JP5614167B2 - Optical deflector, optical scanning device, image forming apparatus, and image projecting apparatus - Google Patents

Description

  The present invention relates to an optical deflector that deflects and scans a light beam such as a laser beam, and more particularly to an optical deflector that uses a piezoelectric power. Further, the present invention relates to an optical scanning device including the optical deflector, The present invention relates to an image forming apparatus provided as a writing unit and an image projecting apparatus provided with the optical deflector as a projection unit scanning unit.

  An optical deflector that deflects and scans a light beam such as a laser beam is widely used in an image forming apparatus such as a copying machine, an image projection apparatus, a laser beam printer, a barcode scanner, and the like. Conventionally, as this type of optical deflector, one using an electrostatic force, one using an electromagnetic force, one using a piezoelectric force, and the like are known.

  There are two types of optical deflectors using electrostatic force, parallel plate type and comb type, so that the comb type electrode can generate a relatively large driving force by the recent improvement of microfabrication technology. However, since a sufficient deflection angle of the light beam cannot be obtained, the drive voltage must be increased to compensate. However, if the drive voltage is increased, the power supply system components become larger, resulting in an increase in size as a whole and an increase in cost.

  In order to obtain a large deflection angle, an optical deflector using electromagnetic force needs to increase the magnetic force of a permanent magnet or increase the current of a coil, leading to an increase in size and an increase in power consumption. Although the use of a magnetostrictive film or the like has been studied for miniaturization, there is a problem that characteristics as a magnetic material are inferior. Further, when a current is passed through the coil, extra heat is generated, and power consumption increases from this point.

  On the other hand, when the piezoelectric power is used, a relatively large driving voltage is required, but a large force can be generated with a small power. In addition, it is possible to obtain a large deformation by changing a slight distortion in the in-plane direction due to the piezoelectric force into a warp by bonding the piezoelectric material to the beam-like elastic member to form a unimorph structure or a bimorph structure. However, the conventional optical deflector using the piezoelectric power still has various problems.

  For example, Patent Document 1 describes an optical deflector that vibrates and rotates a micromirror by vibrating a whole frame body on which the micromirror is swingably supported by a bulk piezoelectric element. However, since the bulk piezoelectric element is used, there is a problem that the excitation amplitude is small, miniaturization is difficult, and the cost is high.

  In Patent Document 2, one end of a pair of piezoelectric bimorphs is fixed to a base in a cantilever shape, the free ends are connected to each other by a connecting member, and the central portion of the connecting member extends in parallel with the piezoelectric bimorph. An optical polarizer having a configuration in which a mirror portion is provided on the twisted deformable member is described. In this optical polarizer, the torsional deforming part has one end as a free end, so that it can be deformed not only in the torsional deformation direction but also in the bending direction, and the mirror part can be rotated in the biaxial direction. However, since the torsional deformable member is arranged in parallel with the piezoelectric bimorph, there is a problem that the moment due to the bending of the bimorph is not fully utilized. Also, regarding the operation in the bending direction orthogonal to the torsion, the deformation amount of the piezoelectric bimorph is very small. Therefore, if the frequency is to be increased, increasing the rigidity of the torsion member makes it difficult to deform in the bending direction. Directional movement has a problem that it is difficult to obtain a large amplitude.

  In Patent Document 3, a pair of elastic support members that are connected to both sides of the mirror portion and support the mirror portion in a swingable manner are respectively paired with a drive beam (cantilever) in which a piezoelectric material is bonded to a beam-like elastic member. ), An optical deflector that rotates and vibrates the mirror unit by supporting the pair of drive beams in opposite directions (reverse phase drive) from the fixed base at right angles to the axis of the elastic support member. Have been described. However, since the mirror part and the support member of the mirror part are configured such that both ends thereof are supported from both directions of the fixed base by a pair of driving beams, the rotational amplitude of the mirror part is limited, and one direction Since it is necessary to arrange a total of four drive beams at the rotation amplitude of the motor, downsizing is difficult and there is a problem that the cost increases.

  Further, in the cited document 4, a frame is provided between the mirror part and a pair of elastic support members that support the mirror part so as to be swingable so as to surround the outer periphery of the mirror part. An optical deflector (micromirror device) is described which is connected by a plurality of connecting members to reduce dynamic deformation of the mirror portion. However, in the configuration of Cited Document 4, the thermal resistance from the mirror part to the elastic support member is small, the temperature of the elastic support member rises due to the temperature rise of the mirror part due to light source irradiation, and the resonance frequency of the deflection mirror system fluctuates greatly. There is a problem to do.

  The present invention solves the above-mentioned problems of a conventional optical deflector using piezoelectric power, and provides an optical deflector that is small in size, has good driving efficiency, can obtain a large rotational amplitude, and can reduce dynamic deformation. There is to do. Furthermore, it is providing the optical deflector which can reduce the fluctuation | variation of the resonant frequency by the temperature rise of a mirror part.

  In addition, the present invention is small in size, high in driving efficiency, large amplitude can be obtained, dynamic deformation can be reduced, and furthermore, optical scanning with good characteristics can be performed using an optical deflector that can reduce fluctuations in resonance frequency. To provide an apparatus.

  In addition, the present invention provides an optical writing apparatus for optical writing using an optical deflector that is small in size, has good driving efficiency, obtains a large amplitude, can reduce dynamic deformation, and can also reduce fluctuations in resonance frequency. An object of the present invention is to provide an image forming apparatus having good performance when used in a unit.

  Furthermore, the present invention is small in size, good in driving efficiency, large amplitude can be obtained, dynamic deformation can be reduced, and furthermore, power consumption can be reduced by using an optical deflector that can reduce variation in resonance frequency, An object of the present invention is to provide an image projection apparatus capable of obtaining a projection with a wide angle of view.

The optical deflector of the present invention includes a fixed base, a mirror part having a light reflecting surface, an inner frame member surrounding the mirror part, a plurality of connecting members connecting the inner frame member and the mirror part, and the mirror A pair of elastic support members that pivotably support the portion via the inner frame member, and a pair of drive beams in which a piezoelectric member is fixed to a beam-shaped member, and the longitudinal direction of the elastic support member and the The longitudinal direction of the drive beam is disposed substantially orthogonally to each other, the other end of the drive beam is fixed to a fixed base, and the mirror portion and the inner frame member are fixed to a fixed base. A pair of the elastic support members are cantilevered with respect to the fixed base, and the drive beam bends and vibrates, whereby torsional deformation occurs in the elastic support member, and the mirror portion is connected to the inner frame member. while rotational vibration integrally with the elastic supporting member The connecting portion of the serial drive beam, the thickness of the light reflecting surface and a direction perpendicular, characterized in that the partially so as to dent thin is formed.

