JPS6073385A - Trouble detecting circuit of ultrasonic obstacle detecting apparatus - Google Patents

Abstract

PURPOSE:To make it possible to automatically detect the trouble of a receiver, by applying a diagnostic pulse for diagnosing trouble to a receiver, and investigating the response signal of the receiver to said pulse. CONSTITUTION:Now, when a receiver 4 gets out of order or is deteriorated, no resonance vibration is generated even if the diagnostic pulse is applied and, therefore, the output S16 of a diagnostic integration means 16 does not reach the predetermined reference value Vr2 of a diagnostic comparing means 17 and the output S17 of the comparing means 17 holds logical ''0''. Therefore, if the receiver 4 is normal and the comparing means 17 issues output S17 at every predetermined cycle T1, the output of a trouble discriminating means 18 always comes to logical ''1'' and a lamp 19a is not lighted but, when the receiver 4 gets out of order, the lamp 19a is lighted to display trouble. By this method, the trouble of a receiver can be automatically detected.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a failure detection circuit of an ultrasonic obstacle detection device that detects an object by receiving ultrasonic waves, particularly a failure of the ultrasonic receiver itself. This relates to a fault detection circuit that can detect faults.

[Prior art]

The ultrasonic obstacle detection device is applied to the rear monitoring device of automatic door service vehicles), and its principle is to emit ultrasonic waves with a very short duration and receive the reflected waves from obstacles. The distance to an obstacle is determined based on the elapsed time from the time the ultrasonic wave is emitted to the time the reflected wave is received. The device displays alarms, etc.

Figure 1 is a schematic configuration diagram showing such a conventional ultrasonic obstacle detection device, and Figures 2 (,) to (f) are timing charts explaining its operation. This conventional ultrasonic obstacle detection device will now be explained.

In FIG. 1, 1 indicates a predetermined period TI and a pulse width T2.
2 is an ultrasonic wave transmitter (hereinafter referred to as a wave transmitter) consisting of a ceramic oscillator, etc.; is a transmitter drive unit that receives the output S1 of the reference time generator 1 and drives the transmitter 2 to emit ultrasonic waves, and a rectangular wave oscillator 3 whose frequency is, for example, 40 KHz.
&, AND gate 3b, and driver 3c, AND gate 3b performs the logical product of the output of the rectangular wave oscillation section 3a and the output S1 of the reference time generation section 1.
The output of the driver 3c is amplified by the driver 3c. Therefore, the output of the transmitter driving section 3 becomes as shown at 83 in FIG. 2(b). 4
is an ultrasonic wave receiver (hereinafter referred to as a wave receiver) made of a ceramic transducer, which has the same resonance frequency as the frequency of the ultrasonic wave emitted from the wave transmitter 2, and has the same resonance frequency as the wave reflected by the obstacle 5.
A receiving integrating section 9 integrates the output of the receiving wave integrating section 8, and a receiving comparing section 9 compares the output of the receiving integrating section 8 with a predetermined reference value Vr1. A distance measuring section 1o measures the distance from the output S9 of the delivery comparison section 9 and the output s1 of the reference time generating section 1 to the obstacle 5. This distance measuring section 1° is composed of a distance signal generation timer 10a and a flip-flop (hereinafter referred to as F, F) 10b.
0a receives the output S1 of the reference time generator 1, and this output 8
2 (f
) is set to logic "1".

F, F, 10b are data input terminals D1 and clock pulse input terminals CK.

It has an output terminal Q and a reset terminal R, and the output 510a of the distance signal generation timer 10a is connected to the data input terminal.
The clock pulse input terminal CK receives the output S9 of the receiving comparator 9, and the reset terminal R receives the output S of the reference time generator 1.
1 are connected to each other, and when the input signal of the clock pulse input terminal CK rises, the state of the input signal of the data input terminal at that time is latched and set to the output terminal Q, and the input signal of the reset terminal R is The rising edge of the signal sets the output of the output terminal Q to logic "o".

Reference numeral 11 denotes an obstacle display unit, which is composed of 2 lamps (l1m), a register (11b1), and a register (11c).
a lights up.

The conventional ultrasonic obstacle detection device 419 is constructed as described above, and detects the obstacle 5 by the following operation.

