JP2011013621A - Light deflector, image forming apparatus and image projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light deflector (optical scanner) which is compact and has a large rotational oscillation.SOLUTION: The light deflector includes: a movable member 40 having a light reflection face; torsion beam members 20a, 20b which support the movable member in a freely rotationally oscillatable manner; a frame member 40 which supports the end parts of the torsion beam members; and driving members 30a, 30b, 30c, 30d which are arranged between the movable member 10 and the frame member 40 and generate warpage, wherein the longitudinal-direction one end of each of the driving member is free and the other end is supported by the torsion beam member. By causing the driving members 30a, 30c, and 30b, 30d to alternately generate the warpage, the torsion beam members 20a, 20b are caused to generate clockwise and counterclockwise twists, thereby the movable member 10 is caused to perform the rotational oscillation.

Description

  The present invention relates to an optical deflector that deflects and scans a light beam such as a laser beam using a small galvanometer mirror, an image forming apparatus in which the optical deflector is incorporated in an optical writing unit, and the optical deflector on a projection surface. The present invention relates to an image projection apparatus incorporated as a scanning unit.

  The optical deflector (optical scanning device) using a micromachine technology with a small galvanometer mirror has the potential for power saving, miniaturization and high speed compared to a polygon mirror or a conventional galvanometer mirror. However, it is expected to be put to practical use because there is a possibility that it can be formed in large quantities at a low cost by using a semiconductor microfabrication technique using a silicon wafer as a material.

  In such an optical deflector, when the silicon wafer is removed and a torsion beam is formed so that the angle of the mirror surface can be changed, the torsion beam that rotatably holds the movable plate that holds the mirror portion. A force in the torsional direction is generated to tilt the mirror to change the outgoing direction of the incident light beam.

  Examples of the driving means include electrostatic driving, electromagnetic driving, and piezoelectric driving. Here, the electrostatic type cannot secure a large displacement because it is necessary to secure the area of the opposing electrode even if it is displaced in order to obtain a driving force. For this reason, when used as a driving means for an optical deflector, it is not expected to increase the light emission angle. In addition, the electromagnetic type has disadvantages such as a reduction in size and a reduction in the cross-sectional area of the coil wiring and an increase in resistance, resulting in high Joule loss and high power consumption due to current driving. Furthermore, since a magnetic body is mounted, if there are other peripheral parts and devices that dislike magnetism, a magnetic shield is required, which may increase the size.

  On the other hand, a cantilever that can be warped in the thickness direction is formed by bimorph, monomorph, bimetal, etc., and the bending force generated in the cantilever is transmitted to the torsion beam, and the piezoelectric element generates a rotational force around the axis of the torsion beam. The system does not have the drawbacks described above.

  FIG. 28 shows a conventional configuration example of a piezoelectric optical deflector. In FIG. 28, reference numeral 10 denotes a movable plate having a mirror surface. The movable plate 10 is supported by a torsion beam member 20a, 20b so as to be swingable, and a drive member 30a, which generates a warp in the thickness direction by a bimorph, a monomorph, or the like. 30b, 30c, and 30d have one end connected to the torsion beam members 20a and 30a and the other end connected to the frame portion 40 to form a cantilever. The drive plates 30a, 30c and 30b, 30d are each warped in the opposite direction, and the direction of the warp is alternately switched, whereby the movable plate 10 having a mirror surface is as shown in FIGS. 29 (a) and 29 (b). Rotate to.

  By the way, an optical deflector is configured as shown in FIG. 28, and a large deflection angle is obtained by switching the warping direction of the piezoelectric film in a state where both ends of the drive member (cantilever) are connected to the frame portion and the torsion beam portion. In order to obtain it, the Young's modulus of the material constituting the cantilever is small, and it is necessary to extend greatly with a slight force. However, in reality, the support part of the mirror is often made of silicon, and silicon is a material with a very high Young's modulus. Therefore, in the configuration where both ends of the cantilever are connected, a large force that tilts the mirror surface is generated. I can't.

  The optical deflector configured as shown in FIG. 28 is described in detail in, for example, Patent Document 1 and Patent Document 2.

  An object of the present invention is to provide an optical deflector that solves the conventional problems as described above and that can obtain a large amount of warpage and a large deflection angle without increasing the size of the apparatus.

  It is another object of the present invention to provide an image forming apparatus and an image projecting apparatus that can improve design flexibility, reduce costs, and reduce size by incorporating such an optical deflector.

  The optical deflector of the invention of claim 1 is a movable member having a light reflecting surface, a torsion beam member that supports the movable member so as to be capable of rotational vibration, a frame member that supports an end of the torsion beam member, A drive member disposed between the movable member and the frame member, having one end in the longitudinal direction free and the other end supported by the torsion beam member, and generating a warp, wherein the drive member is warped By doing so, the torsion beam member is twisted, and the movable member rotates and vibrates.

  According to a second aspect of the present invention, in the optical deflector according to the first aspect, the drive member is disposed at a predetermined distance from the movable member, and a torsion beam member capable of being twisted between the movable member and the drive member. It is characterized by being connected by.

