JPS6196486A - Substance detector - Google Patents

Abstract

PURPOSE:To detect an approaching substance securely and directionally with a simple constitution and to prevent the titled device from the influence of disturbance and misalarm by detecting the substance in accordance with the changes of frequency signals which are based upon the change of stray capacity between sensors and the substance. CONSTITUTION:When the substance approaches the sensors 11, 12, the stray capacity is increased and the level of the attenuation of frequency signals of corresponding networks 31, 32 are increased. The level of the attenuation is changed in accordance with the approaching distance. The attenuated output signals are removed at their noises and sent to voltage variation detecting circuits 61, 62 as DC voltage signals. When the voltage drop is reduced less than a set reference value, the circuits 61, 62 detects the approaching state of the substance and outputs the detected result to an AND circuit 7. The circuit 7 regards that the substance is in the approaching state within a fixed range under the condition that the detecting outputs are in the high level respectively and outputs an alarm signal to an alarm device 10 through a driver 8. Detecting that one sensor detects the substance with a time difference after the other sensor has detected the substance, an alarm releasing circuit 13 releases the alarm.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an object detection device for detecting objects such as obstacles.

Conventional 1 An object detection device used for detecting obstacles when a car is running, for example, emits directional radio waves or ultrasonic waves from a transmitter, and uses a receiver to collect the reflected waves from the object. This system detects objects such as obstacles by receiving signals, but it requires a pair of transmitters and receivers, making the device complex, and since it has directivity, it is difficult to detect objects such as obstacles. This has resulted in a dead zone.

Conventionally, a pair of antennas is provided and a high-frequency signal of the same frequency is applied to each antenna, and when an object to be detected faces the pair of antennas, the unbalance of capacitance between each antenna and the object is detected. A device has been developed that detects an object according to the difference in oscillation frequency caused by the difference in oscillation frequency (see Japanese Patent Publication No. 7852/1983), but such a device requires two systems of antennas and oscillators. This makes the device complicated, and when the object is evenly positioned with respect to the pair of antennas and there is no unbalance in the capacitance between each antenna and the object, even if the object is present, This is not detected, and furthermore, it is not possible to detect objects with directionality.

1. The present invention has been made in consideration of the above points, and uses an HcB configuration to reliably detect objects such as old objects approaching in front of a vehicle in a directional manner and issue an alarm.
The present invention provides an object detection device that can eliminate false alarms caused by disturbances caused by objects in directions other than the detection target, particularly by raindrops falling from an automobile body or the like.

11. The object detection device according to the present invention has several methods to achieve its purpose.
A multi-sensor method is used in which multiple sensors made of electrode members with tropism are installed, and the difference in object detection sensitivity of each sensor is used to provide directional object detection. This system detects objects and issues an alarm in response to changes in frequency signals based on changes in stray capacitance.

In particular, the present invention is characterized in that when an object in a direction other than the detection target subsequently moves in the detection target direction, this is detected and the alarm is forcibly canceled.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a circuit diagram showing the basic principle of object detection according to the present invention, when a frequency signal is applied to the electrode member 1 via a network 3 consisting of divided resistors.

Focusing on the fact that the stray capacitance C between the electrode member 1 and the object ○(01,02) changes depending on the distance between them, and the AC output voltage at the voltage dividing point of the network 3 changes, the electrode member 1 is By using it as a sensor, it can detect objects 0
Detects the falling state of the output voltage when the object approaches 0.
It is designed to detect the approaching state of.

At that time, if the sensor (electrode member) 1 is rod-shaped as shown in the figure, for example, an object 01 located horizontally with respect to the sensor 1 and an object 02 located perpendicularly to the sensor 1 may be detected. become.

Therefore, in particular, in the present invention, for example, an object in the vertical direction
When object 01 is not the object to be detected, it is now possible to selectively detect only the target object 01 in the horizontal direction of sensor 1.

As shown in FIG. 3, the sensors 11 and 12 in at least two object detection systems are provided in parallel, and each sensor 11,
The object detection is made to have directionality by using the difference in detection sensitivity depending on the position of each object 01 and 02 with respect to each object 12.

That is, there are stray capacitances CI and C2 between the sensors 11 and 12 and the ground, respectively, and object 0 is connected to the sensors 11 and 12.
When approaching the network 3 (3+
, 32), but depending on the direction in which the object O approaches the sensors 11, 12, there will be a difference in the attenuation of the frequency signals in each network 31, 32. Considering the relationship shown in FIG. 3, when object 01 approaches the two sensors 11 and 12 from the horizontal direction, and object 02 from the vertical direction, the object o1 approaches each sensor 11. ,12
Since the object 02 is approximately equidistant from the object 02, the changes in its stray capacitance are approximately equal, and the attenuation of the frequency signal in each network 31 and 32 is approximately equal.
In this case, there is a distance difference between the sensors 11 and 12, and the network 32 corresponds to the sensor 12 that is farther away.
The amount of attenuation in the network 31 corresponding to the other sensor 11 is smaller than the amount of attenuation in the network 31 corresponding to the other sensor 11. Therefore, each network 3 corresponding to two sensors 11, 12
By looking at the difference in the amount of attenuation of the frequency signal at 1.32, it becomes possible to detect objects with directionality.

