JP7254380B2 - Extraction device - Google Patents

Description

The present invention relates to an emission device and the like for emitting light and the like.

2. Description of the Related Art Conventionally, an emission device that is mounted on an automobile and emits electromagnetic waves is known. For example, the code-modulation type radar ranging apparatus described in Patent Document 1 emits code-modulated or spectrum-spread electromagnetic waves. A code-modulation type radar rangefinder receives electromagnetic waves reflected by a range-finding object such as an automobile with a receiver, and calculates the distance to the range-finding object.

JP-A-11-83991

As the electromagnetic waves used when detecting the distance to the range-finding object, for example, light such as infrared rays is used. At the left and right ends and outside of the driving lane of automobiles (hereinafter simply referred to as "outside the driving lane"), for example, there are reflectors installed on the center line of the road, the side strip, and the curb of the sidewalk. exist. For this reason, the light emitted by the above-described emitting device is reflected, in particular, by reflectors provided outside the driving lane. Therefore, when the emission device detects an automobile, it may erroneously detect the light reflected by the reflector provided outside the driving lane, thereby deteriorating the accuracy of detecting the automobile.

An object of the present invention is, for example, to provide an emission device or the like that improves vehicle detection accuracy.

(1) The emission device is mounted on a first vehicle, emits light in an emission direction that is in front of or behind the first vehicle, and detects a second vehicle positioned in the emission direction, An emitting portion having directivity characteristics for concentrating and emitting the light in an emitting area, which is an area from which the light is emitted, is provided, and the emitting area is on the left and right of the first part which is a part corresponding to a distant position which is a distant position The width in the direction is smaller than the width in the left-right direction of the second portion, which is a portion below the first portion.

When the emission direction is viewed from the emission device arranged in the first vehicle traveling in a straight lane, the farther the second vehicle is from the emission device, the higher and smaller the second vehicle. In addition, the farther the travel lane is from the emission device, the higher the travel lane and the smaller the width in the left-right direction. In the present invention, in the emission area, the width in the horizontal direction of the first portion corresponding to the distant position is smaller than the width in the horizontal direction of the second portion below the first portion. The first portion is a portion for detecting the second vehicle when the second vehicle is at a distant position. The second part is a part for detecting the second vehicle when the second vehicle is in a close position. The emission area is set according to the size of the second vehicle and the width of the lane in the left-right direction. Therefore, when the emission area is aligned with the straight traffic lane, the amount of light emitted from the emission area to the reflector outside the traffic lane is reduced. Therefore, when the light emitted from the emission device is detected to detect the second vehicle, the possibility of erroneously detecting the reflector on the outside of the travel lane is reduced. Therefore, the detection accuracy of the second vehicle is improved. In addition, it is preferable that the first portion and the second portion are separated from each other in the emission area. Also, the emission area is preferably continuous from the first part to the second part.

In addition, for example, the emission section includes a generation section that generates light, and an emission lens section that refracts the light generated by the generation section and emits the light to the emission region. In this case, the emission device can concentrate the light on the emission area by refracting the light with the emission lens section. Therefore, it is not necessary to make the shape of the generator into a special shape for emitting light to the emission area. Therefore, the cost of the generator can be reduced. Note that the generator may be an LED (Light Emitting Diode). Moreover, it is preferable that the generation unit is particularly an LD (Laser Diode). In this case, even when the emitting device is mounted inside the windshield, the light can be transmitted through the windshield and reach the second vehicle which is farther away.

Further, the emission area is preferably a quadrangle, and at least one of a pair of sides opposed to each other in the left-right direction is inclined inwardly of the emission area as it goes upward. In this case, the brightness of the light irradiated to the reflectors on at least one side in the left-right direction of the driving lane tends to decrease. Therefore, when the light emitted from the emission device is detected to detect the second vehicle, the possibility of erroneously detecting the reflector on the outside of the travel lane is reduced. Therefore, the detection accuracy of the second vehicle is improved.

(2) In the emission device, the emission region preferably has a trapezoidal shape projected onto a plane normal to the emission direction, with the first portion being the upper portion and the second portion being the lower portion. . When the driving lane is viewed from the emission device arranged in the first vehicle, the driving lane is trapezoidal. For this reason, the reflector provided on the second vehicle often falls within a trapezoidal range in which light is concentrated. Therefore, compared to the case where the emission area has a shape different from a trapezoid, the brightness of the light irradiated to the reflector on the outside of the driving lane is likely to become smaller, and the light irradiated to the reflector of the second vehicle is more likely to be reduced. Brightness tends to increase. Therefore, when detecting the second vehicle by detecting the light emitted from the emission device, the second vehicle can be detected more reliably.

In addition, the emission area may be triangular or quadrangular, and both of a pair of sides opposed to each other in the left-right direction may be inclined toward the inside of the emission area as they go upward. In this case, the brightness of the light illuminating both the left and right reflectors of the driving lane tends to decrease. Therefore, when the light emitted from the emission device is detected to detect the second vehicle, the possibility of erroneously detecting the reflector on the outside of the travel lane is reduced. Therefore, the detection accuracy of the second vehicle is improved.

By the way, the exit area may be a triangular shape that can eliminate the influence of the reflector on the outside of the traffic lane. However, since the upper vertex portion of the triangle is a point, if the first vehicle deviates to the left or right from the center of the driving lane, there is a high possibility that the second vehicle cannot be detected. Therefore, the upper side is provided and the emission area is trapezoidal so that even if the first vehicle deviates to the left or right from the center of the driving lane, it can be detected more reliably. The length of the upper side of the trapezoidal emission area may be, for example, the length corresponding to the travel lane at the position of the detection target distance of the second vehicle.

Further, for example, the emission device may include a mounting portion that can be mounted so that the emission direction is horizontal in the first vehicle. Further, it is preferable that each of the oblique sides positioned on the left and right of the trapezoidal emission area and the lines on the left and right of the driving lane viewed from the emission device are nearly parallel. For example, if the angle formed by each of the oblique sides located on the left and right of the trapezoidal emission area and the base is 45 degrees, the angle formed by the left and right lines of the driving lane viewed from the emission device and the left and right direction is 45 degrees. should be set so that In this case, the brightness of the light radiated on the reflector on the outside of the traveling lane tends to decrease, and the brightness of the light radiated on the reflector of the second vehicle tends to increase. Therefore, when detecting the second vehicle by detecting the light emitted from the emission device, the second vehicle can be detected more reliably. It is preferable that the left and right oblique sides of the trapezoidal emission area are located slightly outside the left and right lines of the traffic lane as viewed from the emission device. In this case, it is preferable that the light is less likely to irradiate the reflectors outside the left and right lines of the driving lane as seen from the emission device. Further, it is preferable that the left and right oblique sides of the trapezoidal emission area are located at the same positions as the left and right lines of the traffic lane as seen from the emission device. More preferably, each of the left and right oblique sides of the trapezoidal emission area is inside the left and right lines of the traffic lane viewed from the emission device. In addition, it is preferable that the emission area is adapted to a road having a relatively wide width in the left-right direction, such as a highway. Vehicles tend to move faster on roads that are wide in the left-right direction, so the inter-vehicle distance to the second vehicle is important in terms of driving safety. Driving safety is improved by using the emission device on roads where the speed tends to be high.

(3) In the emission area of the emission device, the brightness of the light at the first portion may be higher than the brightness of the light at the second portion. In this case, the light can reach farther than when the brightness of the light at the first portion is equal to or less than the brightness of the light at the second portion. When the second vehicle is detected by detecting the light emitted from the emission device, because the brightness of the first part for detecting the second vehicle at a distant position is high and the light can reach farther. , the second vehicle, which is farther away, can be detected.

(4) The emitting device includes a light receiving section for receiving reflected light reflected by the light emitted by the emitting section, and the upper portion of the light receiving section is positioned above the area on which the reflected light of the emitting area is incident. It is preferable to have a shape that follows. In this case, compared to the case where the light receiving part does not have a shape along the upper part of the light emitting area, the area usable for receiving the light emitted to the light emitting area can be increased among the light receiving areas of the light receiving part. can be done. Therefore, a wider range of light can be received. Therefore, the emission device can further improve the detection accuracy of the second vehicle.

For example, one photodiode is used as the light receiving unit. When one photodiode is used, if the area available for receiving the light emitted to the emission region is small in the light receiving area of the light receiving section, the sensitivity is lowered. However, as in the present invention, the light-receiving part has a shape along the upper part of the region where the reflected light is incident in the light-emitting region, and by increasing the area that can be used for receiving the light emitted from the light-emitting region, Even with a single photodiode, the sensitivity is improved. Therefore, the emission device can further improve the detection accuracy of the second vehicle.

(5) In the emission device, the emission region has a trapezoidal shape projected onto a plane normal to the emission direction, with the first portion being an upper portion and the second portion being a lower portion, and The light-receiving part is preferably rectangular, and one corner is positioned on the upper side. When one corner of the quadrangular light-receiving part is positioned on the upper side, both of the two sides forming the upper corner are along the upper part of the area where the reflected light of the trapezoidal emission area is incident. For this reason, compared to the case where the light receiving section is arranged so that the upper side of the square is parallel to the horizontal direction, the light receiving area of the light receiving section is used for receiving the reflected light of the light emitted to the output area. possible area can be increased. Therefore, a wider range of light can be received. Therefore, the emission device can further improve the detection accuracy of the second vehicle while using the rectangular light receiving section.

(6) The emission device includes a light receiving lens that guides the reflected light to the light receiving section, the light receiving lens has a plurality of optical central axes, and the optical central axes are positioned inside the light receiving section. do it. In order to widen the light-receiving area of the light-receiving section, it is conceivable to increase the area of the light-receiving section or shorten the focal length of the light-receiving lens. When the area of the light receiving portion is increased, the electric capacity of the light receiving portion increases, and the waveform of the light received is likely to be dull. Therefore, there is a possibility that the detection accuracy of the second vehicle will be lowered. Therefore, there is a limit to enlarging the light receiving portion. Further, when the focal length of the light receiving lens is shortened, the area of the light receiving lens becomes small, and the light collecting ability of the light receiving lens deteriorates. Therefore, there is a possibility that the detection accuracy of the second vehicle will be lowered. Therefore, there is a limit to shortening the focal length of the light receiving lens.

In the present invention, the light receiving lens has multiple optical central axes. Therefore, the light-receiving area in which the light-receiving section can receive light becomes larger than in the case of a lens having one optical central axis. That is, the light receiving area can be increased without increasing the area of the light receiving section. Since the light-receiving area becomes large, it is possible to detect the second vehicle located in a wider range, thereby improving the detection accuracy of the second vehicle.

In addition, compared to the case of having one optical central axis, it is possible to increase the light receiving area while suppressing the decrease in the light collecting ability due to the size of the light receiving lens. Since the light-receiving area becomes large, it is possible to detect the second vehicle located in a wider range, thereby improving the detection accuracy of the second vehicle.

(7) In the emission device, the light receiving lens includes a main lens and an auxiliary lens, the auxiliary lens is arranged below the main lens, and the optical center axis of the auxiliary lens is aligned with the It is preferably located below the optical central axis of the main lens. In this case, light from the lower side can be guided to the light receiving section as compared with the case where only the main lens is provided. Therefore, compared to the case where only the main lens is provided, the area where the light receiving section can receive the light from the lower side becomes larger.

Here, when viewed from the emission device, the longer the distance from the emission device to the second vehicle, the higher the reflector of the second vehicle is located, and the shorter the distance from the emission device to the second vehicle, the higher the second vehicle. The reflectors of the two vehicles are located on the lower side. In the present invention, the region capable of receiving light in the vertical direction is increased by increasing the region capable of receiving light from the lower side. Therefore, compared to the case where only the main lens is provided, the range of distances over which the reflector of the second vehicle can be detected becomes larger. again. The lens does not become too large as compared with the case of enlarging the light receiving range with one lens. Therefore, it is possible to reduce the possibility that the emission device is enlarged. Also, the auxiliary lens is preferably smaller than the main lens.

(8) In the emission device, two auxiliary lenses are provided side by side in the left-right direction, and the optical center axis of one of the auxiliary lenses is located in the left-right direction from the optical center axis of the main lens. It is preferable that the optical central axis of the other auxiliary lens is positioned on the other side in the horizontal direction from the optical central axis of the main lens. In this case, two auxiliary lenses are arranged side by side in the horizontal direction below the main lens. Therefore, compared with the case where one auxiliary lens is provided, the light-receiving range of the portion below the light-receiving area becomes larger in the left-right direction. In the present invention, since the second portion is positioned below the first portion, the width in the horizontal direction of the lower portion of the emission area tends to be larger than the width in the horizontal direction of the upper portion. However, since the two auxiliary lenses are provided, the light receiving range can be set according to the width of the lower portion of the emission area. Therefore, the reflected light of the light emitted to the emission area can be received more reliably, and the detection accuracy of the second vehicle is further improved. Moreover, it is preferable that one of the auxiliary lenses has a shape symmetrical to the other auxiliary lens. Also, the optical central axis of one auxiliary lens and the optical central axis of the other auxiliary lens may be positioned symmetrically with respect to the optical central axis of the main lens.