  According to a third aspect of the present invention, in the optical deflector according to the second aspect, the torsion beam member that supports the driving member and the torsion beam member that connects the movable member and the driving member have different thicknesses. It is characterized by that.

  According to a fourth aspect of the present invention, in the optical deflector according to any one of the first to third aspects, the drive member is disposed to be inclined toward the movable member with respect to an axis of the torsion beam member. It is characterized by that.

  According to a fifth aspect of the present invention, in the optical deflector according to any one of the first to third aspects, the drive member is bent or curved toward the movable member halfway.

  A sixth aspect of the present invention is the optical deflector according to any one of the first to fifth aspects, wherein a free end side of the driving member is heavier than other portions.

  According to a seventh aspect of the present invention, in the optical deflector according to the sixth aspect, a weight adjusting means for adjusting the weight of the free end side of the driving member is provided.

  According to an eighth aspect of the present invention, in the optical deflector according to any one of the first to seventh aspects, the drive member is a piezoelectric monomorph or a bimorph.

  A ninth aspect of the present invention is the optical deflector according to any one of the first to eighth aspects, wherein the frame member is connected to the frame member of the torsion beam member inside the connecting portion and the movable member. A power supply pad for the drive member is provided at a position inside the tip of the member.

  An optical deflector according to a tenth aspect of the present invention is a movable frame, a movable member having a light reflecting surface, a first torsion beam member that supports the movable member so as to be able to rotate and vibrate about an axis in a first direction, One end is connected to the first torsion beam member and the other end is connected to the movable frame, and a first drive member that generates a warp and supports the movable frame so as to be capable of rotational vibration about an axis in a second direction. The second torsion beam member, the fixed frame that supports the end of the second torsion beam member, and the movable frame and the fixed frame. A second driving member that is supported by the second torsion beam member and generates a warp, and the first driving member is warped, whereby the first torsion beam member has a first driving member. Torsion occurs around the axis in the direction, and the movable member rotates in the first direction. When the second drive member is vibrated and warped, the second torsion beam member is twisted about the axis in the second direction, and the movable frame is rotated about the axis in the second direction. And the movable member rotates and vibrates in the second direction.

  An optical deflector according to an eleventh aspect of the present invention is a movable member having a light reflecting surface, a first torsion beam member that supports the movable member so as to be capable of rotational vibration about an axis in a first direction, and the first deflector. A movable frame that supports an end portion of the torsion beam member, and is arranged between the movable member and the movable frame, one end in the longitudinal direction is free and the other end is supported by the first torsion beam member, and warps. A first drive member that generates a fixed base, a second torsion beam member that supports the movable frame so as to be capable of rotational vibration about an axis in a second direction, and one end of the second torsion beam member. And a second drive member connected to the fixed base and generating a warp. The warp of the first drive member causes the first torsion beam member to A twist occurs around the axis in the direction of 1, and the movable member And the second drive member is warped, causing the second torsion beam member to twist about an axis in the second direction, and the movable frame is moved to the second drive member. The movable member rotates and vibrates around a direction axis, and the movable member rotates and vibrates in a second direction.

  An optical deflector according to a twelfth aspect of the present invention includes a movable member having a light reflecting surface, a first torsion beam member that supports the movable member so as to be capable of rotational vibration about an axis in a first direction, and the first A movable frame that supports an end portion of the torsion beam member, and is arranged between the movable member and the movable frame, one end in the longitudinal direction is free and the other end is supported by the first torsion beam member, and warps. A first drive member that generates the second frame, a second torsion beam member that supports the movable frame so as to be capable of rotational vibration about an axis in the second direction, and a fixed member that supports the end of the second torsion beam member. A frame, and a second drive member disposed between the movable frame and the fixed frame, wherein one end in the longitudinal direction is free and the other end is supported by the second torsion beam member to generate a warp. And the first driving member is warped, so that the first driving member The torsion beam member is twisted around the axis in the first direction, the movable member is rotated and vibrated in the first direction, and the second drive member is warped, whereby the second torsion beam is generated. The member is twisted around an axis in the second direction, the movable frame rotates and vibrates around the axis in the second direction, and the movable member rotates and vibrates in the second direction. .

  An image forming apparatus according to a thirteenth aspect of the present invention uses the optical deflector according to any one of the first to ninth aspects to deflect and scan a light beam from a light source to form an image on a photosensitive member. It is characterized by that.

  According to a fourteenth aspect of the present invention, there is provided an image projection apparatus that deflects and scans a light beam from a light source two-dimensionally using the optical deflector according to any one of the tenth to twelfth aspects, and displays an image on a projection surface. Is projected.

  According to the optical deflector of the present invention, since one end of the drive member is not fixed, a large amount of warpage can be obtained, and the movable member holding the mirror surface can be largely rotated and oscillated. Miniaturization is also possible easily.

  By incorporating the optical deflector of the present invention into an image forming apparatus, the degree of freedom in design is improved, and a compact and high-performance image forming apparatus can be realized. Further, by incorporating the optical deflector of the present invention into an image projection apparatus, a small-sized and wide-angle-projection image projection apparatus can be realized.