  Further, the optical deflector of the present invention includes a movable frame, a mirror part having a light reflecting surface, an inner frame member surrounding the mirror part, and a plurality of connecting members connecting the inner frame member and the mirror part, A pair of first elastic support members that swingably support the mirror portion via the inner frame member, a pair of first drive beams having a piezoelectric member fixed to a beam-like member, and the movable frame A pair of second elastic support members supported in a swingable manner, a pair of second drive beams in which a piezoelectric member is fixed to the beam-like member, and a fixed base; The longitudinal direction and the longitudinal direction of the first driving beam are disposed substantially orthogonally to each other, and the other ends of the first driving beam are fixed to the movable frame, and the pair of the first driving beams The mirror portion, the inner frame member, and the pair of first elastic support members on the movable frame. The longitudinal direction of the second elastic support member and the longitudinal direction of the second drive beam are arranged substantially orthogonal to each other and connected to each other. Ends are fixed to a fixed base, and the movable frame and the pair of second elastic support members are cantilevered with respect to the fixed base by a pair of the second drive beams, and the first drive By bending vibration of the beam, torsional deformation occurs in the first elastic support member, the mirror portion rotates and vibrates in the first direction integrally with the inner frame member, and the second drive beam By bending vibration, torsional deformation occurs in the second elastic support member, the movable frame rotates and vibrates, and the mirror portion rotates and vibrates in the second direction integrally with the inner frame member. Features.

  Further, the optical deflector of the present invention includes a movable frame, a mirror part having a light reflecting surface, an inner frame member surrounding the mirror part, and a plurality of connecting members connecting the inner frame member and the mirror part, A pair of first elastic support members for swingably supporting the mirror portion via the inner frame member, a pair of second elastic support members for swingably supporting the movable frame, and a beam-shaped member A pair of drive beams to which a piezoelectric member is fixed, and a fixed base. One end of the pair of first elastic support members is connected to the mirror portion, and the other end is fixed to the movable frame. The mirror portion is swingably supported via the inner frame member, and the longitudinal direction of the second elastic support member and the longitudinal direction of the drive beam are arranged substantially orthogonal to each other, and the two are connected. The other end of the drive beam is fixed to a fixed base, and a pair of the drive beams The movable frame and the pair of second elastic support members are cantilevered with respect to the fixed base, and the pair of drive beams bend and vibrate in opposite phases, whereby the pair of first elastic support members. Rotational vibration occurs around the axis of the mirror, the mirror portion rotates and vibrates in the first direction integrally with the inner frame member, and the pair of vibrating beams bend and vibrate in the same phase. Torsional deformation occurs in the elastic support member, the movable frame rotates and vibrates, and the mirror part rotates and vibrates in the second direction integrally with the inner frame member.

  Furthermore, in the optical deflector of the present invention, the plurality of connecting members that connect the inner frame member and the mirror portion are arranged radially with respect to the center of the mirror portion, and the pair of elastic support members and the inner frame member are connected. The connecting member is not disposed on the extended line of the points. Preferably, the inner frame member and the mirror portion are connected by six or more connecting members.

  Furthermore, the optical deflector of the present invention is characterized in that the center of gravity of the mirror portion is offset in a direction close to the connecting portion side of the drive beam and the fixed base with respect to the central axis of the elastic support member. .

  The optical scanning device of the present invention includes a light source, the optical deflector that deflects the light beam from the light source, and an imaging optical system that forms an image of the deflected light beam in a spot shape on the surface to be scanned. It is characterized by that.

  The image forming apparatus of the present invention also includes the optical scanning device, a photosensitive member that forms a latent image by scanning a light beam, a developing unit that visualizes the latent image with toner, and the toner image is transferred to a recording sheet. And transfer means.

  The image projection apparatus of the present invention includes a light source, a modulator that modulates a light beam from the light source according to an image signal, a collimating optical system that makes the light beam substantially parallel light, and the substantially parallel light. And the above-described optical deflector for deflecting the projected light beam and projecting it on the projection surface.

According to the optical deflector of the present invention, the drive beam cantilever-supports the mirror portion and the pair of elastic support members that support the mirror portion so as to be swingable with respect to the fixed base, and further, the inner frame surrounding the mirror portion By providing a member and connecting the inner frame member and the mirror portion with a plurality of connecting members, it is possible to rotate the mirror portion efficiently and obtain a large rotational amplitude, and to reduce dynamic deformation. . In addition, by not arranging the connecting member on the extension line of the connection point between the pair of elastic support members and the inner frame member, the thermal resistance from the mirror part to the elastic support member can be increased, and the mirror part by light irradiation can be increased. It is possible to reduce the variation of the resonance frequency due to the temperature rise.
Further, since the depression is formed in the connection portion between the elastic support member and the drive beam, the thickness of the connection portion in the direction perpendicular to the light reflecting surface can be partially reduced.

Therefore, by using the optical deflector of the present invention, an optical scanning device with good characteristics can be provided, and by using the optical scanning device for an optical writing unit, an image forming apparatus with good performance can be provided. Furthermore, it is possible to provide an image projection apparatus that uses the optical deflector according to the present invention and has low power consumption and capable of wide angle projection.
Note that further operational effects of the optical deflector of the present invention will become apparent from the description of embodiments described later.

