JPH08313302A - Position detecting device and on-vehicle laser rader - Google Patents

Abstract

PURPOSE: To provide a position detection device having a low cost and high position detection accuracy and an on-vehicle laser radar using such a position detection device. CONSTITUTION: The light emitting point of an LED 58 is arranged so as to coincide with the turning center of a slit plate 60. The center line 66c of a slit 66 is formed so as to pass through the turning center of the slit plate 60. A PSD 62 is arranged behind the slit plate 60. Accordingly, the passing light flux angle α of flux passing through the slit 66 becomes always constant, regardless of the turning angle of the slit plate 60. Therefore, a light belt of always approximately the same width WD is formed in the light accepting area 62a of the PSD 62. Since the passing light flux angle a is small, the light quantity centroid GL of the light belt approximately coincides with the crossing point 62b of the center line 66c of the slit 66 and the light accepting area 62a. That is, by measuring a distance dd, the turning angle θ of the slit plate 60 is obtained with excellent accuracy without providing a complex correction circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detection device and a vehicle-mounted laser radar, and more particularly to position detection of a movable member using a slit.

[0002]

2. Description of the Related Art In order to measure the distance between cars,
An inter-vehicle distance sensor using laser light is used. FIG. 9 shows the configuration of a conventional inter-vehicle distance sensor 2. The conventional inter-vehicle distance sensor 2 is mounted, for example, in the front part of an automobile (not shown), and includes a light emitting unit 4, a scanner 6, an angle sensor 8, and a light receiving unit 1.
0, the controller 12 is provided.

As shown in FIG. 10, the scanner 6 includes a motor (not shown) and a movable mirror 6a which rotates in association with the motor.
It has and. Further, the angle sensor 8 includes an LED 16,
The lens 18, the sensor reflecting mirror 6b formed on the back surface of the movable mirror 6a, and the PSD 20 are provided.

The light emitting section 4 emits a laser beam. The scanner 6 reciprocally scans the emitted laser light in the horizontal direction (X direction) and projects the laser light substantially in front of the vehicle (Y direction).

On the other hand, the light emitted from the LED 16 of the angle sensor 8 is narrowed down by the lens 18, reflected by the sensor reflecting mirror 6b, and then received by the light receiving area 20a of the PSD 20.
Is received by. The PSD 20 detects in which part of the light receiving area 20a the light is received, and outputs it to the controller 12, as shown in FIG.

Based on this output, the control unit 12 calculates information about the rotation angle of the scanner 6, that is, the projection direction of the laser light, and gives an instruction to the motor, whereby the scanner 6 is scanned.
Control the rotation angle of.

On the other hand, the light receiving section 10 receives, of the projected laser light, the laser light reflected by the front vehicle 14, which is the object to be detected. The control unit 12 obtains the distance to the front vehicle 14 from the time required from the emission of the laser light to the reception of the laser light. Further, the direction of the front vehicle 14 is obtained based on the information on the projection direction of the laser light. In this way, the position of the front vehicle 14 on the XY plane can be known.

[0008]

However, such a conventional inter-vehicle distance sensor 2 has the following problems. As shown in FIG. 10, the angle sensor 8 used in the conventional inter-vehicle distance sensor 2 includes an LED 16 and a lens 1 as shown in FIG.
8, the sensor reflecting mirror 6b formed on the back surface of the movable mirror 6a,
It is equipped with a PSD 20.

However, in addition to the LED 16 as a light emitting source and the PSD 20 as a light receiving body, a lens 18 is provided as an optical system element.
Moreover, the sensor reflecting mirror 6b must be used, which increases the manufacturing cost of the angle sensor 8 and thus the manufacturing cost of the inter-vehicle distance sensor 2.

To solve this problem, it is possible to use the angle sensor 22 shown in FIG. 11 (see Japanese Patent Laid-Open No. 60573/1993). The angle sensor 22 has an LED 24 and a PSD 26 that are fixedly provided, and a light shielding disk 28 that is provided between them. Shading disk 28
The spiral slit 30 is formed in the.