At this time, for example, the approaching state of the object o1 in a predetermined direction is detected based on the fact that the amount of attenuation of the frequency signal in each network 31 and 32 is equal. When the object 02 comes in a predetermined direction, it is first detected by the sensor 11 with sufficient sensitivity and then also detected by the sensor 12 with a time difference.

“ Figure 1 shows an embodiment of an object detection device according to the present invention constructed based on the basic principle described above. Here, the configuration is shown when two sensors are used. A network 31.32 consisting of an oscillator 2 that generates a frequency signal of sensor 1
1, 12.

Band-pass filtering amplifiers 41 and 42 that perform noise removal and amplification processing on the high-frequency output voltages of each network 31 and 32, and detectors 51 and 52 that perform detection of each amplified output signal, respectively, and their detection. Voltage fluctuation detection circuits 61 and 62 detect the approach state of an object by looking at the breakdown state of the voltage signal, and detect if there is a voltage drop exceeding a preset condition, and each 'voltage fluctuation detection circuit' An AND circuit 7 that performs AND processing of the detection output signals of 61 and 62, a driver 8 that controls the operation of the alarm 1o through a gate circuit 9 for canceling the alarm according to the AND result, and each voltage fluctuation detection circuit. and an alarm release circuit 13 which issues a 7-alarm release command to the gate circuit 9 in accordance with the combination of detection output signals 61 and 62. Note that the alarm cancellation circuit 13 is a voltage fluctuation detection circuit 61.
is set in response to an AND processing signal between the output signal of the voltage fluctuation detection circuit 61 and the negative output signal of the voltage fluctuation detection circuit 62, and in response to an AND processing signal between the negative output signal of the voltage fluctuation detection circuit 61 and the negative output signal of the voltage fluctuation detection circuit 62. The set output Q signal of the flip-flop FF is supplied to the gate circuit 9 as an alarm release command.

However, with something configured like this.

When a high frequency signal with a constant frequency is applied from the oscillator 2 to each network 31.32, the sensor 11.12
The high-frequency output voltages are appropriately attenuated in proportion to the proximity of objects facing each other, and are sent to band filter amplifiers 41 and 42, where noise induced in each sensor [1, 12, etc.] is removed, and the frequency Fo Only the high frequency components of the signal are amplified.

Then, the frequency signal amplified to a predetermined value is sent to the detector 51.
52, and a DC voltage signal corresponding to the amplitude of the input frequency signal is sent to a voltage fluctuation detection circuit 61.
Sent to 62. The voltage fluctuation detection circuits 61 and 62 detect the falling state of the applied DC voltage signal, and detect the approaching state of an object when the degree of voltage drop becomes below a preset reference level. Then, each detection output is given to an AND circuit 7. The AND circuit 7 alerts the driver 8 that the object is approaching within a certain range on the condition that the voltage fluctuation detection circuits 61 and 62 detect the approaching state of an object and the respective detection outputs are at a high level. Give instructions.

As a result, the alarm 10 will sound or be turned on to issue a warning that the obstacle has entered the dangerous area. At this time, the gate circuit 9 is in an open state for transmitting the drive signal output from the driver 8 to the alarm 1o. In this case, it is assumed that the approach state of the object 01, which is approximately equidistant from each sensor 11, 12, is detected in the relationship shown in FIG. At that time, if the object 02 approaches each cell 11 and 12,
The voltage fluctuation detection circuit 61 on the sensor 11 side detects the approaching state of the object 02 and its detection output becomes high level, but the voltage fluctuation detection circuit 62 on the sensor 12 side detects the human voltage. Since the degree of descent does not fall below the reference value, the approaching state of the object Q2 is not detected, and therefore its detection output becomes a low level, so that the AND circuit 7 does not issue any alarm command to the driver 8.

In addition, in the relationship shown in Figure 3, when an object 02, for example, raindrops on the body of a car, which is initially in a direction other than the detection target, falls and later moves to a predetermined direction that becomes the detection target, indicated by O1 in the diagram. In that case, in the initial state, the output signal of the voltage fluctuation detection circuit 61 on the sensor 11 side is high level, and the output signal of the voltage fluctuation detection circuit 62 on the sensor 12 side is low level, and the flip-flop of the alarm release circuit 13 is activated. The set output Q signal is given to the gate circuit 10 as an alarm cancellation command to forcibly shut off the gate. Thereafter, each voltage fluctuation detection circuit 61 on both the sensors 11 and 12 side with a time difference. .

Therefore, no false alarms due to object detection will be issued. Further, when an object is no longer detected by either of the sensors 11 and 12, the flip-flop FF is reset, thereby returning the gate circuit 9 to its original gate open state.

