JP3214686B2 - Light deflection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light deflecting device used for a distance measuring sensor or the like using a light beam.

[0002]

2. Description of the Related Art FIG. 1 shows a measuring principle in a distance measuring sensor using a light beam. An optical deflector and a light receiving device (both not shown) constituting the distance measuring sensor are separated by two distances l. In the case where the light beam is emitted from the point A to the object A and the reflected light is received by the light receiving device, that is, the point B, the light beam at the point A and the point Assuming that the angle (deflection angle) with the straight line connecting the points I and B is β, and the angle (light receiving angle) between the light beam at the point B and the straight line connecting the points I and B is β, The distance L is obtained by the following equation: L = ltantantantan / tantantantan.

Here, if the light receiving angle β when the deflection angle α of the light beam is continuously changed by the light deflector is measured, a continuous distance L from the object A, that is, the object A Can be measured. As can be seen from the above equation, the measurement accuracy in this case is determined by the accuracy of the deflection angle in the light deflecting device and the accuracy of the light receiving angle in the light receiving device.

Conventionally, a galvanometer mirror or a polygon mirror has been used as an optical deflection device.

As shown in FIG. 2, a galvanometer mirror is a driving device for a galvanometer used as an electric instrument, that is, a driving device 5 including an electromagnetic coil 1, a magnet 2, a yoke 3, a shaft 4, and the like. Instead, a mirror 6 is mounted, and the mirror 6 is reciprocated at a predetermined angle to deflect the light beam from the light source 7. In the galvano mirror, the rotation angle of the mirror 6 can be made almost proportional to the circuit current by carefully designing a magnetic circuit including the electromagnetic coil 1, the magnet 2, the yoke 3, and the like and a balancing spring (not shown). High accuracy can be obtained with a simple structure (however, in practice, since a driving torque is insufficient, a kind of DC servo motor is often used as a driving device).

[0006]

However, in the galvanomirror described above, since the driving device 5 and the mirror 6 are separated from each other, when the mirror is operated at high speed, the shaft 4 and the mirror 6 are twisted, and the rotation angle and the circuit current are reduced. Is not maintained. Therefore, when used in the distance measurement sensor described with reference to FIG. 1, the deflection angle of the light beam becomes inaccurate, and there is a disadvantage that an error occurs in the distance to be obtained. In addition, since the rotation of the shaft 4 is a reciprocating motion, it is difficult to sufficiently lubricate the shaft 4 and a bearing (not shown), and friction is likely to occur. There was a drawback that it would be.

As shown in FIG. 3, a polygon mirror, in which a polygon mirror, here a hexahedron, is provided with a mirror on each side of a hexahedron, is attached to a shaft 10 of a motor 9 and is rotated at a high speed to thereby provide a light source 7. This is to deflect the light beam from the light source. The optical sensor 11 emits a signal when a light beam deflected by each mirror surface of the rotating mirror 8 enters, and this signal is used as a synchronization signal of the optical deflector. In the polygon mirror, if the rotation speed of the rotating mirror 8 is constant and known, the deflection of the light beam is measured by measuring the lapse of time from when the synchronization signal is generated (when the light beam enters the optical sensor 11). The angle can be known indirectly.

In the polygon mirror, since the rotational unevenness of the rotary mirror 8 directly affects the accuracy, a large multi-pole motor is generally employed to reduce the rotational unevenness of the motor itself and reduce the weight of the rotary mirror 8. Since the rotational unevenness is suppressed by increasing the rotational speed and increasing the rotational moment due to the inertia moment, there is a disadvantage that downsizing is difficult.

Further, since these two light deflecting devices both use a mechanical mechanism, when they are mounted on an arm of an industrial robot, for example, the deflection angle is affected by the acceleration due to the operation of the arm. There was the disadvantage of being inaccurate.

It is an object of the present invention to provide a light deflecting device which is small, has high accuracy at the time of high-speed operation, has a long life, and is resistant to external acceleration.