The light emitted from the LED 24 is a light-shielding disc 2
Although it is blocked by 8, a part of the light passes through the slit 30 and reaches the PSD 26 as long linear light in the Y direction in the figure. With this configuration, P of the light-shielding disk 28 is
-Rotational movement in the P direction, of the light passing through the slit 30,
It can be regarded as movement in the X direction.

By adopting such a structure, it is possible to obtain an inexpensive angle sensor 22 which does not use an expensive lens or a sensor reflecting mirror.

However, the angle sensor 22 has the following problems. As shown in FIG. 12A, the slit 30 is L
When it comes directly under the ED 24, the light transmitted through the slit 30 reaches the PSD 26 as an optical band having a width W1.
Therefore, a sufficient amount of light is given to the PSD 26.

However, as shown in FIG. 12B, when the slit 30 comes to a position deviating from directly under the LED 24, the light transmitted through the slit 30 reaches the PSD 26 as a light band having a width W2. Therefore, since a sufficient amount of light is not given to the PSD 26, the position detection accuracy of the PSD 26 deteriorates. In order to prevent the deterioration of the position detection accuracy, the LED 24 having a large output must be used, and an inexpensive angle sensor cannot be provided.

Further, since the amount of received light greatly differs between the state of FIG. 12A and the state of FIG. 12B, the linearity of the output current of the PSD 26 is lost. Therefore, the position detection accuracy of the PSD 26 deteriorates. In order to prevent the deterioration of the position detection accuracy, since a complicated correction circuit is required, it is still impossible to provide an inexpensive angle sensor.

In this case, the ends 30a, 3 of the slit 30 are
0b (see FIG. 11B), a method of widening the width of the slit 30 can be considered (see JP-A-5-60573). However, as shown in FIG.
When the rotational displacement in the −P direction is small, P of the light shielding plate 28 is
-Rotational displacement in the P direction and PS through the slit 30
The linearity between the position of the center of gravity of the optical band reaching D26 and the moving distance in the X direction is greatly impaired. Therefore, the position detection accuracy is extremely reduced.

The present invention solves the problems of the conventional position detecting device such as an angle sensor, is inexpensive, and has a high position detecting accuracy, and a vehicle-mounted laser radar using such a position detecting device. The purpose is to provide.

[0018]

[Means for Solving the Problems]

[0019]

[Technical idea devised to solve the problem] In order to provide an inexpensive position detection device with high position detection accuracy and a vehicle-mounted laser radar using such a position detection device, a light source is used as a light transmitting path. Among the inner walls of (1), a light beam which is substantially parallel to the reference inner wall is provided at a position where it is always supplied regardless of the position of the movable member with respect to the fixed member.

That is, the position detecting device according to claim 1 has a light source, a light shield having a light transmitting path for transmitting a part of the light from the light source, a light receiving area for receiving the light transmitted through the light transmitting path, and a light receiving area. The light receiving position detecting means for detecting the light receiving position in the area, the position information generating means for generating the position information of the movable member based on the output of the light receiving position detecting means, the light receiving position detecting means, a fixed member, or The light shield is provided on one of a movable member or a member interlocking with the movable member, and the light shield is provided on the other of the fixed member or the movable member or a member interlocking with the movable member, and the light source is the reference of the inner wall of the light transmission path The light beam that is substantially parallel to the reference inner wall is always provided regardless of the position of the movable member with respect to the fixed member.

According to a second aspect of the position detecting device of the first aspect, the light source is fixedly provided with respect to the light shield.

A position detecting device according to a third aspect is the position detecting device according to the first aspect, wherein the member provided with the light shield and the member provided with the light receiving position detecting means are configured to rotate relative to each other, Is fixedly provided with respect to the light receiving position detecting means, and is disposed substantially at the center of rotation of the rotating member.

A position detecting device according to a fourth aspect is the position detecting device according to any one of the first to third aspects, wherein the movable member is a movable optical member for optical scanning,
The movable optical member or a member interlocking with the movable optical member is provided with a light shield, and the fixed member is provided with a light receiving position detecting means.

According to a fifth aspect of the present invention, there is provided a vehicle-mounted laser radar using the position detecting device according to the fourth aspect.

[0025]

[Definition of terms] The concept of terms in the claims expressing the technical idea devised to solve the problems will be defined as follows, and the relationship between the terms and examples will be described.