Note that the main lens and the auxiliary lens are preferably formed integrally. In this case, compared to the case where the main lens and the auxiliary lens are formed separately, light is less likely to be bent or reflected at the boundary line between the main lens and the auxiliary lens. Therefore, compared to the case where the main lens and the auxiliary lens are formed separately, the light can be guided more reliably to the light receiving section. Therefore, the detection accuracy of the second vehicle is improved.

(9) In the emission device, the main lens may be circular, and the auxiliary lens may have the same shape as a portion of the main lens adjacent to the auxiliary lens. In this case, the reflected light is received by the light receiving section while the focal lengths of the main lens and the auxiliary lens are the same. Therefore, the detection accuracy of the second vehicle is improved compared to the case where the focal lengths of the main lens and the auxiliary lens are different from each other.

(10) The emission device includes a housing that supports the light receiving section and the light receiving lens, and a reflecting section within the housing that reflects part of the light incident from the light receiving lens and guides it to the light receiving section. and In this case, the brightness of the reflected light reaching the light receiving section is higher than when the reflecting section is not provided. Therefore, the emission device can more reliably detect the second vehicle.

(11) The emitting device includes a non-reflecting section provided below the light receiving section in the housing and making it more difficult to guide the light to the light receiving section than the reflecting section. It is preferable that the light that has reached the upper side of the light receiving section is reflected and guided to the light receiving section. Part of the light from the periphery of the second portion of the emission area reaches above the light receiving section via the main lens or the auxiliary lens. The light reaching above the light receiving section is guided to the light receiving section by the reflecting section. Therefore, the emission device can more reliably detect the nearby second vehicle. On the other hand, part of the light from the periphery of the first portion of the emission area reaches below the light receiving section. Since the low-reflection portion is provided below the light-receiving portion, light is less likely to be reflected. The traffic lane at the position where the light of the first part of the emission device is emitted is narrow in the left-right direction, and the light is easily irradiated to the reflectors outside the traffic lane. Therefore, it is possible to further reduce the possibility of erroneous detection of the reflector.

(12) In the emitting device, it is preferable that the light-receiving section is square, one corner is positioned on the upper side, and the reflecting section extends from each of a pair of sides forming the one corner. In this case, the light reflected by the reflecting section reaches the light receiving section more reliably. Therefore, the detection accuracy of the second vehicle is improved.

(13) In the emission device, the emission section and the light receiving lens may be arranged next to each other. In this case, the emitting area and the area received by the light receiving section tend to overlap, compared to the case where the emitting section and the light receiving lens are separated. Therefore, the detection accuracy of the second vehicle is improved.

(14) The emission device includes emission control means for causing the emission section to emit the light, and equivalent time sampling means for sampling a signal containing the light received by the light receiving section at sampling intervals according to an equivalent time sampling method. and, preferably, the emission control means changes the brightness of the emitted light according to the time from the emission of the light to the sampling by the equivalent time sampling means. For example, the closer the distance from the emission device to the second vehicle, the higher the brightness of the reflected light received by the light receiving unit. Further, for example, when the distance from the emission device to the second vehicle is within a predetermined range due to the characteristics of the lens on the light-emitting side or the characteristics of the lens on the light-receiving side, the reflected light is received by the light-receiving unit. brightness may increase. If the brightness of the reflected light received by the light-receiving unit increases, the amplifier circuit may saturate when the voltage based on the reflected light received by the light-receiving unit is amplified by an amplifier circuit or the like. For this reason, after the amplifier circuit is saturated, it takes time to return to a normal state, and there is a possibility that the detection accuracy of the second vehicle is lowered.

In the equivalent time sampling method, the time from when the light is emitted from the light emitting unit until it is sampled changes according to the distance to the second vehicle. In the present invention, the brightness of the emitted light changes according to the time from when the light is emitted from the light emitting section until it is sampled. Therefore, for example, in a range where the amplifier circuit may be saturated, the luminance of light emitted from the light emitting section can be reduced. Therefore, the possibility of saturating the amplifier circuit is reduced. Moreover, even when saturated, the recovery time from saturation can be shortened. Therefore, the detection accuracy of the second vehicle is improved. In addition, the power consumption is reduced compared to the case where the brightness of the light does not change and the light is always emitted with the brightness for detecting the distant second vehicle. Also, in the equivalent time sampling method, since there is a time during which light is not emitted, strong light is prevented from being continuously output.

By the way, since the frequency of light pulses is high (for example, the unit of pulse frequency is nanosec), a very high sampling frequency is required, which may cause problems such as high component costs. Therefore, in the present invention, sampling is performed by the equivalent sampling method.

In addition, the emitting device emits the light with the intensity necessary for the light to reach the farthest position in the range of the distance for detecting the second vehicle. For this reason, the intensity of light may increase. Further, for example, when the light emitting device is installed in the passenger compartment, the light needs to be transmitted through a windshield or the like, which may increase the intensity of the light. When continuously emitting light with high intensity, it is necessary to consider the effects on the human eye. Therefore, instead of continuously emitting light, pulsed light is emitted and a period of time during which no light is emitted is provided, thereby reducing the average value of the intensity of light. As a result, the influence on the human eyes can be reduced. For example, the interval between pulses may be twice as large as the pulse width. More preferably, the interval between pulses should be 1000 times or more larger than the pulse width.

(15) In the emission device, the emission control means causes the emission unit to emit the light having a lower brightness as the time from emission of the light to sampling by the equivalent time sampling means is shorter. good. The closer the distance from the emission device to the second vehicle, the higher the brightness of the light received by the light receiving unit. In the present invention, the shorter the time from the emission of the light to the sampling by the equivalent time sampling means, the lower the luminance of the light emitted from the light emitting section. Therefore, compared to the case where the brightness of light is not adjusted, the brightness of light received when the distance from the emission device to the second vehicle is short can be reduced. Therefore, it is possible to reduce the possibility of saturation of the amplifier circuit, and improve the detection accuracy of the second vehicle.

(16) In the emission device, the emission control means includes a power circuit that supplies voltage to the emission section, and the power circuit is connected to a DC/DC converter and an output side of the DC/DC converter. a first resistor and a second resistor connected to ground for inputting a divided voltage to the reference input terminal of the DC/DC converter and used to set the output voltage of the DC/DC converter A dividing resistor, an integration circuit to which a pulse signal is input, and a third resistor provided between an output side of the integration circuit and the reference input terminal, and a pulse signal is input to the integration circuit. , the voltage applied to the reference input terminal fluctuates, and the output voltage of the DC/DC converter fluctuates. It is preferable that the light having a low brightness is emitted to the emitting section. In this case, by varying the voltage input to the reference input terminal according to the output from the integrating circuit, the shorter the time from the emission of the light to the sampling by the equivalent time sampling means, the lower the luminance of the emitted light. It is possible to realize the function of emitting to the part.

(17) In the emission device, the equivalent time sampling means includes first acquisition means for acquiring a signal received by the light receiving section before the light is emitted by the emission section; After the light is emitted, at the sampling interval by the equivalent time sampling method, second acquisition means for acquiring the signal received by the light receiving unit; the signal acquired by the first acquisition means; It is preferable to provide a third acquisition means for acquiring a signal based on a difference from the signal acquired by the second acquisition means, and an encoding means for encoding the signal acquired by the third acquisition means.

A signal acquired by the light receiving unit may contain various types of noise such as circuit noise, external electrical noise, and external optical noise. Since the signal level of the reflected light is very small, if the S/N ratio is lowered due to the influence of noise, it becomes a factor of sensitivity deterioration, and the detectable distance of the second vehicle may be shortened. As a means of improving the S/N ratio, a band-pass filter (BPF) may be used. waveform may be distorted. For this reason, it becomes a factor of sensitivity deterioration, and the detectable distance of the second vehicle may be shortened.

In the present invention, a signal based on a difference between a signal obtained before light is emitted and a signal obtained at sampling intervals according to the equivalent sampling method is obtained and encoded. The signal acquired by the first acquisition means is a signal that does not contain reflected light, and is a signal of noise. The signal acquired by the second acquiring means is a signal containing reflected light and noise. A signal based on the difference between a signal containing reflected light and noise and a signal of noise is acquired and encoded, so that the S/N ratio can be improved. Also, since no BPF is used, the waveform of the reflected light is less likely to collapse. Therefore, the possibility of sensitivity deterioration is reduced, and the distance over which the second vehicle can be detected is increased.

(18) The emitting device includes a low-pass filter that passes a band having a frequency lower than that of the light in the signal received by the light-receiving unit, and the first acquisition means receives the signal after passing through the low-pass filter. should be obtained. When a signal containing noise in the same frequency band as the light emitted by the light emitting unit is acquired by the first acquiring means, the noise fluctuating in the same frequency band as the light is superimposed on the light signal by the third acquiring means. There is a possibility that it will be done. In the present invention, noise in the same frequency band as the light is reduced by the low-pass filter and acquired by the first acquiring means. Therefore, the possibility that noise fluctuating in the same frequency band as that of light is superimposed on the light signal by the third acquisition means is reduced. Therefore, the possibility of sensitivity deterioration is reduced, and the distance over which the second vehicle can be detected is increased.

(19) The emitting device may include distance obtaining means for obtaining the distance to the object based on the signal received from the light receiving section. In this case, the emission device can obtain the inter-vehicle distance to the second vehicle.

It is the figure which looked ahead from the inside of the vehicle of the own vehicle. 2 is a block diagram showing an electrical configuration of the laser inter-vehicle rangefinder 1; FIG. 3 is a perspective view of an optical unit 7; FIG. 4 is a plan view of the optical unit 7; FIG. 4 is a diagram showing the shape of an emission region 40 when viewed forward from the laser inter-vehicle range finder 1. FIG. FIG. 6 is a diagram when another vehicle 3 is at a position closer than the position shown in FIG. 5; 4 is a diagram showing luminance and the like of an emission region 40; FIG. FIG. 4 is a front view of the optical unit 7 with the light projecting lens 711 and the light receiving lens 76 removed. 4 is a front view of the optical unit 7; FIG. 4 is a longitudinal sectional view of a light receiving unit 74 in the optical unit 7; FIG. 4 is a diagram for explaining a method of measuring a distance between another vehicle 3 and a laser inter-vehicle rangefinder 1. FIG. 4 is another diagram for explaining the method of measuring the distance between the other vehicle 3 and the laser inter-vehicle rangefinder 1. FIG. 3 is a block diagram showing an emission control circuit 60; FIG. 3 is a block diagram showing a light receiving control circuit 80; FIG. 15 is a diagram showing an example of light reception control by a light reception control circuit 80 shown in FIG. 14; FIG. 3 is a block diagram of a pulse generation circuit 85; FIG. It is a figure which shows the radiation|emission area|region 41 which concerns on a modification. 1 is an external view of a laser inter-vehicle range finder 1; FIG. FIG. 10 is a diagram showing a table 961; FIG. FIG. 13 is a diagram showing a table 962; FIG. FIG. 12 is a diagram showing a table 963; FIG. FIG. 13 is a diagram showing a table 964; FIG.

A laser inter-vehicle distance finder 1, which is an example of the present invention, will be described below with reference to the drawings. In the following description, the upper side, lower side, right side, left side, front side, and rear side of the paper surface of FIG. described as.

An overview of the laser inter-vehicle range finder 1 will be described with reference to FIGS. 1 and 2. FIG. The laser inter-vehicle rangefinder 1 is mounted on the own vehicle 2 and emits light in the emission direction, which is the front or rear of the own vehicle 2 . In this embodiment, the emission direction of light is the front direction of the laser inter-vehicle range finder 1 . The laser inter-vehicle rangefinder 1 receives reflected light from a reflector 31 (see FIGS. 5 and 6) of another vehicle 3 (see FIGS. 5 and 6) positioned in the emission direction, and measures the distance from the other vehicle 3 and , and the laser range finder 1. In this embodiment, the reflecting plate 31 of the other vehicle 3 is provided at a lower portion of the rear surface 32 of the other vehicle 3 so as to be spaced apart in the left-right direction (see FIGS. 5 and 6).

FIG. 1 shows a front view from inside the own vehicle 2 . In FIG. 1, the rearview mirror 29 is indicated by dotted lines. The laser inter-vehicle rangefinder 1 is arranged in front of the rearview mirror 29 .

As shown in FIG. 1 , the laser inter-vehicle distance finder 1 includes a body portion 11 and a mounting portion 19 . The mounting portion 19 includes an attachment portion 191 and a support portion 192 . The body portion 11 has a substantially rectangular parallelepiped shape. A strut portion 192 extends upward from the upper portion of the main body portion 11 . The attachment portion 191 is provided at the upper end of the support portion 192 . The mounting portion 191 has a substantially rectangular plate shape, and is attached to the front glass 91 at the center and upper portion thereof in the left-right direction using, for example, a double-sided adhesive tape or a suction cup. As a result, the laser distance finder 1 is attached to the windshield 91 . The mounting portion 19 supports the body portion 11 so that the angle can be changed. Therefore, the laser inter-vehicle range finder 1 can be mounted on the vehicle 2 so that the emission direction is horizontal in the vehicle 2 . The laser inter-vehicle range finder 1 may be installed at another installation position, for example, on the rear surface of the rearview mirror 29 by providing a mounting portion attached to the rear surface of the rearview mirror 29. should be attached to the In this way, it is possible to suppress the relative distance between the laser inter-vehicle rangefinder 1 and the windshield 91 from changing due to the vibration of the vehicle, and the measurement accuracy of the laser inter-vehicle rangefinder 1 is higher than that at other installation positions. can be enhanced.