  In addition, the further effect | action and effect of the optical deflector of this invention are clear by description of embodiment.

It is a top view of Example 1 of the optical deflector of the present invention. FIG. 2 is a partially enlarged view showing wiring of drive signal lines of the drive member of FIG. 1. It is a figure which shows rotation operation | movement of the movable plate of the optical deflector of FIG. It is a figure which shows an example of the voltage which drives the drive member of FIG. It is a top view of Example 2 of the optical deflector of the present invention. It is a top view of Example 2 similarly of the optical deflector of this invention. It is a top view of Example 2 similarly of the optical deflector of this invention. It is a top view of Example 3 of the optical deflector of the present invention. It is a top view of Example 4 of the optical deflector of the present invention. It is a top view of Example 5 of the optical deflector of the present invention. It is a top view of Example 5 similarly of the optical deflector of this invention. It is a figure which shows the displacement distribution of the thickness direction of a drive member in the structure of FIG. It is a figure which shows the mode of the curvature of a drive member in the structure of FIG. It is a top view of Example 6 of the optical deflector of the present invention. FIG. 15 is a cross-sectional view taken along line AB in the configuration of FIG. 14. It is a top view of Example 6 similarly of the optical deflector of this invention. It is a top view of Example 6 similarly of the optical deflector of this invention. It is a top view which shows before adjustment of Example 7 of the optical deflector of this invention. It is a top view which shows the after adjustment of FIG. It is a top view which shows before adjustment of Example 7 of the optical deflector of this invention. It is a top view which shows the after adjustment of FIG. It is a top view of Example 8 of the optical deflector of this invention. It is a top view of Example 8 similarly of the optical deflector of this invention. It is a top view of Example 8 similarly of the optical deflector of this invention. 1 is an overall configuration diagram of an example of an image forming apparatus in which an optical deflector of the present invention is mounted in an optical writing unit. It is a whole block diagram of an example of the image projector which mounts the optical deflector of this invention. It is a whole block diagram of the other example of the image projector which mounts the optical deflector of this invention. It is a top view which shows the structural example of the conventional optical deflector. It is a figure explaining operation | movement of the optical deflector of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the driving means is a piezoelectric system, but the present invention is not limited to the piezoelectric system.

  FIG. 1 is a plan view of Embodiment 1 of the optical deflector according to the present invention. In FIG. 1, reference numeral 10 denotes a movable plate having a light reflecting layer (mirror surface) provided on the surface, and the movable plate 10 is rotatably supported by a pair of torsion beam members (torsion bar springs) 20a and 20b. The other ends of the torsion beam members 20a and 20b are supported by a frame member (fixed base) 40. And between the movable plate 10 and the frame member 40, torsion is generated in the torsion beam members 20a and 20b, and the movable plate 10 is rotated so that one end in the longitudinal direction is free and the other end is Drive members 30a, 30b, 30c, and 30d that are supported by the torsion beam members 20a and 20b and that warp in the longitudinal direction are provided. Specifically, the drive members 30a, 30b, 30c, and 30d have a monomorph or bimorph structure in which a piezoelectric material is laminated on one or both sides of an elastic member.

  For example, the movable plate 10, the torsion beam members 20a and 20b, and the drive members 30a, 30b, 30c, and 30d are integrally formed by processing a silicon wafer as a material by a micro electro mechanical system (MEMS) process. The movable plate 10 has a light reflecting surface formed by forming a thin film of metal such as aluminum or gold on the surface.

  FIG. 2 is a diagram showing wiring of drive signal lines of the drive member. For convenience, FIG. 2 shows the drive members 30c and 30d, but the same applies to the drive members 30a and 30b. In FIG. 2, 31 and 32 are drive signal lines, and 33 is a common ground line, which are formed by forming a film of platinum or the like on the torsion beam member 20b and etching it so that only necessary portions remain. The drive signal lines 31 and 32 and the common ground line 33 extend to the frame member 40, and a land portion is formed in the frame member 40. A voltage is applied to the drive member 30 c through the drive signal line 31 and the common ground line 33, and a voltage is applied to the drive member 30 d through the drive signal 32 and the common ground line 33. Due to this voltage application, the drive members 30c and 30d are warped. The waveform of the applied voltage may be either a sine wave or a pulse wave, but as described later, the driving member 30c and the driving member 30d have opposite phases. The same applies to the drive member 30a and the drive member 30b.

  Returning to FIG. 1, when the drive members 30a and 30c are warped, for example, on the front side of the paper, the torsion beam members 20a and 20b are twisted in the clockwise direction (as viewed in the direction from 20a to 20b) and movable. The plate 10 rotates as shown in FIG. Next, when the drive members 30b and 30c are similarly warped toward the front side of the paper, the torsion beam members 20a and 20b are twisted counterclockwise, and the movable plate 10 is moved as shown in FIG. To turn. By repeating this, the movable plate (mirror surface) 10 can be reciprocally rotated. Here, it is possible to generate a larger displacement by making the vibration period continuous with a value close to the resonance characteristics of the entire movable part. In order to match the desired frequency (suitable for use conditions) and the resonance characteristics of the movable part, the shape of the movable part, the overall weight, balance, adjustment of the length and thickness of the beam part, What is necessary is just to decide suitably, such as selection.

