JPH0526492Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an object detection device for a vehicle that detects a state in which an object such as an obstacle is approaching a sensor at a relative speed.

Conventional technology Conventionally, an object detection device used for detecting obstacles while driving a car, for example, emits directional radio waves or ultrasonic waves from a transmitter, and receives reflected waves from the object using a receiver. This method is used to detect objects such as obstacles, but it requires a pair of transmitters and receivers, making the device complex, and since it has directivity, it is difficult to detect objects in close proximity. It has become something that creates a dead zone.

In addition, conventionally, a pair of sensors is provided and a high-frequency signal of the same frequency is applied to each, and when an object to be detected faces the pair of sensors, an imbalance in capacitance between each sensor and the object occurs. A device that detects an object according to the difference in oscillation frequency has been developed (see Japanese Patent Publication No. 7852/1983), but such a device requires two systems of sensors and oscillators, making the device difficult to operate. It becomes complicated, and if the object is evenly positioned with respect to a pair of sensors and there is no imbalance in capacitance between each sensor and the object, it may be detected even though the object is present. The disadvantage is that it is not possible to do so.

In addition, especially when this type of object detection device is installed in a moving vehicle such as a car, if the sensor is installed outside the vehicle body, it will be easily damaged by direct external force, so it is recommended to install something with some strength. This naturally limits the materials it can be made of, and the sensor is exposed to the wind and rain or becomes covered in dust, resulting in poor durability and poor object detection sensitivity.

Purpose This invention was made taking the above points into consideration.
A vehicle object that uses a sensor to reliably detect approaching objects such as obstacles through a simple configuration, and that also prevents the sensor from being affected by external forces or being exposed to wind, rain, or dust. A detection device is provided.

Configuration An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 4 is a circuit diagram showing the basic principle of object detection according to the present invention. When a high frequency signal is applied to a series circuit of electrode member 1 and resistor R, when electrode member 1 and object O
Focusing on the fact that the stray capacitance C between them changes depending on the distance between the electrode member 1 and the resistor R, the output voltage at the voltage dividing point between the electrode member 1 and the resistor R changes. The state in which the object O is approaching is detected by detecting the falling state of the output voltage when the object O is approaching.

FIG. 1 shows an embodiment of the object detection device for a vehicle according to the present invention, which is constructed based on the above-mentioned basic principle.
, a network 3 consisting of a resistance divider circuit provided on the output side of the oscillator 2, a sensor 1 consisting of an electrode member connected to the dividing point of the network 3, and a high frequency output signal from the network 3. A bandpass filter amplifier 4 performs noise removal and amplification processing, a detector 5 detects the amplified output signal, and detects the state of an object approaching by observing the falling state of the detected voltage signal. and a voltage fluctuation detection circuit 6 that gives an alarm command to the driver 7 of the alarm device 8.

However, in a device configured in this way, when a high frequency signal with a constant frequency o is given to the network 3 from the oscillator 2, it is attenuated appropriately in proportion to the proximity of the object facing the sensor 1. The resulting high frequency output signal is sent to the bandpass filter amplifier 4, where noise induced in the sensor 1 and the like is removed and only the high frequency component of frequency o is amplified. The predetermined amplified frequency signal is detected by a wave detector 5, and a DC voltage signal corresponding to the amplitude of the input frequency signal is sent to a voltage fluctuation detection circuit 6. The voltage fluctuation detection circuit 6 is
A falling state of the applied DC voltage signal is detected and an alarm command is given to the driver 7. Thereby, the alarm device 8 issues an alarm to that effect by sounding or being driven to turn on.

FIG. 2 shows a specific configuration example of the voltage fluctuation detection circuit 6, which includes a first amplifier 61 that amplifies the output voltage Vo of the detector 5, and a first amplifier 61 that amplifies the output voltage Vo of the detector 5.
a second amplifier 62 that amplifies the voltage with a certain delay element; a comparator 63 that compares the amplified output voltages V1 and V2; A determination circuit 64 that determines whether the time width of the comparison output signal S is longer than a preset time width in order to exclude a detected state.
It is made up of. Note that the amplifiers 61 and 62 are set to have the same gain.
Further, the offset voltage of the comparator 63 is adjusted so that a low level output is produced when V1≧V2, and a high level output is produced when V1<V2.

With this configuration, as shown in FIG. 3, when the input voltage Vo falls over a period of T,
The output voltage V1 of the amplifier 61 falls with the same period T, but the output voltage V2 of the amplifier 63 falls with a certain delay Td.
As a result, T+Td
During the period V1<V2, the output S of the comparator 63 becomes high level. Since the falling period T of the input voltage Vo changes depending on the proximity of the object to the sensor 1, the determination circuit 64 issues an alarm to the driver 7 when the time width of the comparison output S exceeds a predetermined value. Try to give commands. Note that when the position of the object relative to the sensor 1 does not change and the input voltage Vo remains constant, V1=V2, and when the object moves away from the sensor 1, V1>V2 and the output of the comparator 63 becomes It becomes a low level, and no alarm command is issued at that time.

