JPH09230275A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive scanner which prevents the disconnection of a torsion spring in the part fixed to a housing, has excellent durability and is reduced in size and weight. SOLUTION: The torsion spring 5 is mounted in a tensioned state at the housing 1 by a fixing jig 2. A mirror 3 with a magnet is fixed near to the center thereof. A housing fix part 13 where the torsion spring 5 is fixed to the housing 1 is formed larger than the central part fixed with the mirror 3 with the magnet by an electroless plating method. The torsion spring 5 is formed with the plating film which is increased gradually in the wire diameter nearer the housing fixing part 13 from the central part, i.e., to a tapered shape.

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, measuring instruments and the like.

[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, there are those described in Japanese Patent Application Laid-Open Nos. 5-249402 and 5-264917. . Further, as an optical scanning device using a superelastic alloy wire having a high fatigue limit, the present applicant has
Japanese Patent Application No. 7-296788 proposes one having a structure shown in FIG.

The optical scanning device shown in FIG. 11 has a mirror 53 with a magnet whose surface is mirror-finished to reflect light.
Are bonded and fixed to a torsion spring 55 made of a Ni—Ti alloy which is a kind of superelastic alloy. Further, the torsion spring 55 is pulled by a predetermined tension exhibiting superelasticity and then fixed by the fixing jig 52 to the housing 51.
It is configured to be attached to.

A coil 57 is wound around the core 56, and the coil 57 is fixed by a screw (not shown) through a screw hole 58 provided in the core 56 and a hole 54 provided in the housing 51. Reference numeral 59 is a pulse current generator. The pulse current generator 59 and the coil 57 generate a magnetic field in the surroundings to vibrate the magnet-equipped mirror 53. The laser beam 60 emitted from the light source 61 is reflected by the mirror-attached mirror 53 with a mirror surface, and the surface 53 to be scanned is scanned by the resonance of the mirror 53 with a magnet.

The Ni-Ti alloy used for the torsion spring is a kind of so-called shape memory alloy and takes various states depending on stress and temperature. By setting the martensite transformation start temperature, the reverse transformation start temperature, the end temperature, and the tension applied to the torsion spring variously, it is possible to scan a larger scan angle with a stable resonance frequency.

[0006]

However, in the above-mentioned conventional example, although the superelastic alloy adopted as the torsion spring has a high fatigue limit and excellent durability, the torsion spring clamped by the fixing jig 52 is used as the housing. The stress was concentrated on the fixed part fixed to and the breakage of the torsion spring often occurred.

The present invention has been made in order to solve the above-mentioned problems, and increases the wire diameter of the portion fixed to the housing to prevent the breakage of the torsion spring at the fixed portion, which in turn results in durability. It is an object of the present invention to provide an inexpensive optical scanning device which is excellent in size, size, and weight.

[0008]

In order to achieve this object, an optical scanning device according to a first aspect of the present invention is a light source for emitting a laser beam, a torsion spring stretched on a housing, and its torsion. The torsion spring, which is swingably supported by the torsion spring as an axis, reflects the laser beam, and a coil which generates an alternating magnetic field for vibrating the magnet mirror. The wire diameter of the fixed portion fixed to the housing is set thicker than the supporting portion supporting the mirror with magnet.

According to this, when an alternating current is passed through the coil, an alternating magnetic field corresponding to the alternating current is generated around the coil. This alternating magnetic field gives a torque to the mirror with a magnet fixed to the torsion spring, and torsion stress is generated in the torsion spring. That is, since the mirror with a magnet receives a torque by an alternating magnetic field and a restoring force by a torsion spring, when a periodic alternating current is applied to the coil,
The magnet-equipped mirror can be vibrated. Especially,
When the mechanical natural frequency of the vibration system composed of the torsion spring and the mirror with magnet matches the frequency of the alternating current, resonance occurs and the amplitude can be maximized. With such a configuration, the scanning angle of the incident laser beam can be increased. Further, since the wire diameter of the portion where the torsion spring is fixed to the housing is made large, stress concentration on the fixed portion during driving can be suppressed as low as possible, and a long life optical scanning device can be provided.

The optical scanning device according to a second aspect of the present invention is configured such that the torsion spring gradually increases in diameter as it approaches the fixed portion from the support portion. Therefore, the stress concentration applied to the vicinity of the fixed portion during driving is further alleviated, and the optical scanning device having extremely excellent durability can be provided.