It is a perspective view of the optical deflector of Example 1 of this invention. It is a top view of the optical deflector of FIG. It is a figure explaining the structure of the drive beam of the optical deflector of FIG. It is a figure which shows the frequency response characteristic of the rotation amplitude of the mirror part of the optical deflector of FIG. It is a figure which shows two types of natural vibration mode shapes of the mirror part of the optical deflector of FIG. It is a figure which shows the specific example of the mirror support shape by an internal frame member and a connection member. It is a figure which shows the example of calculation of the amount of dynamic deformation in 4 point | piece support. It is the figure which compared the amount of dynamic deformation in 4 point support, 6 point support, and 8 point support. It is a figure which shows the change of the resonant frequency by temperature. It is a figure explaining the heat transfer path | route in a prior art example. It is a figure explaining the heat transfer path | route in Example 1 of this invention. It is a perspective view of the optical deflector of Example 2 of this invention. It is a top view of the optical deflector of FIG. It is a figure which shows the frequency response characteristic of the rotation amplitude of the mirror part of the optical deflector of FIG. It is a figure which shows two types of natural vibration mode shapes of the mirror part of the optical deflector of FIG. It is a figure explaining the relationship between the bending deformation of the drive beam of the optical deflector of FIG. 12, and rotation of a mirror part. It is a perspective view of the optical deflector of Example 3 of this invention. It is a top view of the optical deflector of FIG. It is a perspective view of the optical deflector of Example 4 of this invention. It is a perspective view of the optical deflector of Example 5 of this invention. It is a whole block diagram of an example of the optical scanning device using the optical deflector of this invention. It is a figure which shows the connection of the optical deflector and drive means of the optical apparatus of FIG. It is a whole block diagram of an example of the image forming apparatus which mounted the optical scanning device of FIG. 21 as an optical writing unit. 1 is an overall perspective view of an example of an image forming apparatus using an optical deflector of the present invention. FIG. 25 is a schematic configuration diagram illustrating the image projection apparatus of FIG. 24 including a drive system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall perspective view of a first embodiment of an optical deflector according to the present invention, and FIG. 2 is a plan view thereof. 1 and 2, reference numeral 10 denotes a mirror part having a reflecting surface for reflecting light. A pair of mirror parts 10 are supported on both ends of the mirror part 10 via an internal frame member 20 so as to be swingable. Torsion bar springs 30a and 30b are connected as elastic support members. The inner frame member 20 is provided so as to surround the mirror portion 10 and is connected to the mirror portion 10 by a plurality of connecting members 22, and a pair of torsion bar springs 30 a and 30 b are connected to both sides of the inner frame member 20.
The plurality of connecting members 22 that connect the inner frame member 20 and the mirror unit 10 are arranged radially with respect to the center of the mirror unit 10. However, in this embodiment, the connecting member 22 is not arranged on the extended line of the connection point between the pair of torsion bar springs 30a and 30b and the inner frame member 20. As a result, as will be described later, the dynamic deformation of the mirror portion 10 is reduced, and at the same time, the fluctuation of the resonance frequency due to the temperature rise of the mirror portion can be reduced. In addition, when it is not necessary to consider the fluctuation | variation of a resonant frequency, you may arrange | position a connection member on the extension line of a connection point.
Beam-like members 41a and 41b whose longitudinal direction is substantially perpendicular to the longitudinal direction of the torsion bar springs 300a and 30b are connected to the ends of the torsion bar springs 30a and 30b opposite to the inner frame member 20, respectively. Yes. The other ends of the beam members 41 a and 41 b are connected to the fixed base 50.

  The pair of beam-like members 41a and 41b protrude in the same direction from the fixed member 50, and are disposed only on one side of the torsion bar springs 30a and 30b. The mirror-like member 10 and the inner frame member 20 are supported by the beam-like members 41a and 41b. The torsion bar springs 30 a and 30 b are cantilevered with respect to the fixed base 50. Piezoelectric materials 42a and 42b are laminated on one side of the beam-like members 41a and 41b, respectively, and the driving beams 40a and 40b having a unimorph structure having a plate-like short rail shape are formed by the beam-like members 41a or 41b and the piezoelectric material 42a or 42b. Forming.

  For example, the mirror part 10, the inner frame member 20, the connecting member 22, the torsion bar springs 30a and 30b, and the driving beams 40a and 40b are integrally formed by processing by a MEMS (micro electro mechanical systems) process. The mirror unit 10 forms a reflective surface by forming a thin film of metal such as aluminum or gold on the surface of a silicon substrate.

  Here, the detailed structure of the drive beam will be described with reference to FIG. 3A and 3B are enlarged schematic views showing the driving beam 40a and the fixed base 50 in the vicinity thereof. FIG. 3A is a plan view before being covered with the insulating layer, and FIG. 3B is a plan view after being covered with the insulating layer. (C) is sectional drawing of the AA 'line | wire part of (b). Since the drive beam 40b has the same configuration, the illustration is omitted.

  As shown in FIG. 3, the drive beam 40a is formed on the beam-like member 41a formed so as to protrude from the fixed base 50, with an adhesive layer 43a, a lower electrode 45a, a piezoelectric material (piezoelectric member) 42a, an upper electrode 44a, an insulating member. The layers 46a are formed by sputtering and stacked in order, and are etched so that only necessary portions such as the land portions 47a and 48a remain. The material of the adhesive layer 43a is titanium (Ti), the upper electrode 44a and the lower electrode 45a are platinum (Pt), and the piezoelectric material 42a is lead zirconate titanate (PZT).

  When wiring is drawn from the land portions 47a and 48a and a voltage is applied between the upper electrode 44a and the lower electrode 45a, the piezoelectric material 42a expands and contracts in the in-plane direction on the surface of the beam-like member 41a due to its electrostrictive characteristics. The entire drive beam 40a warps and deforms. The drive beam 40b is also bent and deformed in the same direction as the drive beam 40a by applying a voltage in phase with the piezoelectric member 42a. The waveform of the voltage applied to the piezoelectric members 42a and 42b of the drive beams 40a and 40b may be any of a pulse wave and a sine wave.

  1 and 2, the torsion bar springs 30a and 30b and the driving beams 40a and 40b are arranged so that the longitudinal directions thereof are arranged substantially orthogonal to each other, thereby connecting the driving beams due to the bending vibration of the driving beams 40a and 40b. Since the vertical vibrations at the tips of 40a and 40b act perpendicularly to the torsional central axes of the torsion bar springs 30a and 30b, the bending vibrations of the drive beams 40a and 40b become rotational vibrations (torsional vibrations) of the torsion bar springs 30a and 30b. The mirror portion 10 is largely rotated and vibrated integrally with the inner frame member 20. In addition, since the driving beams 40a and 40b have a configuration in which the torsion bar springs 30a and 30b, the inner frame member 20 and the mirror portion 10 are cantilevered, the tips of the driving beams 40a and 40b can freely vibrate, The mirror unit 10 can obtain a larger angular vibration. Furthermore, since the beam-like members 41a and 41b are disposed only on one side of the torsion bar springs 30a and 30b, the beam can be reduced in size. Functions of the inner frame member 20 and the connecting member 22 will be described later.