"Translucent path": a light path provided in a light-shielding body for transmitting a part of light from a light source. Therefore,
It includes an elongated hole, a polygonal hole, a round hole, a notch provided in a part of the light shield, and a light passage formed of a translucent member. In the embodiment, the slit 66 of FIG. 3 corresponds.

"Reference inner wall": Among the inner walls forming the light transmitting path, an inner wall which forms an angle with the moving direction of the light shield with respect to the light receiving position detecting means is 90 ° or the angle closest to 90 °. Therefore, in addition to the inner wall orthogonal to the moving direction of the light shield with respect to the light receiving position detecting means, the inner wall intersecting the moving direction at an angle other than a right angle is also included. When the inner wall is a curved surface, it means a portion of the inner wall that is orthogonal to the moving direction. In the embodiment, the reference inner wall 66a of FIG. 1 corresponds.

"Movable optical member": A member that rotates or moves in parallel to deflect a light beam emitted from a light source for optical scanning. In the embodiment, the movable mirror 52 of FIG. 3 corresponds.

[0029]

The position detecting device according to claim 1 and the on-vehicle laser radar according to claim 5 are provided with a light shield having a light transmitting path for transmitting a part of the light from the light source, and the light source is connected to the light transmitting path. It is characterized in that a light beam, which is a reference inner wall of the inner wall and is substantially parallel to the inner wall, is always provided regardless of the position of the movable member with respect to the fixed member.

Therefore, the light-transmitting path of the light-shielding body can always transmit the light beam of the same angle regardless of the position of the movable member. Therefore, a light band having almost the same width is always formed in the light receiving area of the light receiving position detecting means. As a result, the relationship between the position of the area center of gravity of the light band formed in the light receiving area and the position of the movable member is substantially linear. Therefore, it is possible to improve the detection accuracy of the position of the movable member by the light receiving position detection means without providing a complicated correction circuit.

A position detecting device according to a second aspect is the position detecting device according to the first aspect, wherein the light source is fixedly provided to the light shield.

Therefore, the amount of light received by the light receiving area of the light receiving position detecting means is always constant. Further, the barycentric position of the amount of received light on the optical band formed in the light receiving area is always constant. Therefore, the relationship between the output of the light receiving position detecting means and the position of the movable member is substantially linear. As a result, the accuracy of detecting the position of the movable member by the light receiving position detecting means can be further improved.

According to a third aspect of the position detecting device of the first aspect, the light source is fixedly provided with respect to the light receiving position detecting means and is disposed substantially at the center of rotation of the rotating member. It is characterized by

Therefore, it is possible to integrally provide the light source and the light receiving position detecting means which both require electric wiring. Therefore, the wiring between the light source and the light receiving position detection means does not hinder the movement of both. In addition, disconnection of wiring due to relative movement does not occur.

A position detecting device according to a fourth aspect is the position detecting device according to any one of the first to third aspects, in which the movable optical member or a member interlocking with the movable optical member is provided with a light shield. The light receiving position detecting means is provided on the fixing member.

Therefore, a relatively heavy light receiving position detecting means is provided on the fixed member, and a relatively light shielding member is provided on the movable optical member for optical scanning, which requires a fast movement. Therefore, the movement of the movable optical member is not hindered.

[0037]

FIG. 2 shows the overall construction of an inter-vehicle distance sensor 32, which is a vehicle-mounted laser radar according to an embodiment of the present invention. The inter-vehicle distance sensor 32 is an automobile (not shown)
It is mounted on the front part of and has a light emitting part 34, a light receiving part 36, and a light emitting and receiving control circuit 38.

The light emitting section 34 includes a laser diode 42 for generating laser light and an LD for driving the laser diode 42.
It has a drive circuit 40, a scanner 44 that scans a laser beam, and an angle sensor 46 that is a position detection device that detects a scanning position by the scanner 44.

The light receiving section 36 receives a laser beam reflected by the front vehicle 14 and converts the laser beam into an electric signal. A light receiving circuit for adjusting the electric signal converted by the photodiode 48 for post-processing. Has 50.

