JPH09243952A - Optical scanning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the disconnection of an elastic wire member at the time of driving and to provide a device having good durability. SOLUTION: This device is composed of a light source 11 transmitting a laser beam, a mirror 3 with magnet being capable of rocking, supported on a housing 1 by means of an elastic wire member 5 and reflecting the laser beam 10 and a coil 7 generating alternating magnetic field for oscillating the mirror 3 with magnet. The part supporting the mirror 3 with magnet of the elastic wire member 5 is formed in a first diameter and the part fixed to the housing 1 is formed in a second diameter larger than the first diameter.

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, the present applicant has proposed an optical scanning device of Japanese Patent Application No. 7-296788 as an optical scanning device having a mirror with a magnet and a coil for generating an alternating magnetic field. This optical scanning device is configured, for example, as shown in FIG. Elastic linear member 55 made of superelastic alloy or the like
Is fixed to the housing 1 by the fixing jig 2 while being pulled by an appropriate tension. The mirror 3 with a magnet, which is mirror-processed on at least one surface of the magnet, is fixed to the elastic linear member 55 at substantially the center by an adhesive agent (not shown).

On the other hand, a coil 7 is wound around the core 6. 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 housing 1. And
When a predetermined current is applied to the coil from the pulse current generator 9, an alternating magnetic field is generated and the mirror with magnet 3 vibrates. Light source 1
The laser beam 10 emitted from the laser beam No. 1 is reflected by the magnet-equipped mirror 3, and the surface 3 to be scanned is scanned when the magnet-equipped mirror 3 resonates.

[0004]

However, in the conventional optical scanning device, the elastic linear member 55 is likely to be broken near the fixed portion between the elastic linear member 55 and the housing 1, and the durability of the device is significantly reduced. It was.

The optical scanning device of the present invention has been made in order to solve the above-mentioned problems, and reduces the disconnection of the elastic linear member during driving, and provides an optical scanning device having extremely excellent durability. Is intended.

[0006]

In order to achieve this object, an optical scanning device according to a first aspect of the present invention is swingable by a light source for emitting a laser beam and an elastic linear member fixed to a housing. Supported by a mirror with a magnet for reflecting the laser beam, and a coil for generating an alternating magnetic field for vibrating the mirror with the magnet, and in particular, the elastic linear member is at least the A portion supporting the magnet-attached mirror is formed to have a first wire diameter, and at least a portion fixed to the housing is formed to a second wire diameter that is thicker than the first wire diameter.

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 including the elastic linear member and the magnet-attached mirror and the frequency of the alternating current match, resonance occurs and the amplitude can be maximized. Can be large. Further, since it is possible to reduce disconnection at the portion of the elastic linear member fixed to the housing during driving, it is possible to provide an optical scanning device having extremely excellent durability.

Further, in the optical scanning device according to a second aspect, the elastic linear member uses a linear member having the second wire diameter, and at least a portion supporting the mirror with magnet is electropolished. It is melted to form a first wire diameter, and at least a portion fixed to the housing is not melted to hold the second wire diameter. Therefore, only the required portion including at least the portion supporting the magnet-attached mirror can be uniformly melted to form the first wire diameter. Further, since it is possible to reduce disconnection at the portion of the elastic linear member fixed to the housing during driving, it is possible to provide an optical scanning device having extremely excellent durability.

Further, in the optical scanning device according to a third aspect of the present invention, the linear member having the second wire diameter is made of a Ti-Ni superelastic alloy, and the electrolytic polishing is performed with a perchloric acid / acetic acid solution. Is used as an electrolytic polishing liquid. Therefore, only the necessary portion including the portion supporting the magnet-attached mirror can be uniformly melted in a short time to form the first wire diameter, and an optical scanning device having high fatigue strength and an extremely long life can be provided. Can be provided.