The transmitter 2 is operated by the transmitter drive unit 3 at 83 in FIG. 2(b).
It is driven by the output waveform shown in , and emits ultrasonic waves with a frequency of 40 KIIz for a period of time Tz (for example, 1 m8 ec) every cycle TI (for example, 100 m5 ec). The emitted wave 2a of the ultrasonic wave from Jin is reflected by the obstacle 5 and becomes a reflected wave 5.
a, the wave is received by the wave receiver 4, resulting in a signal like 84 in Fig. 2 (c7). By doing so, the output S8 shown in FIG. 2(d) is obtained, and this output S8 is compared with a predetermined reference value VrI in the transfer comparison section 9, and the pulse-shaped signal shown in FIG. 2(e) is obtained. An output S9 is generated.By measuring the time between the rising time of this output S9 and the rising time of the output S1 of the reference time generator 1, which is the emission time of the ultrasonic wave, the distance to the obstacle 5 can be easily determined. However, here, if the reflected wave 5a is received during the time T3 corresponding to the predetermined distance to the obstacle 5 after the ultrasonic wave is emitted, it is assumed that the obstacle 5 exists within this distance. lamp 11
I am trying to turn on a. That is, after the ultrasonic wave is emitted, the data input terminals F, F, and 10b are set to logic "1" by the distance signal generation timer 10a during the time T3, and the reflected wave 5& is received during the time T3. Due to the rise of the output S9 of the transfer comparison unit 9 caused by this, the output terminals Q of F, F, 10b have a logic
Since "l" is set, the lamp lla will be lit. After this lamp lla is turned on, when the output s1 of the reference time generator 1 rises at a cycle Tt, F,
F. When the IQb is reset, the light goes off temporarily, and when the reflected wave 5a is received in the next cycle, the light goes off again, and this is repeated again after that, but the time the light is off is compared to the time it is on. The light is so short that it appears to the human eye to be on all the time. Of course, if the obstacle 5 does not exist within the predetermined distance, the lamp 11a will not light up at all.

In this way, it is possible to detect whether or not the obstacle 5 exists within a predetermined distance, and to display it using the lamp 11a.

In this case, since the transmitter 2 and the receiver 4 emit and receive ultrasonic waves, they must be installed in a place where they are in direct contact with the outside air. Therefore, if there is foreign matter such as dust in the air,
Or, it may freeze during cold weather and stop working properly. However, the user has to distinguish between whether the lamp 11a does not light up because the obstacle 5 does not exist within a predetermined distance, or whether the lamp 11a does not light up due to the above-mentioned failure of the transmitter 2 and receiver 4. This is extremely inconvenient.

[Summary of the invention]

In order to improve the disadvantages of the prior art, it is an object of the present invention to provide a failure detection circuit in which the device itself automatically detects deterioration or failure of a receiver. That is, a failure state is attempted to be detected by applying a diagnostic pulse for diagnosing a failure to a wave receiver and examining a response signal of the wave receiver to this pulse.

[Embodiments of the invention]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a schematic configuration diagram showing a first embodiment of the present invention, and elements designated by numerals 1 to 11 are the same as or correspond to the elements in FIG. 1. Reference numeral 12 denotes a diagnostic pulse applying means for applying a diagnostic pulse to the receiver 4 upon receiving the output S1 of the reference time generator 1, as shown at 812 in FIG. 4(c).
A pulse is output after a time T4 from the rising time to of the output S1 of the reference time generator 1. When the diagnostic pulse is applied to the receivers 4, normal resonance vibrations will not occur when the receivers 4 are out of order, so by checking the output of the receiver 4, it is possible to distinguish between normal times and failures. Become. Reference numeral 14 denotes a receiving signal generated by receiving the ultrasonic wave from the receiver 4 and a diagnostic pulse applying means 12.
The switch section 14a and the control section 14b are the identification means for discriminating the diagnosis pulse response signal from the diagnostic pulse response signal. will be accomplished. As a result, the output S4 of the receiver 4 is 8 in Fig. 4(d).
4, the received wave signal S4a and the diagnostic pulse response signal S
4b, and if this output S4b passes through the receiving amplifier section 1, the receiving integrating section 8, and the transfer comparing section 9 as it is,
Even if the obstacle 5 is not present, the diagnostic pulse response signal S
4b, it is possible to prevent the ranging section 10 from mistakenly determining that the obstacle 5 exists, and the rise of the output S1 of the reference time generating section 1 at the time when the ultrasonic wave is emitted. The time 73 during which the distance signal generation timer 10a outputs logic "1" within the time from the time "to" to the time (to +T4) when the first diagnostic pulse S12 is applied to the receiver 4
During the above period (for simplicity, this is referred to as time T3), the contact of the switch unit 14+a is switched to the side A shown in the figure, and the other contacts are controlled by the control unit 14b so that the contacts are switched to the side B shown in the figure. . Therefore, the output s4 of the receiver S4 is temporally divided by this identification means 14, and only the conventional transfer signal 84a shown in FIG. 4(d) is sent to the contact A side, and the diagnostic pulse is sent to the contact B side. Only the response signal S4b appears. 015 is a diagnostic amplification means for amplifying the diagnostic pulse response signal S4b separated by the identification means 14 from the output s4 of the receiver 4, and 16 is this diagnostic amplification means 1.
A diagnostic integrating means 17 integrates the output of 5, and 17 is shown in FIG.
), the output of the diagnostic integrating means 16 shown at 816 is compared with a predetermined reference value ■r2, and this output 817 becomes o1 as shown at 817 in FIG. 4(f).
F, F is a failure determination means for determining the failure state of the receiver 4 based on the output S17 of the diagnostic comparison means 1T of the eight sensors.
, 18a and inverters 18b and 18e, and the data input is the output 5 of the distance signal generation timer 10a.
10a is inverted and inputted so that it becomes logic "1" during the period of fault diagnosis. Therefore, when a pulse is generated at the output 817 of the diagnostic comparison means 17, at the rising edge of the pulse, the output terminals Q of F, F, 18m are set to logic "
1" is output. Further, the set human power 5': tA child S inputs the output S1 of the reference time generating section 10, and sets the output terminal Q to logic "1" at the rising edge of this output S1. 1
Reference numeral 9 denotes a failure display section, which has the same configuration as the obstacle display section 14, and indicates a failure by lighting a lamp 19a.