The light emission / reception control circuit 38 controls the light emitting unit 34 and the light receiving unit 36, and determines the distance and direction from the inter-vehicle distance sensor 32 to the front vehicle 14 based on the information obtained from the light emitting unit 34 and the light receiving unit 36. calculate.

FIG. 3 shows the scanner 44 and the angle sensor 4.
6 shows a detailed configuration of No. 6. The scanner 44 includes a movable mirror 52 that is a movable optical member for optical scanning, and a motor 54 that rotates the movable mirror 52. The movable mirror 52 is fixedly attached to the one end 56a of the rotation shaft 56 of the motor 54, and rotates with the rotation of the motor 54 around the rotation shaft 56 parallel to the Z axis.

The angle sensor 46 uses the LED 5 which is a light source.
8, a slit plate 60 as a light shield, a PSD 62 as a light receiving position detecting means, and an angle conversion circuit 64 as a position information generating means.

The slit plate 60 includes a base portion 60a and a light shielding portion 60b, which are formed so as to be substantially orthogonal to each other. The base portion 60a includes a rotating shaft 56 of the motor 54.
Is fixedly attached to the other end 56b of the. Light-shielding part 6
A slit 66, which is a light transmission path, is provided substantially in the center of 0b. The slit 66 is formed in an elongated shape, and its longitudinal direction coincides with the Z-axis direction.

FIG. 1 is a view of the angle sensor 46 viewed from above (Z axis positive direction). As shown in more detail in FIG. 1, a straight line parallel to the center line 66c of the slit 66 (a pair of reference inner walls 66a (planes parallel to the ZY plane) serving as a reference among the inner walls of the slit 66), Inner wall 66a
A straight line that is equidistant from is formed so as to pass through the rotation center of the slit plate 60, that is, the rotation center 56c of the rotation shaft 56 of the motor 54.

The LED 58 is arranged so that its light emitting point coincides with the rotation center 56c of the rotation shaft 56 of the motor 54.

Behind the light shield 60b of the slit plate 60 (Y
The PSD 62 is disposed on the axial negative direction side) with a predetermined distance from the light shielding unit 60b. The light receiving area 62a of the PSD 62 is arranged so as to be parallel to the XZ plane. Also, in this embodiment, the optical axis center line 5 of the LED 58 is
The PSD 62 is arranged so that 8c passes through the center 62c of the light receiving area 62a in the X direction.

The LED 58 and the PSD 62 are both fixedly attached to the fixing member 68. Further, the PSD 62 has an angle conversion circuit 6 that processes the received light signal input to the PSD 62 to generate an angle signal.
4 are connected (see FIG. 3).

Next, the operation of the inter-vehicle distance sensor 32 will be described. As shown in FIG. 2, the LD drive circuit 40 drives the laser diode 42 in accordance with the regular intermittent light emission timing created by the light emission / reception control circuit 38,
Generates laser light.

As shown in FIG. 3, the laser diode 42
The laser light generated in 1 is reflected by the mirror surface 52a of the movable mirror 52, and is irradiated forward (almost in the Y-axis positive direction). The motor 54 repeatedly reciprocates the movable mirror 52 around the rotation shaft 56 in the Q direction or the R direction, thereby changing the irradiation direction of the laser light in the X direction. Therefore,
The irradiation direction of the laser light differs for each light emission timing.

The irradiation direction of the laser light at each emission timing is related to the rotation angle of the movable mirror 52 (see FIG. 4), and the rotation angle of the movable mirror 52 is detected by the angle sensor 46. That is, since the movable mirror 52 is fixedly attached to the slit plate 60 via the rotary shaft 56 of the motor 54, the rotation angle θ of the slit plate 60 is obtained to rotate the movable mirror 52. You can know the angle.

The rotation angle θ of the slit plate 60 is obtained as follows. As shown in FIG. 4, the slit plate 60
The rotation center of is the rotation center 56c of the rotation shaft 56 of the motor 54.
But also. The light emitting point of the LED 58 is arranged on the center of rotation 56C. In addition, the center line 66 of the slit 66
c passes through the rotation center 56C, that is, the light emitting point of the LED 58. Further, the optical axis center line 58c of the LED 58 is
The light receiving area 62a of 62 passes through the center 62c in the X direction.