  FIG. 4 shows frequency response characteristics of the amplitude of the rotation angle of the mirror unit 10 with respect to the applied voltage to the piezoelectric members 42a and 42b of the driving beams 40a and 40b in the optical deflector of the present embodiment. In FIG. 4, a and b are resonance points, but the mirror unit 10 shows different natural vibration mode shapes in a and b. Here, the natural vibration mode shape at the resonance point a is referred to as mode 1, and the natural vibration mode shape at the resonance point b is referred to as mode 2.

  FIG. 5 shows the natural vibration mode shapes (mode 1 and mode 2) of the mirror unit 10 at the resonance points a and b in the frequency response characteristics of FIG. As shown in FIG. 5A, in mode 1, bending deformation of the torsion bar springs 30a and 30b occurs, and the entire mirror portion 10 changes in the Z direction in the figure. On the other hand, in mode 2, as shown in FIG. 5 (b), the torsion bar springs 30a and 30b are hardly bent, and the torsion bar springs 30a and 30b are largely twisted, so that the mirror portion 10 rotates largely in the vicinity of the mirror center. To do. In the optical deflector, it is necessary to use the frequency in the natural vibration mode of mode 2 because it is necessary to prevent fluctuation in the Z direction of the entire mirror unit and rotate it near the center of the mirror unit 10.

  By applying an applied voltage to the piezoelectric members 42a and 42b of the drive beams 40a and 40b at the natural frequency of mode 2, the mirror unit 10 can obtain a large angular amplitude, and the entire mirror unit 10 varies in the Z direction. Can be prevented. Specifically, the shape of the torsion bar springs 30a, 30b is determined from the mirror part shape (mass) including the inner frame member and the resonance frequency, and the natural frequency of the primary bending deformation mode of the drive beams 40a, 40b is The torsion bar springs 30a and 30b are set so as to substantially match the natural frequency of the primary torsional deformation mode. By doing so, the mirror unit 10 vibrates with a large angular amplitude, and the occurrence of fluctuations in the Z direction is prevented.

  As described above, the waveform of the voltage applied to the piezoelectric members 42a and 42b of the drive beams 40a and 40b may be either a pulse waveform or a wave shape such as a sine wave, and its frequency is the natural frequency of mode 1. It may be in the vicinity.

Next, functions and effects of the inner frame member 20 and the connecting member 22 will be described in detail.
First, reduction of dynamic deformation of the mirror unit 10 will be specifically described. When the mirror unit 10 is vibrated greatly at the resonance frequency, dynamic deformation occurs. However, as shown in FIG. By connecting and supporting with a plurality of connecting members 22 arranged radially with respect to the center of 10, dynamic deformation of the mirror portion 10 can be reduced.

  FIG. 6 is a diagram showing a specific example of the support shape of the mirror portion 10 by the inner frame member 20 and the connecting member 22, wherein (1) is a four-point support, (2) is a six-point support, and (3) is eight points. A specific example of support is shown. 7 shows a specific calculation example of the amount of dynamic deformation when the four-point support shown in FIG. 6 (1) is used, and FIG. 8 similarly calculates the amount of dynamic deformation of the six-point support and the eight-point support. It is the figure compared with the case of 4 point | piece support. Table 1 shows the torsion bar spring width and resonance frequency in each support shape.

  FIG. 8 shows that the amount of dynamic deformation in the six-point support structure of FIG. The configuration of FIG. 1 is based on the six-point support shape of FIG. Of course, as long as the dynamic deformation of the mirror part 10 can be reduced, it is not always necessary to provide 6-point support, and 4-point support, 8-point support, or other support shapes may be used.

  Next, the reduction of the fluctuation of the resonance frequency due to the temperature rise of the mirror unit 10 will be described in detail. Light emitted from a light source such as laser light enters the reflecting surface of the mirror unit 10 and is deflected. At this time, about 80 to 90% of the incident light is deflected, while the remaining about 10 to 20% is converted into heat. Due to this heat, the temperature of the mirror portion 10 rises and is transmitted to the torsion bar springs 30a and 30b, and the resonance frequency is lowered due to the temperature rise of the torsion bar springs 30a and 30b. This is presumably because the resonance frequency of the deflecting mirror system is roughly determined by the moment of inertia of the mirror and the spring constant of the torsion bar spring, but the spring constant of the torsion bar spring decreases as the temperature rises. FIG. 9 shows an example of the actual measurement result of the resonance frequency change due to the temperature change. From FIG. 9, it can be seen that the resonance frequency decreases by about 0.046 to 0.067 (Hz) per 1 ° C.

  As shown in FIG. 1, for a plurality of connecting members 22 that connect the mirror portion 10 and the inner frame member 20, the connecting members 22 are connected to an extension line of a connection point between the pair of torsion bar springs 30 a and 30 b and the inner frame member 20. By not providing the member 22, it is possible to reduce the dynamic deformation of the mirror unit 10 and at the same time reduce the variation (decrease) in the resonance frequency due to the temperature rise of the mirror unit 10. This is apparent when compared with the configuration of FIG. 6 shown in Patent Document 4, for example.

For convenience, consider an equivalent circuit model in which the concentrated heat source Q by laser light irradiation acts on the center of the mirror section. When the distance from the center of the mirror portion to the connection point between the inner frame member and the torsion bar spring (heat transfer path distance) Li, thermal conductivity K, and cross-sectional area A, the thermal resistance R is
R = Li / AK (1)
Given in.
Further, if the temperature drop ΔT at the distance Li from the mirror center to the connection point between the inner frame member and the torsion bar spring is equal to the cross-sectional area A,
ΔT = R · Q = Q · Li / A · K (2)
Given in.
In the case of the configuration of FIG. 6 of Patent Document 4, as shown in FIG. 10, the distance from the mirror center P1 to the connection point P2 between the inner frame member 20 and the torsion bar spring 30b is in line with the torsion bar spring 30b. L1 via the connecting member 22. Therefore, the temperature drop ΔT1 is
ΔT1 = Q · L1 / A · K (3)
Given in.

On the other hand, in the case of the configuration of FIG. 1 of the present embodiment, as shown in FIG. 11, the distance from the mirror center P1 to the connection point P2 between the inner frame member 20 and the torsion bar spring 30b is on the extension line of the torsion bar spring 30b. L2 is used to bypass the connecting member 22 that is not present. In the case of FIG. 1, two connecting members 22 are arranged approximately symmetrically on both sides of the connection point P2, there are two distances L2 from the mirror center P1 to the connection point P2, and the thermal resistance is halved. . Therefore, the temperature drop ΔT2 is
ΔT2 = Q · (L2 / 2) / A · K (4)
Given in.