As shown in FIG. 2, the main body 11 of the laser inter-vehicle rangefinder 1 includes a CPU 101, a light emitting circuit 102, a light receiving circuit 103, an audio circuit 104, a speaker 105, a ROM 106, a RAM 107, and an optical unit 7. The optical unit 7 includes an emission unit 71 and a light reception unit 74 . The emission unit 71 has an LD (Laser Diode) 72 . The emission unit 71 can emit light. The light receiving unit 74 has a photodiode 75 . The light receiving unit 74 can receive the light emitted from the emitting unit 71 and reflected by the reflector 31 or the like. Light emitted and received by the optical unit 7 passes through a transparent plate (not shown) provided on the front surface of the main body 11 and the windshield 91 .

The CPU 101 is electrically connected to the light emitting circuit 102 , the light receiving circuit 103 , the audio circuit 104 , the ROM 106 and the RAM 107 . ROM 106 stores a program or the like for CPU 101 to control laser inter-vehicle rangefinder 1 . RAM 107 temporarily stores various data.

The light emitting circuit 102 is electrically connected to the LD72. The CPU 101 controls lighting and extinguishing of the LD 72 via the light emitting circuit 102 . The light receiving circuit 103 is electrically connected to the photodiode 75 . The light receiving circuit 103 transmits a signal based on the light received by the photodiode 75 to the CPU 101 . The CPU 101 measures the distance between the other vehicle 3 and the laser inter-vehicle rangefinder 1 based on the transmitted signal.

Audio circuit 104 is electrically connected to speaker 105 . The CPU 101 controls the audio circuit 104 to output audio from the speaker 105 . For example, the CPU 101 outputs sound from the speaker 105 when the distance between the other vehicle 3 and the laser inter-vehicle rangefinder 1 becomes equal to or less than a predetermined distance. As a result, the CPU 101 notifies the driver of the own vehicle 2 that the distance between the other vehicle 3 and the laser inter-vehicle rangefinder 1 has become equal to or less than a predetermined distance. Further, for example, the CPU 101 controls the speaker 105 when the distance between the laser range finder 1 and the other vehicle 3 becomes shorter than a predetermined distance (for example, 10 m) within a predetermined time (for example, 0.3 seconds). output audio from Thereby, the CPU 101 notifies the driver of the own vehicle 2 that the other vehicle 3 is approaching.

A schematic configuration of the optical unit 7 will be described with reference to FIGS. 3 and 4. FIG. As shown in FIGS. 3 and 4, in the optical unit 7, an emission unit 71 and a light receiving unit 74 are integrally formed. The emitting unit 71 and the receiving unit 74 are adjacent to each other. Therefore, the light receiving lens 76 provided on the front surface of the light receiving unit 74 is adjacent to the output unit 71 . The light receiving unit 74 is provided on the right side of the emitting unit 71 .

The emitting unit 71 and the receiving unit 74 are box-shaped. The light receiving unit 74 protrudes forward from the emitting unit 71 . Moreover, it protrudes upward from the light receiving unit 74 and the output unit 71 .

The emission region 40, which is the region from which the emission unit 71 emits light, will be described with reference to FIGS. 5 to 7. FIG. The emission unit 71 has a directional characteristic for concentrating and emitting light to the emission region 40 . The shape of the output region 40 shown in FIGS. 5 to 7 is a trapezoidal shape projected onto a plane normal to the output direction.

The emission unit 71 includes an LD 72 (see FIGS. 2 and 8) and a projection lens 711 (see FIG. 3). The emission unit 71 can concentrate the light on the emission region 40 by refracting the light generated by the LD 72 with the projection lens 711 . That is, the emission unit 71 of this embodiment has a trapezoidal directional characteristic due to the projection lens 711 .

In the following description, the lane in which the vehicle 2 is traveling is called a travel lane 50. FIG. As shown in FIG. 5, when viewing the emission direction from the laser inter-vehicle range finder 1 arranged in the own vehicle 2, the linear travel lane 50 becomes narrower in the left-right direction as it goes up. The right line 501 that defines the driving lane 50 inclines to the left as it goes upward, and the left line 502 inclines to the right as it goes upward. An upper tip 503 of the travel lane 50 is a plane parallel to the left-right direction. Thus, the traffic lane 50 has a substantially trapezoidal shape. Therefore, when the other vehicle 3 is at a distant position, the other vehicle 3 is positioned on the upper side (see FIG. 5) and has a smaller width in the left-right direction. When the other vehicle 3 is closer than the distant position, the other vehicle 3 is positioned on the lower side and has a greater width in the left-right direction (see FIG. 6).

The reflector plate 95 is arranged outside in the left-right direction of the driving lane 50 . In addition, the left-right direction outside of the traffic lane 50 includes the left-right direction end portion and the outside of the traffic lane 50 . Left and right ends of the driving lane 50 include lines 501 and 502 . In this embodiment, as an example, reflectors 95 are arranged on the lines 501 and 502 . Note that the reflector 95 may be arranged on the right side of the line 501 and the left side of the line 502 in the travel lane 50 . For example, the reflector 95 may be placed on the curb of a sidewalk.

A portion corresponding to a distant position in the emission area 40 is referred to as a first portion 401 . In this embodiment, the first portion 401 is an upper portion of the emission area 40 and is a portion for detecting the other vehicle 3 when the other vehicle 3 is at a distant position. Also, in the emission area 40 , a portion below the first portion 401 is referred to as a second portion 402 . The second part 402 is a part for detecting the other vehicle 3 when the other vehicle 3 is in a close position. The first portion 401 has a smaller width in the horizontal direction than the second portion 402 . In this embodiment, the second portion 402 is the lower portion of the emission area 40 .

In the emission area 40, the width in the left-right direction of the first portion 401 for detecting the other vehicle 3 at a distant position is larger than the width in the left-right direction of the second portion 402 for detecting the other vehicle 3 closer than the far position. small. The second portion 402 is positioned below the first portion 401 . In this way, the emission area 40 is set according to the size of the other vehicle 3 and the width of the lane 50 in the left-right direction. Therefore, when the emission area 40 is aligned with the straight traffic lane 50, the amount of light emitted from the emission area 40 to the reflecting plate 95 outside the traffic lane 50 is reduced. Therefore, when the other vehicle 3 is detected by detecting the light emitted from the laser inter-vehicle rangefinder 1, the possibility of erroneously detecting the reflecting plate 95 on the laterally outer side of the driving lane 50 is reduced. Therefore, the detection accuracy of the other vehicle 3 is improved.

Furthermore, in the present embodiment, the output region 40 has a trapezoidal shape projected onto a plane normal to the output direction, with the first portion 401 being the upper portion and the second portion 402 being the lower portion. The right oblique side 403 in the emission area 40 inclines leftward as it goes upward, and the left oblique side 404 inclines rightward as it goes upward. The hypotenuse 403 is along the line 501 on the right side of the traffic lane 50 and the hypotenuse 404 is along the line 502 on the left side of the traffic lane 50 .

In FIG. 7, the magnitude of luminance within the emission region 40 is indicated by color densities. In the emission area 40 , the brightness of the light in the first portion 401 is higher than the brightness of the light in the second portion 402 . In this embodiment, the brightness gradually increases from the second portion 402 toward the first portion 401 .

When the driving lane 50 is viewed from the laser inter-vehicle rangefinder 1 arranged in the own vehicle 2, the driving lane 50 has a trapezoidal shape. Therefore, as shown in FIGS. 5 and 6, the reflector 31 provided on the other vehicle 3 often falls within a trapezoidal range where light concentrates. Therefore, compared to the case where the emission region 40 has a shape different from a trapezoid, the brightness of the light irradiated to the reflector 95 outside the driving lane 50 is likely to be reduced, and the reflector 31 of the other vehicle 3 is irradiated. The brightness of the emitted light tends to increase. Therefore, when the other vehicle 3 is detected by detecting the light emitted from the laser inter-vehicle rangefinder 1, the other vehicle 3 can be detected more reliably. In addition, for example, since light is less likely to hit a reflector placed in an unnecessary area such as a roadside strip, erroneous detection of the reflector can be prevented, and the detection distance of other vehicles 3 can be increased. can be done.

Further, as shown in FIG. 7, in the emission region 40, the brightness of the light at the first portion 401 is higher than the brightness of the light at the second portion 402, so the brightness of the light at the first portion 401 is higher than the brightness of the light at the second portion 402. The light can reach farther than when the brightness of the light is less than or equal to . When the other vehicle 3 is positioned at the first portion 401, it is farther away than when it is positioned at the second portion 402 (see FIG. 5). The brightness of the first portion 401 for detecting the other vehicle 3 at a distant position is high, and the light can reach farther. is detected, other vehicles 3 further away can be detected. That is, in the present embodiment, since the light is concentrated and emitted strongly in the distant direction where sensitivity is required, it is possible to efficiently increase the detection distance of the other vehicle 3 . Therefore, the detection distance of the other vehicle 3 can be increased.

The structure of the output unit 71 will be described with reference to FIGS. 3, 4, 8, and 9. FIG. The emission unit 71 includes a housing 712 , an LD 72 (see FIGS. 2 and 8), and a projection lens 711 . The housing 712 has a substantially rectangular parallelepiped shape. As shown in FIG. 8, the housing 712 is provided with a recess 713 recessed from the front to the rear. An LD 72 is arranged at the rear end of the recess 713 . The projection lens 711 is attached to the front surface of the housing 712 (see FIG. 9). The LD 72 emits light, and the light is refracted by the projection lens 711 to be emitted to the emission region 40 (see FIGS. 5 to 7). That is, depending on the shape of the curved surface of the projection lens 711, a trapezoidal directional characteristic can be realized, and furthermore, the brightness of the light in the upper part of the trapezoid can be increased.

The structure of the light receiving unit 74 will be described with reference to FIGS. 3, 4, 8, and 9. FIG. The light receiving unit 74 includes a housing 742 , a photodiode 75 (see FIGS. 2 and 8), and a light receiving lens 76 . The housing 742 has a substantially rectangular parallelepiped shape and is larger than the housing 712 . As shown in FIG. 8, the housing 742 is provided with a recess 743 that is recessed rearward from the front surface. A photodiode 75 is arranged at the rear end of the recess 743 . Photodiode 75 is supported by housing 742 .

As shown in FIGS. 3, 4, and 9, the receiving lens 76 is attached to the front surface of the housing 742. As shown in FIG. That is, the light receiving lens 76 is supported by the housing 742 in front of the photodiode 75 . The light receiving lens 76 guides the reflected light of the light emitted by the emission unit 71 to the photodiode 75 .

The photodiode 75 receives light reflected by the light emitted by the emission unit 71 . As shown in FIG. 7 , an incident area 750 on which reflected light from the trapezoidal output area 40 is incident tends to be trapezoidal like the output area 40 . In FIG. 7, the emission area 40 and the incidence area 750 are shown overlapped. As shown in FIG. 8, the top of the photodiode 75 has a shape along the top of the incident region 750 on which the reflected light from the emitting region 40 (see FIGS. 5 and 7) is incident. More specifically, the photodiode 75 is square with one corner 751 on the top. Sides 752 and 753 forming one corner portion 751 are inclined along the upper portion of the incident area 750 on which the reflected light from the emitting area 40 is incident. In this embodiment, the photodiode 75, which is a square light receiving element, is arranged to be rotated by 45 degrees.

As shown in FIG. 9, the light receiving lens 76 has a plurality of (three as an example in this embodiment) optical central axes 911-913. A plurality of optical central axes 911 to 913 are all located inside the photodiode 75 . The structure of the light receiving lens 76 will be described in detail below.

As shown in FIGS. 3 and 9, the light-receiving lens 76 has a main lens 761 and two auxiliary lenses 762 and 763 . The main lens 761 and auxiliary lenses 762 and 763 are integrally formed. The main lens 761 is a circular lens when viewed from the front. A front surface 7611 of the main lens 761 protrudes forward to form a portion of a sphere. The two auxiliary lenses 762 and 763 are arranged side by side in the horizontal direction below the main lens 761 . Auxiliary lenses 762 and 763 are smaller than main lens 761 . One auxiliary lens 762 has a shape symmetrical to the other auxiliary lens.

In this embodiment, in addition to a main lens 761 which is a normal circular spherical lens, auxiliary lenses 762 and 763 which are spherical lenses having the same curvature as the main lens 761 are arranged on the lower right side and the lower left side of the main lens 761. there is The auxiliary lenses 762 and 763 have the same shape as the portions of the main lens 761 adjacent to the auxiliary lenses 762 and 763 . Note that the same shape includes not only exactly the same shape but also a shape close to the portion of the main lens 761 adjacent to the auxiliary lenses 762 and 763 .