[0011]

According to a first aspect of the present invention, there is provided an optical deflecting device for deflecting a light beam emitted from a light source at a predetermined angle. A second light beam having an electromagnetic coil, an iron piece and a movable part made of an elastic body supporting the iron piece, and a mirror mounted on the movable part are provided, and a current is intermittently applied to the electromagnetic coil. An optical sensor that deflects the two light beams by a deflecting device that vibrates the movable portion by flowing the light, and outputs a signal corresponding to the incident position of the light,
An optical deflector provided at the irradiation position of the deflected second light beam is proposed.

According to a second aspect of the present invention, there is provided a light beam splitting means for splitting a light beam before deflection, and one of the light beams split by the light beam splitting means is used as a second light beam. The light deflecting device according to item 1 is proposed. According to a third aspect of the present invention, a light beam splitting means for splitting the deflected light beam is provided, and the light beam emitted from the light source is directly incident on the deflector, and the deflected light beam is split into the light beam splitting means. The light deflecting device according to claim 1, wherein one of the light beams is divided as a second light beam.

According to a fourth aspect of the present invention, there is provided an optical deflecting device according to any one of the first to third aspects, wherein a damper is mounted on a movable portion of the deflecting device. In a fifth aspect of the present invention, there is provided an optical deflecting device according to any one of the first to fourth aspects, wherein a deflecting device including a prism is used instead of the mirror.

[0014]

According to the first aspect of the present invention, since the light beam is deflected by the deflecting device including the electromagnetic coil, the movable portion made of an iron piece and an elastic body, and the mirror, the shaft or the like is attached to the movable portion itself. There is no bearing, wear is less likely to occur even at high speed operation, it is easy to reduce the size and weight, and the optical sensor that outputs a signal according to the light incident position always measures the deflection angle of the light beam Therefore, high-precision deflection can be realized, and the deflection accuracy does not deteriorate even when an external acceleration is applied.

According to the second aspect, the light beam before deflection is split by the light beam splitting means, and one of them is used as the second light beam, so that the deflection direction of the second light beam can be arbitrarily set. Can be set to According to the third aspect, the deflected light beam is split by the light beam splitting means, and one of them is used as the second light beam, so that the deflection device can be made more compact.

According to the fourth aspect of the present invention, the vibration in the movable portion of the deflection device can be suppressed by mounting the damper. According to the fifth aspect, by using a deflecting device having a prism instead of a mirror, deflection without reflection loss as in the case of a mirror can be realized.

[0017]

FIG. 4 shows a first embodiment of the optical deflecting device of the present invention. In FIG. 4, reference numeral 20 denotes a light source, 30 denotes a light beam dividing means, 40 denotes a deflecting device, and 50 denotes an optical sensor.

The light source 20 emits one light beam. Here, a semiconductor laser is used. The light beam splitting means 30 splits a light beam, and here comprises a diffraction grating 31 and a slit 32. The light beam splitting means 30 is disposed between the light source 20 and the deflecting device 40, splits one light beam emitted from the light source 20 into a plurality of light beams by the diffraction grating 31, and splits the split light beam. Of these, the 0-order light is the first light beam 61 for distance measurement, and one of the primary lights (the primary light appears on both sides) is the second light beam 62 for deflection angle measurement, An extra diffracted light beam is removed by the slit 32.

The deflecting device 40 includes an electromagnetic coil 41, a movable part 42, and a mirror 43 mounted on the movable part 42. The movable part 42 has an iron piece 42a as shown in FIG.
The iron piece 42a includes an elastic body 42b and a frame 42c. The iron piece 42a is attached to one end of the elastic body 42b and is supported via the frame 42c so as to be able to vibrate so as to be orthogonal to the axial direction of the electromagnetic coil 41. The deflecting device 40 is configured such that the first and second light beams 61 and 62 are
It is arranged so that it may hit. 42d is a damper for vibration control.