  FIG. 4 shows an example of a voltage waveform for driving the drive members 30a, 30b, 30c, and 30d. Although a sine wave is shown in FIG. 4, a pulse wave (rectangular wave) may be used as described above. Here, A is the applied voltage to the drive members 30a and 30c, and B is the applied voltage to the drive members 30b and 30d. Further, it is assumed that the driving members 30a to 30d have a monomorph structure in which piezoelectric materials are laminated only on the surface side of the elastic member, and warp occurs only on the front side of the paper surface due to application of voltage.

Now, when to, the warp of the drive members 30a and 30c and the warp of the drive members 30b and 30c are antagonized, so that the movable plate 10 is substantially parallel to the paper surface. When the t _1, the drive member 30a, warpage of 30c up, the drive member 30b, 30d of the warp minimum (zero), and the movable plate 10 is rotated as shown in FIG. 3 (a). Then, at _{t 2,} again driving member 30a, the warp and the driving member 30b of 30c, and warping of 30d are antagonistic, the movable plate 10 is returned to the sheet and parallel state. Then, when the _{t 3,} the drive member 30b, warping of 30d is at maximum, the drive member 30a, 30c warping of is minimized, the movable plate 10 is rotated as shown in FIG. 3 (b). In this way, the movable plate 10 repeats reciprocating vibration. Since one end of the drive members 30a, 30b, 30c, and 30d is not fixed, a large amount of warpage can be obtained and a large deflection angle can be obtained.

When the driving members 30a to 30d have a bimorph structure in which piezoelectric materials are laminated on both the front and back surfaces of the elastic member and are configured to generate warpage on the front side and the back side of the paper surface, a larger deflection angle. It is possible to obtain That is, the monomorph is bonded to the front and back to form a bimorph structure. For example, the voltage shown in FIG. On the other hand, the voltage shown in FIG. 4B is applied to the piezoelectric material on the back side of the driving members 30a and 30c and the voltage material on the front side of the driving members 30b and 30d. By doing this. For example, when the t _1, the drive member 30a, the maximum warpage is generated in the front side of the sheet at 30c, the drive member 30b, the maximum warpage skein occurs on the back side of the paper of 30d, the movable plate 10 is FIG. Rotate as shown in 3 (a). Since the warp on the back side of the paper is added to the warp on the front side of the paper, a large twist (clockwise direction) is generated in the torsion beam members 20a and 20b, and the movable plate 10 rotates more greatly. Then, when the t _2, the drive member 30b, the maximum warpage is generated in the front side of the paper surface 30d, the drive member 30a, and the maximum warpage is generated in the back side of the paper of 30c, the movable plate 10 is It rotates as shown in FIG. Also in this case, since the warp on the back side of the paper is added to the warp on the front side of the paper, a large twist (counterclockwise direction) is generated in the torsion beam members 20a and 20b, and the movable plate 10 rotates more greatly.

  In FIG. 1, a total of four drive members 30a and 30b, 30c and 30d are arranged between the movable member 10 and the frame member 40. However, even if the drive members are 30a and 30d, or only 30c and 30b, the operation is performed. Is possible. The same applies to the optical deflectors of each embodiment described later. The optical deflector of the present invention includes such a configuration.

  5 and 6 are plan views of Embodiment 2 of the optical deflector according to the present invention. 5 and 6, the same parts as those in FIG. 1 are denoted by the same reference numerals. As shown in FIGS. 5 and 6, in the second embodiment, a predetermined distance is provided between the movable plate 10 that holds the mirror surface and the movable portions 30a, 30b, 30c, and 30d, and the torsion beam that can be twisted between them is also provided. The members 20a and 20b are connected to each other. As a result, the drive members 30a, 30b, 30c, and 30d form a two-degree-of-freedom vibration system together with the movable plate 10 that holds the mirror surface. The driving members 30a, 30b, 30c, and 30d are driven in the same manner as in the first embodiment.

  Although it is known that a two-degree-of-freedom vibration system can obtain a larger displacement and can reduce fluctuations in angular velocity, conventionally, a torsion beam is provided outside the movable member holding the mirror. Thus, another movable part is provided as a two-degree-of-freedom vibration system actuator (for example, Patent Documents 3 and 4), and the apparatus has to be enlarged. On the other hand, in the case of the present embodiment, one end of the drive members 30a to 30d is free and is configured to be a mass system at the same time as generating an exciting force, so that the mirror surface can be obtained without increasing the size of the apparatus. A two-degree-of-freedom vibration system can be formed together with the movable plate 10 that holds

  Here, in order to adjust the frequency characteristics, the positions of the drive members 30a to 30d are moved closer to the movable plate 10 (FIG. 5) or closer to the frame portion 40 (FIG. 6). Further, as shown in FIG. 7, the thickness of the torsion beam members 20 a and 20 b is set such that a portion connecting the frame member 40 and the driving members 30 a to 30 d and a portion connecting the driving members 30 a to 30 d and the movable plate 10. Even if they are different, adjustment is possible. Furthermore, both may be adjusted in combination.

