT1 and the second triode VT2 are 9013 type triodes, and the model of the first voltage stabilizing diode VD1 is 1N4148.The first triode VT1 and the second triode VT2 form strong feedback resonator oscillator, and oscillation frequency equals the resonant frequency of T-40-16 ultrasonic transducer.T-40-16 ultrasonic transducer is feedback coupling element, is again output transducer for circuit.The waveform at T-40-16 ultrasonic transducer two ends is similar to square wave, and voltage amplitude approaches supply voltage.In the first triode VT1 base stage, reversal connection the first voltage stabilizing diode VD1 can stablize base voltage to ground.The maximum current that the first triode VT1 collector can reach is U
0/ R
1, the maximum current that the second triode VT2 collector can reach is U
0/ R
2, U
0for the magnitude of voltage of direct supply U, R
1be the resistance value of the first divider resistance R1, R
2it is the resistance value of the second divider resistance R2.
Circuit switches on power after (being that hand push button S is closed), by the first divider resistance R1 and the second divider resistance R2, provides base bias current to the second triode VT2 and the first triode VT1 simultaneously, makes two triodes enter magnifying state.The first triode VT1 first works, the collector of the first triode VT1 amplifies electric current, this small amplification will be amplified and feed back to the base stage of the first triode VT1 by the second triode VT2, again through the amplification of the first triode VT1, form chain reaction, make rapidly the first triode VT1 collector current reach maximum current U
0/ R
1thereby, make the first triode VT1 enter state of saturation, now the first triode VT1 is equivalent to the switch of a connection.Now, the second triode VT2 collector current becomes 0, in cut-off state, the second triode VT2 is equivalent to the switch disconnecting, and the first capacitor C 1 is discharged by the second triode VT2, electric discharge along with the first capacitor C 1, owing to there being the effect of power supply U, the base voltage of the second triode VT2 raises gradually and starts conducting and enters amplification region, in circuit, can occur at once chain reaction again, the second triode VT2 is saturated rapidly, the first triode VT1 cut-off.This time, capacitor C 1 was charged by the first triode VT1.This charge and discharge process can make again the first triode VT1 again saturated, the second triode VT2 cut-off.So go round and begin again, form oscillator signal, this oscillator signal produces the ultrasound wave of 40KHZ by sonac piezoelectric effect.
With reference to Fig. 3, it is the ultrasonic sensor receiving terminal circuit structural representation of a kind of motorbus vision dead zone obstacle detector of the embodiment of the present invention.In this ultrasonic sensor receiving terminal circuit, direct supply U is electrically connected to one end of the 5th resistance R 5, one end of the 6th resistance R 6, and the common node of one end of the 3rd capacitor C 3, the earth potential of GND is electrically connected to the emitter of the 4th triode VT4, the anode of the second voltage stabilizing diode VD2, the common node of one end of the emitter of the 3rd triode VT3 and R-40-16 piezoelectric element, the other end of R-40-16 piezoelectric element is electrically connected to the base stage of the 3rd triode VT3, the common node of one end of the 3rd resistance R 3, the collector of the 3rd triode VT3 is electrically connected to the other end of the 3rd resistance R 3, the other end of the 5th resistance R 5, and the common node of one end of the second capacitor C 2, the other end of the second capacitor C 2 is electrically connected to the negative electrode of the second voltage stabilizing diode VD2, the base stage of the 4th triode VT4, and the common node of one end of the 4th resistance R 4, the other end of the 4th resistance R 4, the collector of four triode VT4, and the common node of the other end of the 6th resistance R 6 is electrically connected to signal output part U2.The 3rd triode VT3 and the 4th triode VT4 are 9018 type triodes, and the model of the second voltage stabilizing diode VD2 is 1N4148.
