JPH0577996B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an object detection device that notifies objects such as obstacles.

Conventional technology Conventionally, object detection devices used, for example, to notify obstacles when driving a car, emit directional radio waves or ultrasonic waves from a transmitter, and receive 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.

Conventionally, a pair of antennas is provided and a high-frequency signal of the same frequency is applied to each antenna. A device has been developed that detects objects according to the difference in oscillation frequency caused by the difference in the oscillation frequency.
(Refer to Publication No. 7852), such a device requires two systems of antennas and oscillators, which makes the device complicated. If there is no capacitance imbalance between the two, the object will not be detected even though it is present.

Purpose The present invention was made in consideration of the above points, and
It is an object of the present invention to provide an object detection device that can reliably detect approaching objects such as obstacles with a simple configuration and has a function to check whether the device operates normally.

Configuration An embodiment of the present invention will be described in detail below 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 the network 3 consisting of divided resistors,
By focusing on the fact that the stray capacitance C between the electrode member 1 and the object O changes depending on the distance between them, and the frequency signal at the voltage dividing point of the network 3 fluctuates, by using the electrode member 1 as a sensor. , the state in which the object O is approaching the sensor is detected by detecting the attenuation state of the frequency signal when the object O approaches the sensor.

FIG. 1 shows an embodiment of an object detection device according to the present invention constructed based on the above-mentioned basic principle. resistance R
A network 3 consisting of a resistance divider circuit with R1 and R2, a sensor (electrode member) 1 connected to the resistance divider point a of the network 3, and noise removal and amplification of the high frequency output signal from the network 3. A bandpass filter amplifier 4 performs processing, a detector 5 detects the amplified output signal, and detects a state in which an object is approaching by looking at the falling state of the detected voltage signal. A voltage fluctuation detection circuit 6, a driver 7 that controls the operation of the alarm 8 according to the detection output signal of the voltage fluctuation detection circuit 6, and a low anti-R3
and a check circuit 9 which gives an on-command to the transistor Q for a certain period of time preset in an internal timer in response to the on-signal Son of the main switch of the device. ing.

However, in the case of the device configured in this way, when a frequency signal having a constant frequency is given to the network 3 from the oscillator 2, it is appropriately attenuated in proportion to the proximity of the object facing the sensor 1. The 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 high frequency components of a constant frequency are 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 detects a state where an object is approaching by detecting a falling state of the applied DC voltage signal,
The detection output is given to the driver 7 as a notification command. As a result, the alarm 8 is driven to ring or turn to notify that the object has been detected.

When the main switch for powering the device is turned on, the timer in the check circuit 9 operates in response to the on signal Son, and the check circuit 9 commands the transistor Q to turn on for a preset period of time (several seconds). As a result, the transistor Q becomes conductive, and the resistor R3 is connected to the network 3. As a result, the potential at the resistance dividing point a in the network 3 drops to a predetermined value, and the high frequency of the network 3 decreases by that amount. The output signal is forced to be attenuated. However, even in this case, a notification command is issued from the voltage fluctuation detection circuit 6 to the driver 7, and the notification device 8 is operated, as in the case of detecting the object described above. Further, after the time set by the timer in the check circuit 9 has elapsed, the transistor Q is turned off, thereby putting the device into a standby state for actual object detection.

Therefore, it is possible to check whether the device is operating normally by operating the alarm 8 for a certain period of time when the main switch is turned on.
Moreover, since the alarm 8 does not operate at that time, it is possible to know that an abnormality has occurred in the apparatus.

FIG. 3 shows a specific configuration example of the voltage fluctuation detection circuit 6, which includes a first amplifier AMR1 that amplifies the output voltage signal Vo of the detector 5, and a first amplifier AMR1 that amplifies the output voltage signal Vo of the detector 5, and a first amplifier AMR1 that amplifies the output voltage signal Vo of the detector 5. A second amplifier AMP2 amplifies the amplified output voltages V1 and V2, and a comparator COMP compares the amplified output voltages V1 and V2, respectively.In order to exclude instantaneous detection of raindrops, etc., the time width of the comparison output signal S is set in advance. It consists of a determination circuit DE that determines whether or not the time width is longer than a set time width. Note that the amplifiers AMP1 and AMP2 are set to have the same gain. Further, the offset voltage of the comparator COMP 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. 4, when the input voltage Vo falls over a period of T,
The output voltage V1 of the amplifier AMP1 falls during the same period T, but the output voltage V2 of the amplifier AMP2 falls with a certain delay Td, resulting in periods V1 and V2 of T+Td, and the comparator
The output S of COMP becomes high level. However,
Since the falling period T of the input voltage Vo changes depending on the degree of approach of the object to the sensor 1, when the time width of the comparison output S exceeds a predetermined value, the judgment circuit DEC issues a sound alarm command to the driver 7. Do it like this. Note that when the position of the object relative to sensor 1 does not change and the input voltage Vo remains constant, V1=V2, and when the object moves away from sensor 1, V1>V2 and the output of comparator COMP becomes It becomes a low level, and no notification command is issued at that time.

FIG. 5 shows an example of application in which the object detection device according to the present invention is used to detect obstacles when reversing a vehicle. Sensors 11 and 12 are provided in parallel on the front of the bumper 14 portion as shown in the figure, and only an approaching obstacle in front that is approximately equidistant from each sensor 11 and 12 is detected and an acoustic warning is given to the driver. This makes it possible to effectively prevent the generation of false alarms due to disturbances in the vertical direction, such as raindrops accumulated on the upper side of the bumper 14, unevenness of the road surface, etc.