  Here, if L2 / 2> L1, ΔT1 <ΔT2. That is, by adopting the configuration of FIG. 1, the heat transfer path becomes long, and as a result, the temperature rise of the torsion bar spring is suppressed (temperature drop ΔT increases), and the fluctuation of the resonance frequency can be reduced. Of course, if the connecting member is not arranged on the extension line of the connection point P2 between the torsion bar springs 30a and 30b and the inner frame member 20, and the heat transfer path can be lengthened, the configuration of FIG. 1 is not necessarily required.

  FIG. 12 is an overall perspective view of a second embodiment of the optical deflector of the present invention, and FIG. 13 is a plan view. 12 and 13, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals.

  1 and 2, the center (center of gravity) of the mirror portion 10 is made to coincide with the central axis of the torsion bar springs 30a and 30b. However, in this embodiment, as shown in FIG. Further, the center (center of gravity) of the mirror portion 10 is offset by a distance ΔS with respect to the torsion bar springs 30a and 30b in the direction approaching the connecting portion between the drive shafts 40a and 40b and the fixed base 50. By doing so, compared to the case of the first embodiment, the mirror portion 10 can be further rotated and vibrated integrally with the inner frame member 20 by utilizing the flexural deformation of the drive beams 40a and 40b. Other configurations, operations, and effects are the same as those in the first embodiment.

  FIG. 14 shows the frequency response characteristics of the rotation angle amplitude of the mirror unit 10 with respect to the voltage applied to the piezoelectric members 42a and 42b of the drive beams 40a and 40b in the case where the center of gravity of the mirror unit 10 of this embodiment is offset. Show. FIG. 15 shows the natural vibration mode shapes (mode 1 and mode 2) of the mirror unit 10 at the resonance points a and b in the frequency response characteristics of FIG.

  Also in the present embodiment, by applying an applied voltage to the piezoelectric members 42a and 42b of the drive beams 40a and 40b at the natural frequency of mode 2, the mirror unit 10 can obtain a large angular amplitude, and the mirror unit 10 The entire variation in the Z direction can be prevented. Moreover, compared to the case of the first embodiment, the mirror unit 10 can obtain a larger angular amplitude.

  FIG. 16 shows the relationship between the bending deformation of the driving beam and the rotation of the mirror part in the mode 2 of this embodiment. The inner frame member 20 is omitted. In mode 2 in which the torsion bar springs 30a and 30b are twisted, when the distance ΔS between the connection part a of the torsion bar springs 30a and 30b and the rotation center b of the mirror part 10 and the rotation angle of the mirror part 10 are θ, the drive beam By setting the bending deformation c in the direction perpendicular to the mirror reflecting surfaces 40a and 40b (Z direction) to be ΔS · sin θ, the rotation center b of the mirror unit 10 is Z when the mirror unit 10 rotates. It can be set as the structure which does not change to a direction. Further, since the center of rotation of the mirror unit 10 is close to the center of gravity O of the mirror unit 10, the moment of inertia is reduced and the natural frequency can be increased. That is, higher speed driving is possible.

  The center of gravity of the mirror unit 10 is the center of gravity of the entire rotating unit including the inner frame member 20 supported by the torsion bar springs 30a and 30b, and the center of gravity including the rib structure on the back surface of the mirror is offset. Good.

  FIG. 17 is an overall perspective view of Embodiment 3 of the optical deflector of the present invention, and FIG. 18 is a plan view. 17 and 18, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals. Although the overall configuration is basically the same as that of the first embodiment, in this embodiment, as shown in FIG. 18, notches 60a and 60b are formed at the connecting portions of the drive beams 40a and 40b and the torsion bar springs 30a and 30b. Has been. Specifically, the driving beams 40a, 40b are arranged so that the end portions on the mirror portion 10 side of the driving beams 40a, 40b are closer to the mirror portion 10 side than the end portions of the torsion bar springs 30a, 30b opposite to the mirror portion 10. Cuts 60a and 60b are formed in the connecting portion between 40b and the torsion bar springs 30a and 30b.

  The torsion bar springs 30a and 20b have a large non-linearity as a spring characteristic. However, as the length becomes shorter, the non-linearity increases and the design becomes difficult. The longer the torsion bar springs 30a and 30b are, the larger the allowable displacement angle is.

  In the present embodiment, the length of the torsion bar springs 30a and 30b is maintained within a desired range, and the drive beams 40a and 40b are arranged in the space-exempted portion, that is, the drive beams 30a and 30b are located inside. By being offset, the entire optical deflector can be further reduced in size. As a result, when the optical deflector is manufactured by the MEMS process, the number of wafers in a single wafer increases, so that the cost can be reduced.

  17 and 18, when the widths of the drive beams 40a and 40b are increased, the drive beams 40a and 40b are twisted, and the force at a portion away from the connection portion with the torsion bar springs 30a and 30b is applied. It is thought that it will not be transmitted. In order to prevent this, it is only necessary to thicken the tip portions of the drive beams 40a and 40b, so that all forces can be used effectively. Specifically, for example, it is conceivable that the end portions of the beam-like members 41a and 41b of the drive beams 40a and 40b are L-shaped. However, it is only necessary to prevent the drive beams 40a and 40b from being twisted, and the shape thereof Can be anything.

  Here, also in the present embodiment, as in the second embodiment, the center (center of gravity) of the mirror portion 10 is the drive beams 40a and 40b and the fixed base 50 with respect to the center line of the torsion bar springs 30a and 30b. The rotational amplitude of the mirror unit 10 can be further increased.

  FIG. 19 shows an overall perspective view of Embodiment 4 of the optical deflector of the present invention. All of the optical deflectors described so far deflect light in a uniaxial direction, but this embodiment is configured to deflect light in a biaxial direction. FIG. 19 shows the case where FIGS. 17 and 18 are applied, but the same applies when FIGS. 1 and 2 are applied.

  In FIG. 19, reference numeral 10 denotes a mirror portion having a reflecting surface for reflecting light. A pair of first mirrors 10 are supported at both ends of the mirror portion 10 via an internal frame member 120 so as to be swingable. First torsion bar springs 130a and 130b as one elastic support member are connected. The inner frame member 120 is connected to the mirror portion 10 by a plurality of connecting members 122, and a pair of first torsion bar springs 130 a and 130 b are connected to both sides of the inner frame member 120.