  FIG. 8 shows a plan view of a third embodiment of the optical deflector according to the present invention. In FIG. 8, the same parts as those in FIG.

  In the optical deflector of the present invention, since one end of the drive unit is not fixed, the drive member does not need to be attached to the end of the torsion beam member (FIGS. 1 and 5). In this case, the portion around the drive member only needs to have a space that can cause the torsion beam member to twist. Therefore, in this embodiment, as shown in FIG. 8, the corners of the frame portion 40 are widened, and inside the connection portion with the frame portion 40 of the torsion beam members 20 a and 20 b (range A in FIG. 8), In addition, the power supply pads 51 to 56 are arranged so that at least a part thereof is included in the position (in the range B in FIG. 8) inside the distal end portion of the movable plate 10. Here, the pads 54, 55 and 56 are connected to the drive signal lines 31 and 32 and the common ground line 33 of the drive members 30c and 30d shown in FIG. Similarly, the pads 51, 52, 53 are connected to the drive signal lines and common ground lines of the drive members 30a, 30b.

  In this embodiment, the power supply pad portion does not interfere with the driving of the driving member, and the frame portion while maintaining the torsion beam at a desired length as compared with the conventional configuration as shown in FIG. Since the power supply pad can be provided inside the optical deflector, the optical deflector can be further reduced in size.

  FIG. 9 shows a plan view of a fourth embodiment of the optical deflector according to the present invention. In FIG. 9, the same parts as those in FIG.

  In order to obtain a large deflection angle, it is necessary to generate a large amount of warp in the driving member or lengthen the driving member itself to increase the displacement of the driving member and generate a larger torsional force on the torsion beam member. . Here, since the amount of warpage is determined by the characteristics of the material constituting the drive member, improvement of the material and film characteristics can be considered with the excitation means using monomorph or bimorph, but the improvement is limited. Further, if the drive member is lengthened to increase the displacement of the drive member, it is necessary to enlarge the frame portion so that the drive portion does not protrude from the frame portion, which increases the size of the apparatus.

  Therefore, in this embodiment, as shown in FIG. 9, the drive members 30a, 30b, 30c, and 30d are arranged not to be perpendicular to the torsion beam members 20a and 20b but inclined to the movable plate 10 side. The effective length of 30a, 30b, 30c, 30d is increased. The operation is the same as in the first embodiment.

  If the drive members 30a, 30b, 30c, and 30d that generate warpage in the thickness direction become longer, the displacement on the free end side becomes larger, so that a larger torsional force is generated around the axes of the torsion beam members 20a and 20b. Can do. In the present embodiment, the drive members 30a, 30b, 30c, and 30d are disposed at an inclination, thereby suppressing the protrusion of the drive members 30a, 30b, 30c, and 30d, and without increasing the size of the frame portion 40. Since the amount of warpage can be increased, the deflection angle of the movable plate 10 can be increased while suppressing an increase in the size of the apparatus.

  10 and 11 are plan views of Embodiment 5 of the optical deflector according to the present invention. 10 and 11, the same reference numerals are given to the same portions as those in FIG.

  As shown in FIG. 9, the drive members 30a, 30b, 30c, and 30d are simply tilted with respect to the torsion beam members 20a and 20b. There is a case where a sufficient amount of warpage cannot be obtained.

  Therefore, in this embodiment, as shown in FIGS. 10 and 11, the driving members 30a, 30b, 30c and 30d are bent or curved. Thereby, longer drive members 30a, 30b, 30c, and 30d can be arranged in a limited space in the frame portion 40, and a greater warp is generated in the drive members 30a, 30b, 30c, and 30d. Thus, a large deflection angle can be obtained while suppressing an increase in the size of the apparatus.

  It is also possible to adopt a structure in which the drive member is obliquely attached to the torsion beam member as shown in FIG. 9 and the drive member is bent. In addition, as shown in FIG. 11, the shape of the drive member can be made to conform to the shape of the movable plate 10.

  FIG. 12 is a diagram showing the displacement distribution in the thickness direction of each part of the drive member in the case of the configuration of FIG. FIG. 13 is a view showing the level of warpage of each part of the drive member. In FIG. 13, X indicates the torsion beam direction, Y indicates the direction perpendicular to the torsion beam, and Z indicates the paper surface direction. Thus, in this embodiment, a large warp can be generated at the tip of the drive member.

  FIGS. 14, 16 and 17 are plan views of Embodiment 6 of the optical deflector according to the present invention. FIG. 15 is a cross-sectional view taken along the line AB of FIG. 14, 16, and 17, the same reference numerals are given to the same portions as those in FIG. 1. The operation is the same as in FIG.

  When the ratio of the weight of the drive member itself to the weight of the entire movable part is small, a large excitation force cannot be generated in the entire movable part. Therefore, in this embodiment, within the range in which the necessary frequency and amplitude can be ensured, the weight on the free end side of the driving member is increased, the moment of inertia of the driving member is increased, and a larger torsional force is applied. A large deflection angle is obtained by being transmitted to the member.

  Here, FIG. 14 is an example in which mass members 61a, 61b, 61c, 61d for increasing the weight are attached to the tips of the drive members 30a, 30b, 30c, 30d, respectively, and FIG. This is an example in which the widths of the tip portions of 30b, 30c, and 30d are widened as shown by 62a to 62d to increase the weight. Further, FIG. 17 shows that the leading ends of the driving members 30a and 30c, 30b and 30d are connected by beam members 63a and 63b so that the movable plate 10 is sandwiched, and the free end sides of the driving members 30a, 30b, 30s and 30d are connected. This is an example in which the weight of is increased. In FIGS. 14 and 16, the thickness of the free ends of the drive members 30a, 30b, 30c, and 30d may be simply increased.

  14, 16, and 17 increase the weight on the free end side of the drive members 30 a, 30 b, 30 c, and 30 d, so that once the movement starts and the vibration reaches the resonance frequency, a large torsion occurs A force can be applied to the torsion beam members 20a and 20b, and the deflection angle of the movable plate 30 can be increased.

  18 to 21 are diagrams for explaining an optical deflector 7 according to the seventh embodiment of the present invention. In FIG. 18 to FIG. 21, the same parts as those in FIG.

  In the previous embodiment 6, if the free end of the drive member is too heavy, the required amount of displacement cannot be obtained and the torsional force required for the torsion beam member cannot be generated. On the other hand, if it is too light, even if the amount of displacement is large, the force in the torsional direction transmitted to the torsion beam member will be small. Further, since the weight and balance of the entire movable part are different from predetermined values, desired resonance frequency characteristics may not be obtained. As described above, when the weight of the front end portion of the driving member is not appropriate, the special behavior of the optical deflector is doubled by the movable portion and the driving portion. Therefore, in this embodiment, weight adjusting means for adjusting the weight on the free end side of the driving member is provided.

  In FIG. 18 (before adjustment) and FIG. 19 (after adjustment), adhesive application surfaces 70a, 71b, 71c, 71d are provided at the distal ends of the drive members 30a, 30b, 30c, 30d, and the adhesive as a mass member is provided there. This is an example in which 72 is adjusted by increasing the weight of the tip by increasing the required amount or number. In this case, it is possible to greatly change the mass in a limited area by mixing a metal powder having a high density with the adhesive.

  In FIG. 20 (before adjustment) and FIG. 21 (after adjustment), dummy members 73a, 73b, 73c, and 73d are previously added as mass members to the distal end portions of the drive members 30a, 30b, 30c, and 30d. In this example, as shown by (a) and (b) in FIG.

  In the actual manufacturing process, a drive waveform is input to the optical deflector using a contact probe or the like, and a rotation operation is performed to check whether or not a desired resonance frequency and deflection angle are obtained and adjusted. . Since the movable part and the drive part can be adjusted simultaneously, it is easy to obtain desired characteristics. In addition, since the adjustment is performed at a position away from the movable member having the mirror surface, there is little possibility that the mirror surface is soiled or damaged, and deterioration of optical characteristics can be prevented.

  22, 23, and 24 are plan views of Embodiment 8 of the optical deflector of the present invention. The optical deflectors described so far all rotate and oscillate the mirror surface in the uniaxial direction, but this embodiment is configured to rotate and oscillate the mirror surface in the biaxial direction.

  FIG. 22 shows the first drive members 130a, 130b, 130c, and 130d having one end connected to the first torsion beam members 120a and 120b and the other end connected to the movable frame 140 in the configuration similar to the conventional structure of FIG. When driven, the first torsion beam members 120a and 120b generate torsion around the Y axis, thereby rotating the movable plate 10 holding the mirror surface around the Y axis. The second torsion beam members 220a, 220b are driven by driving the second driving members 230a, 230b, 230c, 230d having one end connected to the second torsion beam members 220a, 220b and the other end being free. The movable frame 140 is rotated around the X axis by generating a twist around the X axis in 220b. In the case of the configuration of FIG. 22, the outer frame portion (fixed base) 240 can be made small, so that the two-axis drive optical deflector can be miniaturized.

  In contrast to FIG. 22, FIG. 23 uses the form of the present invention around the Y axis, and is connected to the first torsion beam members 120a and 120b at one end and the first driving members 130a and 130b130c having the other end free. , 130d to cause the first torsion beam members 120a, 120b to twist around the Y axis, thereby rotating the movable plate 10 holding the mirror surface around the Y axis. Using the same configuration as in the prior art, driving the second driving members 230a, 230b, 230c, 230d having one end connected to the second torsion beam members 220a, 220b and the other end connected to the fixed base 240, The second torsion beam members 220a and 220b are configured to rotate the movable frame 140 around the X axis by generating a twist around the X axis. In the case of the configuration of FIG. 23, the inner frame portion (movable frame) can be made smaller, so that driving around the X axis can be performed with smaller energy.