In this embodiment, the auxiliary lens 762 is connected to the lower right portion of the main lens 761 and has the same shape as the lower right portion of the main lens 761 . A top surface 762B of the auxiliary lens 762 protrudes forward from the lower right end of the main lens 761 . The upper surface 762B has an arc shape along the lower right end of the main lens 761 when viewed from the front. A lower end 762C of the auxiliary lens 762 is arcuate when viewed from the front. The front surface 762A of the auxiliary lens 762 is curved so as to be located rearward from the upper surface 762B toward the lower end 762C.

The auxiliary lens 763 is connected to the lower left portion of the main lens 761 and has the same shape as the lower left portion of the main lens 761 . A top surface 763B of the auxiliary lens 763 protrudes forward from the lower left end of the main lens 761 . The upper surface 763B has an arc shape along the lower left end of the main lens 761 when viewed from the front. A lower end 763C of the auxiliary lens 763 is arcuate when viewed from the front. A front surface 763A of the auxiliary lens 763 is curved so as to be located rearward from the upper surface 763B toward the lower end 763C.

As shown in FIG. 9, the optical central axes 912 and 913 of the auxiliary lenses 762 and 763 are positioned below the optical central axis 911 of the main lens 761 . Further, the optical center axis 912 of one of the auxiliary lenses 762 and 763 is located on the right side of the optical center axis 911 of the main lens 761, which is one side in the horizontal direction. The optical center axis 913 of the other auxiliary lens 763 is positioned on the left side, which is the other side in the horizontal direction, of the optical center axis 911 of the main lens 761 . The optical central axis 912 and the optical central axis 913 are positioned symmetrically with respect to the horizontal position of the optical central axis 911 of the main lens 761 .

As a result of forming the auxiliary lenses 762 and 763 as described above, the light receiving area 89 where the photodiode 75 can receive light is as shown in FIG. The light receiving area 89 includes light receiving areas 891-893. Light receiving areas 891 , 892 , 893 indicate areas where the main lens 761 , the auxiliary lens 762 , and the auxiliary lens 763 guide the light reflected by the light from the emission area 40 to the photodiode 75 , respectively. The shape of each of the light receiving regions 891-893 corresponds to the shape of the photodiode 75. FIG. A light receiving area 891 formed by the main lens 761 corresponds to the upper portion of the emission area 40 and the incidence area 750 . A light receiving area 892 by the auxiliary lens 762 is located on the lower right side of the light receiving area 891 of the main lens 761 . A light receiving area 893 by the auxiliary lens 763 is located on the lower left side of the light receiving area 891 of the main lens 761 . That is, compared to the case where only the main lens 761 is provided, the area where the photodiode 75 can receive light is widened.

It should be noted that the light-receiving area cannot cover the emission area 40, which is the light-projecting area, with only one normal circular spherical lens and the light-receiving element. For example, when widening the light-receiving area of one lens and light-receiving element, measures such as increasing the area of the light-receiving element and shortening the focal length of the light-receiving lens are conceivable. If the area of the light-receiving element is increased, the electric capacity of the light-receiving element becomes large, and the signal waveform when receiving light tends to be dull, which may reduce the response speed. Therefore, there is a possibility that the detection accuracy of the other vehicle 3 is lowered. Therefore, there is a limit to increasing the area of the light receiving element. Further, when the focal length of the light receiving lens is shortened, the area of the light receiving lens becomes small, and the light collecting ability of the light receiving lens deteriorates. Therefore, there is a possibility that the detection accuracy of the other vehicle 3 is lowered. Therefore, there is a limit to shortening the focal length of the light receiving lens. That is, the area of the light receiving element is limited to the size range of commercially available photodiodes, and the area size and the response speed are in a trade-off relationship. In addition, if the focal length is shortened, the lens diameter (lens area) of the light receiving lens becomes small, and the light condensing ability also deteriorates.

In this embodiment, the light receiving lens 76 has a plurality of optical central axes 911-913. Therefore, the light receiving area 89 where the photodiode 75 can receive light becomes larger than in the case of a lens having one optical central axis (see FIG. 7). That is, the light receiving area 89 can be enlarged without increasing the area of the photodiode 75 . Since the light receiving area 89 is enlarged, other vehicles 3 located in a wider range can be detected, and the detection accuracy of the other vehicles 3 is improved.

In addition, compared to the case of having one optical center axis, the light receiving area 89 can be enlarged while suppressing the decrease in the light collecting ability due to the size of the light receiving lens 76 . Since the light receiving area 89 is enlarged, other vehicles 3 located in a wider range can be detected, and the detection accuracy of the other vehicles 3 is improved.

In addition, since the optical central axes 912 and 913 of the auxiliary lenses 762 and 763 are positioned below the optical central axis 911 of the main lens 761, the light is emitted from the lower side than when only the main lens 761 is provided. can be led to the photodiode 75 . Therefore, the area where the photodiode 75 can receive light from the lower side can be made larger than when only the main lens 761 is provided.

Here, when viewed from the laser inter-vehicle rangefinder 1, the longer the distance from the laser inter-vehicle rangefinder 1 to the other vehicle 3, the higher the reflecting plate 31 of the other vehicle 3 is located (see FIG. 5). The shorter the distance from the rangefinder 1 to the other vehicle 3, the lower the reflector 31 of the other vehicle 3 is located (see FIG. 6). In this embodiment, the light-receiving region 89 capable of receiving light from the lower side is enlarged, thereby increasing the light-receiving region 89 capable of receiving light in the vertical direction. Therefore, compared to the case where only the main lens 761 is provided, the range of distances in which the reflector 31 of the other vehicle 3 can be detected becomes larger. again. The light-receiving lens 76 does not become too large compared to the case where the light-receiving area 89 is enlarged with one lens. Therefore, the possibility that the laser inter-vehicle range finder 1 is enlarged can be reduced.

Also, two auxiliary lenses 762 and 763 are arranged side by side in the horizontal direction below the main lens 761 . Therefore, compared to the case where one auxiliary lens is provided, the lower light receiving area 89 in the light receiving area 89 becomes larger in the horizontal direction (see light receiving areas 892 and 893). In the present embodiment, the second portion 402 of the emission region 40 is positioned below the first portion 401, so the width of the lower portion of the emission region 40 in the horizontal direction tends to be larger than the width of the upper portion in the horizontal direction. It is in. However, since the two auxiliary lenses 762 and 763 are arranged side by side, the light receiving area 89 can be set according to the width of the lower portion of the emission area 40 . Therefore, the reflected light of the light emitted to the emission area 40 can be received more reliably, and the detection accuracy of the other vehicle 3 is further improved.

In addition, since the auxiliary lenses 762 and 763 have substantially the same shape as the portions of the main lens 761 adjacent to the auxiliary lenses 762 and 763, when the focal lengths of the main lens 761 and the auxiliary lenses 762 and 763 are substantially the same, Reflected light is received by the photodiode 75 . Therefore, compared to the case where the main lens 761 and the auxiliary lenses 762 and 763 have different focal lengths, the detection accuracy of the other vehicle 3 is improved.

The top of the photodiode 75 has a shape along the top of the incident area 750 on which the light reflected from the emitting area 40 (see FIGS. 5 and 7) is incident. Therefore, compared to the case where the photodiode 75 does not have a shape along the upper portion of the emission region 40, the area of the photodiode 75 that can be used for receiving the reflected light of the light emitted to the emission region 40 is increased. be able to. Therefore, a wide range of light can be received. Therefore, the laser inter-vehicle range finder 1 can further improve the detection accuracy of the other vehicle 3 . For example, most of the light receiving area 891 shown in FIG. 7 overlaps the incident area 750 .

When one photodiode 75 is used, if the light receiving area of the photodiode 75 that can be used for receiving the reflected light of the light emitted to the emission region 40 is small, the sensitivity is lowered. However, as in the present embodiment, the photodiode 75 can be shaped along the upper portion of the incident region 750 to increase the area that can be used for receiving the light emitted to the emitting region 40 . Therefore, a wider range of light can be received. Therefore, the sensitivity of the photodiode 75 is improved. Therefore, the laser inter-vehicle range finder 1 can further improve the detection accuracy of the other vehicle 3 .

Moreover, in this embodiment, the photodiode 75 is square, and the corner 751 of one is located on the upper side. When one corner 751 of the quadrangular photodiode 75 is located on the upper side, both sides 752 and 753 forming the upper corner 751 are incident light rays reflected by the trapezoidal emission region 40 are received. along the top of region 750; Compared to the case where the photodiode 75 is arranged so that the upper side of the square is parallel to the left-right direction, the light-receiving area of the photodiode 75 can be used to receive the reflected light of the light emitted to the emission region 40 . The usable area can be increased. Therefore, a wider range of light can be received. Therefore, the laser inter-vehicle range finder 1 can further improve the detection accuracy of the other vehicle 3 while using the square photodiode 75 . Moreover, since it is not necessary to form the photodiode 75 in a shape other than a square, the cost can be reduced.

Note that the auxiliary lenses 762 and 763 are smaller in size than the main lens 761 . In the incident area 750, the main lens 761 is prioritized over the auxiliary lenses 762 and 763 for the portion overlapping the light receiving area 891 of the main lens 761, and the reflected light is acquired. When the other vehicle 3 is at a distant position (see FIG. 6), the reflected light from the reflector 31 of the other vehicle 3 at a distant position is acquired, so the gain tends to be small, but the light is received by the main lens 761 having a large size. Therefore, the other vehicle 3 can be detected more reliably. Also, when the other vehicle 3 is in a close position (see FIG. 6), the reflected light from the nearby other vehicle 3 is acquired, so the gain tends to increase. Therefore, the reflected light is acquired by auxiliary lenses 762 and 763 that are small in size. In other words, the portion detected by the auxiliary lenses 762 and 763 added to the main lens 761 in this embodiment does not require a large gain because the other vehicle 3 serving as the target is close, so the sizes of the auxiliary lenses 762 and 763 are reduced. making it smaller. Further, by using the light receiving lens 76 of the present embodiment, light can be collected at a wide angle without reducing the lens diameter proportional to the light collection area.

The internal structure of the housing 742 in the light receiving unit 74 will be described with reference to FIG. In this embodiment, a reflective structure is provided behind the light receiving lens 76 to reflect the light to the photodiode 75 . A detailed description will be given below. A housing 742 of the light-receiving unit 74 has a recess 743 recessed toward the rear, which is formed by the inner wall 77 . The inner wall 77 is formed by two reflective surfaces 771 and 772 and five non-reflective surfaces 773-777.

As an example, the reflecting surfaces 771 and 772 are formed by polishing the inner wall 77 of the housing 742 . Reflective surfaces 771 and 772 reflect part of the light incident from light-receiving lens 76 in housing 742 and guide it to photodiode 75 . In this embodiment, the reflecting surfaces 771 and 772 reflect at least the light reaching above the photodiode 75 and guide it to the photodiode 75 .

The non-reflecting surfaces 773 to 777 are portions where it is more difficult to guide light to the photodiode 75 than the reflecting surfaces 771 and 772 . Of the non-reflective surfaces 773 to 777 , the non-reflective surfaces 774 to 777 are provided below the photodiode 75 inside the housing 742 .

A hole 78 having a square shape in front view for disposing the photodiode 75 is provided in the rear and central portion of the inner wall 77 . The photodiode 75 is rectangular, and one corner 751 is located on the upper side. The hole portion 78 is formed so that one corner portion 781 is positioned upward in accordance with the layout of the photodiode 75 .

The reflective surfaces 771 and 772 extend from a pair of sides 752 and 753 forming an upper corner portion 751 of the photodiode 75, respectively. The reflective surface 771 extends forward from the side 752 and obliquely upward to the left. The reflective surface 772 extends forward from the side 753 and obliquely upward to the right. A non-reflective surface 773 is provided between the reflective surface 771 and the reflective surface 772 .

The non-reflecting surface 774 extends downward from a pair of sides 755 and 756 forming a lower corner 754 of the photodiode 75 . The difficult-reflecting surface 775 extends obliquely forward and leftward from the left portion of the difficult-reflecting surface 774 . The upper end of the non-reflective surface 775 is connected to the lower end of the reflective surface 771 . The difficult-reflecting surface 776 extends obliquely forward and rightward from the right portion of the difficult-reflecting surface 774 . The upper end of the non-reflective surface 776 is connected to the lower end of the reflective surface 772 . The low-reflection surface 777 extends obliquely downward and forward from the lower portion of the low-reflection surface 774 . The lower ends of the low-reflection surfaces 774 , 775 , 776 are connected to the low-reflection surface 777 .

As described above, the light receiving unit 74 in this embodiment is formed. With reference to FIG. 10, the manner in which the reflected light is guided to the photodiode 75 in the light receiving unit 74 will be described. Part of the reflected light corresponding to the light emitted from the emission area 40 is guided to the photodiode 75 via the main lens 761 and auxiliary lenses 762 and 763 (see arrows 791 and 792).