Therefore, from the light emitting point of the LED 58, PS
If the distance from D62 to the light receiving area 62a is L and the distance from the center 62c of the light receiving area 62a in the X direction to the intersection 62b of the center line 66c of the slit 66 and the light receiving area 62a is d, the slit plate 60 turns. The moving angle θ is expressed by the following equation.

Θ = ARCTAN (d / L) ... (Equation 1) When θ is small, (Equation 1) becomes θ = d / L. It can be expressed as (Equation 2). Where ARCTAN (x) is
It represents the arctangent of x.

Since the distance L is known, the rotation angle θ of the slit plate 60 can be calculated based on the equation 1 by calculating the distance d. The distance d is obtained as follows.

As described above, since the light emitting point of the LED 58 is arranged at the center of rotation of the slit plate 60, FIG.
As shown in B, the passing light beam angle α of the light beam passing through the slit 66 is always constant regardless of the rotational position of the slit plate 60.

Therefore, regardless of the rotational position of the slit plate 60, a light band having substantially the same width WD (band-shaped light having a longitudinal dimension in the Z-axis direction) is always formed in the light receiving area 62a of the PSD 62. Since the passing light beam angle α is small, the area centroid GS of the light band substantially coincides with the intersection point 62b of the center line 66c of the slit 66 and the light receiving area 62a.

Further, the intensity of the light emitted from the LED 58 becomes maximum on the optical axis center line 58c of the LED 58 shown in FIGS. 1A and 1B and becomes smaller as the distance from the optical axis center line 58c increases, but the passing luminous flux angle α is small. Therefore, the distribution of the amount of received light on the optical band is substantially uniform. Therefore, the light amount center of gravity G defined as the center of gravity of the received light amount on the light band
L and the area center of gravity GS of the optical band substantially match. Therefore, the light quantity center of gravity GL of the light band is equal to the center line 6 of the slit 66.
6c and the light receiving area 62a intersect 62b.

That is, the distance dd between the center 62c of the light receiving area 62a in the X direction and the light quantity center of gravity GL of the light band formed in the light receiving area 62a, and the center line 66c of the slit 66.
And the distance d to the intersection 62b between the light receiving area 62a and
Almost match.

On the other hand, the ratio of the output currents Id and Ie of the PSD 62 depends on the distance dd. Therefore, by calculating the ratio of the output currents Id and Ie of the PSD 62, the distance dd
That is, the distance d can be obtained.

As shown in FIG. 4, the angle conversion circuit 64 (see FIG. 3) knows the distance d by measuring the ratio of the output currents Id and Ie flowing through the output terminals 62d and 62e of the PSD 62. The rotation angle θ of the slit plate 60 (that is, the movable mirror 52) is calculated from the known distance L.

Thus, according to this embodiment, the PSD
Since the rotation angle of the movable mirror 52 can be measured by measuring the ratio of the output currents Id and Ie of 62, the detection accuracy can be improved without providing the angle sensor 46 with a complicated correction circuit. .

When the rotation angle θ of the slit plate 60 is small, the amount of light received in the light receiving area 62a of the PSD 62 is irrespective of the rotation angle θ of the slit plate 60.
It becomes almost constant.

On the other hand, when the amount of light received in the light receiving area 62a of the PSD 62 is constant, the output current Id of the PSD 62 is
And Ie depend on the distance dd. Therefore, PS
If the output current Id or Ie of D62 is obtained, the distance dd, that is, the distance d can be obtained. That is,
It is not necessary to measure the ratio of the output currents Id and Ie as in the case where θ is large. Therefore, it is not necessary to provide the angle sensor 46 with a division circuit.

When the rotation angle θ of the slit plate 60 is small, the equation 2 can be used instead of the equation 1.
Therefore, it is not necessary to provide a complicated arithmetic circuit in the angle conversion circuit 64 (see FIG. 3).

Therefore, the angle conversion circuit 64 uses the PSD 6
The distance d is known by measuring the output current Id or Ie itself flowing through the output terminals 62d and 62e of the second.
And the known distance L, the rotation angle θ of the slit plate 60 (that is, the movable mirror 52) can be obtained.

That is, when the rotation angle θ of the slit plate 60 is small, the detection accuracy can be improved with a simpler structure.