Further, in the optical scanning device according to the fourth aspect, the elastic linear member uses a linear member having the second wire diameter, and at least a portion supporting the mirror with magnet is chemically etched. It is melted to form a first wire diameter, and at least a portion fixed to the housing is not melted to hold the second wire diameter. Therefore, only the necessary portion including at least the portion supporting the magnet-attached mirror can be easily and uniformly melted to form the first wire diameter, and the optical scanning device with high fatigue strength and extremely long life is provided. Can be provided.

[0011]

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 this embodiment. The housing 1 in a state where the superelastic alloy wire 5 as the elastic linear member is pulled by an appropriate tension.
It is fixed by the fixing jig 2. Both ends 13 of the superelastic alloy wire serving as a fixed portion between the housing 1 and the superelastic alloy wire 5 are formed to have a larger wire diameter than other portions. The magnet-equipped mirror 3 is fixed to the superelastic alloy wire 5 approximately at the center by an adhesive agent or the like (not shown). The magnet-equipped mirror 3 is made of Ni-Co (nickel cobalt) or Sm-Co (samarium cobalt) having a thickness of 0.3 mm, a length of 3 mm, and a width of 6 mm. The super elastic alloy wire 5 has T
An i-Ni-based alloy, a Cu-Zn-based alloy, or the like is used. The wire diameter of the super-elastic alloy wire 5 is 13 at both ends of the wire.
Is about 0.3 mm, the other portions are about 0.15 mm, the total length is about 10 mm, and the lengths of the wire end portions 13 are about 2 mm. The wire diameter of the wire both ends 13 (that is, about 0.3 mm) is the second wire diameter of the present invention, and the wire diameter of other portions (that is, about 0.15 mm).
Is the first wire diameter.

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 housing 1. 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 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.

Next, an example of a method for producing a superelastic alloy wire 5 having a thick wire diameter at both ends by electrolytic polishing using the superelastic alloy wire 5 having a wire diameter of about 0.3 mm will be described. This will be described with reference to FIG. For example, 5vo
A Ti—Ni-based superelastic alloy wire 5 is immersed in an electrolytic polishing solution 21 composed of a 1% perchloric acid-95 vol.% acetic acid solution and connected to the anode side of a DC power source 24. The super elastic alloy wire 5 has a diameter of about 0.3 m, which is the same as the wire diameter of the both ends 13 of the wire.
m is prepared, and both end portions 22 serving as a fixed portion with the housing 1 are masked. The masking is
It is performed by applying a resin or the like on the both ends 22 and drying.

As shown in FIG. 2, when the superelastic alloy wire 5 is rotatably fixed to the motor 26 and is continuously rotated during the processing, the electrolytic polishing is performed more uniformly.

On the other hand, a platinum plate 25 is placed on the cathode side in the electrolytic polishing liquid 21 so as to face the superelastic alloy wire 5. When an electric current is applied at a predetermined voltage in this state, the unmasked central portion 23 of the superelastic alloy wire 5 is electrolytically polished, and the wire diameter is reduced only in that portion. On the other hand, the both end portions 22 masked in advance maintain the wire diameter before the treatment as it is. In practice, for example, when the treatment is performed at room temperature and a voltage of 15 V, when a superelastic alloy wire having a wire diameter of φ0.3 mm is used, the wire diameter can be reduced to about φ0.15 mm by the treatment for 1 to 2 minutes.

It is also possible to form the superelastic alloy wire having the above structure by chemical etching.
As shown in FIG. 3, the superelastic alloy wire 5 having both ends 22 masked is dipped in an etching solution 31. As the etching solution 31, a 1-10% hydrofluoric acid aqueous solution or a 2% hydrofluoric acid-5% hydrogen peroxide aqueous solution is used, and the superelastic alloy wire center is not masked when immersed at room temperature to 50 ° C. The portion 23 is etched so that the wire diameter is reduced only in that portion. The time required for the treatment largely depends on conditions such as temperature and is several minutes to several hours.

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 a 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.

[0021]

[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 expressed by equation 2.

[0023]

[Equation 2]

That is, when the frequency ω of the electric current and the natural frequency ω ₀ of the mechanical system consisting of the magnet-attached mirror 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, by changing the wire diameter φ of the wire and the mass m of the mirror with magnet, optical scanning devices of various frequencies can be manufactured. 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 manufacture an optical scanning device having a desired scanning angle according to a target electric product or electronic device.

