JPS6196485A - Substance detector - Google Patents

Abstract

PURPOSE:To detect an approaching substance securely and directionally with a simple constitution without the influence of disturbance by detecting the substance in accordance with the changes of frequency signals which are based upon the change of stray capacity between sensors and a substance. CONSTITUTION:When the substance approaches the sensors 11, 12, the stray capacity is increased and the level of attenuation of frequency signals of corresponding networks 31, 32 are increased. The level of attenuation is changed in accordance with the approaching direction. The attenuated high frequency output voltages are sent to voltage variation detecting circuits 61, 62 as DC voltage signals removed at their noises through band filter amplifiers 41, 42 and detectors 51, 52. When the degree of the voltage drop is reduced less than a previously set up reference value, the circuits 61, 62 detect the approaching state of the substance and apply respective detecting output 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 of the circuits 61, 62 are in the high level respectively and applies an alarm command to a driver 8. On the basis of the alarm command, the driver 8 rings or lights up an alarm device 9.

Description

[Detailed description of the invention]! BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object detection device for detecting objects such as obstacles.

Traditional 1 Object detection devices used for detecting obstacles when driving, for example, emit directional radio waves or ultrasonic waves from a transmitter, and detect waves reflected from the object using received signals. 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 capacitance imbalance between each antenna and the object is 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. 7-7852). 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 though the object is present, In this case, the object cannot be detected in any direction, and objects cannot be detected with directionality.

1 fish The present invention has been made in consideration of the above points.

Object detection 'JAr!' uses a simple configuration to reliably detect objects such as approaching obstacles with directionality, while also eliminating the influence of disturbances caused by objects in directions other than the detection target direction. i.

1. In order to achieve the object, the object detection device according to the present invention detects an object according to a change in a frequency signal based on a change in stray capacitance between a sensor made of an electrode member and an object to be detected. This is what I did.

In this case, the present invention is particularly characterized in that a plurality of sensors are provided with directionality, and a multi-sensor method is adopted in which object detection is given directionality by utilizing the difference in object detection sensitivity of each sensor.

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 l is By using it as a sensor, it can detect objects ○
Detects the falling state of the output voltage when the object O approaches.
It is designed to detect the approaching state of.

In this case, if the sensor (electrode member) ■ is rod-shaped as shown in the figure, for example, it will detect an object 01 in the horizontal direction and an object 02 in the vertical direction with respect to the sensor 1. become.

Therefore, in particular, in the present invention, for example, an object in the vertical direction 0
2 is not the object to be detected, it is now possible to selectively detect only the object O1 located in the horizontal direction of the target sensor l.

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,
12 for each object 01. -02 The difference in detection sensitivity depending on the position is used to give directionality to object detection.

That is, between the sensors 11 and 12 and the ground, there are 1 displacement capacitances CI and C2, respectively, and the object 0 is connected to the sensors 11 and 1.
2, each stray capacitance C1, C2 increases, and the network 3 (3
1, 32), but depending on the direction in which the object 0 approaches the sensors 11, 12, there will be a difference in the attenuation of the frequency signal in each network 31, 32. Considering the relationship shown in FIG. 3, where object o1 approaches two sensors 11 and 12 from the horizontal direction, and object 02 approaches from the vertical direction, object 01 approaches each sensor 11.
, 12, the changes in their stray capacitances are approximately equal, and the frequency signal attenuation in each network 31, 32 is approximately equal, whereas for object 02, each sensor 11, 1.2, and the amount of attenuation in the network 1 to work 32 corresponding to the sensor 12 which is farther away is smaller than the amount of attenuation in the network 31 corresponding to the other sensor 11. Therefore, by looking at the difference in the amount of attenuation of the frequency signal in each network 31, 32 corresponding to the two sensors 11, 12, it becomes possible to detect an object with directionality.

In case 2, for example, the approaching state of the object O in a predetermined direction is detected based on the fact that the attenuation of the frequency signals in each network 31 and 32 is equal.

FIG. 1 shows an embodiment of an object detection device according to the present invention constructed based on the basic principle described in 01j, and here shows the construction when two sensors are used. That is, the screws 1 to 31.32, each consisting of an oscillation r&2 that generates a constant frequency signal, a resistance divider circuit provided in parallel on the output side of the oscillator 2, and the dividing point of each network 31.32. Each connected sensor 11
, 12 and.

Band-pass filtering amplifiers 41 and 42 that perform noise removal and amplification processing on the high-frequency output voltages from each of the networks 31 and 32, detectors 51 and 52 that perform detection of each amplified output signal, 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 61 .62 detection output signals, and a driver 8 that controls the operation of the alarm device 9 in accordance with the AND output.