Further, the optical scanning device according to claim 3 is
The electroless plating method is used to increase the wire diameter of the torsion spring. Therefore, the optical scanning device having excellent durability can be provided by a simple and inexpensive method.

Further, in the optical scanning device according to the fourth aspect, the torsion spring is made of a superelastic alloy. Since the superelastic alloy has a high fatigue limit, it is possible to provide an optical scanning device having even higher durability.

Further, the optical scanning device according to claim 5 is
Ni-Ti in which torsion spring undergoes phase transformation at room temperature or below
It is made of a superelastic alloy composed of Cu-Zn or Cu-Zn. Since these alloys have a particularly high fatigue limit and are set to cause a phase transformation at room temperature or lower, the austenite phase and martensite phase can be selected with a relatively small tension, and the torsion springs in both phases can be selected. The elastic modulus of is almost unaffected by changes in room temperature. Therefore, it is possible to perform optical scanning at a stable resonance frequency with respect to changes in room temperature.

Further, in the optical scanning device according to the sixth aspect, the torsion spring is stretched around the housing with a tension capable of maintaining an austenite phase. Therefore, light can be scanned at a stable frequency without being greatly affected by changes in room temperature.

Further, the optical scanning device according to a seventh aspect is
The torsion spring is stretched on the housing under a tension that makes the gradient of the stress-strain curve zero, that is, a tension that causes stress-induced martensitic transformation. Therefore, the torsion spring is fixed in a state where the stress-induced martensite phase is generated, has a lower elastic modulus than a normal austenite phase, and the elastic modulus is kept substantially constant even when the room temperature changes. Therefore, even with an alternating magnetic field of the same magnitude, a larger deflection angle can be obtained, and scanning can be performed with a stable resonance frequency and a larger scanning angle.

Further, the optical scanning device according to an eighth aspect of the present invention is configured such that the coil is attachable to and detachable from the housing and is arbitrarily arranged around the magnet-equipped mirror. With such a configuration, it can be freely arranged even in a limited space, and the alternating magnetic field from the coil placed outside limits the space for the system including the magnet-attached mirror and the torsion spring. It is possible to scan light by causing resonance vibration at a desired resonance frequency without receiving it.

Further, the optical scanning device according to claim 9 is
The current waveform flowing through the coil is a rectangular waveform. When such a driving waveform is used, torque can be applied to the magnet-equipped mirror until the elastic restoring force of the torsion spring becomes maximum, so that the scanning width can be maximized.

[0018]

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 torsion spring 5 is attached to the housing 1 by the fixing jig 2 while being pulled by the tension (indicated by the arrow a or b) shown in FIG.
The magnet-equipped mirror 3 is fixed near the center of the torsion spring 5 with an adhesive (not shown). The magnet-equipped mirror 3 has a thickness of 0.3 mm, a length of 3 mm, and a width of 6 mm.
Ni-Co (nickel cobalt) or Sm-Co
(Samarium cobalt). Torsion spring 5
Is made of a superelastic alloy (for example, Ni—Ti alloy), and has a wire diameter of about 140 μm and a length of about 10 mm in the central portion.
The portion where the torsion spring 5 is fixed to the housing 1 is thicker than the central portion where the magnet mirror 3 is fixed by electroless plating or the like. The portion fixed to the housing is the housing fixing portion 13.

On the other hand, a coil 7 is wound around the core 6, for example, about 300 turns. Coil 7 is core 6
It is fixed to the housing 1 by a screw (not shown) through a screw hole 8 provided in the housing 1 and a hole 4 provided in the housing 1. A pulse current generator 9 is connected to both ends of the winding of the coil 7, and when an electric current of about 100 mA at 3 V is applied to the coil by the pulse current generator 9, an alternating magnetic field is generated, Mirror with magnet 3
Vibrates. Laser beam 10 emitted from a light source 11
Is reflected by the magnet-equipped mirror 3, and the surface to be scanned 12 is scanned by the resonance of the magnet-equipped mirror 3.

Housing fixing portion 13 of torsion spring 5
Is the cheapest and easiest to form by electroless plating. The electroless plating film can be variously selected depending on the material of the torsion spring 5, but in the case of Ni-Ti alloy, it is desirable to perform Ni plating. An example of the method will be described with reference to FIGS. 8 and 9.