Here, when a current is applied to the electromagnetic coil 41, the iron piece 42a receives the magnetic force, and the elastic body 42b is bent and drawn to the electromagnetic coil 41. Therefore, the iron piece 42a
Is swung so as to approach the electromagnetic coil 41. At this time, since the mirror 43 is also swung at the same time, the light beam is deflected downward in FIG. Next, when the current of the electromagnetic coil 41 is cut off, the magnetic force disappears, so that the resilient force of the elastic body 42b causes the iron piece 42a to further swing from the original position to the opposite side due to inertia.
The light beam is deflected upward in FIG. The operation is similar to that of a buzzer, and a light beam can be deflected up and down by intermittently supplying a current to an electromagnetic coil. According to this structure, there is no such thing as a shaft or a bearing for connecting the movable part, and there is no fear of abrasion. Therefore, performance is not degraded, and stable operation can be expected for a long time.

Further, in the movable section 42, if the iron piece 42a contacts the electromagnetic coil 41, a problem of vibration or noise may occur, or the operation of the movable section 42 may be disturbed. I have. However,
The iron piece 42a may come into contact with the electromagnetic coil 41 due to a transient current at the time of turning on the power or vibration applied from the outside. Since the electromagnetic force is roughly inversely proportional to the cube of the distance, once it comes into contact, it will be in a state like over-excitation, and it will not return to its original state as it is. Therefore, the vibration is controlled by the damper 42d.

The optical sensor 50 outputs a signal according to the incident position of the light beam, and here comprises a semiconductor element (PSD) that outputs a photocurrent according to the incident position of the light. The optical sensor 50 reflects the second light reflected by the mirror 43.
And the deflection angle is read from the incident position of the second light beam.

Next, the operation of the device will be described.

The light beam emitted from the semiconductor laser 20 is split into a plurality of light beams by a diffraction grating 31, and the zero-order light is used as a first light beam 61 for distance measurement and one of the primary lights Is taken out as a second light beam 62 for measuring the deflection angle, and the remaining light beam is removed by the slit 32. The first light beam 61 and the second light beam 62 impinge on the mirror 43 of the deflecting device 40 and are reflected.

The reflected first light beam 61 is projected onto an object (not shown), and the second light beam 62 is incident on the optical sensor 50. It changes depending on the angle. As described above, since the optical sensor 50 outputs a signal corresponding to the incident position of light,
The deflection angle of the second light beam 62 can be obtained from the signal, and the first light beam is reflected by the same mirror 43 as the second light beam, and the deflection angle becomes the same. The deflection angle of one light beam can also be obtained.

Since it is sufficient that the first and second light beams are always in a fixed relationship, the angle of the deflecting device 40 between the portion where the first light beam hits and the portion where the second light beam hits is adjusted. As the two different mirrors, the deflection direction of the first light beam and the deflection direction of the second light beam can be set separately.

In this embodiment, the diffraction grating and the slit are used as the light beam splitting means. However, a cube beam splitter constituted by combining prisms can be used. Further, in this embodiment, the two split light beams are both incident on the deflecting device and deflected. However, one light beam is incident and the deflected light beam is
A configuration in which the book is divided into books is also possible.

FIG. 6 shows a second embodiment of the present invention, in which one light beam is split after being deflected. That is, in the drawing, reference numeral 70 denotes a light beam splitting means including a diffraction grating 71 and a slit 72, which is disposed between the deflecting device 40 and the optical sensor 50. The diffraction grating 71 and the slit 72 are configured so as to correspond to the deflection range of one light beam after being deflected by the deflector 40, and thereby, similar to the first embodiment, for the distance measurement. One light beam and a second light beam for measuring the deflection angle can be obtained. Other configurations and operations are the same as those of the first embodiment.

In the light deflecting device of the present invention, unlike the conventional galvanometer mirror or polygon mirror, it is difficult to estimate the deflection angle of the light beam from the circuit current or other information.
Therefore, the deflection angle of the light beam is constantly measured using an optical sensor. Further, in principle, it is not possible to control the deflection angle of the light beam to a desired angle at an arbitrary time, but this does not pose a problem when measuring the contour shape of the object as described with reference to FIG.

The optical deflection apparatus of the present invention has the following advantages as a result of constantly measuring the deflection angle.

