JPS6125087A - Object detector - Google Patents

Abstract

PURPOSE:To detect an approaching obstacle accurately, by dividing a sensor into sections corresponding to blocks to distribute the detection range of an object of an object among subsensors arranged in blocks respectively. CONSTITUTION:A fixed high frequency signal reaches a network 32 from a signal generator 2, a high frequency output voltage is sent to bandpass filters 41 and 42 as properly damped in proportion to the access of an object facing subsensors 11 and 22. Here, noises induced in the sensors 11 and 12 or the like are removed and = high frequency components thereof are amplified. Then, after detected with detectors 51 and 52, a DC voltage signal corresponding to the amplitude of an input frequency signal is sent to = voltage variations detecting circuits 61 and 62, which detect droping thereof separately. As the drop in the voltage falls below the set reference, an alarm command for warning that the object reaches a dangerous area can be provided to a driver 8 through an OR circuit 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an object detection device that detects the approach of an object such as an obstacle.

Conventionally, object detection devices used for detecting obstacles when driving a car, for example, emit directional radio waves or ultrasonic waves from a transmitter, and use 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, an imbalance in capacitance between each antenna and the object occurs. A device has been developed that detects an object according to the difference in oscillation frequency (see Japanese Patent Publication No. 7852/1983), but in such a device, the object is detected evenly with respect to the pair of antennas. This method has the disadvantage that when an object is located and no imbalance occurs in the capacitance between each antenna and the object, the object is not detected even though it is present.

The present invention was made in consideration of the above points, and provides an object detection device that can reliably detect approaching objects such as obstacles with a simple configuration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now 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 high frequency signal is applied to a series circuit of electrode member 1 and resistor R, the distance between electrode member 1 and object 0 changes Focusing on the fact that the high-frequency output voltage at which voltage dividing point between the electrode plate 1 and the resistor R changes as the stray capacitance C changes, and by using the electrode member l as a sensor, the output voltage when an object 0 approaches it can be calculated. The approach state of the object O is detected by detecting the descending state of the object O.

However, when such means for detecting the object O is used, the detection sensitivity of the object O is approximately proportional to the size of the object O if the approach conditions and materials of the object O are the same. However, if the size of the object 0 to be detected exceeds the size of the sensor 1, the detection sensitivity will not increase even if the object 0 becomes larger.

FIG. 3 shows the characteristics of detection sensitivity with respect to the size of the object O to be detected. Considering the characteristics, when comparing the detection sensitivity of small object 01 and large object 02 for sensor 1 (large), (medium), and (small), respectively,
The (medium) sensor is even more (
The (small) sensor is more sensitive to objects 01 and 0 than the medium) sensor.
It can be seen that the difference in detection sensitivity between No. 2 and No. 2 is small. That is,
As the size of the sensor 1 becomes smaller, variations in detection sensitivity due to differences in the size of the object 0 to be detected are reduced.

Therefore, in particular, in the present invention, when detecting an object based on the basic principle described above, in order to reduce variations in detection sensitivity due to the size of the object O, when it is desired to detect whether or not the object O is within a certain range, The detection range of the object O is divided into multiple blocks, the sensor 1 is divided into multiple blocks corresponding to each block, and the object 0 is detected by each divided small sensor for each block. This is to take measures to effectively reduce variations in detection sensitivity due to differences in the size of the object 0.

FIG. 1 shows an embodiment of an object detection device according to the present invention, and here shows a configuration in which the sensor is divided into two small sensors. That is, a network 31,32 consisting of an oscillator 2 that generates a constant frequency signal and a resistance divider circuit provided in parallel on the output side of the oscillator 2.
and small sensors 11 and 12 each consisting of an electrode plate connected to the division points of each of the networks 31 and 32, and the high-frequency output voltages from the networks 3 and 32 are subjected to noise removal and amplification processing, respectively. Bandpass filter amplifiers 41 and 42, and detectors 51 and 51 for detecting each amplified output signal thereof. ．． 52, voltage fluctuation detection circuits 61 and 62, which detect the approaching state of an object by looking at the falling state of the detected voltage signal, and detect if there is a voltage drop exceeding a preset condition, and each voltage. The variation detection circuit 6] is composed of an OR circuit 7 that performs OR processing on the detection output signals of the fluctuation detection circuit 6] and 62, and a driver 8 that controls the operation of the alarm device 9 in accordance with the OR output.