On the other hand, part of the reflected light corresponding to the second portion 402 (see FIGS. 5 to 7) of the emission region 40 is not directly guided to the photodiode 75, but passes through the main lens 761 or the auxiliary lenses 762 and 763 and passes through the photodiode. It reaches above diode 75 (see, for example, arrow 793). The reflected light reaching above the photodiode 75 is reflected by the reflecting surfaces 771 and 772 and guided to the photodiode 75 (see arrow 794). Therefore, the brightness of the reflected light reaching the photodiode 75 is higher than when the reflecting surfaces 771 and 772 are not provided. The light from the second portion 402 is reflected by the reflector 31 of the other nearby vehicle 3 (see FIG. 6). Since the reflecting surfaces 771 and 772 are provided, the brightness of the light reflected by the reflecting plate 31 of the other vehicle 3 nearby reaches the photodiode 75 is increased. Therefore, the laser inter-vehicle range finder 1 can more reliably detect the other vehicle 3 nearby.

Part of the reflected light from the periphery of the first portion 401 of the emission region 40 reaches below the photodiode 75 (see arrow 795). Since the low-reflection surfaces 774 to 777 are provided below the photodiode 75 , light is less reflected than the reflection surfaces 771 and 772 . Therefore, reflected light is less likely to be guided to the photodiode 75 . The traveling lane 50 at the position where the light of the first portion 401 of the laser inter-vehicle range finder 1 is emitted has a narrow width in the left-right direction, and the light is likely to irradiate the reflecting plate 95 outside the traveling lane 50 . However, since the reflected light is less likely to be guided to the photodiode 75 by the non-reflective surfaces 774 to 774, the possibility of the laser distance meter 1 erroneously detecting the reflector 95 can be further reduced.

Also, the reflective surfaces 771 and 772 extend from a pair of sides 752 and 753 forming one corner portion 751 of the photodiode 75 (see FIG. 8). Therefore, the light reflected by the reflector 31 of the other vehicle 3 reaches the photodiode 75 more reliably than when the reflecting surfaces 771 and 772 do not extend from the sides 752 and 753 . Therefore, the detection accuracy of the other vehicle 3 is improved.

In addition, the brightness of the reflected light reaching the photodiode 75 is higher than in the case where the reflecting surfaces 771 and 772 are not provided. Therefore, the laser inter-vehicle range finder 1 can detect the other vehicle 3 more reliably.

As described above, the optical unit 7 in this embodiment is formed. The emission unit 71 can focus the light on the emission area 40 by refracting the light with the projection lens 711 . Therefore, it is not necessary to make the shape of the LD 72 into a special shape for emitting light to the emission region 40 . Therefore, the cost of LD72 can be reduced.

In addition, the output unit 71 and the light receiving lens 76 are arranged next to each other. For this reason, compared to the case where the output unit 71 and the light receiving lens 76 are separated, the output area 40 and the incident area 750 where light is received by the photodiode 75 are more likely to overlap. Therefore, the detection accuracy of the other vehicle 3 is improved.

Further, by forming the optical unit 7 as described above, it is possible to obtain a light receiving directivity matching the light projecting directivity.

Also, the light receiving unit 74 and the emitting unit 71 are adjacent to each other in the horizontal direction. Therefore, the length of the optical unit 7 in the vertical direction can be shortened compared to the case where the optical units 7 are vertically adjacent to each other. Therefore, when the laser inter-vehicle range finder 1 is mounted above the windshield 91 as shown in FIG. 1, it is difficult for the driver to see it.

The equivalent sampling method in this embodiment will be described with reference to FIGS. 11 and 12. FIG. In this embodiment, when the laser inter-vehicle rangefinder 1 calculates the distance from the laser inter-vehicle rangefinder 1 to the other vehicle 3, an equivalent time sampling method (sequential sampling) is used. An equivalent time sampling method is used to process an ultra-high-speed light-receiving pulse waveform (repetitive waveform) by converting the time axis to an order that can be captured by a low-rate AD converter. The equivalent-time sampling method is a method of down-converting a waveform by repeatedly sampling with a slightly shifted sampling start point, resulting in a large number of sample points on the waveform.

The CPU 101 causes the emission unit 71 to emit light by lighting the LD 72 . Further, the CPU 101 samples the signal based on the light received by the LD 72 at sampling intervals according to the equivalent time sampling method. Since the frequency of light is high, a very high sampling frequency is required, which may cause problems such as high component costs. Therefore, in this embodiment, sampling is performed by the equivalent sampling method.

The shorter the distance from the laser inter-vehicle rangefinder 1 to the other vehicle 3, the more light is emitted from the emission unit 71, and the time it takes for the reflected light from the reflector 31 of the other vehicle 3 to reach the laser inter-vehicle rangefinder 1. becomes shorter. That is, the time required for light emitted from the emission unit 71 according to the distance between the laser inter-vehicle rangefinder 1 and the other vehicle 3 and the reflected light from the reflector 31 of the other vehicle 3 to reach the laser inter-vehicle rangefinder 1 changes. Therefore, the CPU 101 controls the light emitting unit 71 to change the time from when the light is emitted to when the sampling is performed, thereby detecting the other vehicle 3 at a near position to the other vehicle 3 at a far position. do.

In this embodiment, the CPU 101 changes the brightness of the emitted light according to the time from when the light is emitted by controlling the emission unit 71 to when the sampling is performed. More specifically, in the present embodiment, as shown in FIG. 12, the CPU 101 controls the emission unit 71 to emit light with a lower brightness as the time from emission of light to sampling is shorter. It is emitted to the unit 71 . In one measurement (one set), the received light signal is sampled by sweeping the monitoring distance range of the other vehicle 3 by equivalent time sampling. , the pulse light level of the LD 72 is controlled in proportion to the distance.

11 and 12 will be described. In the following description, the pulsed light emitted from the laser inter-vehicle rangefinder 1 may be referred to as pulsed light. FIGS. 11A and 11B show the light emitted from the laser range finder 1 when the brightness is constant regardless of the time from when the light is emitted by controlling the emission unit 71 to when the sampling is performed. It shows the magnitude of the brightness of the pulsed light and the brightness of the reflected light. FIGS. 12A and 12B show pulsed light when the brightness of the emitted light is changed according to the time from when the light is emitted by controlling the emission unit 71 to when the sampling is performed. It shows the brightness and the magnitude of the brightness of the reflected light.

The vertical axis in FIGS. 11A and 12A represents the brightness of the light emitted by the emission unit 71, and the horizontal axis represents the distance to the other vehicle 3 to be detected by the laser range finder 1. It represents the distance L. 11B and 12B, the vertical axis represents the brightness of the light received by the light receiving unit 74, and the horizontal axis represents the distance to the other vehicle 3 to be detected by the laser inter-vehicle rangefinder 1. It represents the distance L. The distance L between the laser inter-vehicle rangefinder 1 and the other vehicle 3 is longer in the right direction on the horizontal axis. In the following description, the pulsed light emitted by the emission unit 71 may be referred to as pulsed light Pa (a=1 to n). The pulsed light for detecting the other vehicle 3 with the shortest distance L is defined as pulsed light P1, and the pulsed light for detecting the other vehicle 3 with the longest distance L is defined as pulsed light Pn. The laser inter-vehicle rangefinder 1 repeatedly emits the pulsed light P1 to the pulsed light Pn.

The number of pulsed lights from pulsed light P1 to pulsed light Pn is, for example, 4096 (that is, n=4096), but the number of pulsed lights is reduced in FIGS. there is The length of time for which one pulsed light is emitted is, for example, 20 to 29 nS. The time from the emission of one pulsed light to the emission of the next pulsed light is, for example, 57 μs. (The drawing is a conceptual diagram and the interval of 57 μs is shown to be short, but in reality it is 57 μs, which is more than 1000 times as long as 20 to 29 nS.) The interval from when the reflected light is sampled becomes longer from the pulsed light P1 toward the pulsed light Pn. That is, regarding the interval from the emission of the pulsed light Pa from the emission unit 71 until the reflected light is sampled, the interval from sampling to the left becomes shorter on the horizontal axis.

In the case of the example shown in FIG. 11A, the brightness of the pulsed light Pa emitted from the emitting unit 71 is constant regardless of the distance L (for example, constant at 16 W from the pulsed light P1 to the pulsed light Pn). For example, when the other vehicle 3 is at the position PL1, the light is reflected by the reflector 31 of the other vehicle 3, so the brightness of the reflected light received by the light receiving unit 74 increases as shown at point P11. Further, when the other vehicle 3 is at PL2, which is farther than the position PL1, the light is reflected by the reflector 31 of the other vehicle 3, so the brightness of the reflected light received by the light receiving unit 74 is large as shown at point P12. Become.

When the other vehicle 3 is nearby, the brightness of the light reflected by the reflector 31 of the other vehicle 3 and received by the light receiving unit 74 increases. Therefore, as shown in FIG. 11, when the brightness of the pulsed light Pa is constant, the brightness of the light at the point P11 is higher than the brightness of the light at the point P12.

Referring to FIG. 12, the brightness of pulsed light Pa is changed in accordance with the time from emission of pulsed light Pa by controlling emission unit 71 to sampling. Control will be explained. As shown in FIG. 12A, the brightness of the pulsed light Pa emitted from the emitting unit 71 decreases as the distance L decreases (for example, the pulsed light Pn is 16 W, and the pulsed light P1 is 16 W). 1/4 of 4W). That is, the CPU 101 causes the emission unit 71 to emit the pulsed light Pa with lower brightness as the time from the emission of the light by the emission unit 71 to the sampling is shorter.

In this case, for example, when the other vehicle 3 is at the position PL1, the light is reflected by the reflector 31 of the other vehicle 3, so the brightness of the reflected light received by the light receiving unit 74 is as shown at point P21. growing. Further, when the other vehicle 3 is at PL2, which is farther than the position PL1, the light is reflected by the reflector 31 of the other vehicle 3, so the brightness of the reflected light received by the light receiving unit 74 is large as shown at point P22. Become.

When the other vehicle 3 is nearby, the brightness of the light reflected by the reflector 31 of the other vehicle 3 and received by the light receiving unit 74 increases. However, the brightness of the pulsed light Pa emitted from the emitting unit 71 becomes weaker as the distance L becomes shorter. It is smaller than the difference D1 between the luminance at point P11 and the luminance at point P12.

As described above, in this embodiment, the brightness of the pulsed light Pa emitted from the emission unit 71 is controlled. The closer the distance L from the laser inter-vehicle rangefinder 1 to the other vehicle 3 is, the higher the brightness of the reflected light received by the light receiving unit 74 is likely to be (see FIG. 11B). Further, for example, when the distance L from the laser range finder 1 to the other vehicle 3 is within a predetermined range due to the characteristics of the light emitting lens 711 or the light receiving lens 76, the photodiode The brightness of the reflected light received by 75 may increase. If the brightness of the reflected light received by the photodiode 75 increases, the amplifier circuit may saturate when a signal based on the reflected light received by the photodiode 75 is amplified by an amplifier circuit or the like. Therefore, it takes time to return to a normal state after the amplifier circuit saturates, and there is a possibility that the detection accuracy of the other vehicle 3 will decrease. For example, at point P11 shown in FIG. 11B, the amplifier circuit may saturate.

In the equivalent time sampling method, the time from when the pulsed light Pa is emitted from the emission unit 71 until it is sampled by the CPU 101 changes according to the distance to the other vehicle 3 . In the present embodiment, the brightness of the emitted pulsed light Pa changes according to the time from when the pulsed light Pa is emitted from the emission unit 71 until it is sampled (see FIG. 12). Therefore, for example, the brightness of the light emitted from the emission unit 71 can be reduced in a range where the amplifier circuit may be saturated. Therefore, the possibility of saturating the amplifier circuit is reduced. Therefore, the detection accuracy of the other vehicle 3 is improved as compared with the case where the amplifier circuit saturates and a long recovery time occurs. Also, even when saturated, the recovery time can be shortened. In addition, the power consumption is reduced as compared with the case where the brightness of the pulsed light Pa does not change and the light is always emitted with the brightness for detecting the other vehicle 3 in the distance (see FIG. 11). In addition, since the brightness of each pulsed light Pa and the average light output of the pulsed light Pa are reduced, the level of light reflected on the windshield 91 can be reduced.

In addition, the laser inter-vehicle rangefinder 1 emits light with an intensity necessary for the light to reach the furthest position in the range of the distance for detecting the other vehicle 3 . For this reason, the intensity of light may increase. Further, for example, when the laser inter-vehicle distance finder 1 is installed in the passenger compartment, the intensity of the light may be further increased because the light needs to be transmitted through the windshield 91 and the like. When continuously emitting light with high intensity, it is necessary to consider the effects on the human eye. Therefore, in the present embodiment, instead of continuously emitting light, pulsed pulsed light Pa is emitted and a time period during which light is not emitted is provided to reduce the average value of light intensity. As a result, the influence on the human eyes can be reduced. For example, the interval between the pulsed lights Pa may be set to be twice as large as the width of the pulse. More desirably, the interval between the pulsed lights Pa should be made 1000 times or more larger than the pulse width.

