JPH09243942A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve the stress concentration occurring at both ends of an elastic wire-shaped member for supporting a mirror with a magnet at the time of driving so as to lessen the disconnection of the elastic wire-shaped member and to greatly improve its durability by forming the elastic wire-shaped member to an endless form. SOLUTION: The superelastic alloy wire 5 formed to the endless form by previously fixing its both terminals to each other by welding, etc., is fixed to struts 14 by means of fixing jigs 2 in the state of applying suitable tension therein through two pieces of round bar-shaped supporting members 13. Then the alternating magnetic fields meeting alternating currents are generated on the peripheral of a coil 7 when the AC currents are passed to the coil 7. The alternating magnetic fields apply torque on the mirror 3 with the magnet fixed to the superelastic alloy wire 5. The superelastic alloy wire 5 is, therefore, capable of vibrating the mirror 3 with the magnet by the restitutive force generated by the torque and twist. The superelastic alloy wire 5 formed to the endless form is supported along the curved surfaces formed at the round bar-shaped supporting members 13 and, therefore, the stress concentration occurring at both ends is relieved and the disconnection is lessened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used in office equipment such as laser printers, bar code readers, laser scanning micrometers, and measuring instruments.

[0002]

2. Description of the Related Art Conventionally, as an optical scanning device having a mirror with a magnet and a coil for generating an alternating magnetic field, one having a structure shown in FIG. 4, for example, is known. An elastic linear member 55 made of a superelastic alloy or the like is fixed to the housing 51 by a fixing jig 52 while being pulled by an appropriate tension. At approximately the center of the elastic linear member 55, the mirror 3 with a magnet, which is mirror-finished on at least one surface of the magnet,
It is fixed with an adhesive (not shown).

On the other hand, a coil 7 is wound around the core 6. The coil 7 is fixed to the housing 51 with a screw (not shown) through a screw hole 8 provided in the core 6 and a hole 54 provided in the housing 51. Then, when a predetermined current is passed through the coil from the pulse current generator 9, an alternating magnetic field is generated and the magnet-equipped mirror 3 vibrates.
The laser light 10 emitted from the light source 11 is reflected by the mirror 3 with a magnet, and the surface 3 to be scanned is scanned when the mirror 3 with a magnet resonates.

[0004]

However, in the conventional optical scanning device, disconnection frequently occurs near the fixing portion between the elastic linear member 55 and the housing 51 during driving, which causes the durability of the device to be remarkably reduced. It was.

The optical scanning device of the present invention has been made in order to solve the above-mentioned problems, and alleviates the stress concentration generated at both ends of the elastic linear member during driving, and breaks the elastic linear member. It is an object of the present invention to provide an optical scanning device that is reduced in number and has extremely excellent durability.

[0006]

In order to achieve this object, an optical scanning device according to a first aspect of the present invention includes a light source for emitting a laser beam and an elastic linear member swingably supported by a housing. Targeting a mirror with a magnet for reflecting light and a coil for generating an alternating magnetic field for vibrating the mirror with magnet, in particular, the elastic linear member is formed in an endless shape, and the housing Includes a supporting member that stretches and supports the elastic linear member in a curved shape at least at two locations, and the magnet-equipped mirror can be swung on a linear portion of the elastic linear member that is stretched and supported by the supporting member. To support. Therefore, when an alternating current is passed through the coil, an alternating magnetic field corresponding to the alternating current is generated around the coil. Since this alternating magnetic field gives a torque to the magnet-equipped mirror fixed to the elastic linear member, torsion stress is generated in the elastic linear member. Therefore, the elastic linear member receives a torque due to the alternating magnetic field and a restoring force due to the torsion, so that the mirror with magnet can be vibrated by the periodic alternating current. In particular, when the mechanical natural frequency of the vibration system consisting of the elastic linear member and the magnet-attached mirror and the frequency of the alternating current match, resonance occurs, the amplitude can be maximized, and the scanning angle of the incident laser beam can be increased. can do. Further, since the elastic linear member formed endlessly is supported along the curved surface formed by the support member, stress concentration generated at both ends of the elastic linear member during driving is relaxed, and as a result, the elastic linear member is It is possible to provide an optical scanning device in which breakage of members is reduced and which has extremely excellent durability.

Further, in the optical scanning device according to a second aspect, the supporting member is composed of a supporting rod having a curved surface. Therefore, the support member can be configured easily and inexpensively.