FIG. 6 shows an example of the configuration of the object detection device at that time. Here, two object detection systems are provided corresponding to each sensor 11, 12, and the output signals of the voltage fluctuation detection circuits 6, 61, 62 in each system are ANDed by the AND circuit 10, and then The signal is given to the driver 7 as a detection command. However, with this configuration, when an obstacle in front that is approximately equidistant from the sensors 11 and 12 is detected and the output signals of the voltage fluctuation detection circuits 61 and 62 both become high level, A detection command will be issued to the driver 7. Furthermore, if an object is located above or below at different distances from the sensors 11 and 12, the object will be detected by the sensor system that is closer to the object, but the sensor system that is farther away from the other object will detect the object. Object detection is not performed by the system, and therefore no detection command is issued to the driver 7.

FIG. 7 shows a specific example of the circuit configuration of the object detection device according to the present invention when two sensor systems are provided to detect obstacles when the vehicle is reversing. In the figure, the same reference numerals as in FIG. 6 indicate the same structure.

Here, bias voltage Vcc1 is applied to the negative input side of the comparator COMP in the voltage fluctuation detection circuits 6, 61, and 62 via the Zener diode ZD1, and the positive input side is connected to the Zener diode ZD.
2 input signal V by grounding through 2
By setting upper and lower limits for comparison of 1 and V2, 2 input signals V
When V1 and V2 are within the comparison range, a normal comparison operation is performed, and when it is outside the comparison range, a constant high level output is always produced. But such a comparator COMP
By using this, even minute changes in voltage fluctuation due to the approach of an object can be detected satisfactorily. FIG. 8 shows the input characteristics on the negative side and positive side of the comparator COMP, respectively. Vb in the diagram
indicates the voltage at point b, and Vc indicates the potential at point c. Here, the comparison range is V _ZD2 and Vcc1-
This is the area between V and _ZD1 .

When the main switch SW for powering the device is turned on, the battery BATT is connected and constant bias voltages Vcc1 and Vcc2 (Vcc1>Vcc2) are applied to each part. Note that 15 in the figure indicates a voltage stabilizing circuit. Main switch now
When the SW is turned on and bias voltage is applied to each part of the device, the power check timer circuit TM1
operates and issues a detection command to the driver 7 for the timer set time, which causes the alarm 8 to activate the oscillation circuit.
It operates intermittently in synchronization with the oscillation frequency of the OSC, thereby making it possible to check whether the eight systems of alarms are operating normally.

In addition, in the check circuit 9, when the car is put into reverse gear after the timer setting time in the power check timer circuit TM1 has elapsed after the main switch SW is turned on, the back lamp lighting signal BL at that time goes high. As a result, the output signal of the abnormality check timer circuit TM2 becomes low level for the timer setting time, and during that time, transistors Q, Q1, and Q2 in each sensor system 1, 11, and 12 are turned on, and each network 3, 31, and 32 are forcibly lowered. As a result, each sensor system enters a pseudo state of object detection, and when the output of each voltage fluctuation detection circuit 6 becomes high level, an alarm command is given to the driver 7, which causes the alarm 8 to adjust to the oscillation frequency of the oscillation circuit OSC. It is possible to check that each sensor system is operating normally by synchronizing and intermittent operation. In addition, CMP2 in the figure
indicates a comparison circuit.

Effects As described above, in the object detection device according to the present invention,
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 converting the converted voltage signal into a constant value. means for time delaying, means for detecting a falling state of the voltage signal by comparing the delayed voltage signal with the original voltage signal, means for operating an alarm upon detection, and means for operating an alarm in response to turning on a power switch. means for temporarily forcibly operating the alarm, and means for forcibly causing a voltage signal to fall in response to shifting the gear of the vehicle to a forward or reverse position after turning on the power switch. When checking whether the device is operating normally in order to avoid false alarms that the object has not been detected, the Nothing will happen if the system of the alarm system that sends the sound alarm of object detection is malfunctioning, so first check to see if the alarm is working properly when the power switch is turned on.
Next, when the car's gear is engaged, it automatically and efficiently checks whether the main body of the device is operating normally according to each operation step, and then checks the relative position in the direction of travel of the car. This system has the excellent advantage of being able to reliably detect only approaching objects such as obstacles, and appropriately providing the driver with sound notification to that effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the object detection device according to the present invention, FIG. 2 is a circuit diagram showing the basic principle of object detection according to the present invention, and FIG. 3 is a voltage fluctuation detection diagram in the same embodiment. A block diagram showing a specific configuration example of the circuit, FIG. 4 is a time chart of signals of each part in the voltage fluctuation detection circuit, and FIG. 5 is a diagram showing a specific example of sensor installation in an automobile.
FIG. 6 is a block diagram showing a configuration example of an object detection device according to the present invention when two sensor systems are provided;
7th is an electrical connection diagram showing a specific example of the circuit configuration of the object detection device according to the present invention when two sensor systems are provided to detect obstacles when reversing a vehicle; FIG. FIG. 6 is a diagram showing input characteristics on the − side and the + side of the comparator COMP in the figure, respectively. 1... Sensor (electrode member) 2... Oscillator, 3... Network, 4... Bandpass filter amplifier, 5... Detector, 6
... Voltage fluctuation detection circuit, 7... Driver, 8... Alarm, 9... Check circuit.

Claims (1)

[Claims] 1. 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 converting the converted voltage signal into a voltage signal. means for delaying a certain period of time, means for detecting a falling state of the voltage signal by comparing the delayed voltage signal with the original voltage signal, means for operating an alarm upon detection, and means for turning on a power switch. means for temporarily forcibly operating the alarm in response;
An object detecting device comprising means for forcibly causing a voltage signal to fall in response to shifting the gear of an automobile to a forward or reverse position after turning on a power switch.