However, in the lever configured in this way, when a high frequency signal with a constant frequency Fo is given from the oscillator 2 to each network 31, 32, the approach of the object facing the sensors 11 and 12, respectively, is changed. The high-frequency output voltage that has been appropriately attenuated in proportion is sent to band filter amplifiers 41 and 42, where the noise induced in each sensor 11, 12, etc. is removed, and only the high-frequency component of the frequency Fo is amplified. It is done. The predetermined amplified frequency signals are detected by detectors 51 and 52, and a DC voltage signal corresponding to the amplitude of the input frequency signal is sent to voltage fluctuation detection circuits 61 and 62. Voltage fluctuation detection circuit 61.6
2 detects the falling state of the given DC voltage signal, detects the approaching state of an object when the degree of voltage drop becomes less than a preset reference value, and outputs each detection output. is given to the 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 approaching state of the object is detected in the voltage fluctuation detection circuits 61 and 62 and the respective detection outputs are at a high level. Give instructions. As a result, the alarm device 9 is driven to ring or turn on to notify the user of this fact. In this case, it is assumed that the approaching state of the object 01, which is approximately equidistant from each sensor 11, 12, is detected in the relationship shown in FIG.

At this time, when the object O2 approaches each sensor 11, 12, the voltage fluctuation detection circuit 61 on the sensor 11 side detects the approaching state of the object O2 and its detection output becomes a high level. However, in the voltage fluctuation detection circuit 62 on the sensor 12 side, the degree of fall in the input voltage does not fall below the reference value and the approaching state of the object 02 is not detected, so the detection output becomes low level. Therefore, the AND circuit 7 does not issue any warning command to the driver 8.

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 the output voltage A second amplifier A M P 2 that amplifies vO with a certain delay element, a comparator COMP that compares the amplified output voltages Vl and V2, respectively, and a time width of the comparison output signal S that is set in advance. and a determination circuit DEC that determines whether the width is greater than or equal to the width. Note that the amplifiers AMPI and AMP2 are set to have the same gain. Also, the comparator COMP is Vl≧v
The offset voltage is adjusted so that a low level output is produced at 'Vl<V2' and a high level output is produced at 'Vl<V2.

With this configuration, as shown in FIG.
When the input voltage Vo falls for a period of T, the amplifier AMPI
The output voltage Vl of the amplifier AN decreases during the same period, but the output voltage Vl of the amplifier AN
The output voltage v2 of P2 falls with a certain delay Td, and as a result, Vl<V2 for a period of T+Td(7), and the output S of "C comparison @COMP becomes high level."

Therefore, the falling period T of the input voltage Vo is
2. Therefore, when the time width of the comparison output S exceeds a predetermined value, the determination circuit DEC determines that the object is approaching within a certain range and sends a signal to the driver 8. ! ! to give information commands. Note that when the position of the object relative to each sensor 11, 12 does not change and the input voltage ■0 becomes constant, V1=V
2, and when the object moves away from each sensor 11 and 12, Vl>V2 and the comparators C and O
The output of MP 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 13 as shown in the figure, detecting only the obstacle in front and giving a warning to the driver that the obstacle has entered the dangerous area. This makes it possible to effectively prevent false alarms from occurring due to external disturbances, such as raindrops accumulated on the upper side of the bumper 13 or unevenness of the road surface.

Further, FIG. 7 shows another example of application, in which obstacles on both sides of the front of the vehicle 10 can be detected particularly well, and a pair of sensors are installed on both sides of the bumper 13. Sensors IIA and 11B are provided, and the pair of sensors IIA.

A sensor 12 is provided in parallel with 11B. In this case, three object detection systems corresponding to the sensors IIA, IIB, and 12 are required, and the voltage fluctuation detection circuit 6 (61A) in these systems is required.

61B, 62) when processing each output signal.

As shown in FIG. 8, after each output signal of the voltage fluctuation detection circuits 61A and 61B corresponding to the sensors IIA and 11B is processed by the OR circuit 14, the OR processed signal and the voltage fluctuation detection circuit corresponding to the sensor 12 are processed. 62 is processed by the AND circuit 7, and the alarm device 9 is appropriately driven by the AND processed signal via the driver 8.

As described above, in the object detection device according to the present invention, changes in each stray capacitance between a plurality of sensors made of directional electrode members and an object to be detected are detected by changes in frequency signals. means for performing two substitutions, means for detecting the approaching state of an object according to the attenuation of each of these frequency signals, and means for taking a logical product of each of these detection outputs;
It is configured with a means for notifying object detection according to the logical product output, and with a simple configuration, it is possible to reliably detect approaching objects such as obstacles with directionality, and it is possible to detect objects such as approaching obstacles with directionality. It has the excellent advantage of being able to effectively eliminate the influence of disturbances caused by objects.

[Brief explanation of the drawing]

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. A diagram showing 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,
Figure 5 is a time chart of various signals in the voltage fluctuation detection circuit, Figures 6 and 7 are diagrams showing specific installation examples of sensors in automobiles, and Figure 8 is each sensor system in the case of Figure 7. FIG. 2 is a block diagram showing an example of a configuration of an object detection signal processing circuit according to FIG. 11.12... Sensor (electrode member) 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...Alarm device

Claims (1)

[Claims] Means for replacing each change in stray capacitance between a plurality of sensors consisting of electrode members provided with directionality and an object to be detected with a change in a frequency signal, An object detection device comprising means for detecting the approaching state of objects, means for calculating the logical product of the respective detection outputs, and means for notifying object detection according to the logical product output.