JPH11212013A - Mirror drive type scanner and laser sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the mirror drive type scanner and laser sensor which are simple in structure and easily made compact. SOLUTION: When a laser sensor 3 receives an operation command from a controller 30,a laser driving part 22 drives a laser oscillator 11 to generate a laser beam 5. Simultaneously, an actuator which drives a reflecting mirror 12 and is induced with an AC driving voltage supplied form the mirror driving part 21 to vibrate. The vibration of the actuator is converted into the swing motion of the reflecting mirror 12 directly or indirectly by using a rod member, a rotating member, a crank mechanism, etc., and an object surface G is scanned with the laser beam 5 according to the motion. The laser beam which is diffused and reflected at a reflection point S on the object surface G foms an image on the photodetection surface of a photodetector 15 by an optical system 14. The imaging position on the light receiving surface varies with the position of the reflection point S. The three-dimensional position of the reflection point S is found in the principle of trigonometrical survey from the imaging position and the direction of the laser beam 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mirror driven scanner for scanning with a light beam such as a laser beam, and a laser sensor using the mirror driven scanner as a light beam scanning means.

[0002]

2. Description of the Related Art LD (laser diode, hereinafter the same).
Scanners that obtain a scanning beam by combining a light source such as described above and a movable reflection mirror driven by a driving mechanism (hereinafter, referred to as “mirror-driven scanner”) have already been used in various devices. One of the typical devices using a mirror-driven scanner is a laser sensor.

A laser sensor converts a laser beam emitted from a laser light source into a scanning beam whose traveling direction periodically and repeatedly changes using a movable reflection mirror, and is formed at a scanning beam projection position on an object surface. This is a three-dimensional position sensor that detects the position of a luminescent spot based on the principle of triangulation (see the embodiment for details).

A galvanometer is generally used as a mirror driving mechanism for causing the movable reflecting mirror to perform such a scanning operation. A driving mechanism using a galvanometer performs mirror driving by using deformation of a coil incorporated as an actuator, and has a drawback in terms of easy miniaturization. This is one factor that hinders further miniaturization of equipment. A scanner using a piezoelectric element as an actuator has also been developed, but a scanner suitable for practical use in terms of reliability, durability and the like has not been obtained.

[0005]

SUMMARY OF THE INVENTION One object of the present invention is to use a piezoelectric element as an actuator, and to reduce the size of a mirror-driven optical device by which the size of the device can be easily reduced. To provide a scanner. Another object of the present invention is to provide a laser sensor employing such a mirror-driven optical scanner in a laser beam scanning unit.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a mirror driven scanner having a light source, a reflecting mirror for reflecting a light beam emitted from the light source, and a reflecting mirror driving means for driving the reflecting mirror. The above technical problem has been solved by adding a mechanical device to the driving means using an actuator using a piezoelectric element.

According to an improvement in accordance with the present invention, the reflecting mirror driving means includes actuator means including at least one piezoelectric element, and means for supplying a driving voltage to the actuator and causing the actuator to vibrate. The mirror oscillates, and light beam scanning is performed.

[0008] In one preferred embodiment, the actuator is an actuator composed of a bimorph type piezoelectric element, and the reflection mirror is attached to the tip of the actuator.

In another preferred embodiment, the reflection mirror driving means further includes a rod-shaped member rotatably supported at one end thereof, and the reflection mirror is fixed to the other end of the rod-shaped member. The rod-like member is driven by the vibration of the actuator acting on the rod-like member between the one end and the other end of the rod-like member, and the reflecting mirror swings accordingly.

In another preferred embodiment, the reflection mirror driving means further includes a rotatable member provided so as to be rotatable about one rotation axis, and the reflection mirror is movable at a position on the rotation axis. , And the vibration of the actuator acts on the rotatable member at a position deviated from the rotation axis, so that the rotatable member is driven, and the reflection mirror rotates and swings accordingly.

In still another preferred embodiment, the reflection mirror driving means further includes a rotatable member provided to be rotatable about one rotation axis, and a crank mechanism coupled to the actuator. The reflecting mirror is fixed to the rotatable member at a position on the rotation axis, and the vibration of the actuator acts on the rotatable member via the crank mechanism at a position off the rotation axis, so that the rotatable member is driven. Then, the reflection mirror rotates and swings accordingly.

