JPH046883B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to an obstacle detection device for an automobile.

<Prior Art> In general, an automobile obstacle detection device is used to automatically detect obstacles in the driver's blind spot and prevent the automobile from colliding with the obstacles. This type of device emits light that blinks at a predetermined period from a light emitter, and determines whether or not the period of incident light received by a light receiver is within the predetermined period. There is a device that can accurately detect obstacles by determining whether or not the light is reflected by an obstacle (see Japanese Patent Laid-Open No. 53-85025).

[Problem to be solved by the invention] However, this conventional obstacle detection device detects in which part of the blind spot area the obstacle is located, and has the disadvantage that it cannot determine the distance to the obstacle. .

Here, at least one light-emitting element and a large number of light-receiving elements are used, preferably a large number of light-receiving element groups are repeatedly scanned, and the distance is measured by paying attention to the relative change in the amount of light input to the light-receiving element. "Distance meter"
(Japanese Unexamined Patent Publication No. 56-608) has been proposed. This invention is based on a rangefinder using a light emitting element and a light receiving element, including a light receiving element group including a large number of light receiving elements,
It has a light emitting element disposed on at least one side of the light receiving element group and two needle holes that determine the input and output positions of the light, and the light emitted from the light emitting element is reflected by an object and detected by a specific light receiving element. The distance to the object is measured by the optical path taken to the object.

By the way, in the above proposal, since one needle hole is used to guide the reflected light to each light receiving element, the following problems are considered to occur.

First, in order to ensure distance measurement accuracy in the above configuration, it is necessary to largely distribute the reflected light that has passed through a single needle hole to each light receiving element, and there is a considerable distance between the needle hole and the group of light receiving elements. It was necessary to ensure that Therefore, with this proposal, the dimensions in the distance measurement direction will be large, and especially when this distance meter is mounted on a car, the amount of protrusion from the vehicle body in the distance measurement direction (toward the obstacle) will be large. This increases the size of the device, making it undesirable as an on-vehicle device.

Next, the structure of the reflected light introduction part to the light receiving element group is composed of holes, and this is thought to be based on the idea that light is guided to each of the large number of light receiving elements with a single hole. Therefore, there is a technical premise that this hole allows reflected light to freely enter from multiple directions. By the way, if we consider the case where the above-proposed rangefinder configured on this premise is installed in a car, the environment in which the car is placed, that is, the sunlight, the stop lamp and cross lamp of the car equipment, surrounding street lights, and the lamps of other cars. In an environment where various types of light exist, these lights will freely enter the light receiving element from multiple directions through the hole described above, and at the light receiving element, these lights will interfere with the light reflected from obstacles. , it is thought that the amount of light detected by the light receiving element will no longer be appropriate. As mentioned above, in conventional automobile obstacle detection devices, the light emitted from the light emitter flashes at a predetermined period to distinguish between these various types of light and the light from the light emitter. Considering the environment in which the car is placed, it is not appropriate for the rangefinder to configure the reflected light introducing section with holes that allow light to freely enter from multiple directions. This is not desirable in terms of ensuring proper operation.

The present invention was devised in view of the above-mentioned conventional problems, and its purpose is to make the device more compact so that it can be easily mounted on a vehicle, and to make it suitable for the environment in which the vehicle is placed. An object of the present invention is to provide an obstacle detection device for a vehicle that can ensure appropriate ranging performance.

<Means for Solving the Problems> The present invention provides a light emitter that emits light toward the outside of the vehicle body, a drive circuit that turns on the light emitter at a predetermined period, and a drive circuit that connects the light emitter in parallel to the light emitter. A plurality of light receivers are arranged to receive incident light, and as the separation distance of each light receiver from the light emitter increases, the angle formed by each of the light receivers with the light emitting axis is sequentially set to be larger. A plurality of incident light guide cylinders individually guide incident light incident at different angles to each receiver, while preventing interference of incident light at angles other than the set angle with respect to each receiver; It includes a plurality of signal discrimination circuits that discriminate whether the period of light is the same as the predetermined period and outputs an output signal, and a display device that displays the distance to the obstacle based on the output signals from these signal discrimination circuits. It is characterized by:

<<Operation>> To describe the operation of the present invention, light that blinks at a predetermined period is emitted from the emitter, and as the separation distance from each light receiver from the emitter increases, the radiation from the emitter increases. Incident light is individually received by a plurality of light receivers through a plurality of incident light guide cylinders whose angles with the optical axis are set to be successively larger. Then, the signal determining means determines that the incident light received by each light receiver has the same period as the predetermined period and is reflected light from an obstacle, and an output signal based on this determination is input to the display device. , the presence of obstacles and the distance to the obstacles are displayed.