Further, in the present embodiment, the shorter the time from the emission of the pulsed light Pa to the sampling by the CPU 101, the weaker the pulsed light Pa emitted from the emission unit 71 (see FIG. 12). Therefore, compared to the case where the brightness of the pulsed light Pa is not adjusted (see FIG. 11), the brightness of the reflected light received when the distance from the laser vehicle distance finder 1 to the other vehicle 3 is short can be reduced. (See FIG. 12). Therefore, the possibility that the amplifier circuit is saturated can be reduced, and the detection accuracy of the other vehicle 3 is improved.

In this way, the level of the amplifier circuit is set as high as possible in order to obtain sensitivity when monitoring the other vehicle 3 at a long distance, and the level is set at a level higher than necessary when monitoring the other vehicle 3 at a short distance. A small level of pulsed light Pa is output so as not to saturate.

An electrical configuration for emitting the pulsed light Pa shown in FIG. 12A will be described with reference to FIG. At least part of the emission control circuit 60 shown in FIG. 13 is included in the light emitting circuit 102 (see FIG. 2). As shown in FIG. 13, the emission control circuit 60 includes a power supply circuit 61, a fourth resistor 651, and a switch 68. The power supply circuit 61 supplies voltage to the LD 72 of the emission unit 71 . The power supply circuit 61 includes a DC/DC converter 63 , a dividing resistor 62 , an integrating circuit 64 and a third resistor 614 . The DC/DC converter 63 is a high voltage DC/DC voltage circuit for the power supply of the LD72. The DC/DC converter 63 has an input terminal 631, an output terminal 632, a reference input terminal 633, and the like.

Divided resistor 62 includes a first resistor 621 and a second resistor 622 . Terminal 621A of first resistor 621 is electrically connected to output terminal 632 of DC/DC converter 63, and terminal 621B of first resistor 621 is connected to terminal 622A of second resistor 622 and DC/DC converter 63. is electrically connected to the reference input terminal 633 of the . Terminal 622A of second resistor 622 is electrically connected to terminal 621B of first resistor 621 and reference input terminal 633 of DC/DC converter 63, and terminal 622B is electrically connected to ground. The dividing resistor 62 inputs the divided voltage to the reference input terminal 633 of the DC/DC converter 63 . A dividing resistor 62 is used to set the output voltage of the DC/DC converter 63 .

The integration circuit 64 has an input terminal 641 and an output terminal 642 . Terminal 614 A of third resistor 614 is electrically connected to output terminal 642 of integrating circuit 64 . Terminal 614 B of third resistor 614 is electrically connected to reference input terminal 633 , terminal 621 B of first resistor 621 , and terminal 622 A of second resistor 622 .

The output terminal 632 of the DC/DC converter 63 is electrically connected to the terminal 651A of the fourth resistor 651 . A terminal 651B of the fourth resistor 651 is electrically connected to the anode terminal 721 of the LD72. A cathode terminal 722 of the LD 72 is connected to a switch 68 composed of a transistor or the like. Switch 68 is electrically connected to ground. The switch 68 is turned on and off under the control of the CPU 101 or by an oscillator output signal.

A voltage Vin is input to an input terminal 631 of the DC/DC converter 63 . A pulse signal S1 is input to an input terminal 641 of the integration circuit 64 . By inputting the pulse signal S1 to the integrating circuit 64, the voltage input to the reference input terminal 633 of the DC/DC converter 63 fluctuates as shown by the waveform S2. The waveform S2 is a waveform in which the voltage rises over time in the portion 611, becomes constant in the portion 662, and decreases in the portion 663, which is repeated.

By inputting the voltage of the waveform S2 to the reference input terminal 633, the voltage output from the output terminal 632 of the DC/DC converter 63 fluctuates as shown by the waveform S3. The waveform S3 is a waveform in which the voltage rises in the portion 671, becomes constant in the portion 672, and decreases in the portion 673 with the lapse of time. That is, the voltage divided by the dividing resistor 62 is forcibly varied by the integration circuit 64 and the third resistor 614, thereby varying the voltage applied to the reference input terminal 633 and creating the waveform S3. of. Thus, by inputting the waveform S2, which is the ramp signal generated by the integration circuit 64, to the reference input terminal 633 of the DC/DC converter 63, which is the high-voltage DC/DC circuit for the power supply of the LD 72, the waveform S3 can be generated. is realized.

Waveform S3 is applied to LD72. While the voltage of the portion 673 of the waveform S3 is being applied to the LD 72, the switch 68 is repeatedly turned on and off to output the pulsed light Pa shown in FIG. 12(A). That is, the shorter the time from the emission of the pulsed light Pa by the laser inter-vehicle rangefinder 1 to the sampling by the equivalent time sampling means, the weaker the emitted light.

Thus, in the present embodiment, by varying the voltage input to the reference input terminal 633 according to the output from the integrating circuit 64, the shorter the time from the emission of the pulsed light Pa to the sampling by the CPU 101, the , the function of causing the emission unit 71 to emit the pulsed light Pa of low brightness can be realized.

An embodiment for improving the S/N ratio (Signal-Noise ratio) during equivalent time sampling will be described with reference to FIGS. 14 and 15. FIG. In the present embodiment, during equivalent-time sampling, unwanted components on the lower side (lower frequency side) of the received light signal band are strongly attenuated to improve the S/N. As a method for this, during equivalent time sampling, the light receiving signal immediately before light emission is sampled separately from the light receiving timing, and is pulled by a differential amplifier 83 (described later) which is a differential circuit. A detailed description will be given below.

As shown in FIG. 14, the light receiving control circuit 80 includes a low-pass filter (LPF) 81, a sample and hold circuit (S&H) 821, an S&H 822, a differential amplifier 83, and an A/D converter 84. . A received light signal from the photodiode is input to the LPF 81 and S&H 822 . LPF 81 is electrically connected to S&H 82 . S&H 821 is electrically connected to the negative input terminal of differential amplifier 83 . S&H 822 is electrically connected to the positive input terminal of differential amplifier 83 . An output terminal of the differential amplifier 83 is electrically connected to the A/D converter 84 . A/D converter 84 is electrically connected to CPU 101 .

The S&H 821 is a circuit that acquires a signal received by the photodiode 75 before the LD 72 emits the pulsed light Pa (see FIGS. 11 and 12). A pre-sampling pulse is input to the S&H 821 . The pre-sampling pulse is set at an interval that causes the S&H 821 to acquire the signal received by the photodiode 75 before the pulsed light Pa is emitted by the LD 72 . The interval between each pulse in the presampling pulse is constant. Of the signals received by the photodiode 75, the LPF 81 passes a band having a frequency lower than that of the pulsed light Pa emitted by the LD 72. FIG. Therefore, the S&H 821 acquires the signal after passing through the LPF 81 .

The S&H 822 is a circuit that acquires the signal acquired by the photodiode 75 at sampling intervals according to the equivalent sampling method after the LD 72 emits the pulsed light Pa. An equivalent time sampling pulse is input to the S&H 822 . The equivalent time sampling pulse is set to an interval that causes the S&H 821 to acquire a signal based on the reflected light acquired by the photodiode 75 at a sampling interval according to the equivalent sampling method after the LD 72 emits the pulsed light Pa. .

A differential amplifier 83 acquires a signal based on the difference between the signal acquired by the S&H 821 and the signal acquired by the S&H 822, and amplifies the signal level. A/D converter 84 encodes the signal obtained by differential amplifier 83 . The encoded signal is input to the CPU 101 and used to calculate the distance L to the other vehicle 3 .

Signal processing by the light receiving control circuit 80 will be described with reference to FIG. A waveform 991 in FIG. 15A is based on the luminance when only the reflected light from the reflector 31 of the other vehicle 3 is received by the photodiode 75 when the reflector 31 of the other vehicle 3 is at the position PL3. It represents the signal level, and the value increases around the position PL3. A waveform 992 represents the signal level when various noises such as circuit noise, extraneous electrical noise, and extraneous light noise are added to the waveform 991 . Since various noises are added to the waveform 992, the value is larger than that of the waveform 991 by the magnitude E1.

FIG. 15B shows timings at which the pre-sampling pulse PPb (b=1 to n) and the equivalent time sampling pulse SPc (c=1 to n) are input. The S&H 821 acquires the signal acquired by the photodiode 75 at the timing when the presampling pulse PPb is input. The S&H 822 obtains the signal obtained by the photodiode 75 at the timing when the equivalent time sampling pulse SPc (c=1 to n) is input.

Each pre-sampling pulse PPb is input to the S&H 821 before the pulsed light Pa (a=1 to n) shown in FIGS. 11 and 12 is emitted. For example, the first pre-sampling pulse PP1 is input to the S&H 821 before the pulsed light P1 (see FIGS. 11 and 12) is emitted. The second pre-sampling pulse PP2 is input to the S&H 821 after the pulsed light P1 is emitted and before the pulsed light P2 (see FIGS. 11 and 12) is emitted.

Since each pre-sampling pulse PPb is input to the S&H 821 before the pulsed light Pa shown in FIGS. 11 and 12 is emitted, the reflected light of the pulsed light Pa is not received by the photodiode 75 . Thus, a signal of magnitude E1 is obtained in the S&H 821. That is, signals based on various types of noise such as circuit noise, external electrical noise, and external optical noise are obtained. Since the LPF 81 is provided, even if the reflected light of the pulsed light Pa is received by the photodiode 75, the signal component based on the reflected light is removed.

Each equivalent-time sampling pulse SPc (c=1 to N) is input to the S&H 822 at the timing when the reflected light is received after the pulsed light Pa shown in FIGS. 11 and 12 is emitted. That is, it is input to the S&H 822 at sampling intervals according to the equivalent time sampling method. As the equivalent time sampling pulse SPc goes toward SP1, SP2, . Therefore, the longer the distance L to the other vehicle 3 is, the later the timing at which the reflected light of the pulsed light Pa is received. That is, by delaying the timing at which the equivalent time sampling pulse SPc is input to the S&H 822, reflected light corresponding to the distance L can be received. For example, the signal at point P31 where waveform 992 has the largest value is acquired by S&H 822 when equivalent time sampling pulse SPm+2 is input to S&H 822 .

A differential amplifier 83 amplifies the difference between the signal based on the luminance when the pre-sampling pulse PPb is input to the S&H 821 and the signal based on the luminance when the equivalent time sampling pulse SPc is input to the S&H 821. . The amplified signal is encoded by A/D converter 84 and input to CPU 101 .

For example, when the first measurement is performed, a signal based on the luminance etc. when the pre-sampling pulse PP1 is input to the S&H 821 and a signal based on the luminance etc. when the equivalent time sampling pulse SP1 is input to the S&H 821. The difference is amplified by differential amplifier 83 . The signal based on the luminance etc. when the pre-sampling pulse PP1 is input to the S&H 821 and the signal based on the luminance etc. when the equivalent time sampling pulse SP1 is input to the S&H 821 are the light reflected by the reflector 31 of the other vehicle 3. is a noise component (signal of magnitude E1) that does not include , the output from the differential amplifier 83 approaches 0 as compared to the case where the noise components cancel each other out and do not cancel each other out.

When the m+2th measurement is performed, the difference between the signal based on the luminance when the presampling pulse PPm+2 is input to the S&H 821 and the signal based on the luminance when the equivalent time sampling pulse SPm+2 is input to the S&H 821 is , is amplified by the differential amplifier 83 . A signal based on luminance or the like when the pre-sampling pulse PPm+2 is input to the S&H 821 is a noise component (signal of magnitude E1). A signal based on the luminance when the equivalent time sampling pulse SPm+2 is input to the S&H 821 is a signal containing noise components and reflected light from the reflector 31 of the other vehicle 3 (signal of magnitude E2). Therefore, the signal based on the luminance when the presampling pulse PPm+2 is input to the S&H 821, which is a noise component, is removed from the signal based on the luminance when the equivalent time sampling pulse SPm+2 is input to the S&H 821. Therefore, a signal with reduced noise components is encoded and input to the CPU 101 . That is, a signal of magnitude E3 is amplified, encoded, and input to CPU 101 .

CPU101 acquires the distance with the other vehicle 3 based on the input signal. That is, the CPU 101 can obtain the inter-vehicle distance to the other vehicle 3 based on the pulsed light Pa received by the photodiode 75 .

As described above, the signal acquired by the photodiode 75 may contain various types of noise such as circuit noise, extraneous electrical noise, and extraneous optical noise. Since the signal level of the reflected light is very small, if the S/N ratio decreases due to the influence of noise, it becomes a factor of sensitivity deterioration (decrease in the maximum detection distance), and the distance at which other vehicles 3 can be detected may be shortened. be. As a means of improving the S/N ratio, it is conceivable to use a band-pass filter (BPF). Signal waveforms may be distorted. As a result, the sensitivity may be degraded, and the distance at which the other vehicle 3 can be detected may be shortened. Therefore, in this embodiment, a signal synchronized with noise is generated and subtracted from the equivalent time sampling output signal, thereby reducing the influence of noise without destroying the waveform. Details are described below.