First, both ends of the superelastic alloy 81 to be plated are subjected to pretreatment such as alkali degreasing and acid activation treatment, and then the superelastic alloy 81 is fixed to the holder 83 as shown in FIG. Then, the required plating portion is immersed in the plating liquid 82. The plating solution is a general electroless Ni plating solution (Ni-P, N
i-B etc.). In the case of electroless Ni-P plating, a film is generally formed at a bath temperature of 85 to 95 [deg.] C. and a pH of about 4.5 at a plating rate of 15 to 20 [mu] m / hr, depending on the bath composition.

In FIG. 8, the housing fixing portion 13 is provided at each end.
Although the method for forming the above is illustrated, it is also possible to fold the superelastic alloy 81 from the central portion in two and plate both ends simultaneously.

By immersing the superelastic alloy 81 in the plating solution for a predetermined time, as shown in FIG. 9, the torsion spring 5 having the housing fixing portion 13 having a desired wire diameter can be formed. The required wire diameter of the housing fixing portion 13 can be selected within a range of about φ50 μm to 1 mm, depending on the wire diameter of the superelastic alloy 81 and the usage conditions.

The boundary between the central portion of the non-plated superelastic alloy 81 and the housing fixing portion 13 has a step in the usual method. Therefore, the superelastic alloy 81 is continuously raised little by little during the plating, and a bath is gradually added. By taking it out, the wire diameter can be gradually increased as it approaches the housing fixing portion 13 from the central portion, and a so-called tapered plating film is formed. For that purpose, in FIG. 8, the holder 83 may be configured to be continuously movable up and down. By thus forming the taper shape, the stress concentration at the time of driving can be further alleviated, and eventually, the torsion spring 5 can be effectively prevented from being disconnected.

Since it is difficult to accurately obtain the predetermined length of the housing fixing portion 13 by this method, the plated portion is made a little longer in advance, and is cut to a predetermined length later. Better.

Further, since the electroless Ni-P coating has the property of being hardened by heat treatment, especially when it is desired to set the housing fixing portion 13 to have a high hardness, the plated portion has about 3 parts.
Vickers hardness of 90 if heat-treated at 00 ℃ for about 1 hour
The housing fixing portion 13 having a high hardness of about 0 to 1000 can be obtained. However, heat treatment may change the shape memory effect of the superelastic alloy, so it is desirable to perform heat treatment by local heating as much as possible.

In the above embodiment, the housing fixing portion 13
Although a method of using electroless plating has been described for forming the above, other various methods such as a ceramic or metal spraying method, a resin coating method and the like can be considered.

Next, the superelastic alloy used as the material of the torsion spring 5 will be described. Ni-T adopted here
A superelastic alloy such as i alloy is a kind of so-called shape memory alloy and takes various states depending on stress and temperature. The optical scanning device according to a sixth aspect of the present invention is the optical scanning device according to the seventh aspect, in which the torsion spring 5 is fixed by the tension indicated by the arrow a in FIG.
The optical scanning device described in 1 is a case where the optical scanning device is fixed by the tension of arrow b. In either case, since it is involved in the mechanism of phase transformation, the phase transformation of the shape memory alloy will be mainly described.

The shape memory alloy is divided into a shape memory region and a superelastic region at the boundaries of the reverse transformation start temperature As and the reverse transformation end temperature Af shown in FIG. When it is used below the reverse transformation start temperature As, it exhibits a so-called shape memory effect, and when it is used at a temperature above the reverse transformation end temperature Af point, it exhibits a superelastic effect. The transformation temperature means the austenite phase (state (1) of FIG. 4 (b) and state γ of FIG. 2) of the alloy to the martensite phase ((2) of FIG. 4 (b),
The temperature at the time of changing to the state (3) and the states of α and β in FIG. 2 is the temperature at the time of changing from the martensite phase to the austenite phase, contrary to the reverse transformation temperature. The martensitic transformation in the shape memory alloy can occur at temperature or stress, as shown in FIGS.
In this embodiment, stress-induced transformation that is particularly caused by stress is used.