In particular, in the present invention, unlike the conventional method in which incident light is distributed to a plurality of light receiving elements using a single needle hole, the light is distributed to each of the plurality of light receiving elements,
Equipped with multiple incident light guide cylinders that individually introduce incident light, there is no need to set distances for distributing the light, making the device more compact. ), and can be preferably applied as an on-vehicle device.

Furthermore, in the present invention, unlike the conventional needle hole, the part for introducing the incident light to the light receiver is configured to individually guide the incident light incident at a set angle to each light receiver, and to introduce the incident light at a set angle other than the set angle. Since the structure is composed of cylindrical incident light guide cylinders that prevent the interference of incident light to each receiver, the considerable length of the inner wall surface of these cylinders acts as a barrier to the entry of light, and various types of light are prevented from entering. It is possible to restrict the light from entering the light receiver freely from multiple directions, and it is possible to prevent these lights and incident light reflected from obstacles from interfering with each other at the light receiver.

<<Example>> Hereinafter, an example of the present invention will be described with reference to the drawings.

1 and 2 show an obstacle detection device for a motor vehicle according to an embodiment of the present invention. In the figure, 1
is a sensor unit fixed to the rear end of the car body, 2 is a casing of sensor unit 1,
A support plate 3 is fixed in the vertical direction inside the casing 2, and an infrared lamp 4 that emits light toward the outside of the vehicle body is attached to the lower part of the support plate 3. Above, infrared photodiodes 5, 6, and 7 that receive incident light are arranged in parallel in the vertical direction with respect to the infrared lamp 4.
installed. Further, a cylindrical radiation opening 2a is formed in the lower part of the outer wall of the casing 2 to radiate infrared rays from the infrared lamp 4 to the rear of the vehicle within a horizontal plane H. Above this radiation opening 2a, each As the distance between each of the infrared photodiodes 5, 6, and 7 from the infrared lamp 4 increases, the angles formed with the respective radiation optical axes (indicated by horizontal plane H in the figure) of 0°, θ ₁ , θ ₂ ( However, θ ₂ > θ ₁
)
are sequentially set larger, and the set angles are 0°, θ ₁ , θ ₂
While guiding the incident light incident at the angle to each infrared photodiode 5, 6, 7 individually,
A plurality of incident light guide cylinders 2b, 2c, and 2d are formed to prevent interference of incident light other than θ ₁ and θ ₂ with respect to each infrared photodiode 5, 6, and 7.

FIG. 3 shows an electrical circuit diagram of the device of this embodiment,
In the figure, 1, 4, 5, 6, and 7 are the above-mentioned sensor unit, infrared lamp, and infrared photodiode, 8 is an oscillator that oscillates a signal at a predetermined frequency, for example, 45 Hz, and 9 is the oscillation frequency of the oscillator 8, which is described above. A drive circuit for blinking an infrared lamp 4, 1
0, 11, 12 are amplifiers for amplifying the output signals of the infrared photodiodes 5, 6, 7; 13;
14 and 15 are band pass filters (hereinafter referred to as BPF) that pass only the 45 Hz signal among the outputs of the amplifiers 10, 11, and 12; 16, 17, and 18;
are the outputs of BPF13, 14, 15 and the reference voltage 19
It is a comparator for comparing the amplifiers 10 and 1 with the amplifiers 10 and 1.
1, 12, BPF13, 14, 15 and comparator 1
6, 17, and 18 indicate that the period of the incident light received by the infrared photodiodes 5, 6, and 7 is the same as the predetermined frequency, and that the incident light is emitted from the infrared lamp 4 and hits the obstacle. Signal discrimination circuits 20a, 20b, 20c that discriminate infrared rays reflected by and output signals.
It consists of Reference numerals 21, 22, and 23 indicate display elements that light up in response to the outputs of the signal discrimination circuits 20a, 20b, and 20c, respectively; 26 indicates a display device; 24 indicates a battery; and 25 indicates when the transmission of the automobile is operated to the reverse position. The reverse switch that is turned on, Vcc, is the drive power supplied to each of the above circuits.

Next, the operation will be explained.