In the vehicle object detection device configured as described above, in particular, in the present invention, when the sensor 1 is attached to the vehicle, the sensor 1 is
It is characterized in that it is provided inside a part of the vehicle made of an insulating material with a low dielectric constant.

For example, as shown in FIG.
The bumper 10 is made of an insulating material with a low dielectric constant such as synthetic resin, and the sensor 1 is attached to the back side of the bumper 10 as shown in FIG. 6a. In addition, the sensor 1 may be embedded in the bumper 10 as shown in figure b, or the sensor 1 may be embedded in the bumper 10 as shown in figure c.
As shown in the figure, the sensor 1 is installed in a groove 11 formed on the front surface of the bumper 10, and the groove 11 is covered with a cover 12 which also serves as a molding and is made of an insulating material with a low dielectric constant such as synthetic resin. Appropriate measures such as

In addition, other parts of a vehicle made of an insulating material with a low dielectric constant include a molding part or a part of the body (in some recent cars, part of the body is made of synthetic resin other than metal). etc., and the sensor 1 may be appropriately attached inside that part by means similar to that shown in FIG.

However, according to the present invention, the sensor 1 is provided inside a part of the vehicle made of an insulating material with a low dielectric constant so that it is not exposed to the outside, so that the sensor 1 is not exposed to external force directly. This prevents damage or exposure to wind, rain, or dust, which reduces durability and object detection sensitivity.

Therefore, the material and shape of the sensor 1 can be widely selected without giving much importance to the strength and durability of the sensor 1, and a plate-shaped, line-shaped or foil-shaped electrode member or a conductive painted surface can be used as the sensor 1. In addition, since the sensor 1 is not exposed to the outside, it does not affect the external finish of the vehicle.

In this case, in particular, in the present invention, the sensor 1 is installed inside the part made of an insulating material with a low dielectric constant, without having to be separately attached to the vehicle, and by using an existing resin bumper etc., the part of the bumper etc. Since the sensor 1 is provided inside, the sensor 1 can be easily installed in the vehicle.

As described above, the object detection device for vehicles according to the present invention has a simple overall configuration, so there are fewer failures, and there is no dead zone in the nearby area, so the closer the object is, the better the detection state is, and the longer the object is, the more durable it is. This makes it possible to detect only objects that are approaching the sensor with high speed and sensitivity, which is particularly advantageous in detecting obstacles when the vehicle is running.

Effects As described above, in the object detection device for a vehicle according to the present invention, there is provided a means for replacing a change in stray capacitance between a sensor made of an electrode member and an object to be detected with a change in a frequency signal, and a method for replacing the change in frequency signal with a change in the frequency signal. and a means for converting the voltage signal into a voltage signal, and applying the voltage signal to two amplifiers provided so that one amplified signal lags the other amplified signal, and comparing each amplified signal with a comparator. means for detecting that the voltage signal is in a falling state and determining that an object is approaching the sensor at a relative speed; It is designed to be installed inside the bumper, and with its simple configuration, it can reliably detect the state of approaching objects. It has the excellent advantage of being able to effectively prevent deterioration in durability and object detection sensitivity due to exposure to water.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a vehicle object detection device according to the present invention, Fig. 2 is a block diagram showing a specific configuration example of a voltage fluctuation detection circuit in the same embodiment, and Fig. 3 is a block diagram showing a voltage fluctuation detection circuit according to the embodiment. Figure 4 is a circuit configuration diagram showing the basic principle of object detection according to the present invention; Figure 5 is a perspective view showing how the sensor is installed in a car; Figure 6 is a time chart of signals of each part in the detection circuit.
Figures a, b and c are side sectional views respectively showing means for installing the sensor on the bumper. 1... Sensor (electrode member), 2... Oscillator, 3
... network, 4 ... bandpass filter amplifier, 5 ...
...Detector, 6...Voltage fluctuation detection circuit, 7...Driver, 8...Alarm, 10...Bumper.

Claims (1)

[Scope of utility model registration request] A means for replacing a change in stray capacitance between a sensor made of an electrode member and an object to be detected with a change in a frequency signal, a means for converting the frequency signal into a voltage signal, and a means for amplifying the voltage signal on one side. The signal is applied to two amplifiers installed so that the signal lags behind the other amplified signal, and by comparing each amplified signal with a comparator, it is detected that the voltage signal is in a falling state, and the object is detected. 1. An object detection device for a vehicle, comprising means for determining that the object is approaching the sensor at a relative speed, the sensor being provided inside a bumper made of an insulating material of the vehicle.