Further, in the optical scanning device according to a third aspect of the present invention, the support bar has a groove having a curved bottom surface at a portion where the elastic linear member engages. Therefore,
It is possible to prevent the elastic linear member from being displaced in the axial direction of the support rod and reliably support the elastic linear member.

Further, in the optical scanning device according to the fourth aspect, the elastic linear member is composed of a Ti—Ni-based superelastic alloy wire. Therefore, it is possible to provide an optical scanning device having a high fatigue limit and an extremely long life.

Further, in the optical scanning device according to a fifth aspect, the elastic linear member is composed of a Cu—Zn superelastic alloy wire. Therefore, it is possible to provide an optical scanning device having a high fatigue limit and an extremely long life.

Further, in the optical scanning device according to the sixth aspect, the elastic linear member is composed of a stainless wire which is shot peened to improve the fatigue limit. Therefore, it is possible to provide an optical scanning device that is extremely inexpensive and has excellent durability.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of the optical scanning device of the present invention.

The housing 1 is made of an endless superelastic alloy wire 5 whose ends are fixed in advance by welding or the like.
In addition, the super elastic alloy wire 5 is fixed to the support column 14 by the fixing jig 2 in a state where the super elastic alloy wire 5 is appropriately tensioned through the two round bar-shaped support members 13. still,
The superelastic alloy wire 5 constitutes the elastic linear member of the present invention, and the round rod-shaped support member 13 constitutes the support member and the support rod, respectively.

At least one of the two rod-shaped support members 13 of the support column 14 is vertically movable by the fixing jig 2, and the tension of the superelastic alloy wire 5 can be freely set.

A groove 15 having a curved bottom surface is provided at substantially the center of the round bar-shaped support member 13. The superelastic alloy wire 5 is attached to the groove 15 to mount the superelastic alloy wire 5 thereon. It has a structure that can prevent the horizontal displacement of the.

For the superelastic alloy wire 5, a Ti-Ni type alloy or a Cu-Zn type alloy is used. The wire diameter of the superelastic alloy wire 5 is about 140 μm and the length is about 10 mm.

The magnet-equipped mirror 3 is fixed to the center of the superelastic alloy wire 5 with an adhesive or the like (not shown). The magnet-equipped mirror 3 includes Ni-Co alloy or S.
An m-Co alloy or the like is used, and its size is 3 mm in length,
The width is about 6 mm and the thickness is about 0.3 mm.

On the other hand, a coil 7 is wound around the core 6, for example, about 300 turns. The coil 7 is fixed to the housing 1 by a screw (not shown) through a screw hole 8 provided in the core 6 and a hole 4 provided in the support 14. Then, when a current of, for example, about 100 mA at 3 V is applied to the coil 7 by the pulse current generator 9, an alternating magnetic field is generated and the mirror with magnet 3 vibrates.
The laser beam 10 emitted from the light source 11 is reflected by the mirror 3 with a magnet, and the mirror 3 with a magnet resonates to scan the surface 12 to be scanned.

Next, the operation of the optical scanning device of this embodiment will be described.

Now, when a pulse current as shown in FIG. 1 is passed through the coil 7, the coil 7 is forward and backward shown in FIG.
A so-called alternating magnetic field is generated as shown in FIGS. The center 3 is fixed to the superelastic alloy wire 5 and the magnet-equipped mirror 3 installed in front of the coil 7 is
It receives a torque of MH cos θ by the alternating magnetic field. (M is the magnetic moment of the mirror with magnet, H is the strength of the magnetic field, θ
In addition, in case of twist angle θ, super elastic alloy wire 5
Also, the restoring force by kθ is received at the same time (k: spring constant).

Further, when the magnet-equipped mirror 3 vibrates at high speed, a damping force proportional to dθ / dt is also received due to the frictional resistance with the air and the frictional resistance inside the superelastic alloy wire 5. When the torque is applied periodically (angular frequency ω), the magnet-equipped mirror 3 starts torsional vibration. When this vibration system is expressed by an equation, Equation 1 is obtained.

[0023]

[Equation 1]

This is an equation in the case where a forcing force is applied to the damping vibration system, and its general solution is represented by equation 2.

[0025]

[Equation 2]

That is, when the frequency ω of the electric current and the natural frequency ω ₀ of the mechanical system composed of the mirror with magnet 3 and the superelastic alloy wire 5 match, a so-called resonance state occurs, and the maximum deflection angle is obtained. In the case of the present embodiment, the voltage applied to the coil 7 is 3 V, the coil current is about 100 mA, and about 800
It resonates at Hz, and its deflection angle is about 50 degrees, that is, the laser beam is scanned at a scanning angle of about 100 degrees.