In this obstacle detection device, when the transmission of the automobile is operated to the reverse position, the reverse switch 25 is turned on and the drive power Vcc is supplied to the device. Then, the oscillator 8 first oscillates at a frequency of 45 Hz, the drive circuit 9 causes the infrared lamp 4 to blink at the above frequency, and the infrared lamp 4 emits infrared rays to the rear of the automobile through the radiation opening 2a of the casing 2. On the other hand, the infrared photodiodes 5, 6, and 7 receive light at different angles of 0°, θ ₁ , and θ 2 that are incident through the incident light guide cylinders 2b, 2c, and _2d of the casing 2, respectively, and , 6, and 7 flow in accordance with the amount of light, and the voltages across the photodiodes 5, 6, and 7 are amplified by amplifiers 10, 11, and 12, respectively, and then sent to comparators 16, 17, and 18. is input. Now, if there is no obstacle behind the car, the infrared rays emitted by the infrared lamp 4 do not return to the photodiodes 5, 6, and 7, and therefore enter the photodiodes 5, 6, and 7. Even if there is light, it is something other than the above-mentioned emitted light, such as sunlight or electric light, and the output signals of the photodiodes 5, 6, and 7 have the above-mentioned frequency of 45Hz.
It does not contain components with the same frequency as . accordingly
The output signals of BPF13, 14, 15 are reference voltage 1
9 or less, the outputs of the comparators 16, 17, and 18 become low, and the display elements 21, 22, and 23 do not light up. Especially for light other than emitted light, in this embodiment, the incident light guide cylinders 2b, 2c, and 2d
The incident light incident at set angles of 0°, θ ₁ , θ ₂ is individually guided to each infrared photodiode 5 , 6 , 7 , while the incident light at set angles other than 0°, θ ₁ , θ ₂ is The considerable length of the inner wall surface of the cylinders 2b, 2c, 2d acts as a barrier, and the photodiodes 5, 6, 7
Entry to the side will be prevented.

Furthermore, if there is an obstacle behind the vehicle, the infrared rays emitted by the infrared lamp 4 will hit the obstacle and be reflected and return toward the sensor unit 1 at the rear end of the vehicle. Now, when the distance between the vehicle and the obstacle is long, only the reflected infrared rays that are substantially parallel to the horizontal plane H reach the sensor unit 1. Therefore, in this case, only the photodiode 5 receives the infrared rays reflected by the obstacle, and the output of the photodiode 5 has a frequency
Since it contains many components of the same frequency as 45Hz,
The output of the BPF 13 becomes higher than the reference voltage 19, and the output of the comparator 16 becomes high.
As shown in the figure, only the display element 21 lights up.

In addition, when the distance between the car and the obstacle is medium, neither long nor short, the infrared rays reflected by the obstacle in the angle range of 0° to _θ1 reach the sensor unit 1, and the lower Since only the two photodiodes 5 and 6 receive the infrared rays from the obstacle, in this case the two display elements 21 and 22 light up as shown in FIG. 4.

Furthermore, if the distance between the car and the obstacle is close,
This time, the infrared rays in the angular range 0° to θ ₂ reach the sensor unit 1, and all the photodiodes 5, 6, 7
receives the infrared rays, so in this case, the fourth
As shown in the figure, all display elements 21, 22, 23
will light up, and as a result, the display elements 21,
By observing the lighting conditions of 22 and 23, the distance to the obstacle can be known.

In the device of this embodiment as described above, the three infrared photodiodes 5, 6, and 7 have different incident angles.
Since it receives light at 0°, θ ₁ , and θ ₂ and determines the distance to the obstacle and displays it, the distance to the obstacle can be easily known.

In particular, in this embodiment, unlike the conventional case in which incident light is distributed to a plurality of light receiving elements using a single needle hole, a plurality of infrared photodiodes 5,
A plurality of incident light guide cylinders 2b, 2c, and 2d that individually introduce incident light in correspondence to each of 6 and 7.
, there is no need to set a distance for distributing the light, the device can be made more compact, and the amount of protrusion from the vehicle body in the ranging direction (towards obstacles) can be reduced, making it suitable for use as an in-vehicle device. I can do it.

In this case, by utilizing the characteristics of the detection limit distance with respect to the incident angle to the infrared photodiode as shown in FIG. 5, and by providing more infrared photodiodes with different incident angles,
It is possible to detect the distance to an obstacle with even greater precision.

Another way to determine the distance to an obstacle is to scan a light emitting device in a vertical plane, but in this case the structure of the device becomes complicated and is not very desirable. Since scanning is not performed and the light emitting device etc. are fixed, the structure of the device is very simple.

In addition, in the above embodiment, infrared rays are emitted at a predetermined frequency and the reflected light from obstacles is identified, so malfunctions of the device due to sunlight, electric light, etc. can be prevented, and as a result, obstacles behind the vehicle can be detected. can be detected accurately.