  The plurality of connecting members 122 that connect the inner frame member 120 and the mirror unit 10 are arranged radially with respect to the center of the mirror unit 10. However, the connecting member 122 is not disposed on the extension line of the connection point between the pair of first torsion bar springs 130 a and 130 b and the inner frame member 120. This is the same as FIG. 1 and FIG.

  The ends of the pair of first torsion bar springs 130a and 130b on the side opposite to the inner frame member 120 have a pair of first torches as a longitudinal direction substantially perpendicular to the longitudinal direction of the first torsion bar springs 130a and 130b. Drive beams 140a and 140b are connected. As described with reference to FIG. 3, the first drive beams 140a and 140b are formed by laminating piezoelectric materials on one side of the beam-like member to form a flat strip-like unimorph structure. The first drive beams 140a and 140b are connected so as to protrude in the same direction from one side inside the frame-shaped movable frame 150 having a hole in the center, and are connected to one side of the first torsion bar springs 130a and 130b. The mirror 10, the inner frame member 120, and the first torsion bar springs 130 a and 130 b are cantilevered with respect to the movable frame 150 by the driving beams 140 a and 140 b.

  Further, on both sides of the movable frame 150, a second torsion bar as a pair of second elastic support members that are orthogonal to the first torsion bar springs 130a and 130b and support the movable frame 150 in a swingable manner. The springs 220a and 220b are connected. The ends of the second torsion bar springs 220a and 220b opposite to the movable frame 150 have a pair of second drive beams 230a with the direction substantially perpendicular to the longitudinal direction of the second torsion bar springs 220a and 220b as the longitudinal direction. , 230b are connected. The second drive beams 230a and 230b are also laminated with a piezoelectric material on one side of the beam-like member to form a flat strip-like unimorph structure. The second drive beams 230a and 230b are connected so as to protrude in the same direction from the fixed base 240, and are disposed only on one side of the second torsion bar springs 220a and 220b. 230b, the movable frame 150 and the second torsion bar springs 220a, 220b are cantilevered with respect to the fixed base 240.

  In the present embodiment, the first torsion bar springs 130a and 130b are vibrated by the first drive beams 140a and 140b, so that the mirror unit 10 is integrated with the inner frame member 120 into the first torsion bar springs 130a and 130b. The movable frame 150 is rotated around the axis of the second torsion bar springs 220a, 220b by rotating the second drive beams 230a, 230b to the second torsion bar springs 220a, 220b. And rotate. Here, the natural frequency of the vibration mode in the first rotation direction around the axis of the first torsion bar springs 130a and 130b and the second rotation direction around the axis of the second torsion bar springs 220a and 220b are made different. In addition, by driving the first drive beams 130a and 130b and the second drive beams 220a and 220b at the respective frequencies, the mirror unit 10 can be greatly rotated in two axial directions integrally with the inner frame member 120. .

  FIG. 20 shows an overall perspective view of Embodiment 5 of the optical deflector of the present invention. The optical deflector of the present embodiment also deflects light in the biaxial direction, but differs in configuration and driving method from the fourth embodiment.

  In FIG. 20, reference numeral 10 denotes a mirror part having a reflecting surface for reflecting light. A pair of first mirrors 10 are supported on both sides of the mirror part 10 via an internal frame member 120 so as to be swingable. First torsion bar springs 130a and 130b as one elastic support member are connected. The inner frame member 120 is connected to the mirror unit 10 by a plurality of connecting members 122, and a pair of first torsion bar springs 130 a and 130 b are connected to both sides of the inner frame member 120. The configuration of the connecting member 122 is the same as that in FIG.

  The ends of the pair of first torsion bar springs 130a, 130b opposite to the inner frame member 120 are connected to the inner sides of two opposing sides of a frame-shaped movable frame 150 having a hole in the center. A pair of second torsion bar springs (second elastic support members) whose longitudinal direction is perpendicular to the first torsion bar springs 130a and 130b are provided on the outer sides of the other two opposite sides of the movable frame 150. ) 220a and 220b are connected. The ends of the second torsion bar springs 220a and 220b opposite to the movable frame 150 are driven beams 230a and 230b whose longitudinal direction is substantially perpendicular to the longitudinal direction of the second torsion bar springs 220a and 220b. Is connected. The drive beams 230a and 230b are connected so as to protrude in the same direction from the fixed base 240, and are disposed only on one side of the second torsion bar springs 220a and 220b. The second torsion bar spring 202 is cantilevered with respect to the fixed base 240. The driving beams 230a and 230b are formed by laminating piezoelectric materials on one side of the beam-like member to form a flat strip-like unimorph structure.

  In this embodiment, the movable frame 150 is rotated about the axis of the second torsion bar springs 220a and 220b by applying in-phase vibrations to the second torsion bar springs 220a and 220b by the drive beams 230a and 230b. Further, the drive beams 230a and 230b vibrate both sides of the second torsion bar springs 220a and 220b in opposite phases, thereby rotating around the axes of the first torsion bar springs 130a and 130b. I am doing so. As a result, the mirror unit 10 rotates in the first rotation direction around the axis of the first torsion bar springs 130a and 130b and in the second rotation direction around the axis of the second torsion bar springs 220a and 220b.

  Specifically, the natural frequencies of the vibration modes in the first rotation direction and the second rotation direction are made different from each other, and the drive beams 220a and 220b are driven in the same phase and in opposite phases by signals including the respective frequency components. Thus, the mirror unit 10 can be largely rotated in the biaxial direction. In the present embodiment, the first drive beams 140a and 140b of the fourth embodiment shown in FIG. 19 are unnecessary, and the manufacture is simple and the cost can be reduced.

  The present embodiment provides an optical scanning device as an optical writing unit of an image forming apparatus using the optical deflector that deflects light in one axial direction of the first to third embodiments.

  FIG. 21 is an overall configuration diagram of the optical scanning device of this embodiment, and FIG. 22 is a connection diagram of an optical deflector used in the optical scanning device and driving means.

  In FIG. 21, the laser light from the laser element 1020 passes through the collimator lens system 1021 and is then deflected by the optical deflector 1022. As this optical deflector 1022, the optical deflector having any one of the configurations of the first to fifth embodiments is used. The laser beam deflected by the optical deflector 1022 is then applied to a beam scanning surface 1022 such as a photosensitive drum through a scanning optical system 1023 including a first lens 1023a, a second lens 1023b, and a reflection mirror 1023c.