(1) A deflection device having a structure similar to a buzzer as shown in this embodiment is advantageous in terms of miniaturization and weight reduction and cost reduction, but the relationship between the current flowing through the electromagnetic coil and the deflection angle is elastic. Because of the elasticity of the body, there is no linear relationship. In addition, when operated at high speed, a delay occurs due to inertia, and it is difficult to determine the deflection angle from the current of the electromagnetic coil. However, since the deflection angle is always measured in the apparatus of the present invention, such a defect does not occur, and the advantages of small size, light weight, and low cost can be utilized.

(2) Since the deflection angle is always measured in the device of the present invention, even if the deflection angle of the mirror is disturbed by an externally applied acceleration, for example, when the mirror is attached to a robot arm, the deviation is not affected. Angle can be measured when
No problem.

The drawback of the apparatus of the present invention is that it is necessary to add an optical sensor for measuring the deflection angle and an arithmetic circuit for obtaining the deflection angle from the output signal thereof. This is not particularly problematic because the effect of reducing the cost of the deflecting device is greater than ever.

[0034]

As described above, according to the first aspect of the present invention, the light beam is deflected by the deflecting device including the electromagnetic coil, the movable portion including the iron piece and the elastic body, and the mirror. There is no shaft or bearing in the movable part itself, and it is hard to wear even when operated at high speed, and it is easy to reduce the size and weight.
In addition, the optical sensor that outputs a signal corresponding to the incident position of the light can always measure the deflection angle of the light beam, so that high-precision deflection can be realized, and the deflection accuracy does not deteriorate even when an external acceleration is applied. There is an advantage.

According to the second aspect of the present invention, the light beam before deflection is split by the light beam splitting means, and one of the split light beams is used as the second light beam to deflect the second light beam. The direction can be set arbitrarily. According to the third aspect of the present invention, the deflected light beam is split by the light beam splitting means, and one of them is used as the second light beam, so that the deflection device can be made more compact.

Further, according to the fourth aspect of the present invention, the vibration in the movable portion of the deflecting device can be suppressed by mounting the damper. According to the fifth aspect of the present invention, by using a deflecting device having a prism instead of a mirror, deflection without reflection loss as in the case of a mirror can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a measurement principle in a distance measurement sensor using a light beam.

FIG. 2 is a configuration diagram showing an example of a conventional light deflection device.

FIG. 3 is a configuration diagram showing another example of a conventional light deflecting device.

FIG. 4 is a configuration diagram showing a first embodiment of the light deflecting device of the present invention.

FIG. 5 is an explanatory diagram showing a detailed configuration and operation of the deflection device.

FIG. 6 is a configuration diagram showing a second embodiment of the light deflecting device of the present invention.

[Explanation of symbols]

20 light source, 30, 70 light beam splitting means, 31, 7
DESCRIPTION OF SYMBOLS 1 ... Diffraction grating, 32,72 ... Slit, 40 ... Deflecting device, 41 ... Electromagnetic coil, 42 ... Movable part, 42a ... Iron piece,
42b: elastic body, 43: mirror, 50: optical sensor.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-202713 (JP, A) JP-A-56-147116 (JP, A) JP-A-56-146115 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) G02B 26/10

Claims (5)

(57) [Claims] 1. An optical deflector for deflecting a light beam emitted from a light source by a predetermined angle, comprising: preparing a second light beam having a predetermined relationship with the light beam; A movable portion made of an elastic body to be supported, and a mirror mounted on the movable portion,
An optical sensor that deflects the two light beams and outputs a signal corresponding to a light incident position by a deflecting device that oscillates a movable portion by intermittently flowing an electric current to an electromagnetic coil is used as a second optical sensor after the deflection. An optical deflecting device provided at a light beam irradiation position. 2. A light beam splitting means for splitting a light beam before deflection is provided, and one of the light beams split by the light beam splitting means is used as a second light beam. 2. The light deflecting device according to 1. 3. A light beam splitting means for splitting the deflected light beam, wherein the light beam emitted from the light source is directly incident on the deflector, and the deflected light beam is split by the light beam splitting means. 2. The light deflecting device according to claim 1, wherein one of the light beams is used as a second light beam. 4. The optical deflecting device according to claim 1, wherein a damper is mounted on a movable portion of the deflecting device. 5. The optical deflecting device according to claim 1, wherein a deflecting device having a prism is used instead of the mirror.