Next, as shown in FIG. 2, the light emission / reception control circuit 38 gives a rotation control signal to the motor 54 based on the detection output of the angle sensor 46. In this way, the rotation angle of the movable mirror 52, that is, the irradiation direction of the laser light is feedback-controlled.

The emitted laser light is reflected by the front vehicle 14 and returns to the photodiode 48 when the front vehicle 14 is present. The returned laser light is converted into an electric signal by the photodiode 48. This converted electric signal is called a received light electric signal.

The light receiving circuit 50 amplifies the received light electrical signal, and when the amplified received light electrical signal is equal to or higher than a predetermined threshold value, sends the amplified light receiving electrical signal to the light emitting and receiving control circuit 38.

The light emission / reception control circuit 38 calculates the time required from the light emission to the light reception based on the light emission timing and the time when the amplified received light electrical signal is received, and based on this time, the inter-vehicle distance sensor 32 detects the front vehicle. Calculate the distance to 14. Further, the light emission / reception control circuit 38
The direction of the front vehicle 14 is calculated based on the information on the irradiation direction of the laser light sent from the angle sensor 46. In this way, the inter-vehicle distance and the direction of the forward vehicle 14 can be known.

Next, FIG. 5 shows the structure of an inter-vehicle distance sensor 72 according to another embodiment of the present invention. The inter-vehicle distance sensor 72 is an LE among the members forming the angle sensor 74.
In that the D58 is fixedly attached to the slit plate 60, as shown in FIG.
Unlike the inter-vehicle distance sensor 32, which has an angle sensor 46 that is configured to rotate relative to.

With this structure, as shown in FIG. 6, the amount of light received by the light receiving area 62a of the PSD 62 is always constant regardless of the size of the rotation angle θ of the slit plate 60.

Therefore, if the output current Id or Ie of the PSD 62 is obtained, the distance dd, that is, the distance d can be obtained. Therefore, even if the rotation angle θ of the slit plate 60 is large, the detection accuracy can be improved without providing the angle sensor 74 with a division circuit.

As shown in FIG. 6, in this inter-vehicle distance sensor 72, when fixing the LED 58 to the slit plate 60, the center line 6c of the optical axis and the center line 6 of the slit 66 are used.
6c and the optical axis center line 7
6c and the center line 66c of the slit 66 do not necessarily have to match. However, by making these coincide with each other, the detection accuracy of the angle sensor 74 can be further improved because, for example, a light band with a larger amount of light is formed in the light receiving area 62a.

Further, when fixing the LED 58 to the slit plate 60, the light emitting point of the LED 58 is arranged so as to coincide with the rotation center of the slit plate 60.
The slit plate 60 does not have to be aligned with the center of rotation.

Next, FIG. 7 shows the structure of an angle sensor 82 according to still another embodiment of the present invention. Angle sensor 8
2 is used instead of the angle sensor 46 in the inter-vehicle distance sensor 32 shown in FIG. In the angle sensor 82, the light shield portion 84b of the slit plate 84 is a plane orthogonal to the rotation axis 56, and the light shield portion 60b of the slit plate 60 is a plane parallel to the rotation axis 56 (FIG. 3). Different).

Therefore, in the angle sensor 82,
Unlike the angle sensor 46, the slit 86 is formed in a direction orthogonal to the rotation axis 56. Further, the light receiving area 62a of the PSD 62 is arranged in parallel with the light shielding portion 84b of the slit plate 84. By forming in this way,
The present invention can be applied to an inter-vehicle distance sensor even when the size of the slit plate 84 in the Z-axis direction is limited.

In each of the above embodiments, the case where the angle sensor is used as the inter-vehicle distance sensor has been described as an example.
The angle sensor according to the present invention can be used, for example, for detecting the fulcrum angle of the steering handle of an automobile.

Next, FIG. 8 shows a structure of a parallel position sensor 92 according to still another embodiment of the present invention. The parallel position sensor 82 is used to detect the amount of parallel movement of the slit plate 94, unlike the angle sensors according to the above-described embodiments.