In addition to being able to cut out light other than light reflected from obstacles by emitting light of a predetermined frequency in this way, in this embodiment, the part where the incident light enters the infrared photodiodes 5, 6, and 7 is Unlike the conventional needle hole, the setting angle is 0°, θ ₁ , θ ₂
The incident light is guided to each infrared photodiode 5, 6, and 7 individually, and the set angle is 0°, θ ₁ ,
Each infrared photodiode 5 for incident light other than θ ₂ ,
Since the structure is composed of cylindrical incident light guide cylinders 2b, 2c, and 2d that prevent interference with 6 and 7, the considerable length of the inner wall surface of these cylinders acts as a barrier to the entry of light, and various types of light are prevented. The infrared photodiodes 5, 6, 7 can be prevented from freely entering the infrared photodiodes 5, 6, 7 from multiple directions, and these lights and the incident light reflected from the obstacles can be prevented from entering the infrared photodiodes 5, 6, 7.
It is possible to prevent interference between parts. Therefore, distance measurement using this device is not appropriate in the environment in which a car is placed, that is, in an environment where various types of light exist, such as sunlight, stop lamps and cross lamps onboard equipment, surrounding street lights, lamps of other cars, etc. can do.

Note that in the above embodiment, three display elements 21, 2
The distance to the obstacle can be determined by the combination of the lighting states of the display elements 21, 22, 23, and 23, which are determined by logic operations on the outputs of the signal discrimination circuits 20a, 20b, 20c. 23 may directly display the distance to the obstacle.

Further, in the above embodiment, the signal discrimination circuits 20a, 20
b, 20c are configured using BPFs 13, 14, 15, but these signal discrimination circuits 20a, 20b, 2
0c may be configured using other means as long as it can determine whether the period of the incident light is the same as the predetermined period. Further, in the above embodiment, an obstacle behind the vehicle is detected, but the present invention may be adapted to detect an obstacle in front of the vehicle, which is a blind spot in a large vehicle such as a bus.

<<Effects of the Invention>> As described above, according to the automobile obstacle detection device according to the present invention, light that flashes at a predetermined period is emitted from the light emitter, and the distance between each light receiver from the light emitter is large. The incident light is individually received by a plurality of light receivers through a plurality of incident light guide cylinders whose angles with the emission optical axis from the light emitter are set to gradually increase, and each light receiver receives the incident light individually. The signal determining means determines that the received incident light has the same period as the predetermined period and is reflected light from an obstacle, and an output signal based on this determination is input to the display device to indicate the presence of the obstacle. Since the distance to the obstacle is displayed, it is possible to appropriately detect the obstacle and determine the distance to the obstacle.

In particular, in the present invention, unlike the conventional method in which incident light is distributed to a plurality of light receiving elements using a single needle hole, the light is distributed to each of the plurality of light receiving elements,
Since it is equipped with multiple incident light guide tubes that individually introduce incident light, there is no need to set distances for distributing the light, and the device can be made more compact. Since the amount of protrusion in the object direction can be reduced, it can be preferably applied as an in-vehicle device.

Furthermore, in the present invention, unlike the conventional needle hole, the part for introducing the incident light to the light receiver is configured to individually guide the incident light incident at a set angle to each light receiver, and to introduce the incident light at a set angle other than the set angle. Since the structure is composed of cylindrical incident light guide cylinders that prevent the interference of incident light to each receiver, the considerable length of the inner wall surface of these cylinders acts as a barrier to the entry of light, and various types of light are prevented from entering. It is possible to restrict the light from entering the light receiver freely from multiple directions, and it is possible to prevent these lights and the incident light reflected from obstacles from interfering with the light receiver, and therefore to properly It is possible to ensure excellent ranging performance.

[Brief explanation of drawings]

FIG. 1 is a partial side view of an automobile having an obstacle detection device according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional side view of the device, FIG. 3 is an electric circuit diagram of the device, and FIG. The figure shows the relationship between the distance to an obstacle and the blinking state of the display element of the device, and FIG. 5 shows the change in the detection limit distance with respect to the angle of incidence on the infrared photodiode. 2b, 2c, 2d...incident light guide cylinder, 4...
...Infrared lamp (emitter), 5, 6, 7...Infrared photodiode (receiver), 9...Drive circuit,
20a, 20b, 20c...signal discrimination circuit, 26
...Display device.

Claims (1)

[Scope of Claims] 1. A light emitter that emits light toward the outside of the vehicle body; a drive circuit that blinks the light emitter at a predetermined period; and a drive circuit that is arranged in parallel with the light emitter and emits incident light. As a plurality of light receivers receive light, and as the separation distance of each light receiver from the light emitter increases, the angle formed by each of the light receivers with the light emitting axis is set to be larger in turn, and the incident light is incident at the set angle. a plurality of incident light guide cylinders that individually guide light to each light receiver while preventing interference of incident light at angles other than the set angle with respect to each light receiver; The present invention is characterized by comprising a plurality of signal discrimination circuits that output signals after determining whether the signals are the same as the period, and a display device that displays the distance to an obstacle based on the output signals from these signal discrimination circuits. Obstacle detection device for automobiles.