  As shown in FIG. 22, the optical deflector 1022 is electrically connected to the driving means 1024. The driving unit 1024 applies a driving voltage between the lower electrode and the upper electrode of the optical deflector 1022. As a result, the mirror portion of the optical deflector 1022 rotates to deflect the laser light, and the beam scanning surface 1022 is optically scanned.

  As described above, the optical scanning device using the optical deflector according to the present invention is optimal as a constituent member of an optical writing unit for an image forming apparatus such as a photographic printing type printer or a copying machine.

  The present embodiment provides an image forming apparatus in which the optical scanning device according to the sixth embodiment is mounted as a constituent member of an optical writing unit.

  FIG. 23 shows an overall configuration diagram of an example of the image forming apparatus of this embodiment. In FIG. 23, reference numeral 1001 denotes an optical writing unit, which emits a laser beam to a surface to be scanned and writes an image. Reference numeral 1002 denotes a photosensitive drum as an image carrier that provides a surface to be scanned as an object to be scanned by the optical writing unit 1001.

  The optical writing unit 1001 scans the surface (scanned surface) of the photosensitive drum 1002 in the axial direction of the photosensitive drum 1002 with one or a plurality of laser beams modulated by the recording signal. The photosensitive drum 1002 is rotationally driven in the direction of an arrow 1003, and an optical latent image is formed on the surface charged by the charging unit 1004 by optical scanning by the optical writing unit 1001. The electrostatic latent image is visualized as a toner image by the developing unit 1005, and the toner image is transferred to the recording paper 1007 by the transfer unit 1006. The transferred toner image is fixed on the recording paper 1007 by the fixing unit 1008. Residual toner is removed by the cleaning unit 1009 from the surface portion of the photosensitive drum that has passed the transfer unit 1006 facing portion of the photosensitive drum 1002.

  A configuration using a belt-like photoconductor in place of the photoconductor drum 1002 is also possible. Further, the toner image may be temporarily transferred to a transfer medium other than the recording paper, and the toner image may be transferred from the transfer medium to the recording paper and fixed.

  The optical writing unit 1001 includes a light source unit 1020 as a laser element that emits one or a plurality of laser beams modulated by a recording signal, a light source driving unit 1500 that modulates a laser beam, and the uniaxial of the present invention described so far. An optical deflector 1002 that deflects the laser beam in the direction, and a connection for imaging the laser beam (light beam) modulated by the recording signal from the light source unit 1020 on the mirror surface of the mirror substrate of the optical deflector 1022. An image optical system 1021 and a scanning optical system 1023 that is a means for forming an image of one or a plurality of laser beams reflected and deflected by a mirror surface on the surface (scanned surface) of the photosensitive drum 1002 Is done. The optical deflector 1022 is incorporated in the optical writing unit 1001 in a form mounted on a circuit board 1025 together with an integrated circuit (driving means) 1024 for driving the optical deflector 1022.

  The optical deflector 1022 consumes less power for driving than the conventional rotary polygon mirror, which is advantageous for power saving of the image forming apparatus. Further, since the wind noise during vibration of the mirror substrate of the optical deflector 1022 is smaller than that of the rotary polygon mirror, it is advantageous for improving the quietness of the image forming apparatus. Furthermore, the optical deflector 1022 requires much less installation space than the rotary polygon mirror, and also has a small amount of heat generation, so that it can be easily downsized, and therefore advantageous for downsizing the image forming apparatus. is there.

  Note that the conveyance mechanism of the recording paper 1007, the driving mechanism of the photosensitive drum 1002, the control means such as the developing means 1005 and the transfer means 1006, the driving system of the light source unit 1020, and the like may be the same as those in the conventional image forming apparatus. Is omitted.

  The present embodiment provides an image projection apparatus equipped with an optical deflector that deflects light in the biaxial direction as in the fourth and fifth embodiments.

  FIG. 24 shows an overall configuration diagram of the image projection apparatus of the present embodiment. In FIG. 24, laser light sources 2001-R, 2001-G, and 2001-B that emit laser beams having three different wavelengths of red (R), green (G), and blue (B) are attached to a housing 2000. In the vicinity of the emission ends of the laser light sources 2001-R, 2001-G, 2001-B, a condenser lens 2002 that condenses the emitted light from the laser light sources 2001-R, 2001-G, 2001-B into substantially parallel light. -R, 2002, 002-B are arranged. The R, G, and B laser beams that are substantially parallel by the condenser lenses 2002-R, 2002, and 002-B pass through the mirror 2003 and the half mirror 2004, and are combined by the combining prism 2005. Incident on the mirror surface. As the optical deflector 2006, an optical deflector (two-dimensional reflection angle variable mirror) configured to deflect light in two-axis directions as in the seventh and eighth embodiments is used. The combined laser light incident on the mirror surface of the optical deflector 2006 is two-dimensionally deflected and scanned by the optical deflector 2006 and projected onto the projection surface to project an image.

  FIG. 25 is a schematic configuration diagram including the control system of the image projection apparatus of the present embodiment. In FIG. 25, a three-wavelength laser light source and a condensing lens are shown together, and a mirror, a half mirror, and a combining prism are omitted.

  The image generation unit 2011 generates an image signal according to the image information, and the image signal is sent to the light source drive circuit 2013 via the modulator 2012, and the image synchronization signal is sent to the scanner drive circuit 2014. The scanner drive circuit 2014 supplies a drive signal to the optical deflector 2006 according to the image synchronization signal. By this drive signal, the mirror unit 10 of the optical deflector 2006 resonates and vibrates in two orthogonal directions with an amplitude of a predetermined angle (for example, about 10 deg), and the incident laser light is two-dimensionally deflected and scanned. On the other hand, the intensity of the laser light emitted from the laser light source 2001 is modulated by the light source driving circuit 2013 in accordance with the timing of the two-dimensional deflection scanning of the optical deflector 2006, and thereby a two-dimensional image is projected on the projection surface 2007. Information is projected. Intensity modulation may modulate the pulse width or the amplitude. The modulator 2012 performs pulse width modulation or amplitude modulation on the image signal, and modulates the modulated signal into a current that can drive the laser light source 2001 by the light source driving circuit 2013 to drive the laser light source 2001.