R-40-16 piezoelectric element adopts the principle of piezoelectric effect, when ultrasound wave, on this piezoelectric element, exerts pressure, and makes this piezoelectric element generation strain, produces sine voltage signal.The voltage signal now producing is fainter, so be provided with the 3rd triode VT3 and the 4th triode VT4 in circuit, by the voltage signal to faint, carries out two-stage amplification and modulation, by signal output part U2 output voltage signal.
R-40-16 piezoelectric element is connected between the base stage and emitter of the 3rd triode VT3, the faint voltage signal being received carries out one-level amplification by the 3rd triode VT3, the collector of the 3rd triode VT3 is connected with the base stage of the 4th triode VT4 by the second capacitor C 2 again, the 4th triode VT4 carries out secondary amplification by voltage signal again, form final output voltage, wherein the second capacitor C 2 plays the effect of filtered noise, modulation signal in circuit.The 3rd resistance R 3 and the 4th resistance R 4 are respectively the 3rd triode VT3 and the 4th triode VT4 provides base current.The second voltage stabilizing diode VD2 of reversal connection between the 4th triode VT4 base stage and emitter can stablize the base voltage of the 4th triode VT4, stablizes quiescent point.The effect that can play protection direct supply of the 3rd capacitor C 3.
With reference to Fig. 4, it is the ultrasonic signal treatment circuit schematic diagram of a kind of motorbus vision dead zone obstacle detector of the embodiment of the present invention.The signal output part U2 of ultrasonic sensor is electrically connected to the in-phase input end of voltage comparator M, the inverting input of voltage comparator M is electrically connected to one end of the 7th resistance R 7, and the common node of one end of the 8th resistance R 8, the output terminal of voltage comparator M is electrically connected to the negative electrode of the 3rd voltage stabilizing diode VD3, one end of the 9th resistance R 9, and the common node of the base stage of the 5th triode VT5, the negative power end of voltage comparator M, the other end of the 8th resistance R 8, the anode of the 3rd voltage stabilizing diode VD3, and the common node ground connection of the emitter of the 5th triode VT5, the positive power source terminal of voltage comparator M, the other end of the 7th resistance R 7, and the common node of the other end of the 9th resistance R 9 is electrically connected to direct supply U, the collector of the 5th triode VT5 is electrically connected to direct supply U after serial connection phonetic alarm T.
The input voltage of the inverting input of voltage comparator M is reference voltage, this reference voltage level is determined by a minute compression functions for the 7th resistance R 7 and the 8th resistance R 8, select the 7th resistance R 7 and the 8th resistance R 8 of suitable resistance, both can obtain the reference voltage signal of amplitude and specific.The 9th resistance R 9 is the base resistance of the 5th triode VT5, and for the 5th triode VT5 provides base current, the 3rd voltage stabilizing diode VD3 plays the effect of stablizing base voltage.If the input voltage of the in-phase input end of voltage comparator M is U
2, the input voltage of the inverting input of voltage comparator M is U
1, work as U
2>U
1time, voltage comparator M exports high level signal, and now the 5th triode VT5 conducting, is equivalent to closed switch, and phonetic alarm is given the alarm; Work as U
2<U
1time, end of oppisite phase voltage is during higher than in-phase end, voltage comparator M output low level signal, and now the 5th not conducting of triode VT5, phonetic alarm is not worked.
When driver feels traffic conditions more complicated around of motorbus or is difficult to predicting road conditions, driver can press hand push button S, make hand push button S closed, make motorbus of the present invention vision dead zone obstacle detector in running order, thereby can detect the road conditions of vision dead zone.
Motorbus of the present invention vision dead zone obstacle detector can detect all road conditions of vehicle periphery as far as possible all sidedly, and realizes in real time and detecting, and reduces better the generation of the accident that rolls.
Obviously, those skilled in the art can carry out various changes and modification and not depart from the spirit and scope of the present invention the present invention.Like this, if within of the present invention these are revised and modification belongs to the scope of the claims in the present invention and equivalent technologies thereof, the present invention is also intended to comprise these changes and modification interior.