By the way, the problem to be solved by the present invention is to reduce the disconnection of the superelastic alloy wire (elastic linear member) 5 at the fixed portion with the housing 1 during driving, and to improve the durability. It was to provide an optical scanning device. In order to reduce the breakage of the superelastic alloy wire 5, it is only necessary to uniformly increase the wire diameter of the superelastic alloy wire 5, but if the wire diameter is increased, the scanning angle θ is significantly reduced. Now, the frequency ω of current, the mirror 3 with magnet and the super elastic alloy wire 5
When the natural frequency ω ₀ of the mechanical system consisting of is equal to each other, that is, in the resonance state, (2-1) of Expression 2 is as follows.

[0028]

(Equation 3)

Since ω ₀ is proportional to the square of the wire diameter φ of the superelastic alloy wire, if the wire diameter φ becomes thicker, the scanning angle θ will be significantly reduced. From this, it is desirable that the wire diameter in the vicinity of the central portion of the superelastic alloy wire 5, that is, in the vicinity of the portion where the magnet-attached mirror 3 is attached, be as thin as possible within a range that can withstand the torsional stress applied during driving.
It is desirable that both ends of the superelastic alloy wire 5 have a large wire diameter so as to withstand the stress concentration applied to the fixed portion with the housing 1.

In the above embodiment, the waveform of the current flowing through the coil 7 is a rectangular wave. Because, as shown in FIG. 4, the torque applied to the magnet mirror by the twist angle θ is
This is because MH cos θ, and the alternating magnetic field H cos θ acts on the magnetic moment M, and when θ = ωt, Formula 1 is satisfied. FIG. 5 shows how the mirror with a magnet vibrates at a twist angle θ due to a rectangular wave current. From equation (2-2), when ω = ω ₀ , α = 90 °, that is, θ has a phase delay of 90 ° with respect to the alternating magnetic field. That is, the twist angle θ of the mirror with magnet 3 becomes maximum at a 90 ° delay from the switching of the magnetic field, and the restoring force kθ (k: spring constant) of the superelastic alloy wire 5 also becomes maximum. The points a, b, c, d of the current waveform are the vibration states (a), (b), (c) of the mirror 3 with a magnet,
It corresponds to (d). 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 embodiment described in detail above, and various changes can be made without departing from the gist of the present invention.

For example, in the above-mentioned embodiment, the core 6 and the housing 1 are provided separately, but as shown in FIG. An optical scanning device in which the alloy wire 5 is stretched by the fixing jig 2 and the mirror 3 with a magnet is attached near the center of the superelastic alloy wire 5 to form a core and a housing by one member. Can also be considered. With such a configuration, the housing 1 is not required, so that the size and weight of the device can be reduced. Further, the work of assembling the housing 1 and the core 6 is not necessary, so that the workability can be improved. Furthermore, since the magnet-equipped mirror 3 can be brought closer to the coil 7, a larger magnetic field can be given to the magnet-equipped mirror 3.

Further, in the above embodiment, the wire diameter of the wire both ends 13 is set to about 0.3 mm, but the wire diameter of the portion supporting the magnet-equipped mirror 3 is not limited to this. It should be thicker than the above.

Further, in the above-described embodiment, the length of each of the wire end portions 13 is set to about 2 mm, but the length is not limited to this, and at least a portion other than a portion supporting the magnet-equipped mirror 3 is provided. In addition, as long as it includes at least a portion fixed to the housing 1, it may be formed longer or shorter than this.

[0035]

As is apparent from the above description,
An 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 an elastic linear member that is fixed to a housing, and a mirror with a magnet that reflects the laser beam. The elastic linear member has at least a portion for supporting the magnet-attached mirror formed to have a first wire diameter, in particular, for an object including a coil that generates an alternating magnetic field for vibrating the magnet-attached mirror. And, at least a portion fixed to the housing is formed with a second wire diameter larger than the first wire diameter.

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 including the elastic linear member and the magnet-attached mirror and the frequency of the alternating current match, resonance occurs and the amplitude can be maximized. Can be large. Further, since it is possible to reduce disconnection at the portion of the elastic linear member fixed to the housing during driving, it is possible to provide an optical scanning device having extremely excellent durability.

According to a second aspect of the present invention, in the optical scanning device, the elastic linear member uses a linear member having the second wire diameter, and at least a portion supporting the magnet-attached mirror is electropolished. It is melted to form a first wire diameter, and at least a portion fixed to the housing is not melted to hold the second wire diameter. Therefore, only the required portion including at least the portion supporting the magnet-attached mirror can be uniformly melted to form the first wire diameter. Further, since it is possible to reduce disconnection at the portion of the elastic linear member fixed to the housing during driving, it is possible to provide an optical scanning device having extremely excellent durability.

In the optical scanning device according to a third aspect of the present invention, the linear member having the second wire diameter is made of a Ti—Ni-based superelastic alloy, and the electrolytic polishing is performed with a perchloric acid / acetic acid solution. Is used as an electrolytic polishing liquid. Therefore, only the necessary portion including the portion supporting the magnet-attached mirror can be uniformly melted in a short time to form the first wire diameter, and an optical scanning device having high fatigue strength and an extremely long life can be provided. Can be provided.

Further, in the optical scanning device according to a fourth aspect, the elastic linear member uses a linear member having the second wire diameter and at least a portion supporting the mirror with magnet is chemically etched. It is melted to form a first wire diameter, and at least a portion fixed to the housing is not melted to hold the second wire diameter. Therefore, only the necessary portion including at least the portion supporting the magnet-attached mirror can be easily and uniformly melted to form the first wire diameter, and the optical scanning device with high fatigue strength and extremely long life is provided. Can be provided.

[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 diagram showing an example of a method for producing a superelastic alloy wire having thick wire diameters at both ends by electrolytic polishing.

FIG. 3 is a diagram showing an example of a method for producing a superelastic alloy wire having thick wire diameters at both ends by chemical etching.

FIG. 4 is a schematic diagram in which a mirror with a magnet receives a torque from an alternating magnetic field.

FIG. 5 is a diagram showing how a magnet-attached mirror vibrates with a rectangular wave current.

FIG. 6 is a perspective view showing a configuration of a modified example of the optical scanning device.

FIG. 7 is a diagram showing a configuration of a conventional optical scanning device.

[Explanation of symbols]

 1 Housing 3 Mirror with Magnet 5 Super Elastic Alloy Wire 7 Coil 10 Laser Beam 11 Light Source 21 Electrolytic Polishing Liquid 22 Super Elastic Alloy Wire Both Ends

Claims (4)

[Claims] 1. A light source which emits a laser beam, and a magnet-equipped mirror which is swingably supported by an elastic linear member fixed to a housing and which reflects the laser beam, and a vibrating magnet-attached mirror. In the optical scanning device including a coil that generates an alternating magnetic field, the elastic linear member forms at least a portion supporting the magnet-attached mirror with a first wire diameter, and at least a portion fixed to the housing. An optical scanning device having a second wire diameter thicker than the first wire diameter. 2. The elastic linear member is formed to have a first linear diameter by using a linear member having the second linear diameter to dissolve at least a portion supporting the magnet-attached mirror by electrolytic polishing. The optical scanning device according to claim 1, wherein the second wire diameter is held without melting at least a portion fixed to the housing. 3. The linear member having the second wire diameter is made of Ti--N
The optical scanning device according to claim 2, wherein the optical scanning device is made of an i-type superelastic alloy, and the electrolytic polishing uses a perchloric acid / acetic acid solution as an electrolytic polishing liquid. 4. The elastic linear member is formed into a first linear diameter by using a linear member having the second linear diameter and at least a portion supporting the magnet-attached mirror is dissolved by chemical etching. The optical scanning device according to claim 1, wherein the second wire diameter is held without melting at least a portion fixed to the housing.