As shown in FIG. 8, the slit plate 94 is
It is provided parallel to the Y-plane and reciprocates in the X-axis direction. The slit 96 is provided in the slit plate 94 and has a longitudinal dimension in a direction parallel to the Y axis. The LED 58 is arranged above the slit plate 94 (on the Z axis positive direction side), and the LED 58 is fixedly attached to the slit plate 94.

The light emitting point of the LED 58 is arranged so as to be located on a plane parallel to the ZY plane and including the center line 96c of the slit 96. PSD62 is
It is provided below the slit plate 94 and is fixedly attached to the fixing member 68. The light receiving area 62a of the PSD 62 is configured to be parallel to the slit plate 94.

With this structure, the amount of movement of the slit plate 94 in the X direction can be detected. That is, the present invention can be applied to a position detection device for detecting the position of a member that moves in parallel.

In each of the above embodiments, the PSD
62 is fixedly attached to the fixed member 68, and the slit plate is attached to the movable member or a member interlocking with the movable member, but conversely, the slit plate is fixedly attached to the fixed member 68 and the PSD 62 is moved to the movable member or It can also be configured to be attached to a member that interlocks with the movable member.

The LED 58, which is a point light source, is used as a light source.
However, other point light sources may be used. Further, as the light source, a line light source or a surface light source can be used in addition to the point light source. When a linear light source is used, the longitudinal direction of the linear light source is arranged in parallel with the longitudinal direction of the slit, and the longitudinal direction of the linear light source is arranged at a predetermined angle (eg 90 °) with the longitudinal direction of the slit. You can also do it.

The PSD 62 is used as the light receiving position detecting means.
However, a photodiode array in which a plurality of photodiodes are arranged may be used as the light receiving position detecting means.

Further, a slit (an elongated hole provided in the slit plate (see FIGS. 3, 5, 8
(See Fig. 7) or an elongated notch (see Fig. 7)), but as the light-transmitting path, other than the slit, a square hole, a round hole, etc. having substantially the same ratio of dimensions in the longitudinal direction and the lateral direction are used. Can be used. Further, as the light transmitting path, a part corresponding to a slit or a hole, that is, a part for transmitting light is formed by a transparent material.

In the above-described embodiment, as shown in FIG. 2, the inter-vehicle distance sensor 32 and the like are configured by hardware logic. However, a part or the whole of the hardware logic is configured by using a CPU. You may comprise.

[0088]

The position detecting device according to claim 1 and claim 5
The vehicle-mounted laser radar is equipped with a light-shielding body having a light-transmitting path that allows a part of the light from the light source to pass therethrough, and the light source emits light rays that are substantially parallel to the reference inner wall of the inner wall of the light-transmitting path. It is characterized in that it is provided at a position where it is always supplied regardless of the position of the movable member relative to the fixed member.

Therefore, the light-transmitting path of the light-shielding body can always transmit the light flux of the same angle regardless of the position of the movable member. Therefore, a light band having almost the same width is always formed in the light receiving area of the light receiving position detecting means. As a result, the relationship between the position of the area center of gravity of the light band formed in the light receiving area and the position of the movable member is substantially linear. Therefore, it is possible to improve the detection accuracy of the position of the movable member by the light receiving position detection means without providing a complicated correction circuit. That is, it is possible to obtain a position detecting device that is inexpensive and has high position detecting accuracy, and a vehicle-mounted laser radar that uses such a position detecting device.

A position detecting device according to a second aspect is the position detecting device according to the first aspect, wherein the light source is fixedly provided with respect to the light shield.

Therefore, the amount of light received in the light receiving area of the light receiving position detecting means is always constant. Further, the barycentric position of the amount of received light on the optical band formed in the light receiving area is always constant. Therefore, the relationship between the output of the light receiving position detecting means and the position of the movable member is substantially linear. As a result, the accuracy of detecting the position of the movable member by the light receiving position detecting means can be further improved. That is, it is possible to obtain a position detecting device that is inexpensive and has high position detecting accuracy.

According to a third aspect of the position detecting device of the first aspect, the light source is fixedly provided with respect to the light receiving position detecting means, and is arranged substantially at the center of rotation of the rotating member. It is characterized by

Therefore, it is possible to integrally provide the light source and the light receiving position detecting means which both require electrical wiring. Therefore, the wiring between the light source and the light receiving position detection means does not hinder the movement of both. In addition, disconnection of wiring due to relative movement does not occur. That is, it is possible to obtain a more reliable position detection device.

A position detecting device according to a fourth aspect is the position detecting device according to any one of the first to third aspects, wherein the movable optical member or a member interlocking with the movable optical member is provided with a light shield. The light receiving position detecting means is provided on the fixing member.

Therefore, a relatively heavy light receiving position detecting means is provided on the fixed member, and a relatively light shielding member is provided on the movable optical member for optical scanning, which requires fast movement. Therefore, the movement of the movable optical member is not hindered. That is, it is possible to obtain a more reliable position detection device.

[Brief description of drawings]

FIG. 1 is a view of an angle sensor, which constitutes an inter-vehicle distance sensor according to an embodiment of the present invention, seen from above.

FIG. 2 is a diagram showing an overall configuration of an inter-vehicle distance sensor according to an embodiment of the present invention.

FIG. 3 is a drawing showing a detailed configuration of a scanner and an angle sensor that constitute an inter-vehicle distance sensor according to an embodiment of the present invention.

FIG. 4 is a view showing operating states of a scanner and an angle sensor that form an inter-vehicle distance sensor according to an embodiment of the present invention.

FIG. 5 is a diagram showing a detailed configuration of a scanner and an angle sensor which constitute an inter-vehicle distance sensor according to another embodiment of the present invention.

FIG. 6 is a view of an angle sensor forming an inter-vehicle distance sensor according to another embodiment of the present invention as seen from above.

FIG. 7 is a view showing a configuration of an angle sensor which constitutes an inter-vehicle distance sensor according to still another embodiment of the present invention.

FIG. 8 is a view showing a configuration of a parallel position sensor according to still another embodiment of the present invention.

FIG. 9 is a diagram showing an overall configuration of a conventional inter-vehicle distance sensor.

FIG. 10 is a drawing showing a detailed configuration of an angle sensor that constitutes a conventional inter-vehicle distance sensor.

FIG. 11 is a view showing the configuration of another conventional angle sensor.

FIG. 12 is a view showing the operation of another conventional angle sensor.

[Explanation of symbols]

58 ... LED 60 ... Slit plate 62 ... PSD 62a ...- Light receiving area 62b ...- Intersection point of slit center line and light receiving area 66 ... Slit 66c ・ ・ ・ ・ Center line of slit dd ・ ・ ・ Distance between the center of the light receiving area in the X direction and the center of gravity of the light band GL ・ ・ ・ Center of light amount of the light band WD ・ ・ ・ Light Width of band α ・ ・ ・ ・ ・ ・ Passed beam angle θ ・ ・ ・ ・ ・ Slit plate rotation angle

Claims (5)

[Claims] 1. A position detecting device for detecting the position of a movable member relative to a fixed member, comprising: a light source; a light shield having a light-transmitting path for transmitting a part of light from the light source; The light receiving position detecting means has an area and detects the light receiving position in the light receiving area, and the position information generating means generates position information of the movable member based on the output of the light receiving position detecting means. A fixed member, or a movable member or a member that interlocks with the movable member, and the light-shielding member is provided on the other of the fixed member or the movable member or a member that interlocks with the movable member. A light beam that is substantially parallel to the reference inner wall of the inner wall of the road is always provided regardless of the position of the movable member with respect to the fixed member. Position detector. 2. The position detecting device according to claim 1, wherein the light source is fixedly provided with respect to the light shield. 3. The position detecting device according to claim 1, wherein the member provided with the light shield and the member provided with the light receiving position detecting means are configured to relatively rotate, and the light source is used as the light receiving position detecting means. A position detecting device, wherein the position detecting device is fixedly provided to the rotating member, and is disposed substantially at the center of rotation of the rotating member. 4. The position detecting device according to any one of claims 1 to 3, wherein the movable member is a movable optical member for optical scanning, and the movable optical member or the movable optical member is interlocked. The position detecting device is characterized in that a light-shielding member is provided on the member for holding, and a light receiving position detecting means is provided on the fixing member. 5. A vehicle-mounted laser radar using the position detecting device according to claim 4.