The first embodiment of this invention is configured as described above, and
The operation will be explained in detail below. Regarding the operation of detecting the obstacle 5 by the receiver 4 receiving the reflected wave of the ultrasonic wave emitted from the transmitter 2 by the obstacle 5, the conventional ultrasonic type shown in FIG. 1' is used. It is similar to the obstacle detection device.

That is, when performing an operation to detect the obstacle 5, the switch portion t4a of the identification means 14 is set to the contact AI! Since it is set to It, the same operation as in FIG. 1 is performed.

Now, distance! Output 51 of ft signal generation timer 10a
When 0a is logic "0", the failure detection operation of the receiver 4 is performed during the time (T1-Ta) until the obstacle detection operation is performed in the next cycle. First, the output S of the reference time generator 1
1 rises for an appropriate time T4 (however, T3<
After T4<Tt), the diagnostic pulse applying means 12 applies a diagnostic pulse to the receiver 4.

If the receiver 4 is normal, it will freely oscillate at the resonant frequency due to this diagnostic pulse. The waveform at this time is shown in Figure 4 (
The waveform has a damped vibration as shown in S4b of d).

The response signal of the wave receiver 4 is passed through the contact B side by the identifying means 14, the diagnostic amplifying means 15, and the diagnostic integrating means 16, so that it becomes a signal waveform as shown at 816 in FIG. 4(f). This output S16 is compared with a predetermined reference value Vyz of the diagnostic comparison means 17, and a pulse like 817 in FIG. 4(f) is output.

If the receiver 4 is broken or deteriorated,
Even if a diagnostic pulse is applied, no resonance vibration occurs, so the output S16 of the diagnostic integrating means 16 does not reach the predetermined reference value Vr+ of the diagnostic comparing means 11, and the output 817 of the diagnostic comparing means 1T becomes a logic "0". ” will be retained. Therefore, if the receiver 4 is normal and the diagnostic comparing means 17 outputs an output S17 as shown in FIG.

The output terminal Q of 18a is always logic ``1''.The output of the fault determining means is always logic ``1'' and the lamp 19^ does not light up, but when a failure occurs, the lamp 19a lights up (
To be more precise, it will light up intermittently) to indicate a malfunction.

FIG. 5 is a circuit diagram showing a second embodiment of the invention,
Elements numbered 1-19 are the same as or correspond to the elements in FIG. Here, the diagnostic pulse application means 1
2 consists of registers 12a and 12b and a pulse generator 20, and the pulse generator 20 outputs the same pulse as 812 in FIG. The output S4 of the receiver 4 is inputted to the wave receiving amplifier T without passing through the identification means 14 as shown in FIG. It passes through the comparison section 9. This is an effective means when the received signal by the reflected wave 5a of the receiver 4 and the diagnostic pulse response signal by the diagnostic pulse applying means 12 are approximately the same in magnitude. Needless to say, the configuration becomes easier. Therefore, the output S8 of the integration unit 8 for delivery and the output S9 of the comparison unit 9 for wave reception are respectively shown in FIG. 6(d) t (e
) of 88. It will be like S9. The output S9 of the received wave comparing section 9 is identified by the identifying means 21 and distributed to the distance measuring section 10 and the failure determining means 18. This identification means 21
is ANDGATE 21a, 21b, Innogu-2
21C as shown in the figure, and when the output 510a of the distance signal generation timer 10a is logic "1",
The output S9 of the receiving comparison section 9 is inputted only to the ranging section 10,
Similarly, when the logic is "0", the signal is input only to the failure determination means 18.