Differences in deformation between a usual metal material and a superelastic alloy under shear stress will be described with reference to the schematic diagram of FIG. In a normal metal material, when shear stress exceeds a limit, atoms slip adjacent to each other and shear strain occurs, as shown in FIG. Even if the external force is removed, this strain is energetically stable and does not return to its original state. In other words, due to repeated stress, this strain accumulates and finally leads to a fracture generally called metal fatigue. On the other hand, in the case of a superelastic alloy, as shown in FIG. 4B, a phase transformation occurs due to an external force, and the stress-induced martensite phase, that is, the superelastic region is reached. At this time, the crystal structure is deformed, but it does not normally slide adjacently like a metal atom. Further, when the external force is removed, the martensite phase (β in FIG. 2) above the reverse transformation temperature is energetically unstable, and therefore tries to return to the austenite phase (γ in FIG. 2) again. Therefore, even if the metal is repeatedly subjected to repeated stress to the extent of fracture, in the case of a superelastic alloy, the fracture does not occur only by causing a phase change in which the crystal structure changes.

The present invention skillfully utilizes such properties of superelastic alloys. That is, in the optical scanning device according to the sixth aspect, the torsion spring 5 is applied with a tension that remains in an austenite phase, and the torsion is repeatedly applied in this state. That is, (1) and (2) in FIG. 4B are repeatedly reciprocated.

Further, in the optical scanning device according to the seventh aspect, a larger tensile tension is applied to the torsion spring 5 to completely cause the stress-induced transformation to the martensite phase (superelastic region), and then fixed in that state. Repeatedly giving torsion. That is, (2) and (3) of FIG. 4B are repeatedly reciprocated. In this case, since the elastic modulus in the martensite phase is smaller than that in the austenite phase (FIG. 6), the magnet-equipped mirror swings more under the same alternating magnetic field.

Further, as shown in FIG. 5, in the case of Ni-Ti, for example, the reverse transformation temperature of the superelastic alloy can be freely designed by adjusting the Ni concentration and mixing of impurities. For example, if the Ni concentration is 5
If it is set to about 0.6%, a superelastic alloy having a reverse transformation temperature of about 0 ° C can be formed. Moreover, even if a small amount of Co is mixed as an impurity, a superelastic alloy having a reverse transformation temperature of about 0 ° C. can be formed. That is, if the reverse transformation end temperature Af point is set to 0 ° C. and a predetermined tension is applied at room temperature, the superelastic region is relatively easily entered,
As shown by the double-headed arrow in FIG. 2, even if there is a slight change in room temperature, it does not deviate from that region.

Further, in order to show the stability of the elastic modulus in the change of temperature in the superelastic region, FIG. 6 shows the relationship between the elastic modulus of this alloy and temperature. (A) shows the relationship between the elastic modulus and temperature when no load is applied, that is, when the tension is 0, and (b) shows the relationship between elastic modulus and temperature when a predetermined tension is applied. At the transformation point, the elastic modulus changes rapidly, but in the martensite phase and austenite phase, it takes a stable and almost constant value. That is, even when the torsion is repeatedly applied in the superelastic region, the elastic modulus at that time is stable with respect to the ambient (mainly room temperature) temperature change, so that the stability of the resonance frequency is also guaranteed.

Next, the operation of the optical scanning device having the above configuration will be described.

When a pulse current is applied to the coil 7 by the pulse current generator 9, the coil 7 is moved forward and backward as shown in FIG.
As shown in (a) and (b) of FIG. The magnet-equipped mirror 3 whose center is fixed to the torsion spring 5 and which is installed in front of the coil 7 receives a torque of MH cos θ due to the alternating magnetic field (M is the magnetic moment of the magnet-equipped mirror 3 and H is the magnetic field). Strength, θ is the deflection angle.) When the torsion angle is θ, the restoring force kθ of the torsion spring 5 is also received. further,
When the magnet-equipped mirror 3 vibrates at high speed, d due to frictional resistance with air, frictional resistance inside the torsion spring, etc.
A damping force proportional to θ / dt is also received. 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, the following Equation 1 is obtained.

[0038]

[Equation 1]

This is an equation when a forcing force is applied to the damping vibration system, and its general solution is expressed by the following equation 2.

[0040]

[Equation 2]

That is, the frequency ω of the current and the natural frequency ω of the mechanical system including the mirror with magnet and the torsion spring
_{When 0} and ₀ match, a so-called resonance state is reached and the maximum deflection angle is obtained. In the case of this embodiment, the voltage applied to the coil is 3 V, the coil current is about 100 mA, and the frequency is about 800 Hz.
It resonates at about 50 degrees and its scanning angle is about 1 degree.
The laser beam is scanned at 00 degrees.

The above embodiment is an example of realizing an optical scanning device, and those skilled in the art can make various modifications without departing from the spirit of the present invention.