FIG. 4 shows a specific configuration example of the voltage fluctuation circuit 6 (61, 62), in which the first amplifier AMPI amplifies the output voltage vO of the detector 5 (51, 52), and a second amplifier AMP2 that amplifies Vo with a certain delay element; and amplified output voltages Vl,
Comparator GOMP for comparing V2 and its comparison output signal S
and a determination circuit DEC that determines whether the time width of is greater than or equal to a preset time width. In addition, amplifier A
MPI and AMP2 are set so that their respective gains are the same. Further, the offset voltage of the comparator GOMP is adjusted so that it produces a low level output when 1≧v2, and a high level output when Vl<V2.

With this configuration, as shown in FIG.
Input type: When the voltage vO falls in a period of T, the amplifier AMP
Although the output voltage v1 of I drops during the same period T, the output voltage v1 of amplifier A
The output voltage 2 of NP2 falls with a certain delay Td, and as a result, Vl<V2 during the period T+Td, and the output S of the comparator CQMP becomes high level. However, since the fall period T of the input voltage Vo changes depending on the proximity of the object to each sensor 11, when the time width of the comparison output S exceeds a predetermined value, the determination circuit DEC determines that the object is constant. It is determined that the vehicle is approaching within the range, and a warning command is given to the driver 8. Note that when the position of the object relative to each sensor 11, 12 does not change and the input voltage Vo becomes constant, Vl=V2, and when the object moves away from each sensor 11, 12, Vl>V2, respectively. The output of the comparator COMP becomes low level, and no alarm command is issued at that time.

FIG. 6 shows an example of application in which the object detection device according to the present invention is used to detect obstacles when a car is running. Sensors 11 and 12 are installed in parallel on the front of section 15 as shown in the figure, detecting only the obstacle in front, and alerting the driver when the obstacle enters the danger area. Disturbances caused by, for example, raindrops accumulated on the upper side of the bumper 15 or unevenness of the road surface: This makes it possible to effectively prevent the occurrence of the A9 alarm. In this case, especially when raindrops that have accumulated on the body of the automobile 14 or the upper side of the bumper 15 fall and are detected by the sensors 11 and 12, the alarm is canceled as described above, and a false alarm due to obstacle detection is caused. It will no longer be served.

FIG. 7 shows another example of application, in which obstacles on both sides of the front of the vehicle 14 can be detected well, and a pair of sensors are installed on both sides of the bumper 15. IIA and IIB are provided, and a sensor 12 is provided in parallel with the pair of sensors IIA and 11B. In this case, three object detection systems are required, each corresponding to each sensor IIA, IIB, and 12.
Voltage fluctuation detection circuit 6 (61A) in the system of L et al.

61B, 62), the eighth
As shown in the figure, each output signal of voltage fluctuation detection circuits 61A and 61B corresponding to sensors IIA and IIB is outputted to an OR circuit 1.
6, and then the OR processed signal and sensor 1
2) of the voltage fluctuation detection circuit 62 corresponding to the voltage fluctuation detection circuit 62 is processed by the AND circuit 7, and the alarm device 10 is appropriately driven via the driver 8 by the AND processed signal.

Gai J2 The object detection device according to the present invention has been described above.

Means for replacing each change in stray capacitance between at least two sensors consisting of electrode members provided with directionality and an object to be detected into changes in frequency signals, and a means for replacing each change in stray capacitance with a change in frequency signal, and in accordance with attenuation of each frequency signal. A means for detecting the approaching state of an object, a means for taking a logical product of each detection output, and a V of object detection according to the logical product output.
: It is composed of a means for generating an alarm, and a means for detecting that an object is detected by the other sensor with a time difference after the detection of the object by one sensor, and causing the alarm M to be canceled. This configuration makes it possible to reliably detect objects such as obstacles approaching in front of the vehicle in a directional manner and issue a warning, while also detecting the effects of disturbances caused by objects other than the direction being detected, especially raindrops falling from the vehicle body. It has the excellent advantage of eliminating false alarms.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of an object detection device according to the present invention, Fig. 2 is a circuit diagram showing the basic principle of object detection according to the invention, and Fig. 3 is an object detection using two sensors. 1 shows an example of the state, FIG. 4 is a block diagram showing a specific configuration example of the voltage fluctuation detection circuit in the same embodiment, FIG. 5 is a time chart of various signals in the voltage fluctuation detection circuit, and FIGS. FIG. 7 is a diagram showing a specific example of sensor installation in an automobile, and FIG. 8 is a block diagram showing an example of the configuration of a processing circuit for object detection signals by each sensor system in the case of FIG. 11.12... Sensor 2... Oscillator 31.32
...Network 41.42...Band filter amplifier 51.52...Detector 61.62...Voltage fluctuation detection circuit 7...AND circuit 8...Driver
9...Gate circuit 10...Alarm device 13...Alarm release circuit Fig. 2 Fig. 3 7+7717 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8

Claims (1)

[Claims] Means for replacing each change in stray capacitance between at least two sensors comprising electrode members provided with directionality and an object to be detected into changes in a frequency signal, and a means for replacing each change in a frequency signal with a change in each frequency signal, A means for detecting the approach state of an object, a means for calculating the logical product of each detection output, a means for issuing an object detection alarm according to the logical product output, and a time difference after the object is detected by one sensor. and means for detecting that an object has been detected by the other sensor and canceling the alarm.