  Here, a rotating scanning mirror such as a polygon mirror can be used as the light deflecting unit, but the optical deflector (two-dimensional reflection angle variable mirror) 2006 having the configuration of the seventh and eighth embodiments of the present invention is rotated. Since power consumption for driving is smaller than that of the scanning mirror, it is advantageous for power saving of the image projection apparatus. Further, since the wind noise during vibration of the mirror substrate of the optical deflector 2006 is smaller than that of the rotating scanning mirror, it is advantageous for improving the quietness of the image projection apparatus. Furthermore, the optical deflector 2006 requires much less installation space than the rotary scanning mirror and has a small amount of heat generation, so it can be easily downsized, and is therefore advantageous for downsizing the image projection apparatus. is there.

DESCRIPTION OF SYMBOLS 10 Mirror part 20 Internal frame member 22 Connection member 30a, 30b Torsion bar spring (elastic support member)
40a, 40b Drive beam 41a, 41b Beam-like member 42a, 42b Piezoelectric member 50 Fixed base 60a, 60b Notch 120 Internal frame member 122 Connection member 130a, 130b First torsion bar spring 140a, 140b First drive beam 150 Movable Frames 220a, 220b Second torsion bar springs 230a, 230b Second drive beam (drive beam)
240 fixed base

Japanese Patent No. 3129219 Japanese Patent No. 3246106 JP 2008-083603 A JP 2007-065649 A

Claims (10)

A fixed base, a mirror part having a light reflecting surface, an inner frame member surrounding the mirror part, a plurality of connecting members connecting the inner frame member and the mirror part, and the mirror part via the inner frame member A pair of elastic support members that are swingably supported, and a pair of drive beams in which a piezoelectric member is fixed to the beam-shaped member,
The longitudinal direction of the elastic support member and the longitudinal direction of the drive beam are arranged substantially orthogonally, and both are connected, the other end of the drive beam is fixed to a fixed base, and a pair of the drive beams, The mirror part, the inner frame member, and the pair of elastic support members are cantilevered with respect to the fixed base,
While the drive beam is bending-vibrated, torsional deformation occurs in the elastic support member, and the mirror portion rotates and vibrates integrally with the inner frame member ,
An optical deflector , wherein a recess is formed in a connecting portion between the elastic support member and the driving beam so that a thickness in a direction perpendicular to the light reflecting surface is partially reduced . A movable frame, a mirror part having a light reflecting surface, an inner frame member surrounding the mirror part, a plurality of connecting members connecting the inner frame member and the mirror part, and the mirror part via the inner frame member A pair of first elastic support members that are swingably supported, a pair of first drive beams in which a piezoelectric member is fixed to the beam-shaped member, and a pair of second supports that swingably support the movable frame. An elastic support member, a pair of second drive beams in which a piezoelectric member is fixed to the beam-shaped member, and a fixed base,
The longitudinal direction of the first elastic support member and the longitudinal direction of the first drive beam are arranged substantially orthogonally to each other, and the other end of the first drive beam is fixed to the movable frame. The pair of first drive beams are cantilevered with respect to the movable frame by the mirror portion, the inner frame member, and the pair of first elastic support members,
The longitudinal direction of the second elastic support member and the longitudinal direction of the second drive beam are arranged substantially orthogonally to each other, and the other end of the second drive beam is fixed to a fixed base. The movable frame and the pair of second elastic support members are cantilevered with respect to the fixed base by the pair of second drive beams,
When the first driving beam is subjected to bending vibration, torsional deformation occurs in the first elastic support member, and the mirror portion rotates and vibrates in the first direction integrally with the inner frame member,
When the second driving beam vibrates, the second elastic support member undergoes torsional deformation, the movable frame rotates and vibrates, and the mirror portion is integrated with the inner frame member. An optical deflector that rotates and vibrates in a direction. A movable frame, a mirror part having a light reflecting surface, an inner frame member surrounding the mirror part, a plurality of connecting members connecting the inner frame member and the mirror part, and the mirror part via the inner frame member A pair of first elastic support members that are swingably supported, a pair of second elastic support members that swingably support the movable frame, and a pair of drives in which a piezoelectric member is fixed to the beam-shaped member A beam and a fixed base;
The pair of first elastic support members has one end connected to the mirror part, the other end fixed to the movable frame, and the mirror part supported to be swingable via the inner frame member,
The longitudinal direction of the second elastic support member and the longitudinal direction of the drive beam are arranged substantially orthogonally to each other, and the other end of the drive beam is fixed to a fixed base, and a pair of the drive In the beam, the movable frame and the pair of second elastic support members are cantilevered with respect to the fixed base,
The pair of drive beams bend and vibrate in opposite phases to generate rotational vibration around the pair of first elastic support members, and the mirror portion is integrated with the inner frame member in the first direction. Oscillate and rotate
When the pair of vibrating beams bend and vibrate in the same phase, torsional deformation occurs in the second elastic support member, and the movable frame rotates and vibrates, and the mirror portion is integrated with the inner frame member. An optical deflector that vibrates in the direction of 2.   The plurality of connecting members that connect the inner frame member and the mirror portion are arranged radially with respect to the center of the mirror portion, and on an extension line of a connection point between the pair of the elastic support member and the inner frame member. 4. The optical deflector according to claim 1, wherein the connecting member is not disposed.   The optical deflector according to any one of claims 1 to 4, wherein the inner frame member and the mirror portion are connected by six or more connecting members.   The center of gravity of the mirror part is offset in a direction approaching the connection part side of the drive beam and the fixed base with respect to the central axis of the elastic support member. The optical deflector according to any one of 5. The first drive beam and the first drive beam are arranged so that an end surface of the first drive beam on the mirror portion side is closer to the mirror portion side than an end portion on the opposite side to the mirror portion of the first elastic support member. 3. An optical deflector according to claim 2 , wherein a cut is formed in a connecting portion of the elastic support member . A light source, an optical deflector according to any one of claims 3 to 6 for deflecting a light beam from the light source, and an imaging optical system for imaging the deflected light beam in a spot shape on a surface to be scanned. optical scanning apparatus you, comprising. 9. An optical scanning device according to claim 8, a photoconductor for forming a latent image by scanning with a light beam, a developing means for developing the latent image with toner, and a transfer means for transferring the toner image to a recording sheet. An image forming apparatus . A light source;
A modulator that modulates a light beam from the light source according to an image signal;
A collimating optical system in which the light beam is substantially parallel light;
An image projection apparatus comprising: the optical deflector according to claim 1, which deflects and projects the substantially parallel light beam onto a projection surface .