In this embodiment, a signal acquired before the pulsed light Pa is emitted (a signal acquired at the timing of the pre-sampling pulse PPb) and a signal acquired at the sampling interval by the equivalent sampling method (equivalent time sampling pulse SPc A signal based on the difference from the signal acquired at the timing of ) is acquired and encoded. The signal obtained by the S&H 821 is a signal that does not contain reflected light and is a noise signal. The signal acquired by the S&H 822 is a signal containing reflected light and noise. A signal based on the difference between a signal containing reflected light and noise and a signal of noise is acquired and encoded, so that the S/N ratio can be improved. Also, since no BPF is used, the waveform of the reflected light is less likely to collapse. Therefore, the possibility of sensitivity deterioration is reduced, and the distance at which the other vehicle 3 can be detected is increased.

Also, when a signal containing noise in the same frequency band as the light emitted by the LD 72 is acquired by the S&H 821, the noise fluctuating in the same frequency band as the light is superimposed on the light signal by the differential amplifier 83. It may get lost.

In this embodiment, the noise in the same frequency band as the light is reduced by the LPF 81 and acquired by the S&H 821 . Therefore, the differential amplifier 83 reduces the possibility that noise fluctuating in the same frequency band as the light is superimposed on the light signal. Therefore, the possibility of sensitivity deterioration is reduced, and the distance at which the other vehicle 3 can be detected is increased.

In this way, as means for attenuating noise below the desired signal band, two sets of sampling circuits (S&H821 and S&H822) are provided in the equivalent time sampling portion separately from the BPF by frequency discrimination. A sampling pulse (pre-sampling pulse PPb) is given at a fixed timing immediately before, and the other is given at normal equivalent time sampling timing. By subtracting the former sampling circuit output from the latter sampling circuit output in a differential circuit (differential amplifier 83), the lower side (lower frequency side) noise components are strongly attenuated. Also, the received light signal input to the pre-emission sampling is passed through the LPF 81 to reduce noise.

An example of a method for generating the equivalent time sampling pulse SPc will be described with reference to FIG. The pulse generation circuit 85 shown in FIG. 16 includes integration circuits 851 and 852 and a comparator 853 . The integrating circuit 851 and the integrating circuit 852 are electrically connected to the comparator 853 .

In this embodiment, two output voltages with different cycles from the integration circuits 851 and 852 are input to the comparator 853 to sweep the rising and falling timings and generate the equivalent time sampling pulse SPc.

The voltage of the waveform 55 is input to the integrating circuit 851 . A waveform 55 is a waveform in which rectangular waves are repeated. The voltage of the waveform 56 is input to the integrating circuit 852 . Waveform 56 is a continuous pulse signal. The period of waveform 55 is greater than the period of waveform 56 .

When waveform 55 is input to integration circuit 851, waveform 57 is output. A waveform 57 is a waveform in which the voltage rises at a portion 571 and gradually decreases at a portion 572 . When waveform 56 is input to integrator circuit 852, waveform 58 is output. A waveform 58 is a waveform that rises at a portion 581, becomes a constant voltage at a portion 582, and gradually decreases at a portion 583. FIG.

When waveforms 57 and 58 are input to comparator 853, waveform 59 is output. A waveform 59 is a waveform obtained by outputting the equivalent time sampling pulse SPc, and the rising and falling timings are swept. Thus, in this embodiment, the output voltages (that is, the waveforms 57 and 58) of the two integration circuits 851 and 852 with different periods are input to the comparator 853 to sweep the rising and falling timings. It outputs an equivalent time sampling pulse SPc. Thus, in this embodiment, by applying the voltages of the two integrating circuits 851 and 852 with different periods to the comparator 853, a sampling trigger signal that sweeps the rising (or falling) timing can be obtained.

As described above, the equivalent time sampling pulse SPc is generated in this embodiment. The equivalent time sampling method can down-convert a received light pulse waveform on the order of several nanoseconds to several tens of nanoseconds at an arbitrary magnification. Therefore, it becomes difficult to require a high-speed signal processing circuit after receiving the light.

In the above embodiment, the laser inter-vehicle rangefinder 1 is an example of the "emission device" of the present invention. The photodiode 75 is an example of the "light receiving section" of the present invention. The reflecting surfaces 771 and 772 are examples of the "reflecting section" of the present invention. The difficult-reflecting surfaces 774 to 777 are examples of the “difficult-reflecting portion” of the present invention. The extraction control circuit 60 is an example of the "extraction control means" of the present invention. The light reception control circuit 80 is an example of the "equivalent time sampling means" of the present invention. S&H821 is an example of the "first acquisition means" of the present invention. S&H822 is an example of the "second acquisition means" of the present invention. The differential amplifier 83 is an example of the "third acquisition means" of the present invention. CPU101 which measures the distance with the other vehicle 3 based on the signal light-received from the photodiode 75 is an example of the "distance acquisition means" of this invention.

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible. For example, although the emission area 40 is trapezoidal, it is not limited to this. The emission area 40 preferably has a shape in which at least one of a pair of sides facing each other in the left-right direction inclines toward the inside of the emission area 40 as it goes upward. In this case, the brightness of the light irradiated to the reflector 95 on at least one side in the left-right direction of the traffic lane 50 tends to decrease. Therefore, when the other vehicle 3 is detected by detecting the light emitted from the laser inter-vehicle rangefinder 1, the possibility of erroneously detecting the reflector 95 on the outside of the driving lane 50 is reduced. Therefore, the detection accuracy of the other vehicle 3 is improved. For example, if only the right side 413 has a shape that tilts leftward as it goes upward, as in the emission area 41 shown in FIG.

By the way, the emission area 40 is preferably a triangular shape that can eliminate the influence of the reflector plate 95 on the laterally outer side of the traffic lane 50 . However, since the upper vertex of the triangle is a point, if the own vehicle 2 deviates left or right from the center of the driving lane 50, there is a high possibility that the other vehicle 3 cannot be detected. Therefore, as shown in FIGS. 5 to 7, an upper side 405 is provided and the emission area 40 is trapezoidal so that even when the vehicle 2 deviates to the left or right from the center of the driving lane, it can be detected more reliably. The length of the upper side 405 of the trapezoidal emission area 40 may be, for example, the length corresponding to the travel lane 50 at the position of the detection target distance of the other vehicle 3 .

It should be noted that, as in the present embodiment, the emission region 40 may be continuous from the upper first portion 401 to the lower second portion 402 . Moreover, in the emission area 40, the first part 401 and the second part 402 are preferably separated. In addition, the generation unit that generates light is an LED (Light
Emitting Diode). It is particularly preferable if the generation unit is the LD 72 as in this embodiment. Even when the laser inter-vehicle rangefinder 1 is mounted inside the windshield 91, the LD 72 can transmit the light through the windshield 91 and reach the other vehicle 3 further away.

Moreover, the emission area 40 may be triangular or quadrangular, and both of a pair of sides opposed to each other in the left-right direction may be inclined inwardly of the emission area 40 toward the upward direction. In this case, the brightness of the light irradiated to both the left and right reflectors 95 of the traffic lane 50 tends to be low. Therefore, when the other vehicle 3 is detected by detecting the light emitted from the laser inter-vehicle rangefinder 1, the possibility of erroneously detecting the reflector 95 on the outside of the driving lane 50 is reduced. Therefore, the detection accuracy of the other vehicle 3 is improved. In the present embodiment, the emission area 40 is rectangular, and a pair of oblique sides 403 and 404 facing each other in the left-right direction are inclined inwardly of the emission area 40 toward the upper direction.

Further, it is preferable that each of the oblique sides 403 and 404 located on the left and right of the trapezoidal emission area 40 and the left and right lines 501 and 502 of the driving lane 50 as viewed from the laser range finder 1 are nearly parallel. For example, when the angle R1 (see FIG. 5) formed by each of the oblique sides 403 and 404 located on the left and right sides of the trapezoidal emission area 40 and the bottom side 406 is 45 degrees, the driving lane as seen from the laser range finder 1 The angle R2 (see FIG. 5) formed by the left and right lines of 50 and the left and right direction should be set to 45 degrees. In this case, the brightness of the light radiated onto the reflector 95 on the outside of the travel lane 50 tends to decrease, and the brightness of the light radiated onto the reflector 31 of the other vehicle 3 tends to increase. Therefore, when the other vehicle 3 is detected by detecting the light emitted from the laser inter-vehicle rangefinder 1, the other vehicle 3 can be detected more reliably.

Also, the oblique sides 403 and 404 positioned on the left and right of the trapezoidal emission area 40 are preferably located slightly outside the left and right lines 501 and 502 of the driving lane 50 as viewed from the laser range finder 1 . In this case, it is preferable that light is less likely to irradiate the reflectors outside the left and right lines 501 and 502 . Further, preferably, the left and right oblique sides 403 and 404 of the trapezoidal emission area 40 are at the same positions as the left and right lines 501 and 502 of the driving lane 50 as viewed from the laser range finder 1 . More preferably, the left and right oblique sides 403 and 404 of the trapezoidal emission area 40 are inside the left and right lines 501 and 502 of the driving lane 50 as seen from the laser range finder 1 . In addition, the emission area 40 may be adapted to a road having a relatively wide width in the left-right direction, such as a highway. Vehicles tend to travel faster on roads that are wide in the left-right direction, so the inter-vehicle distance to other vehicles 3 is important in terms of driving safety. The use of the laser inter-vehicle range finder 1 on roads where the speed tends to increase improves the safety of driving.

Also, in this embodiment, the luminance gradually increases from the second portion 402 toward the first portion 401 (see FIG. 7). However, it is preferable that the entire emission area 40 has the same brightness. Moreover, it is preferable that the luminance is high in the central portion of the emission area 40 and that the luminance decreases toward the top, bottom, left, and right. Also, it is preferable that the brightness of the first portion 401 is lower than the brightness of the second portion 402 .

Also, the optical central axes 912 and 913 of the auxiliary lenses 762 and 763 are preferably located below the optical central axis 911 of the main lens 761 . Since the auxiliary lenses 762 and 763 are provided, light from the lower side can be led to the photodiode 75 more than when only the main lens 761 is provided. Therefore, the area where the photodiode 75 can receive light from the lower side becomes larger than when only the main lens 761 is provided.

Further, although the laser inter-vehicle rangefinder 1 has been described as an example, it is preferable that the inter-vehicle distance cannot be measured. For example, the emission device of the present invention may be a device capable of detecting only the presence or absence of another vehicle 3 instead of the laser inter-vehicle rangefinder 1 . Further, the emission device of the present invention should be a device capable of emitting light, and should not be capable of receiving reflected light. In this case, it is preferable that the light is received by another device and the other vehicle 3 is detected.

Moreover, it is preferable that the LPF 81 (see FIG. 6) is not provided. Cost can be reduced if the LPF 81 is not provided. Also, the light receiving control circuit 80 may have a configuration other than the example shown in FIG. Also, the circuit configuration for emitting light may be a configuration other than the example shown in FIG. Also, the first resistor 621, the second resistor 622, and the third resistor 614 are not limited to one resistor, and may be a combination of multiple resistors.

Moreover, although the reflecting surfaces 771 and 772 shown in FIG. 8 are formed by polishing the inner wall 77 of the housing 742, they may be formed by a method other than polishing. For example, the reflective surfaces 771 and 772 may be formed by metal plates, plating, or gloss processing. Moreover, it is preferable that the non-reflective surface 773 is a reflective surface. Further, it is preferable that the non-reflective surfaces 773 to 777 are not provided. Moreover, it is preferable that the reflecting surfaces 771 and 772 are not provided. When the reflective surfaces 771 and 772 are not provided, the cost of forming the reflective surfaces 771 and 772 can be reduced.

Also, the photodiode 75 may be arranged in an arrangement other than the arrangement in which one corner portion 751 is positioned on the upper side. Also, the photodiode 75 should not be square. Also, a light receiving element other than the photodiode 75 may be used. For example, a CCD may be used.

Also, the shapes of the auxiliary lenses 762 and 763 may be different from those of the present embodiment. Also, the number of auxiliary lenses is not limited. One auxiliary lens may be provided. More than two auxiliary lenses may be provided. Also, the position of the auxiliary lens is not limited. For example, the position of the auxiliary lens may be changed according to the shape of the emission area 40 . Also, the shapes of the auxiliary lenses 762 and 763 may be different from those of the present embodiment. Moreover, it is preferable that the auxiliary lenses 762 and 763 are not provided. Also, the shape of the main lens 761 should not be circular. At least part of the optical central axes 911 to 913 of the light receiving lens 76 should be positioned outside the photodiode 75 .

Moreover, it is preferable that the emitting unit 71 and the receiving unit 74 are vertically adjacent to each other. In this case, the lateral width of the laser distance finder 1 can be reduced. Moreover, the emitting unit 71 and the light receiving unit 74 are preferably separated from each other.

Further, the place where the laser inter-vehicle range finder 1 is mounted is not limited. For example, the laser inter-vehicle rangefinder 1 may be attached to the rear glass of the vehicle 2 . Also, the light emission direction is preferably backward. Also, the laser inter-vehicle rangefinder 1 is preferably arranged outside the vehicle 2 . For example, the laser inter-vehicle range finder 1 may be arranged at the front end or the rear end of the vehicle 2 outside the vehicle. Further, it is preferable that the mounting portion 19 is not provided. In this case, costs can be reduced.