In the above-described embodiment, the scanning angle is about 100 degrees and the scanning frequency is 800 Hz. However, the optical scanning device having various frequencies can be manufactured by changing the wire diameter φ of the wire and the mass m of the mirror with magnet. be able to.
For example, when manufacturing a 400 Hz optical scanning device, the frequency f is proportional to (k / m) ^1/2 , and the spring constant k is proportional to φ ⁴ , so that the square of φ is proportional to the frequency. .
Since φ = 400 μm and the resonance frequency was 800 Hz, an optical scanning device of about 400 Hz can be manufactured by using a superelastic alloy wire of about φ = 100 μm under the same conditions as above.

Further, as can be seen from the coefficient MH / I of the equation (2), by using a mirror with a magnet having various strengths (M) or a magnetic field of various amplitudes (H = ni, n:
The number of coil windings i: current)
It is possible to bring an optical scanning device having a desired scanning angle according to the target electric product or electronic device.

In the present invention, the waveform of the current flowing through the coil 7 is a rectangular wave. Because, as shown in FIG. 2, the torque applied to the magnet-equipped mirror due to the twist angle θ is MHc.
os θ, which means that the alternating magnetic field Hcos θ acts on the magnetic moment M of the mirror with a magnet, and θ =
This is because the expression 1 is established when ωt is set.

FIG. 3 shows how the mirror with a magnet vibrates at a twist angle θ due to a rectangular wave current. From the formula (2-2),
When ω = ω ₀ , α = 90 °, that is, θ has a 90 ° phase delay with respect to the alternating magnetic field. That is, the twist angle θ of the mirror with magnet is delayed by 90 ° from the switching of the magnetic field.
Is maximized, and the restoring force kθ (k: spring constant) of the superelastic alloy wire 5 is also maximized. The points a, b, c, d of the current waveform correspond to the vibration states (a), (b), (c), (d) of the mirror with magnet, respectively. When the rectangular wave is used, torque can be applied to the magnet-equipped mirror 3 until the restoring force of the superelastic alloy wire 5 is maximized, so that the scanning width can be maximized as compared with other current waveforms. However, if there is a margin in the scanning width, it is possible to sufficiently scan even a periodic waveform such as a SIN wave or a triangular wave. Further, in the present embodiment, the present optical scanning device is configured by utilizing the resonance phenomenon in order to minimize the current flowing through the coil 7, but if the power has a margin, the optical scanning device is driven by removing the resonance point. However, there is no functional problem. The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the scope of the invention.

For example, in the above-mentioned embodiment, the support member is constituted by the round bar-shaped support member 13. However, a large number of angular members are arranged in a curved surface, and the superelastic alloy wire 5 is stretched and supported in a curved surface shape. It may be configured to do so.

Further, in the above-mentioned embodiment, an example in which a superelastic alloy wire is used as the elastic linear member has been described, but it goes without saying that the elastic linear member is not limited to this as long as it has excellent elastic performance. For example, a stainless wire has a diameter of 10 to 1
Further cost reduction can be achieved by using a stainless steel wire which is sprayed with a steel ball of 00 μm to harden the surface of the stainless steel wire, which is subjected to surface treatment such as so-called shot peening to improve the fatigue limit. Since the fatigue limit can be improved by a simple process using an inexpensive stainless wire, it is possible to provide an optical scanning device that is extremely inexpensive and has excellent durability.

In the above embodiment, the superelastic alloy wire 5 and the mirror 3 with magnet are arranged in front of the coil 7 for convenience, but an alternating magnetic field around the coil 7 causes a magnetic moment M of the mirror 3 with magnet. It may be located anywhere as long as it occurs in a substantially right angle direction. Further, in the above-described embodiment, the housing 1 including the superelastic alloy wire 5 and the magnet-equipped mirror 3 is screwed and fixed to the coil 7, but it may be detachably attached. In this way, the distance between the coil 7 and the magnet-equipped mirror 3 can be made variable, and as a result, the scanning angle can also be made variable.

In the above embodiment, the magnet-equipped mirror 3 is arranged only on one side of the straight portion of the superelastic alloy wire 5, but it may be arranged on the other side.

In the above embodiment, the core 6 has a cylindrical shape, but the shape can be freely changed as long as it is made of a non-magnetic material. The rod-shaped support members 13 and the columns 14 that form the housing 1 can be made of any material as long as they are non-magnetic materials.

In the above embodiment, the superelastic alloy wire is stretched and supported by the two rod-shaped supporting members.
You may support with a rod-shaped support member more than one.

[0037]

As is apparent from the above description,
The optical scanning device according to claim 1 of the present invention includes a light source that emits a laser beam, a mirror that is swingably supported by a housing by an elastic linear member, and has a magnet for reflecting the laser beam, and a magnet. In particular, the elastic linear member is formed in an endless shape, and the housing has a curved surface at least at two positions, which is formed of a coil that generates an alternating magnetic field to vibrate the mirror. Equipped with a support member that stretches and supports
The magnet-equipped mirror is swingably supported on a linear portion of the elastic linear member stretched and supported by the support member.
Therefore, when an alternating current is passed through the coil, an alternating magnetic field corresponding to the alternating current is generated around the coil. Since this alternating magnetic field gives a torque to the magnet-equipped mirror fixed to the elastic linear member, torsion stress is generated in the elastic linear member. Therefore, the elastic linear member receives a torque due to the alternating magnetic field and a restoring force due to the torsion, so that the mirror with magnet can be vibrated by the periodic alternating current. In particular, when the mechanical natural frequency of the vibration system consisting of the elastic linear member and the magnet-attached mirror and the frequency of the alternating current match, resonance occurs, the amplitude can be maximized, and the scanning angle of the incident laser beam can be increased. can do. Further, since the elastic linear member formed endlessly is supported along the curved surface formed by the support member, stress concentration generated at both ends of the elastic linear member during driving is relaxed, and as a result, the elastic linear member is It is possible to provide an optical scanning device in which breakage of members is reduced and which has extremely excellent durability.

In the optical scanning device according to the second aspect, the supporting member is composed of a supporting rod having a curved surface. Therefore, the support member can be configured easily and inexpensively.

Further, in the optical scanning device according to a third aspect of the present invention, the support bar has a groove having a curved bottom surface at a portion where the elastic linear member engages. Therefore,
It is possible to prevent the elastic linear member from being displaced in the axial direction of the support rod and reliably support the elastic linear member.

Further, in the optical scanning device according to the fourth aspect, the elastic linear member is composed of a Ti—Ni-based superelastic alloy wire. Therefore, it is possible to provide an optical scanning device having a high fatigue limit and an extremely long life.

Further, in the optical scanning device according to the fifth aspect, the elastic linear member is composed of a Cu—Zn based superelastic alloy wire. Therefore, it is possible to provide an optical scanning device having a high fatigue limit and an extremely long life.

Further, in the optical scanning device according to the sixth aspect, the elastic linear member is composed of a stainless wire which is shot peened to improve the fatigue limit. Therefore, it is possible to provide an optical scanning device that is extremely inexpensive and has excellent durability.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an optical scanning device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram in which a mirror with a magnet receives a torque from an alternating magnetic field.

FIG. 3 is a diagram showing how a mirror with a magnet vibrates according to a rectangular wave current.

FIG. 4 is a perspective view showing a configuration of a conventional optical scanning device.

[Explanation of symbols]

 1 Housing 3 Mirror with Magnet 5 Superelastic Alloy Wire 7 Coil 10 Laser Beam 11 Light Source 13 Round Bar Support Member

Claims (6)

[Claims] 1. A light source that emits a laser beam, a mirror that is swingably supported by a housing by an elastic linear member and that reflects the laser beam, and an alternating magnetic field for vibrating the mirror with a magnet. In the optical scanning device including a coil for generating, the elastic linear member is formed in an endless shape, and the housing includes a supporting member that stretches and supports the elastic linear member in a curved shape at least at two positions, An optical scanning device, wherein the magnet-equipped mirror is swingably supported on a linear portion of the elastic linear member stretched and supported by the support member. 2. The optical scanning device according to claim 1, wherein the support member is formed of a support rod having a curved surface. 3. The optical scanning device according to claim 2, wherein the support bar has a groove having a curved bottom surface at a portion where the elastic linear member engages. 4. The optical scanning device according to claim 1, wherein the elastic linear member is made of a Ti—Ni-based superelastic alloy wire. 5. The optical scanning device according to claim 1, wherein the elastic linear member is made of a Cu—Zn-based superelastic alloy wire. 6. The optical scanning device according to claim 1, wherein the elastic linear member is composed of a stainless wire that has been subjected to shot peening treatment to improve a fatigue limit. .