When the present invention is embodied as a laser sensor, a mirror drive scanner having a laser light source, a reflection mirror for reflecting a light beam emitted from the light source, and reflection mirror driving means for driving the reflection mirror is provided. In a laser sensor including a light projection unit including a light detection unit that detects a luminescent spot formed on an object surface by a laser beam projected from the light projection unit, a reflection mirror driving unit having the above characteristics is employed. You.

In the mirror-driven scanner and the laser sensor according to the present invention, since the vibration of the actuator using the piezoelectric element is converted into the swing of the mirror through a mechanism having a simple structure, a conventional method using a galvanometer is used. Compared to a mirror-driven scanner and a laser sensor, miniaturization is easier and economical.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining the main configuration of a laser sensor using a mirror-driven optical scanner according to the present invention. Referring to FIG. 1, the main body of the laser sensor 3 includes a light projecting unit 10 and a light detecting unit 13. The light projection unit 10 includes a laser oscillator (LD) 11 and a reflection mirror 12 for beam scanning, and the light detection unit 13 includes an optical system 1 for imaging.
4 and a light receiving element 15. The reflection mirror 12 is driven by a drive mechanism including an actuator using a piezoelectric element, and details thereof will be described later.

The circuit unit 20 includes a drive unit 21 for operating a drive mechanism of the reflection mirror, a laser drive unit 22, and a signal detection unit 23. These components are connected to a controller 30 that controls the entire operation of the laser sensor 3.

The mirror drive unit 21 includes a D / A converter, a piezoelectric element driver, and the like. The mirror drive unit 21 converts a digital control signal sent from the controller 30 into an analog signal, and converts the digital control signal into an analog signal via the piezoelectric element driver. An AC voltage is supplied to an actuator (piezoelectric element) of the drive mechanism. Further, the signal detection unit 23 detects an incident position (bright spot position) S of the laser beam 5 on the object based on the light receiving position of the light receiving element 15.

The controller 30 may also serve as a control device for a system using the laser sensor 3. For example, in the case of a robot system in which a laser sensor is mounted on the hand of a robot and used, the controller 30 may also serve as a robot controller.

When the laser sensor 3 receives an operation command from the controller 30, the laser driving unit 22
1 is driven to generate a laser beam 5. In parallel with this, the drive mechanism of the reflection mirror 12 is operated by the mirror drive unit 21 and the swing of the reflection mirror 12 is started. That is, the AC drive voltage supplied from the mirror drive unit 21 causes periodic deformation (vibration) in the actuator. As will be described later, the vibration of the actuator is directly or indirectly converted into the swinging motion of the reflection mirror 12, and the laser beam 5 scans the object surface G accordingly.

The laser beam diffusely reflected at the reflection point S on the object surface G forms an image on the light receiving surface of the light receiving element 15 by the optical system 14. The imaging position on the light receiving surface changes according to the position of the reflection point S. The light receiving element 15 includes a CCD array,
A position detection detector (abbreviated to PSD) or the like is used.

Here, a one-dimensional CC is used as the light receiving element 15.
It is assumed that a D array is used. The light (image of the reflected light) hitting the light receiving surface of the light receiving element 15 is converted into an electric charge,
It is stored in that cell. The electric charge accumulated in the cell is changed by one every predetermined period in accordance with the CCD scanning signal from the signal detector 23.
The signals are sequentially output from the end and sent to the controller 30 via the signal detection unit 23.

The scanning cycle of the CCD is set sufficiently shorter than the scanning cycle of the reflection mirror 12 (for example, several hundredths).
And the transition of the angle (posture) of the reflection mirror 12 and C
The transition of the output state of the CD element can be grasped at any time. The output state of the CCD element is grasped by the cell position (cell number) of the maximum output, and the cell position where the reflected light is incident is detected. From the position of the incident cell and the direction of the laser beam 5, the three-dimensional position (on the sensor coordinate system) of the reflection point S is determined by the principle of triangulation.

The configuration and function described here are not particularly different from those of the conventional laser sensor except for matters related to the drive mechanism of the reflection mirror 12. Therefore, in the following description, the main configuration of the scanner centered on the driving mechanism of the reflection mirror 12 and the form of the actuator employed therein will be described with reference to some embodiments.

First Embodiment As shown in FIG. 2, in this embodiment, an actuator 51 composed of a bimorph type piezoelectric element is used in this embodiment. One end of the actuator 51 is fixed to the actuator fixing section 50, and the reflection mirror 12 is mounted and fixed to the other end.

The actuator 51 composed of a bimorph type piezoelectric element has a structure in which two piezoelectric elements 51a and 51b are united. As shown in FIG. 3, (a) a parallel type and (b) There is a series type, and any type of actuator 51 may be employed.