For example, in the above embodiment, the superelastic alloy Ni-Ti alloy was used, but Ag-Cd, A
u-Cd, Cu-Sn, Cu-Al-Ni, Ni-A
Any superelastic alloy, such as 1 and Fe-Pt, that causes stress-induced phase transformation may be used.

In this embodiment, the scanning angle is 100 degrees,
Although the scanning frequency of 800 Hz has been described as an example, optical scanning devices of various frequencies can be manufactured by changing the wire diameter φ of the torsion spring made of the above alloy and the mass m of the mirror with magnet. For example, when manufacturing an optical scanning device of 400 Hz, the frequency f is proportional to (k / m) ^1/2 , and the spring constant k is proportional to φ ^4.
The power will be proportional to the frequency. Since φ = 140 μm and resonance frequency 800 Hz, approximately φ = 1
An optical scanning device of about 400 Hz can be manufactured by using a torsion spring of 00 μm under the same conditions as above.

Further, as can be seen from the coefficient MH / I of Equation 2, by using a mirror with a magnet of various strengths (M), or a magnetic field of various amplitudes (H = ni,
An optical scanning device having a desired scanning angle can be provided in accordance with a target electric product or electronic device by giving n: the number of coil windings, i: current), that is, the current i.

Further, in this embodiment, for convenience, the coil 7 is used.
The torsion spring 5 and the mirror 3 with a magnet are arranged in front of the coil.
The magnetic moment M may be arranged at any position as long as it is generated at a substantially right angle.

Further, in the present embodiment, the housing 1 to which the torsion spring 5 and the magnet-equipped mirror 3 are fixed is
Although fixed to the coil 7 with screws, it may be arranged so as to be detachable and separable. As a result, for example, as shown in FIG. 10, it is possible to dispose the coil 7, the magnet-equipped mirror 3, the light source 11, the scanned surface 12, and the like. Further, by varying the distance between the coil 7 and the magnet-equipped mirror 3, the magnitude of the alternating magnetic field can be varied, and as a result, the scanning angle can also be varied.

Further, in this embodiment, the waveform of the current flowing through the coil 7 is a rectangular wave. When the rectangular wave is used, torque can be applied to the magnet-equipped mirror 3 until the restoring force of the torsion spring 5 becomes maximum, so that the scanning width can be maximized as compared with other current waveforms. Furthermore, since the scan width can be maximized at the lowest current value, the energy efficiency is the best. 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, in order to minimize the current flowing through the coil 7, the present optical scanning device is constructed by utilizing the resonance phenomenon. However, if the electric power has a margin, the resonance point is removed and the optical scanning is performed. There is no functional problem even if the scanning device is driven.

[0050]

As is apparent from the above description, according to the optical scanning device of the first aspect of the present invention, the support portion supporting the magnetized mirror of the torsion spring stretched on the housing. On the other hand, since the wire diameter of the fixed part fixed to the housing is set to be thick, the torsional stress is generated in the torsion spring due to the torque given to the mirror with magnet by the alternating magnetic field according to the alternating current flowing in the coil, The mirror is vibrated by a periodic alternating current to obtain a large scanning angle, and the stress concentration on the housing fixing portion during driving can be suppressed as low as possible, so that the light can be scanned for a long period of time.

Further, according to the optical scanning device of the second aspect, the wire diameter of the torsion spring gradually becomes thicker as it approaches the fixed portion of the housing with the magnet from the supporting portion of the mirror with magnet. Stress concentration applied during driving is further alleviated, and durability is improved.

Further, according to the optical scanning device of the third aspect, since the electroless plating method is used to increase the diameter of the torsion spring wire, the optical scanning excellent in durability is extremely easy and inexpensive. Can make a device.

Further, according to the optical scanning device of the fourth aspect, since the torsion spring is made of a superelastic alloy having a high fatigue limit, the optical scanning device further excellent in durability can be provided.

Further, according to the optical scanning device of the fifth aspect, a superelastic alloy of Ni—Ti type or Cu—Zn type having a particularly high fatigue limit is used for the torsion spring, and a phase transformation occurs at room temperature or lower. Since the austenite phase and the martensite phase can be selected with a relatively small tension, and the elastic modulus of the torsion spring in both phases is hardly affected by the temperature change at room temperature, Optical scanning can be performed at a resonance frequency that is stable against changes.

Further, according to the optical scanning device of the sixth aspect, since the torsion spring is fixed to the housing with the tension capable of maintaining the austenite phase, the torsion spring is not greatly affected by a change in room temperature and has a stable frequency. The light can be scanned.