  FIG. 24 uses the form of the present invention around the X and Y axes. The first driving members 130a, 130b, and 130c having one end connected to the first torsion beam members 120a and 120b and the other end being free. , 130d to cause the first torsion beam members 120a, 120b to twist around the Y axis, thereby rotating the movable plate 10 holding the mirror surface around the Y axis, and around the X axis. , One end is connected to the second torsion beam members 220a, 220b, and the other end is driven to the free second driving member 230a, 230b, 230c, 230d, one end supports the movable frame 140, and the other end is a fixed base. The second torsion beam members 220a and 220b supported by 240 are configured to rotate the movable frame 140 around the X axis by generating a twist around the X axis. In the case of the configuration of FIG. 24, by having the advantages of FIGS. 22 and 23, the inner movable frame 140 can be made smaller, so that the drive around the X axis can be performed with less energy, and the outer movable frame 140 is also made smaller. By being able to do so, it becomes possible to reduce the size of the two-axis drive optical deflector.

  The present embodiment provides an image forming apparatus in which the uniaxially driven optical deflector of the first to seventh embodiments is mounted as a constituent member of an optical writing unit.

  FIG. 25 shows an overall configuration diagram of the image forming apparatus of the present embodiment. In FIG. 25, 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 with 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 through the transfer unit 1006 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 scans a laser beam in one axis direction, 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 the laser beam. An optical deflector (the optical deflector according to the first to fifth embodiments described above) 1022 and a laser beam (light beam) modulated by a recording signal from the light source unit 1020 are connected to the mirror surface of the optical deflector 1022. An imaging optical system 1021 for imaging and one or a plurality of laser beams reflected and deflected by the mirror surface of the optical deflector 1002 are imaged on the surface (scanned surface) of the photosensitive drum 1002. It comprises a scanning optical system 1023 as a means. 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 writing unit 1001 configured using the optical deflector 1022 according to the present invention has the following advantages. Since the optical deflector 1022 has little deformation on the mirror surface and the beam shape is stable, writing with a stable beam spot diameter is possible and power consumption for driving is smaller than that of a rotating polygon mirror. It is advantageous for improving the image quality and power saving of the image forming apparatus. Further, since the wind noise during vibration of the mirror surface 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 the optical deflector 1022 generates a small amount of heat, so that the optical writing device 1001 can be easily downsized. Therefore, it is advantageous for downsizing the image forming apparatus. Further, since the optical deflector 1022 can perform high-speed reciprocating scanning, the image recording speed can be increased.

  Note that the conveyance mechanism of the recording paper 1007, the driving mechanism of the photosensitive drum 1002, the control unit such as the developing unit 1005 and the transfer unit 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. No. 25 is omitted.

  The present embodiment provides an image projection apparatus equipped with a two-axis drive optical deflector as in the eighth embodiment and displaying an image on a projection surface (screen) by two-dimensionally scanning the light beam. is there.

  FIG. 26 shows an overall configuration diagram of the image projection apparatus of the present embodiment. This image projection apparatus includes a red light source 2001-R that emits red (R) laser light, a green light source 2001-R that emits green (G) laser light, and a green light source that emits blue (B) laser light. 2001-B, a dichroic prism (synthetic prism) 2003 that receives R, G, B laser beams emitted from the respective light sources 2001-R, 2001-G, 2001-B and emits them as synthesized laser beams, and this dichroic prism An optical deflector (the optical deflector according to the eighth embodiment of the present invention described above) 2003 that two-dimensionally scans the combined laser light emitted from 2003 and projects it onto a projection surface (screen) 2004 is configured. Note that the image projection apparatus may have a configuration in which a projection surface (screen) 2004 is integrated.

  The red light source device 2001-R is a semiconductor laser (LD) having a center wavelength of 630 nm, and the blue light source device 2001-B is a semiconductor laser (LD) having a center wavelength of 430 nm. The green light source device 2001-G emits green laser light having a center wavelength of 540 nm. Although omitted in FIG. 26, the laser light emitted from these light sources 2001-R, 2001-G, 2001-B is synchronized with the horizontal / vertical synchronizing signal of the image, and the pixel value of the RGB component of each pixel of the image information. The amount of light emission is changed according to. Such R, G, and B laser beams are combined by the dichroic prism 2002 and are incident on the mirror surface of the optical deflector 2003.

  The optical deflector 2003 is an optical deflector having a two-axis drive configuration of the above-described eighth embodiment, and the movable plate 10 that holds the mirror surface is rotated around two axes in synchronization with the horizontal / vertical synchronization signal of the image. As a result, the laser light incident on the mirror surface is deflected and scanned two-dimensionally. As a result, the laser beam is scanned in the horizontal and vertical directions of the projection plane (screen) 2001 in synchronization with the horizontal / vertical synchronization signal of the image, and a desired image is displayed on the projection plane 2004.

  As shown in FIG. 27, the dichroic prism 2002 is omitted, and R, G, and B laser beams emitted from the respective color light sources 2001-R, 2001-G, and 2001-B are optical deflectors (Embodiment 8). The light deflector 2003 may be directly incident.

  26 and 27 show an example of the configuration of an image projection apparatus that projects a color image, but in the case of a monochrome image, only one light source may be used.

DESCRIPTION OF SYMBOLS 10 Movable plate 20a, 20b Torsion beam member 30a, 30b, 30c, 30d Drive member 40 Frame member 51-56 Pad 61a-61d Mass part 62a-62d Mass part 63a, 63b Beam member 71a-71d Adhesive application surface 72 Adhesive 73a to 73d Dummy members 120a and 120b First torsion beam members 130a to 130d First drive member 140 Movable frames 220a and 220b Second torsion beam members 230a to 230d Second drive member 240 Fixed base

JP 2005-128147 A JP 2008-083603 A JP 2005-208578 A JP 2006-067706 A

Claims (14)

A movable member having a light reflecting surface, a torsion beam member that supports the movable member so as to be capable of rotational vibration, a frame member that supports an end of the torsion beam member, and the movable member and the frame member disposed between the movable member and the frame member A drive member that generates a warp, with one end in the longitudinal direction being free and the other end being supported by the torsion beam member,
When the drive member is warped, the torsion beam member is twisted, and the movable member rotates and vibrates.   2. The optical deflector according to claim 1, wherein the driving member is disposed at a predetermined distance from the movable member, and the movable member and the driving member are connected by a torsion beam member that can be twisted. .   The optical deflector according to claim 2, wherein the torsion beam member that supports the driving member and the torsion beam member that connects the movable member and the driving member have different thicknesses.   4. The optical deflector according to claim 1, wherein the drive member is disposed to be inclined toward the movable member with respect to an axis of the torsion beam member. 5.   The optical deflector according to claim 1, wherein the driving member is bent or curved toward the movable member in the middle.   6. The optical deflector according to claim 1, wherein a free end side of the driving member is heavier than other portions.   The optical deflector according to claim 6, further comprising weight adjusting means for adjusting a weight on a free end side of the driving member.   The optical deflector according to any one of claims 1 to 7, wherein the driving member is a piezoelectric monomorph or a bimorph.   The power supply pad of the drive member is provided at a position inside the connection portion of the frame member with the frame member of the torsion beam member and inside the distal end portion of the movable member. The optical deflector according to claim 1, wherein the optical deflector is characterized in that: A movable frame, a movable member having a light reflecting surface, a first torsion beam member that supports the movable member so as to be capable of rotational vibration about an axis in a first direction, and one end connected to the first torsion beam member The other end of which is connected to the movable frame and generates a warp, the second torsion beam member that supports the movable frame so as to be able to rotate and vibrate about an axis in the second direction, and the first A fixed frame that supports an end of the second torsion beam member, and is arranged between the movable frame and the fixed frame, and one end in the longitudinal direction is free and the other end is supported by the second torsion beam member. A second drive member that generates warpage,
When the first driving member is warped, the first torsion beam member is twisted around an axis in the first direction, and the movable member is rotated and vibrated in the first direction.
When the warp occurs in the second driving member, the second torsion beam member is twisted around the axis in the second direction, and the movable frame rotates and vibrates around the axis in the second direction. Then, the movable member rotates and vibrates in the second direction.
An optical deflector characterized by: A movable member having a light reflecting surface, a first torsion beam member that supports the movable member so as to be capable of rotational vibration about an axis in a first direction, and a movable frame that supports an end of the first torsion beam member And a first driving member that is disposed between the movable member and the movable frame, is supported by the first torsion beam member at one end in the longitudinal direction and is supported by the first torsion beam member, and fixed. A base, a second torsion beam member that supports the movable frame so as to be capable of rotational vibration about an axis in the second direction, one end connected to the second torsion beam member, and the other end connected to the fixed base. And a second drive member that generates warpage,
When the first driving member is warped, the first torsion beam member is twisted around an axis in the first direction, and the movable member is rotated and vibrated in the first direction.
When the warp occurs in the second driving member, the second torsion beam member is twisted around the axis in the second direction, and the movable frame rotates and vibrates around the axis in the second direction. Then, the movable member rotates and vibrates in the second direction.
An optical deflector characterized by: A movable member having a light reflecting surface, a first torsion beam member that supports the movable member so as to be capable of rotational vibration about an axis in a first direction, and a movable frame that supports an end of the first torsion beam member And a first driving member disposed between the movable member and the movable frame, wherein one end in the longitudinal direction is free and the other end is supported by the first torsion beam member, and warps. A second torsion beam member for supporting the movable frame around an axis in the second direction so as to be capable of rotational vibration, a fixed frame for supporting an end of the second torsion beam member, the movable frame and the fixed frame; And a second driving member that generates a warp with one end in the longitudinal direction being free and the other end being supported by the second torsion beam member,
When the first driving member is warped, the first torsion beam member is twisted around an axis in the first direction, and the movable member is rotated and vibrated in the first direction.
When the warp occurs in the second driving member, the second torsion beam member is twisted around the axis in the second direction, and the movable frame rotates and vibrates around the axis in the second direction. Then, the movable member rotates and vibrates in the second direction.
An optical deflector characterized by:   An image forming apparatus, wherein the light deflector according to any one of claims 1 to 9 is used to deflect and scan a light beam from a light source to form an image on a photosensitive member.   13. An image projecting apparatus, wherein the light deflector according to claim 10 is used to two-dimensionally deflect and scan a light beam from a light source and project an image on a projection surface. .

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