However, in the device configured in this way, when a high frequency signal with a constant frequency Fo is given to the network 3 from the oscillator 2, the small sensor T] is proportional to the approach of the object facing the small sensor 12. The high frequency output voltage suitably attenuated is sent to the bandpass filter amplifiers 41 and 42, where noise induced in the small sensors 11, 12, etc. is removed and only the high frequency component of the frequency Fo is amplified. 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. The voltage fluctuation detection circuits 61 and 62 each detect the voltage drop state of the applied DC voltage signal, and detect an object through the OR circuit 7 when the degree of voltage drop falls below a preset reference value. A warning command is given to the driver 8 on the assumption that the driver has entered the dangerous area. Thereby, the alarm device 9 is activated to sound or turn on to issue an alarm to that effect.

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 AMP2 that amplifies Vo with a certain delay element; and amplified output voltages Vl,
Comparator COMP 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 COMP is adjusted so that a low level output is produced when V1≧■2, and a high level output is produced when V1<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 v1 of the amplifier AN falls during the same period T, but the output voltage v1 of the amplifier AN
The output voltage of P2 2 will fall with a certain delay Td, resulting in a period of T+Td V ] <V 2
As a result, the output S of the comparator COMP becomes high level.

Therefore, during the falling period T of the input voltage ■0, the small sensor 11,
1.2, so when the time width of the comparison output S reaches a predetermined wind speed, the determination circuit DEc determines that the object has entered the dangerous area and issues an alarm to the driver 8. Try to give commands. Note that when the position of the object relative to the small sensors 11 and 12 does not change and the input voltage Vo becomes constant, V1=V2, and when the object moves away from the small sensors 11 and 12, Vl>V2, respectively. The output of the comparator COMP becomes low level, and no alarm command is issued at that time.

As described above, in the object detection device according to the present invention, the structure of all seven devices is simple, so there are fewer failures, and there is no dead zone at close range, so the closer the object is, the better the detection state is. In addition, especially in the present invention, since the approaching state of one object is detected in parallel by a plurality of small sensors divided into small parts, the detection sensitivity is affected by the difference in the size of the object to be detected. Variations can be effectively reduced, and the target object can be detected reliably without compromising the ability to detect relatively small objects that are the object of detection, even when disturbances are caused by large objects that are not the object of detection. This is advantageous in detecting obstacles when a car is running, for example.

As described above, the object detection device according to the present invention includes a means for replacing a change in stray capacitance between a sensor consisting of an electrode plate and an object to be detected with a change in a frequency signal, and an attenuation of the frequency signal. =8-, in which the detection range of the object is divided into a plurality of blocks, the sensor is divided into a plurality of blocks corresponding to each block, and each block is This system uses divided small sensors to detect the approaching state of an object.With a simple configuration, it is possible to reliably detect the approaching state of an object, and it also detects differences in the size of the objects to be detected. It has the excellent advantage of being able to effectively reduce variations in detection sensitivity due to

[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 a detection sensitivity depending on the size of the object. FIG. 4 is a block diagram showing a specific configuration example of the voltage fluctuation detection circuit in the same embodiment, and FIG.
The figure is a time chart of various signals in the voltage fluctuation detection circuit.

Claims (1)

[Claims] A sensor consisting of 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 means for detecting the approaching state of the object according to the attenuation of the frequency signal. In this way, the object detection range is divided into multiple blocks, and the sensor is divided into multiple blocks corresponding to each block, and each divided small sensor is used to detect the approaching state of the object. An object detection device characterized by: