JPH10260006A - Range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve distance measurement accuracy of a range finder by measuring distance to a detected object based on the scanning angle of light before the light enters on the object. SOLUTION: Optical beam LB which is X-axially scanned using a first galvano-mirror 11 is Y-axially scanned further by a second galvano-mirror 12, and the optical beam LB is irradiated on the surface of a detected object 2. The optical beam LB which reflects on the surface of the detected object 2 is focused on a two-divided light receiving element 13 by a light receiving lens 4. Distance L from the light receiving lens 4 to the detected object 2 is calculated using rotational angle of the second galvano-mirror 12 at the moment when a light spot S is received in the intermediate point between two light receiving faces 13a and 13b of the two-divided light receiving element 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device for measuring a distance to a detected object or detecting whether or not an object exists in an area set at a predetermined distance.

[0002]

2. Description of the Related Art FIG. 1 is a perspective view showing a distance measuring device 1 according to a conventional example. In the distance measuring device 1, after the light beam LB pulsed from the semiconductor laser element 3 is collimated by the light projecting lens 9 and the light beam LB collimated by the light projecting lens 9 is reflected by the scanner 6, , The light beam LB transmitted through the half mirror 7
Is projected on the surface of the detection object 2, and the light beam LB reflected by the detection object 2 is condensed by the light receiving lens 4 on the light receiving surface of a position detecting element (hereinafter referred to as PSD) 5 for distance measurement. On the other hand, the light beam LB reflected by the half mirror 7 is received by the PSD 8 for detecting the scanning direction.

[0006] By rotating the scanner 6, the light beam LB reflected by the scanner 6 is one-dimensionally scanned along the surface of the detection object 2. This scanning direction is calculated from the output of the scanning direction detection PSD 8.

At the same time, the light receiving position on the light receiving surface of the distance measuring PSD 5 changes depending on the distance from the distance measuring device 1 to the detection object 2, so that the distance measuring device in the scanning direction detected by the scanning direction detecting PSD 8 is used. The distance from 1 to the detected object 2 is calculated based on the output of the PSD 5 for distance measurement.

Therefore, according to this distance measuring apparatus, it is possible to recognize the distance to the detection object along the scanning direction of the light beam, that is, the surface shape along the scanning direction of the light beam.

[0006]

However, in the distance measuring apparatus of the above type, the light beam reflected by the detection object is received by the PSD for distance measurement, and based on the light receiving position, the light beam is transmitted to the detection object. Therefore, the distance measurement must be performed based on the light receiving position of the poor-quality light beam after being scattered and reflected by the detection object, and the distance measurement accuracy is poor. In addition, since the surface states of the detection objects are different from each other, the conventional method of detecting the light beam reflected by the detection object has a problem that the measurement accuracy varies depending on the detection object.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described drawbacks of the prior art, and has as its object to measure a distance to a detection object based on a light beam before being projected on the detection object. Accordingly, an object of the present invention is to improve the distance measuring accuracy of the distance measuring device.

[0008]

SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a distance measuring device for judging whether or not a light projecting portion for emitting a light beam and a light beam reflected by a detection object are received at a predetermined position or a predetermined region. A light-receiving unit, a scanning unit that scans the light beam emitted from the light-emitting unit in a direction in which an angle formed with the optical axis of the light-receiving unit changes, and a scanning direction of the light beam by the scanning unit, the detection object, Means for detecting before being projected, and means for measuring a distance to a detected object based on a scanning direction when the light beam is received at a predetermined position or a predetermined area of a light receiving unit. And

In the distance measuring device according to the first aspect, the scanning direction of the light beam when the light beam is received at a predetermined position or a predetermined area of the light receiving unit is detected by the light beam before being projected on the detection object. Since the distance to the detection object is measured based on the scanning direction, the distance to the detection object can be measured based on a high-quality light beam before being scattered and reflected by the detection object. The ranging accuracy of the device can be improved.

Further, since the distance to the detection object is measured based on a high-quality light beam before being scattered and reflected by the detection object, the measurement result of the distance to the detection object is influenced by the surface condition of the detection object. And the variation in measurement accuracy can be reduced.

According to a second aspect of the present invention, in the distance measuring apparatus according to the first aspect, the scanning means for scanning the light beam in two directions and the two scanning directions of the light beam by the scanning means are detected. Means, wherein one of the scanning speed, scanning range, and scanning area of the light beam in a scanning direction different from the scanning direction used to measure the distance to the detection object is made variable.

In the distance measuring device according to the present invention, any one of the scanning speed, the scanning range, and the scanning area of the light beam is variable. By broadening the scanning range of the light beam and increasing the scanning speed to keep the light beam scanning in a coarse state, it is possible to monitor the detected object over a wide area and increase the response of the detected object recognition. it can. On the other hand, when a detected object is detected, the scanning range of the light beam is narrowed in a specific area or the scanning speed is reduced, so that the light beam scanning is made dense and the distance measurement accuracy of the detected object is increased. Can be.

According to a third aspect of the present invention, there is provided a distance measuring device which emits a light beam at a substantially constant angle with respect to an optical axis of a light receiving portion, and light emitted from the light emitting portion and reflected by a detection object. A light receiving unit that determines whether a beam is received at a predetermined position or a predetermined area; and a unit that detects an object when the light beam is received at a predetermined position or a predetermined area of the light receiving unit. It is characterized by.

The distance measuring device according to the first aspect can be used like a photoelectric switch. The distance measuring device according to claim 3 shows a configuration in that case,
In this case, since the direction of the light beam is fixed according to the detection distance or the detection area of the detection object, the light beam scanning means and the scanning direction detection means are not required, and the configuration can be simplified. it can.

Therefore, according to the distance measuring apparatus of the third aspect, the configuration is simple and the distance measuring accuracy is good.
Variations in distance measurement accuracy due to the surface state of the detected object are small, and an area-limited distance measuring device can be provided.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 2, 3 and 4 show a distance measuring apparatus 10 according to an embodiment of the present invention.
FIG. 4 is a view on arrow A in FIGS. 2 and 3. FIG. 2 shows a state when the light beam LB is projected on the point P1 or P2 in FIG. 4, and FIG. 3 shows a state when the light beam LB is projected on the point P3 in FIG. ing.

As shown in FIG. 2, the distance measuring device 10 includes a semiconductor laser device 3, a light projecting lens 9, a first galvanometer mirror 11, a second galvanometer mirror 12, a light receiving lens 4,
And an optical system including a two-division light receiving element 13 having two light receiving surfaces such as a two-division photodiode.

As shown in FIG. 5 or 6, the light receiving element 13 is divided into two light receiving surfaces 13 divided by a straight line.
a and 13b. The light receiving lens 4 opposed to the two-piece light receiving element 13 is arranged so that its optical axis passes through the dividing line (boundary) 13c of the two-piece light receiving element. The distance between
It is almost equal to the focal length f of the light receiving lens 4.

In the following description, the X-axis direction is determined in parallel with the dividing line 13c between the light receiving surfaces 13a and 13b of the two-piece light receiving element, and the Z-axis direction is determined in parallel with the optical axis of the light receiving lens. The Y-axis direction is defined in a direction orthogonal to the X-axis direction and the Z-axis direction, and the configuration of the distance measuring device will be described using these coordinate axis directions.

The semiconductor laser device 3 is arranged so as to project a light beam LB toward the first galvanometer mirror 11 in parallel with the Z axis. The first galvanometer mirror 11 is arranged such that the rotation axis is parallel to the YZ plane and forms an angle of 45 ° with the Y-axis direction. Therefore, the light beam LB projected from the semiconductor laser element 3 and collimated by the light projecting lens 9 is reflected by the first galvanometer mirror 11 and travels in parallel with the Y-axis direction, but by rotating the first galvanometer mirror 11 The light beam LB is scanned in the XY plane.

At a position facing the Y-axis direction from the first galvanometer mirror 11, the rotation axis is parallel to the X-axis.
A second galvanometer mirror 12 is provided. Then
The light beam LB reflected by the first galvanometer mirror 11 is
It is reflected obliquely downward by the second galvanometer mirror 12,
The light is projected on the surface of the detection object 2 placed diagonally below the second galvanometer mirror 12.

Therefore, when the first galvanometer mirror 11 is rotated, the light projection point on the detection object 2 moves substantially in the X-axis direction as shown in FIG. 2 or approximately in the Y-axis direction as shown in FIG.

The light beam LB reflected on the surface of the detection object 2
Is narrowed down to a small light receiving spot S by the light receiving lens 4 and is irradiated on the two-divided light receiving element 13. And 2
It is detected whether or not an image is uniformly formed between the light receiving surfaces 13a and 13b of the divided light receiving element 13 (or on the dividing line 13c). FIG. 5 shows a state where the light spot S is displaced on the light receiving surfaces 13a and 13b of the two-part light receiving element 13 with the rotation of the second galvanometer mirror 12 in the light projecting state of FIG. 2, and FIG. In the light state, the light receiving surface 13 of the two-divided light receiving element 13 is rotated by rotation of the second galvanometer mirror 12.
The light spot S is displaced on a and 13b.

(Explanation of Principle of Distance Measurement) Next, with the above-described optical configuration, the object 2
A method of calculating the distance L (distance along the Z-axis direction) based on the principle of triangulation will be described with reference to FIG. Now, the distance in the Y-axis direction between the optical axis of the light receiving lens 4 and the light projection point of the second galvanometer mirror 12 is B, and the distance between the center plane of the light reception lens 4 and the light projection point of the second galvanometer mirror 12 is The distance in the Z-axis direction is C, and the first galvanometer mirror 11
The distance in the Y-axis direction between the light projection point of the second galvanometer mirror 12 and the light projection point of the second
Is located at the focal position of the light receiving lens 4 (focal length: f). These values are determined by the optical arrangement of the distance measuring device 10. The distance of the detection object 2 is measured with reference to the center plane of the light receiving lens 4, and the distance from the center plane of the light reception lens 4 to the surface of the detection object 2 (distance along the Z-axis direction) is L. Furthermore, the rotation angle β of the second galvanometer mirror and the rotation angle β of the light beam LB by the second galvanometer mirror 12 are based on the time when the light beam LB reflected by the second galvanometer mirror 12 is reflected right below (in the negative direction of the Z axis). The deflection angle (the angle formed between the light beam LB projected on the YZ plane and the Z axis, not the angle formed between the light beam LB and the Z axis) θ2 is determined ( _second angle).
The rotation angle β of the galvanometer mirror 12 becomes β = 0 when the light reflecting surface of the second galvanometer mirror 12 forms an angle of 45 ° with the Y-axis direction). Accordingly, there is a relationship of θ ₂ = 2β between the deflection angle θ ₂ and the rotation angle β of the second galvanometer mirror 12.

The first galvanometer mirror 1 is set so that the light beam LB is projected on the surface of the detection object 2 at the position P1 or P2 in FIG.
When the second galvanometer mirror 12 is rotated with the angle of 1 fixed, the light projection point of the light beam LB on the surface of the detection object 2 moves in the Y-axis direction as shown in FIG.
Also on the light receiving surfaces 13a and 13b of the two-part light receiving element 13, as shown in FIG. 5, the image forming position of the light spot S moves in the Y-axis direction and crosses the dividing line 13c. As shown in FIG.
The center of the light spot S is divided into two lines 13 of the light receiving element 13
c, that is, two light receiving surfaces 13a, 1
Assuming that the value of the deflection angle θ ₂ of the light beam LB when the outputs from 3b become equal is θ ₂₀ , the following relationship can be easily obtained from FIG. (LC) · tan θ ₂₀ = B (1)

Two light receiving surfaces 13 of the two-divided light receiving element 13
a, When the rotational angle beta ₀ of the second galvanometer mirror 12 when the output from the equal 13b, the relationship of θ ₂₀ = 2β _0, the rotation angle of the second galvanometer mirror 12 at this time beta ₀
Is detected, the distance to the detected object 2 is obtained from the following equation (2) from the above equation (1). L = [B / tan (2β ₀ )] + C (2)

The first galvanomirror 11 is arranged so that the light beam LB is projected onto the surface of the detection object 2 at the position P3 in FIG.
FIG. 3 shows a state in which the second galvanomirror is rotated in a state where the angle is fixed. In this case, since the distance L to the detection object 2 is different, the light spot S
Are shifted in the X-axis direction, and the value of the deflection angle θ ₂₀ of the light beam or the value of the rotation angle β ₀ of the second galvanometer mirror 12 when the outputs of the two-segment light receiving elements 13 are equal are different. However, also in this case, the distance L to the detection object 2 is
Is obtained from the above equation (2).

Therefore, the first galvanometer mirror 11 and the second
While rotating the galvanomirror 12, the rotation angle α of the first galvanomirror 11 when the two outputs of the two-piece light receiving element 13 become equal, and the second galvanomirror 1 at that time.
If the rotation angle β ₀ (α) is detected, the distance to the detection object 2 can be measured by the following equation (3) as a function of the rotation angle α of the first galvanometer mirror 11. L (α) = [B / tan [2β ₀ (α)]] + C (3) As a result, the function L of the rotation angle α of the first galvanometer mirror 11 is obtained.
As (α), the surface shape of the detection object 2 (cross section) on the ZX plane including the optical axis of the light receiving lens 4 can be obtained.

Further, the distance L to the detection object 2 can be easily obtained as a function of the coordinates in the X-axis direction. FIG.
Is a diagram showing a ray trajectory along the ray path of the light beam LB from the reflection by the first galvanometer mirror 11 to the surface of the detection object (actually, the light beam LB is the second
It is bent at the reflection point of the galvanometer mirror 12). As is clear from this figure, the scanning angle of light by the first galvanometer mirror 11 with respect to the Y-axis direction is defined as θ ₁ , and the scanning angle θ ₁
Assuming that x = 0 in the X-axis direction on the surface of the detection object 2 when = 0, the detection object on which the light beam LB with the scan angle θ ₁ is projected when the two outputs of the two-piece light receiving element 13 are equal. The x coordinate of the light projection point (detection point) on the two surfaces is represented by the following equation (4). x = [D + (B / sin θ ₂₀ )] tan θ ₁ (4)

Further, if the rotation angle of the first galvano mirror 11 is α based on the attitude of the first galvanomirror 11 when the light beam LB reflected by the first galvanomirror 11 is emitted in parallel with the Y axis, Since the scanning angle θ ₁ of the light beam is represented by θ ₁ = 2 (α / √2), the above equation (4) is expressed as follows: x = [D + [B / sin (2β ₀ )] tan (√2α) ... (5) can be written.

Therefore, the above equations (3) and (5), namely, L (α) = [B / tan [2β ₀ (α)] + C (3) x = [D + ｛B / sin [2β _0] (Α)]｝] tan (√2α) (5) By eliminating the scanning angle α from (5), the distance to the detection object 2 can be expressed as a function L (x) of the x coordinate, and A dimensional surface (irregularity) shape can be obtained.

FIG. 8 is a block diagram showing the electrical configuration of the distance measuring device 10 of the above-described type. In the distance measuring device 10, the light projecting system includes a semiconductor laser device 3, a semiconductor laser device (LD) drive circuit 20, a first galvanometer mirror 11, and a galvanometer mirror drive circuit 21 that rotationally drives the first galvanometer mirror 11. , 2nd galvanometer mirror 1
2, a galvanomirror driving circuit 22 for rotating and driving the second galvanomirror 12 and a control circuit 23.

The semiconductor laser device driving circuit 20 controls the semiconductor laser device 3 based on a control signal from the control circuit 23.
Is pulsed to emit a light beam L from the semiconductor laser element 3.
B is emitted. At the same time, the galvanomirror driving circuits 21 and 22 rotate the first and second galvanomirrors 11 and 12, respectively, based on a control signal from the control circuit 23. Due to the rotation of the first and second galvanometer mirrors 11 and 12, the light beam LB emitted from the semiconductor laser element 3 and collimated by the light projecting lens 9 is projected on the surface of the detection object 2 in the X-axis direction and the Y-axis direction. Dimensionally scanned.

The measuring system of the distance measuring device 10 includes a first encoder 2 for detecting the rotation angle α of the first galvanometer mirror 11.
7. Second detection of rotation angle β of second galvanometer mirror 12
Encoder 28, two-segment light receiving element 13 having two light receiving surfaces 13a, 13b, two light receiving amplifiers 24a, 24
b, differential amplifier 25, comparator 26, and arithmetic circuit 2
9.

The rotation angles α and β of the first and second galvanometer mirrors 11 and 12 are detected by the first and second encoders 27 and 28, and the detected values of the rotation angles α and β are always sent to the arithmetic circuit 29. ing. Here, if rotary encoders are used as the first and second encoders 27 and 28, higher measurement accuracy can be obtained as compared with the case where a rotation angle is measured by a half mirror and a PSD.

The light receiving signals I ₁ ,
I ₂ is received amplifiers 24a, after being amplified while being converted into voltage signals V _1, V ₂ by 24b, is converted by the differential amplifier 25 the difference signal (V ₂ -V _1), the difference (V ₁ −V ₂ ) is compared with a constant threshold value Vth in the comparator 26. When the difference (V ₁ −V ₂ ) becomes equal to or less than a predetermined threshold value Vth, the arithmetic circuit 29 calculates the rotation angle α of the first galvanometer mirror 11 and the second rotation angle α from the outputs of the first and second encoders 27 and 28 at that moment. Rotation angle β of galvanometer mirror 12
₀ is read, and the distance L (α) of the detected object 2 at the rotation angle α (or the scanning angle θ ₁ ) is obtained by the above equation (3)
And store it in memory. Alternatively, the distance L (x) at the coordinate x on the surface of the detection object 2 is obtained by the above equations (3) and (5) and stored in the memory.

In this way, for example, when the distance L (x) relating to the x coordinate on the surface of the detection object 2 is obtained, the arithmetic circuit 2
9 outputs the result as distance information or surface shape information of the detected object 2.

According to the distance measuring apparatus of the present invention, as shown in the above equation (3), when the light spot S is positioned on the dividing line 13c of the two-part light receiving element 13, the second galvanomirror Since the distance L of the detection object 2 can be obtained from the rotation angle β ₀ or the direction θ ₂₀ of the light beam LB, the high-quality light beam L before being scattered and reflected by the detection object 2 can be obtained.
The distance to the detection object 2 can be obtained based on the scanning direction of B (or a variable for controlling the scanning direction of the light beam LB), and the distance detection accuracy can be increased. Also, since it is not affected by the surface condition of the detection object 2,
Variations in detection accuracy are unlikely to occur. The two-divided light receiving element 13 detects the light reflected by the detection object 2, but does not detect the light receiving position as in the conventional example.
Since it is only necessary to determine whether or not it is located at a predetermined position or a fixed area (in this embodiment, on the dividing line 13c), the determination accuracy can be increased as compared with detecting the light receiving position by PSD.

The above embodiment can be variously changed in design. For example, in the above embodiment, whether or not a light spot is received at a predetermined position or a predetermined area of the light receiving element is detected by the two-divided light receiving element 13.
It is also possible to determine whether or not light is received at a predetermined position or a predetermined area (that is, a slit position) by a combination of a slit corresponding to the dividing line and a light receiving element such as a photodiode.

In the above-described embodiment, the rotation angles of the first galvanometer mirror 11 and the second galvanometer mirror 12 are directly detected by the first and second encoders 27 and 28. Galvanometer mirror 12
A pulse step motor may be used as an actuator for rotating the mirror, and the rotation angles of the first and second galvanometer mirrors 11 and 12 may be detected from a control signal for driving the pulse step motor.

Alternatively, a light receiving element such as a photodiode is provided at the scanning start position of the light beam LB to detect the scanning start time, and the scanning direction of the light beam LB is known from the time from the scanning start and the scanning speed. Is also good.

Also, by using a half mirror,
A part of the light beam LB immediately after being scanned by the first and second galvanometer mirrors 11 and 12 may be guided to a PSD or a CCD, and the scanning direction of the light beam LB may be detected from the light receiving position. Even in such a configuration, it is possible to improve the measurement accuracy by detecting the scanning direction of the undisturbed light beam LB before entering the detection object 2 and measuring the distance L of the detection object 2 based on the detection direction. it can.

(Second Embodiment) FIG. 9 is a schematic structural view showing an area-limited type distance detecting device 30 according to another embodiment of the present invention. In this distance detection device 30, the angle of the second galvanometer mirror 12 is fixed so that the scanning angle θ ₂ of the light beam LB reflected by the second galvanometer mirror 12 becomes a fixed angle θ _0, and the detection object 2 is moved by a predetermined distance. Alternatively, the distance measurement device 30 outputs the signal only when the distance measurement device 30 exists in a predetermined area. That is, the distance of the detection object 2 to be detected is L
In this case, the angle of the light beam LB is set to an angle θ ₀ that satisfies L = [B / tan (θ ₀ )] + C (6). Thus, the distance detecting device 10 can be used like a photoelectric switch. The detection range can be adjusted by the magnitude of the threshold value ± Vth of the comparator 26.

For example, FIGS. 9 and 10 illustrate the case where the warpage of the lead of the IC 31 is detected. The light beam LB is emitted from the distance measuring device 30 to the lead 32 of the IC 31 set at a predetermined position. By driving the first galvanomirror 11, the light beam LB is emitted along the line of the lead 32. ing. Here, lead 32
In the case where there is no warpage, the lead 32 which is not detected by the distance measuring device 30 and warps upward as shown in FIG.
Is to be detected.

For example, the light beam LB reflected by a non-warped lead 32, such as the lead 32 at the left end or right end in FIG. 10A, is not received on the dividing line 13c of the two-part light receiving element 13. As shown in b), the output (V ₂ −V ₁ ) of the difference amplifier 25 is within the threshold range ± V of the comparator 26.
It is outside th and is not output from the arithmetic circuit 29. On the other hand, if the lead 32 is warped, the output (V ₂ −V ₁ ) of the differential amplifier 25 becomes equal to the threshold range ± of the comparator 26 as shown in the second lead 32 from the right in FIG. Vth
The detection signal is output from the arithmetic circuit 29 as shown in FIG.

As a result, the lead 3 of the IC 31 to be inspected
It is possible to detect how many of the leads 2 are warped and at what position the leads 32 are warped. Further, in such a usage method, the configuration can be simplified, and the arithmetic circuit 29 does not require a complicated operation.

In this embodiment, since the angle of the second galvanomirror 12 is fixed, the second galvanomirror 12 is limited to such a usage.
May be omitted. That is, the light beam 11 scanned by the first galvanometer mirror 11 may be directly applied to the detection object 2.

(Third Embodiment) FIG. 11 is a schematic plan view showing a light projecting system of a distance measuring device 40 according to still another embodiment of the present invention. In this distance measuring device 40,
A telecentric scan lens 41 is inserted between the first galvanometer mirror 11 and the second galvanometer mirror 12.

When the telecentric scan lens 41 is disposed in front of the first galvanometer mirror 11, the light beam LB reflected by the first galvanometer mirror 11 passes through the telecentric scan lens 41 and then travels along the Y axis as shown in FIG. It is converted into a parallel light beam parallel to the direction. Therefore, when observed on the ZX plane, the first embodiment (FIG. 4)
Light beam LB obliquely to the detection object 2 as in the case of
Is not radiated, and as shown in FIG. 12, the light beam LB can be scanned in the X-axis direction while being parallel to the Z-axis.
The absolute position of the light projection point on the detection object 2 can be easily obtained from the scanning angles of the first and second galvanometer mirrors 11, 12.

More specifically, the first galvanomirror 11
Assuming that the distance between the optical lens and the telecentric scan lens 41 is E, the x coordinate of the light beam LB is as follows: x = Etan (θ ₁ ) = Etan (√2α) (7), and the above equation (4) or (5) It is simpler than the formula.

(Fourth Embodiment) FIGS. 13A and 13B are views showing a distance measuring apparatus 42 according to still another embodiment of the present invention. This distance measuring device 42 measures the distance of an object passing below the two-divided light receiving element 13 and the light receiving lens 4, and changes the rotation range and the rotation speed of the first galvanometer mirror 11 to change the object. The scanning range and scanning speed of the light beam LB in the X-axis direction can be changed before and after the detection.

More specifically, while the detection object 2 is not detected, as shown in FIG. 13A, the distance measuring device 42 controls the scanning range and scanning speed of the light beam LB by the first galvanometer mirror 11. To the maximum. Therefore, although the detection accuracy is coarse, the presence or absence of the detection object 2 is monitored over a wide range with a coarse resolution. When detecting the detection object 2, the distance measurement device 42 narrows the scanning range of the light beam LB to the minimum range including the detection position of the detection object 2 as shown in FIG. . Distance measuring device 4
2 precisely measures the distance to the detection object 2 in this state.

By making the scanning range and scanning speed of the light beam LB variable as described above, the speed of object detection can be increased, and the distance can be measured with a fine resolution at the time of distance measurement.
The surface shape of the detection object 2 can be measured finely.

When detecting the surface shape of the detection object 2 placed below the light receiving lens 4, even if the position of the detection object 2 is uncertain, the position of the detection object 2 is automatically found at high speed ( (FIG. 13A) Then, the surface shape of the detection object 2 can be detected in a state where the resolution is made fine (FIG. 13B).

In the above embodiment, the galvanomirror is used as the light scanning means. However, the present invention is not particularly limited. For example, a polygon mirror other than the galvanomirror may be used. In the above embodiment, two galvanometer mirrors are combined, but only one raster scan type scanner may be used.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a conventional distance measuring device.

FIG. 2 is a schematic front view showing a distance measuring device according to an embodiment of the present invention.

FIG. 3 is a front view showing a state where light beams are projected on different positions of a detection object in the distance measuring device of the above.

FIG. 4 is a view taken in the direction of arrow A in FIG. 2 or FIG. 3;

FIG. 5 is a diagram showing an image forming state of a light spot on a two-segment light receiving element in the light projecting state of FIG. 2;

FIG. 6 is a diagram showing an image forming state of a light spot on a two-segment light receiving element in the light projecting state of FIG. 3;

FIG. 7 is a diagram illustrating the relationship between the rotation angles of first and second galvanometer mirrors and the position of the light projection point on the surface of the detection object in the x-axis direction in the distance measuring device.

FIG. 8 is a block diagram showing an electrical configuration of the above distance measuring device.

FIG. 9 is a schematic front view showing a distance measuring device according to another embodiment of the present invention.

10A is an explanatory diagram showing a state of scanning a light beam along a lead, FIG. 10B is a diagram showing a signal output from a differential amplifier to a comparator, and FIG. 10C is a diagram showing a signal output from an arithmetic circuit; FIG.

FIG. 11 is a schematic plan view showing a distance measuring device according to still another embodiment of the present invention.

FIG. 12 is a diagram showing a state in which a light beam is scanned on a detection object in the distance measuring device.

13A and 13B are explanatory views of a distance measuring device according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 1st galvanometer mirror 12 2nd galvanometer mirror 13 Two-segment light receiving element 25 Differential amplifier 26 Comparator 27 1st encoder 28 2nd encoder 29 Arithmetic circuit 41 Telecentric scan lens

Claims (3)

[Claims] A light-emitting unit that emits a light beam; a light-receiving unit that determines whether a light beam reflected by a detection object is received at a predetermined position or a predetermined area; Scanning means for scanning in a direction in which the angle between the light beam and the optical axis of the light receiving unit changes, and means for detecting the scanning direction of the light beam by the scanning means before the light beam is projected onto a detection object; Means for measuring a distance to a detection object based on a scanning direction when a light beam is received at a predetermined position or a predetermined area of the light receiving unit. 2. A scanning device comprising: a scanning unit for scanning a light beam in two directions; and a unit for detecting two scanning directions of the light beam by the scanning unit, wherein the scanning unit is used for measuring a distance to a detection object. The distance measuring apparatus according to claim 1, wherein one of a scanning speed, a scanning range, and a scanning area of the light beam in a scanning direction different from the direction is made variable. 3. A light projecting unit for emitting a light beam at a substantially constant angle with respect to an optical axis of a light receiving unit, and a light beam emitted from the light projecting unit and reflected by a detection object at a predetermined position or a predetermined area. A distance measuring device comprising: a light receiving unit that determines whether light is received; and a unit that detects an object when the light beam is received at a predetermined position or a predetermined area of the light receiving unit.