The parallel type actuator is characterized in that it has an intermediate electrode 54 in addition to the surface electrodes 52 and 53, and an AC drive voltage is applied between the surface electrodes 52 and 53 and the intermediate electrode 54. Polarization occurs as shown by arrows in the piezoelectric elements 51a and 51b. In a series-type actuator, by applying an AC driving voltage between the surface electrodes 52 and 53, the polarization as indicated by the arrow is caused by the piezoelectric element 51.
a, 51b.

When any type of actuator is employed, vibration accompanied by bending deformation is induced in the actuator 51 as shown in FIG. Thereby, the dashed line display 1
2 ', the reflection mirror 12 oscillates and the scanning laser beams LB2, L
B2 ′ is generated.

[Second Embodiment] As shown in FIG. 4, the main part of this embodiment uses an actuator 61 that utilizes the longitudinal vibration of a piezoelectric element. One end of the actuator 61 is fixed to the actuator fixing part 60, and the plunger 64 is mounted and fixed to the other end. The configured actuator 61 is configured by one piezoelectric element and has surface electrodes 62 and 63.

A ring member 65 is provided at the tip of the plunger 64.
The rod-shaped member 71 is inserted into the ring member 65. The inner diameter of the ring member 65 is designed to be slightly larger than the outer diameter of the rod-shaped member 71. However, the plunger 64 and the rod-shaped member 7
1 may be fastened. Further, an embodiment in which the rod-shaped member 71 is directly fixed to the distal end of the actuator 61 without using the plunger 64 or the ring member 65 can be adopted.

One end (root) of the rod-shaped member 71 is supported by a shaft support 73 provided on the base 70, and is supported so as to swing around the axis B. The other end (tip) of the rod-shaped member 71 is provided with a reflection mirror mounting portion 72, and the reflection mirror 1 is provided.
2 are installed. When an AC driving voltage is applied between the surface electrodes 62 and 63 of the actuator 61, vibration (length vibration) accompanied by expansion and contraction is caused in the direction indicated by the double arrow.

As a result, the plunger 64 reciprocally vibrates, and the vibration is transmitted to the intermediate portion (between the distal end portion 72 and the shaft support portion 73) of the rod-shaped member 71 via the ring member 65, and the rod-shaped member 71 is moved around the axis B. Rocks. As a result, the reflection mirror 12 swings, and a scanning laser beam LB2 is generated from the incident laser beam LB1.

[Third Embodiment] As shown in FIG. 5, the main part of the actuator 61 used in this embodiment is the same as that used in the second embodiment. This is an actuator that utilizes the above. One end of the actuator 61 is fixed to the actuator fixing part 60, and one end of a metal rod 80 having a slight elasticity is joined and fixed to the other end. The actuator 61 includes
It is composed of two piezoelectric elements and has surface electrodes 62 and 63.

The other end of the metal rod 80 is joined and fixed to an edge of a disk 83b forming a part of the rotation member 83 together with the rotation shaft 83a. One end (tip) of the rotation shaft 83a
, The reflection mirror 12 is attached so as not to remove the rotation axis A of the rotation member 83. The other end (root) of the rotation shaft 83 a is supported by a bearing 82 provided on the base 81 so as to be able to rotate around the rotation axis A.

The surface electrodes 62 and 63 of the actuator 61
When an AC drive voltage is applied during the period, vibration accompanied by expansion and contraction (length vibration) is caused in the direction indicated by the double arrow.

As a result, the metal rod 80 reciprocates and acts on the rotation member 83 via the edge of the disk 83b (note that the metal rod 80 is located at a position off the rotation axis A). A rotation oscillation is caused around the axis A. As a result, the reflection mirror 12 oscillates around the rotation axis A, and the scanning operation is achieved (the laser beam is not shown).

[Fourth Embodiment] As shown in FIG. 6, the actuator 51 used in this embodiment is a bimorph type piezoelectric element like the one used in the first embodiment. One end of the actuator 51 is fixed to the actuator fixing part 50, and one end of a highly rigid link rod 100 is joined and fixed to the other end.

The other end of the link rod 100 is a universal joint 102
And is connected to another link rod 103 via the.
The tip of the link bar 103 is joined and fixed to the edge of the disk 92b. The disk 92b has a rotating shaft 9
A rotation member 92 is formed together with 2a, and has a rotation axis A. The reflection mirror 12 is attached to the tip of the rotation part 92a so as not to remove the rotation axis A.

The rotation shaft portion 92a is inserted between a tip portion and the other end (connection portion with the disk 92b) to a bearing portion 91 provided on the shelf-like member 90, and rotates around the rotation shaft A. It is supported so that it can rotate. When a drive voltage is applied to the actuator 51, vibration accompanied by bending deformation (see the description of the first embodiment) is caused in the direction indicated by the double arrow.

As a result, the link bar 100 reciprocates. Here, the link rods 100 and 103 and the universal joint 10
Reference numeral 2 forms a crank mechanism, and reciprocating vibration of the link bar 100 is converted into rotation of the disk 92b. As a result, rotation of the entire rotation member 92 around the rotation axis A is caused, and the reflection mirror 12 also rotates about the rotation axis A. Thereby, a scanning operation is achieved (illustration of a laser beam is omitted).

[Fifth Embodiment] As shown in FIG. 7, the actuator 110 used in this embodiment is
This is an actuator using the sliding vibration of the piezoelectric element. That is, the actuator 110 has the surface electrodes 112, 1
When an AC voltage is applied between the surface electrodes 112 and 103, expansion and contraction deformation of opposite phases occurs on both side surfaces.

One end of the actuator 111 is fixed to the actuator fixing portion 110, and one end of each of metal rods 114 and 115 having slight elasticity is joined to both side surfaces.
Fixed. The other ends of the metal rods 114 and 115 are joined and fixed to the edge of a disk 122b that forms a part of the rotation member 122 together with the rotation shaft 122a. Both joints
The fixing portion is located symmetrically with respect to the rotation shaft portion 122a.

At one end (tip) of the rotation shaft 122a,
The reflection mirror 12 is attached so that the rotation axis A of the rotation member 122 is not removed. The other end (root) of the rotation shaft portion 122a is connected to a bearing portion 121 provided on the base 120.
Thus, it is supported so as to be able to swing around the rotation axis A.

The surface electrode 112 of the actuator 111,
When an AC drive voltage is applied between the pair 113 and a sliding vibration is caused as shown by a double arrow, the metal rods 114 and 115 are generated.
Reciprocally oscillate in opposite phases to each other,
Acts on the rotation member 122 through an edge portion of the rotation member A (note that the rotation member is off the rotation axis A), and the rotation member 122 is caused to rotate around the rotation axis A as a whole. As a result, the reflection mirror 12 oscillates around the rotation axis A,
A scanning operation is achieved (illustration of a laser beam is omitted).

As described above, various types of vibrations, such as length vibration, bending vibration, and slip vibration, can be used for the driving force for the mirror driving and the actuator for providing the driving force. In addition, each of the actuators 201, 202, 2 shown in FIG.
As shown in FIG. 03, a (a) radial vibration, (b) thickness vibration (vibration in the direction between the electrodes), (c) respiratory vibration (alternating deformation in two eccentric axis directions) and the like are used as reflection mirrors. May be caused to act on a swinging member, a rotation member, or the like, which is coupled to the mirror, to cause the swinging rotation or the rotation swing of the reflection mirror.

[0044]

According to the present invention, it is possible to provide a mirror-driven scanner and a laser sensor which can be easily reduced in size and are more economical than conventional mirror-driven scanners and laser sensors using a galvanometer. Can be done.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a main configuration of a laser sensor incorporating a scanner improved according to the present invention.

FIG. 2 is a diagram illustrating a main part of a mirror driving mechanism according to the first embodiment of the present invention.

FIGS. 3A and 3B are diagrams illustrating (a) a parallel type and (b) a series type structure of an actuator constituted by a bimorph type piezoelectric element.

FIG. 4 is a diagram illustrating a main part of a mirror driving mechanism according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a main part of a mirror driving mechanism according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating a main part of a mirror driving mechanism according to a fourth embodiment of the present invention.

FIG. 7 is a diagram illustrating a main part of a mirror driving mechanism according to a fifth embodiment of the present invention.

FIG. 8 shows an actuator constituted by a piezoelectric element;
It is a figure explaining (a) radial vibration, (b) thickness vibration, and (c) respiratory vibration.

[Explanation of symbols]

 Reference Signs List 3 laser sensor 10 projection unit 11 laser oscillator (LD) 12, 12 'reflection mirror 13 light detection unit 14 imaging optical system 15 light receiving element 20 circuit unit 21 mirror drive unit 22 laser drive unit 23 signal detection unit 30 controller 50 , 60, 110 Actuator fixing part 51 Actuator (using bimorph type piezoelectric element) 52, 53, 62, 63, 112, 113 Surface electrode 54 Intermediate electrode 61, 111 Actuator 64 Plunger 65 Ring member 71 Bar-shaped member 72 Mirror mounting part 73 Shaft support 70 Base 80, 114, 115 Metal rod 81, 120 Base 82, 91, 121 Bearing 83, 92, 122 Rotating member 83a, 92a, 122a Rotating shaft 83b, 92b, 122b Disk 90 Shelf member 100, 103 Rin Hook 102 Universal joint 201 Actuator (radial vibration) 202 Actuator (thickness vibration) 203 Actuator (breathing vibration) LB1 Laser beam (stationary) LB2, LB2 'Scanning laser beam

Claims (10)

[Claims] 1. A mirror driven scanner comprising: a light source; a reflecting mirror that reflects a light beam emitted from the light source; and a reflecting mirror driving unit that drives the reflecting mirror. Actuator means including one piezoelectric element, and means for supplying a drive voltage to the actuator to vibrate the actuator, wherein the vibration of the actuator causes the reflection mirror to oscillate and light beam scanning is performed. The mirror-driven scanner. 2. The mirror-driven scanner according to claim 1, wherein the actuator is an actuator formed of a bimorph-type piezoelectric element, and the reflection mirror is attached to a tip of the actuator. 3. The reflection mirror driving means further includes a rod-shaped member pivotally supported at one end thereof and provided to be swingable, wherein the reflection mirror is fixed to the other end of the rod-shaped member. 2. The rod-shaped member is driven by the vibration of an actuator acting on the rod-shaped member between the one end and the other end of the member, and the reflecting mirror swings accordingly. 3. A mirror driven scanner described in 1. 4. The reflection mirror driving means further comprises a rotatable member provided so as to be rotatable about one rotation axis, and the reflection mirror is positioned relative to the rotation member at a position on the rotation axis. The vibration of the actuator acts on the rotatable member at a position deviated from the rotation axis, whereby the rotatable member is driven, and the reflection mirror rotates and swings accordingly. The mirror-driven scanner according to claim 1, wherein: 5. The reflection mirror driving means further comprises: a rotatable member provided to be rotatable about one rotation axis; and a crank mechanism coupled to the actuator, and The reflection mirror is fixed to the rotation member, and the vibration of the actuator acts on the rotation member via the crank mechanism at a position deviated from the rotation axis, so that the rotation member is driven. 2. The mirror-driven scanner according to claim 1, wherein the reflection mirror rotates and swings accordingly. 6. A light projection unit including a laser light source, a reflection mirror for reflecting a light beam emitted from the light source, a mirror driving type scanner having reflection mirror driving means for driving the reflection mirror, and the light projection. A laser sensor including a light detection unit that detects a luminescent spot formed on an object surface by a laser beam projected from the unit, wherein the reflection mirror driving unit includes an actuator unit including at least one piezoelectric element; and The laser sensor, further comprising: means for supplying a drive voltage to the actuator to vibrate the actuator, wherein the vibration of the actuator causes the reflection mirror to oscillate to perform light beam scanning. 7. The mirror-driven scanner according to claim 6, wherein the actuator is an actuator composed of a bimorph type piezoelectric element, and the reflection mirror is attached to a tip of the actuator. 8. The reflection mirror driving means further includes a rod-shaped member rotatably supported at one end thereof, and the reflection mirror is fixed to the other end of the rod-shaped member. 7. The bar-shaped member is driven by the vibration of an actuator acting on the bar-shaped member between the one end and the other end of the member, and the reflecting mirror is swung accordingly. Laser sensor described in 1. 9. The reflection mirror driving means further includes a rotatable member provided so as to be rotatable about one rotation axis, and the reflection mirror is positioned relative to the rotation member at a position on the rotation axis. The vibration of the actuator acts on the rotatable member at a position deviated from the rotation axis, whereby the rotatable member is driven, and the reflection mirror rotates and swings accordingly. The laser sensor according to claim 6, wherein 10. A rotating member provided so as to be capable of swinging around one rotation axis, the reflection mirror driving means comprising:
Further comprising a crank mechanism coupled to the actuator, wherein the reflection mirror is fixed to the rotatable member at a position on the rotation axis, and the vibration of the actuator is at a position off the rotation axis. The laser sensor according to claim 6, wherein the rotation member is driven by acting on the rotation member via a mechanism, and the reflection mirror is rotated in accordance with the rotation of the rotation member.