Further, according to the optical scanning device of the seventh aspect, the torsion spring is fixed with a tension at which the gradient of the stress-strain curve becomes zero, that is, a tension causing the stress-induced martensitic transformation. , The stress-induced martensite phase is fixed in the generated state, the elastic modulus is lower than the normal austenite phase, the elastic modulus is kept almost constant even when the room temperature changes, even in the alternating magnetic field of the same magnitude, A larger deflection angle is obtained, and a larger scanning angle can be scanned at a stable resonance frequency.

According to the optical scanning device of the eighth aspect, the coil is attachable to and detachable from the housing,
Moreover, since it is arranged arbitrarily around the magnet-equipped mirror, it can be freely arranged even in a limited space, and the alternating magnetic field from the coil placed outside is generated by the magnet-equipped mirror and the torsion spring. It is possible to scan the light by causing resonance vibration at a desired resonance frequency in the system described above without being restricted by space.

Further, according to the optical scanning device of the ninth aspect, since the current waveform flowing in the coil is a rectangular waveform, torque can be applied to the mirror with magnet until the elastic restoring force of the torsion spring becomes maximum. Yes, the scan width can be maximized. Furthermore, since the scanning width can be maximized with a low current, an optical scanning device with the highest energy efficiency can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a configuration of an optical scanning device according to an embodiment.

FIG. 2 is a diagram showing a phase transformation with respect to temperature and stress of the superelastic alloy used in the present embodiment.

FIG. 3 is a diagram showing stress-strain characteristics of the superelastic alloy used in the present embodiment.

FIG. 4 is a schematic diagram showing shear strain due to phase transformation of the superelastic alloy used in the present embodiment and shear strain of general metal.

FIG. 5 is the transformation point and Ni of the superelastic alloy used in this embodiment.
It is a figure showing the relationship with a density.

FIG. 6 is a diagram showing temperature characteristics of elastic coefficient of the superelastic alloy used in the present embodiment.

FIG. 7 is a schematic diagram in which the magnet-equipped mirror used in the present embodiment receives torque from an alternating magnetic field.

FIG. 8 is a diagram showing a method of forming a housing fixing portion by electroless plating.

FIG. 9 is a view showing a torsion spring in which a housing fixing portion is formed.

FIG. 10 is a perspective view showing another embodiment of the optical scanning device of the present invention.

FIG. 11 is a diagram showing an example of a conventional optical scanning device using a torsion spring made of a superelastic alloy and a mirror with a magnet.

[Explanation of symbols]

 1 Housing 3 Mirror with magnet 5 Torsion spring 7 Coil 10 Laser beam 13 Housing fixing part 81 Super elastic alloy

Claims (9)

[Claims] 1. A light source for emitting a laser beam, a torsion spring stretched on a housing, a magnet-equipped mirror swingably supported by the torsion spring with the torsion spring as an axis and reflecting the laser beam, and the magnet. In a light scanning device including a coil that generates an alternating magnetic field for vibrating a mirror with a magnet, the torsion spring has a line of a fixed portion fixed to the housing with respect to a support portion supporting the mirror with a magnet. An optical scanning device having a large diameter. 2. The optical scanning device according to claim 1, wherein the torsion spring is configured so that the wire diameter gradually increases as it approaches the fixed portion from the supporting portion. 3. The optical scanning device according to claim 1, wherein an electroless plating method is used to increase the wire diameter of the torsion spring. 4. The optical scanning device according to claim 1, wherein the torsion spring is made of a superelastic alloy. 5. The optical scanning device according to claim 4, wherein the torsion spring is made of a Ni—Ti-based or Cu—Zn-based superelastic alloy that undergoes a phase transformation at room temperature or lower. 6. The optical scanning device according to claim 4, wherein the torsion spring is stretched around the housing with a tension capable of maintaining an austenite phase. 7. The torsion spring is stretched on the housing by being given a tension at which the gradient of the stress-strain curve becomes zero, that is, a tension causing a stress-induced martensitic transformation. The optical scanning device according to claim 4. 8. The optical scanning device according to claim 1, wherein the coil is attachable to and detachable from the housing, and is arbitrarily arranged around the magnet-equipped mirror. 9. The rectangular wave current for generating an alternating magnetic field is supplied to the coil.
Or the optical scanning device according to 8.