FIG. 7 shows a third embodiment of the invention, in which elements designated by numerals 2 to 19 are the same as or correspond to the elements in FIG. In this embodiment, in the embodiment shown in FIG. 3 or FIG. 5, the logical operation function related to time control is performed by the microcomputer 22, and the number of parts constituting the circuit can be significantly reduced. can.

Further, the configuration after the wave reception integrating section 1 may be configured as shown in FIG. 8 depending on the magnitude of the wave reception signal and the diagnostic pulse response signal.

Furthermore, although the failure of the receiver 4 is indicated by lighting the lamp 19a, it is not limited to the indication of a failure, and by detecting a failure, switching to a spare receiver prepared in case of a failure is possible. You can also do it like this.

〔Effect of the invention〕

As explained above, according to the present invention, an ultrasonic obstacle detection device includes a diagnostic pulse application means, a receiver output selection means, a diagnostic amplification means, a diagnostic integration means, a failure determination means,
Since the failure detection circuit including the identification means is provided, failures in the receiver can be detected, and the reliability of the device is improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a conventional ultrasonic obstacle detection device, FIG. 2 is a timing chart explaining the operation of FIG. 1, and FIG. 3 is a schematic configuration diagram showing a first embodiment of the present invention. ,
FIG. 4 is a timing chart explaining the operation of FIG. 3;
FIG. 5 is a circuit diagram showing a second embodiment of the invention, FIG. 6 is a timing chart explaining the operation of FIG. 5, FIG. 7 is a schematic configuration diagram showing a third embodiment of the invention, and FIG. The figure is a partial explanatory diagram showing another embodiment of the invention. 1...Reference time generator, 2...Transmitter, 3.Φ
... Transmitter drive unit, 4... Receiver, T... Amplifying section for receiving wave, 8... Integrating section for receiving wave, 9... Comparing section for receiving wave, DESCRIPTION OF SYMBOLS 10... Distance measuring unit, 11... Obstacle display unit, 12... Diagnostic pulse application means, 22... Fist microcomputer, 14.21-- Writing/identification means, 1
5...Diagnostic amplification means, 16...Diagnostic integration means, 17...Diagnostic comparison means, 18...Failure determination means, 19...Failure display section, 20. ...Pulse generator. Agent Masuo Oiwa

Claims (2)

[Claims] (1) A reference time generator that emits a pulse signal that has a predetermined period and indicates the reference time, and a transmitter drive unit that receives the output of the reference time generator and drives the ultrasonic transmitter to emit ultrasonic waves. , a receiving amplifying section that amplifies the received signal of the ultrasonic receiver, a receiving integrating section that integrates the output of the receiving amplifying section, and a receiving integrating section that uses the output of the receiving integrating section as a predetermined standard. An ultrasonic obstacle detection device comprising a receiving comparison section for comparing the received wave comparison section with a value, and a distance measuring section for measuring the distance to the obstacle from the output of the reception comparison section and the output of the reference time generation section. a diagnostic pulse applying means for applying an impulse signal to the ultrasonic receiver based on the output of the reference time generator; a diagnostic amplifying means for amplifying the response signal; a diagnostic integrating means for integrating the output of the diagnostic amplifying means; a diagnostic comparing means for comparing the output of the diagnostic integrating means with a predetermined reference value; failure determination means for determining a failure state of the ultrasonic receiver based on the output of the comparison means; and failure determination means for determining the failure state of the ultrasonic receiver based on the output of the delivery signal of the ultrasonic receiver and the output of the diagnostic pulse application means; A failure detection circuit for an ultrasonic obstacle detection device, comprising identification means for distinguishing between a response signal generated by an ultrasonic obstacle detection device. (2) At least the receiving wave amplifying section also serves as the diagnostic amplifying means, the receiving integrating section also serves as the diagnostic integrating means, or the receiving comparing section also serves as the diagnostic comparing means. A failure detection circuit for an ultrasonic obstacle detection device according to claim 1.