As an example, the appearance of the laser inter-vehicle range finder 1 may be as shown in FIG. 18 . A main body 11 of the laser inter-vehicle distance finder 1 includes a housing 110 . A light projecting lens 711 , a light receiving lens 76 and a speaker 105 are arranged on the front surface 111 of the laser inter-vehicle rangefinder 1 . A MODE key 121 , an UP key 122 , a DOWN key 123 and three LEDs 125 are arranged on the rear surface 112 of the laser inter-vehicle rangefinder 1 . The MODE key 121, UP key 122, and DOWN key 123 are made of synthetic resin such as plastic, for example. A miniUSB connector 126 is arranged on the upper surface 113 of the laser inter-vehicle rangefinder 1 .

CPU 101 (see FIG. 2) detects that MODE key 121, UP key 122, and DOWN key 123 have been pressed. The CPU 101 also controls lighting of the LED 125 . The CPU 101 can communicate with external devices (for example, PCs, mobile terminals, etc.) via a miniUSB connector. At the lower ends of the front face 111 and the back face 112, sighting devices 124 are arranged in the front-rear direction. A slit is provided at the lower end of the sighting device 124 . A sight 124 is used when the orientation of the laser range finder 1 is adjusted. The user looks at the slit of the sighting device 124 from behind and adjusts the direction of the laser inter-vehicle rangefinder 1 while aligning the slits of the sighting devices 124 arranged in the front and rear.

CPU 101 performs control shown in tables 961 to 964 (see FIGS. 19 to 22) based on data stored in ROM 106. FIG. The CPU 101 outputs sounds shown in a table 961 (see FIG. 19) from the speaker 105 based on the inter-vehicle distance to the other vehicle 3 measured based on the optical unit 7 . As shown in the table 961, the voice output by the CPU 101 by controlling the speaker 105 can be selected from, for example, voice 1 (announcer style), voice 2 (anime voice), and buzzer sound. If a collision occurs in X seconds from now, the CPU 101 outputs a collision notice from the speaker 105 to notify the user. Further, for example, when the other vehicle 3 is further approached from the position where the advance notice of collision is notified, the CPU 101 outputs the collision warning from the speaker 105 to notify the user of the collision. Collision warnings are different for low speeds and high speeds (see "Collision Warning (Low Speed)" and "Collision Warning (High Speed)" in table 961). Further, when the other vehicle 3 ahead starts while the own vehicle 2 is stopped, the CPU 101 outputs start information from the speaker 105 to notify the user.

When voice 1 (announcer style) is set, the CPU 101 outputs a collision warning "ah", a collision warning (low speed) "dangerous", a collision warning (high speed) "dangerous", and start information "preceding vehicle start". to output When the voice 2 (animation voice) is set, the CPU 101 outputs a collision warning "Kya", a collision warning (low speed) "Be careful", a collision warning (high speed) "Dangerous!", and start information "GO!" output. When the buzzer sound is set, the CPU 101 outputs a collision warning "beep", a collision warning (low speed) "beep beep", a collision warning (high speed) "beep beep", and start information "p-p-p-p". do.

When the UP key 122 or the DOWN key 123 is pressed long, the CPU 101 sets the sensitivity shown in the table 962 (FIG. 20). The sensitivity setting can be set between 0 and 3. When the UP key 122 is long pressed, the CPU 101 increases the sensitivity setting from 0 to 3. When the DOWN key 123 is pressed long, the CPU 101 decreases the sensitivity setting from 3 to 0. Sensitivity setting "0" is a setting of "non-detection". The CPU 101 does not detect the other vehicle 3 when setting the sensitivity to "0". Further, the sensitivity increases as the sensitivity setting goes from 1 to 3. That is, the CPU 101 facilitates detection of the other vehicle 3 .

The CPU 101 can set the state of the laser range finder 1 to any one of "S1. operation mode", "S2. glass correction mode", and "S3. detection confirmation mode" shown in the table 963 (see FIG. 21). is. The operation mode is a mode for normal operation. The glass correction mode is a mode for reducing the influence of the windshield 91 .

The glass correction mode will be explained in more detail. Part of the light emitted from the LD 72 and reaching the windshield 91 is reflected by the windshield 91 and reflected toward the photodiode 75 . For example, assuming that the light emitted from the LD 72 and reaching the windshield 91 is 100%, 95% is transmitted through the windshield 91 and emitted forward. Then, 2-3% of the light is reflected by windshield 91 and reaches photodiode 75 .

On the other hand, part of the light transmitted through the windshield 91 and emitted forward is reflected by the reflector 31 of the other vehicle 3 ahead and reaches the photodiode 75 . Since the reflector 31 exists in a part of the light irradiation range, less than 1% of the light reflected by the reflector 31 reaches the photodiode 75 . That is, the light (less than 1%) reflected by the reflector 31 and reaching the photodiode 75 is smaller than the light (2 to 3%) that is reflected by the windshield 91 and reaches the photodiode 75 . Therefore, the light reflected by the windshield 91 and reaching the photodiode 75 has a great influence. The glass correction mode is performed to reduce the influence of light reflected by the windshield 91 and reaching the photodiode 75 .

Specifically, in the glass correction mode, light is emitted from the LD 72 when there is no other vehicle 3 ahead. Since there is no other vehicle 3 ahead, the light is not reflected by the reflector 31. - 特許庁Therefore, the CPU 101 can acquire the brightness of the light reflected by the windshield 91 and reaching the photodiode 75 . In the glass correction mode, the CPU 101 stores the brightness of the light reflected by the windshield 91 and reaching the photodiode 75 in the RAM 107 or other storage medium. When detecting another vehicle 3 in the operation mode, the CPU 101 subtracts the brightness of the light reflected by the windshield 91 and reaching the photodiode 75 stored in the glass correction mode from the brightness of the detected light. This reduces the influence of the light reflected by the windshield 91 and reaching the photodiode 75 .

As shown in table 963 , when UP key 122 is pressed for a short time in “S1. operation mode”, CPU 101 increases the volume output from speaker 105 . When the DOWN key 123 is pressed for a short time, the CPU 101 reduces the volume output from the speaker 105 . When the UP key 122 is pressed long, the CPU 101 increases sensitivity (see FIGS. 20 and 21). When the DOWN key 123 is pressed long, the CPU 101 lowers the sensitivity (see FIGS. 20 and 21). When the MODE key 121 is pressed for a short time, the CPU 101 switches between voice and buzzer. More specifically, switching is made between voice 1 (announcer style), voice 2 (anime voice), and buzzer sound shown in table 961 (see FIG. 19). When the MODE key 121 is pressed long, the CPU 101 shifts the state of the laser distance finder 1 to "S2. glass correction mode".

The glass correction mode changes to "S2-1. Neutral", "S2-2. Running", and "S2-3. Completed". "S2-1. Neutral" is a mode in which nothing is done at the time of setting and waits for execution of glass correction or pressing of a cancel key. When the MODE key 121 is pressed long, the CPU 101 determines that the cancel key has been pressed. In this case, the CPU 101 shifts the state of the laser range finder 1 to "S3. detection confirmation mode" without executing glass correction. When the DOWN key 123 is pressed for a short time, the CPU 101 shifts the state of the laser range finder 1 to "S2-2. Execution" in order to execute glass correction.

In "S2-2. Execution", the CPU 101 executes the glass correction. After about three seconds have passed since the start of glass correction, the CPU 101 shifts the state of the laser range finder 1 to "S2-3. Complete". Notification of the judgment result (OK or NG). The notification is performed by, for example, outputting sound from the speaker 105 or controlling lighting of the LED 125 . When the glass correction is normally executed (OK), the CPU 101 shifts the state of the laser distance finder 1 to "S1. Operation mode". If the glass correction is not performed normally, the CPU 101 shifts the state of the laser range finder 1 to "S2-1. Neutral".

As described above, when the MODE key 121 is pressed long in "S2-1. Neutral", the CPU 101 shifts the state of the laser range finder 1 to "S3. Detection confirmation mode". The detection confirmation mode is a mode for confirming whether the direction of the laser inter-vehicle rangefinder 1 is correct. In the detection confirmation mode, for example, the detected distance is represented by the pitch of beeps. When the UP key 122 is pressed for a short time, the CPU 101 increases the volume output from the speaker 105 . When the DOWN key 123 is pressed for a short time, the CPU 101 reduces the volume output from the speaker 105 . When the MODE key 121 is pressed long, the CPU 101 shifts the state of the laser distance finder 1 to "S1. Operation mode".

CPU 101 controls the state of LED 125 as shown in table 964 (see FIG. 22). LED1, LED2, and LED3 of table 963 are included in LED125 (see FIG. 18). An LED 1 is an LED for indicating the state of the laser inter-vehicle distance finder 1 (device state). LED2 is an LED for indicating warnings and notifications to the user. LED3 is an LED for indicating an error to the user.

Assume that the laser range finder 1 is in the operating mode (see FIGS. 21 and 22). In this case, the CPU 101 lights the LED1 in green. In addition, "collision warning (high speed)", "collision notice (low speed)", "collision notice", "start information", "volume change", "sensitivity change", "notification sound change (voice)", "notification When the "sound change (buzzer)" state is reached, the CPU 101 causes "red blinking", "yellow blinking", "yellow blinking", "blue blinking", "yellow lighting (1 second)", and "blue lighting ( 1 second)”, “blue lighting (1 second)”, and “yellow lighting (1 second)”.

In addition, in the states of "Err (error) 1", "Err2", "Err3", "Err4", and "Err5", the CPU 101 flashes "red flashing", "blue flashing", "yellow flashing", The LED 3 is controlled so as to "blink green" and "blink white". Err1 is an error indicating that glass correction has not been completed. Err2 is an error indicating that the aging time after power-on is in effect. Err3 is an error indicating that the operation has stopped due to high temperature

Assume that the laser range finder 1 is in the glass correction mode (see FIGS. 21 and 22). In this case, the CPU 101 lights the LED 1 in yellow. In addition, in the states of "executing", "completed (successful)", and "unexecuted or completed (failed)", the CPU 101 indicates "lights in green", "lights in blue", and "lights in red", respectively. LED2 is controlled so that “Unexecuted or completed (failed)” is a state in which glass correction has not been completed.

Assume that the laser range finder 1 is in the detection confirmation mode (see FIGS. 21 and 22). In this case, the CPU 101 blinks the LED1 in yellow. Further, the CPU 101 lights the LED 2 in red when the vehicle ahead (that is, the other vehicle 3) is not detected, and lights the LED 2 in green when the vehicle ahead is detected. As described above, CPU 101 performs control shown in tables 961-964.

1 laser inter-vehicle rangefinder 2 host vehicle 3 other vehicle 7 optical units 31, 95 reflectors 40, 41 emission area 50 driving lane 60 emission control circuit 62 division resistor 63 DC/DC converter 64 integration circuit 71 emission unit 74 light receiving unit 75 Photodiode 76 Light receiving lens 80 Light receiving control circuit 83 Differential amplifier 84 A/D converters 89, 891, 892, 893 Light receiving region 401 First part 402 Second part 403, 404 Oblique side 614 Third resistor 621 First resistor 622 Second resistor 633 Reference input terminal 651 Fourth resistor 750 Incidence area 751 Corners 752, 753, 755, 756 Sides 761 Main lenses 762, 763 Auxiliary lenses 771, 772 Reflective surfaces 773 to 777 Non-reflective surfaces 911, 912, 913 optical central axis

Claims (3)

A device that is mounted on a vehicle and emits light to a predetermined emission area to detect an object in the emission area,
an emission section that emits light to the emission area;
a housing having an opening that opens toward the direction in which the emission area is located;
A light-receiving unit provided inside the housing so that its center is positioned above the center of the opening in the vertical direction, and receives reflected light reflected by the light emitted by the light-emitting unit. a light receiving unit that
with
the width in the horizontal direction of the first part of the emission area is smaller than the width in the horizontal direction of the second part of the emission area, which is an area below the first part;
A lens having a plurality of optical central axes is provided on the opening side of the housing.
Device. A device that is mounted on a vehicle and emits light to a predetermined emission area to detect an object in the emission area,
an emission section that emits light to the emission area;
a housing having an opening that opens toward the direction in which the emission area is located;
a light receiving unit provided at a position above the center in the vertical direction inside the housing for receiving reflected light reflected by the light emitted by the emitting unit;
with
the width in the horizontal direction of the first part of the emission area is smaller than the width in the horizontal direction of the second part of the emission area, which is an area below the first part;
The inner wall surface of the housing includes a first inclined portion located above the light receiving portion and inclined downward from the opening toward the back, and a first inclined portion located below the light receiving portion and extending toward the opening. a second inclined portion that slopes upward from the portion toward the back,
the light-receiving portion is provided closer to the first inclined portion than the second inclined portion in the vertical direction ,
A lens having a plurality of optical central axes is provided on the opening side of the housing.
Device. a reflecting portion that reflects the reflected light and guides it to the light receiving portion in a portion of the inner wall surface of the housing that is positioned above the light receiving portion; A hard-to-guide and difficult-to-reflect part are provided respectively,
2. The reflecting portion and the non-reflecting portion are arranged above the light receiving portion along the circumferential direction when the inner wall surface of the housing is viewed from the direction in which the emission area is positioned. Or the device according to 2.

Images