JP6162933B2 - Vibrating device, optical scanning device, video projection device, and image forming device - Google Patents

Description

  The present invention relates to a vibration device, an optical scanning device, a video projection device, and an image forming device.

  An optical scanning device including a vibration element that vibrates due to a resonance phenomenon has an advantage that optical scanning with a large amplitude can be performed with a small amount of power. According to Patent Document 1, an optical scanning device including a mirror with a magnet that reflects a laser beam and a coil that generates an alternating magnetic field to vibrate the mirror with a magnet is proposed. As a result, a large vibration frequency can be obtained, and an optical scanning device that is small, light, and inexpensive can be provided.

JP-A-9-197333

  In general, the optical scanning apparatus must vibrate the vibrating element at a constant frequency from the start of driving of the vibrating element to the stop of driving. However, the vibration element does not vibrate at a constant frequency due to factors such as the environment in which the optical scanning device is installed and the heat generated from the drive unit. This is because when the temperature of the vibration element changes, the resonance frequency of the vibration element also changes.

  In Patent Document 1, when an alternating current is passed through a coil, an alternating magnetic field corresponding to the alternating current is generated around the coil. This alternating magnetic field generates torque in the driving magnet, and the driving magnet and the adhesive are fixed thereto. The mirror that has been oscillated resonantly. Therefore, heat is generated when a current is passed through the coil. In particular, since the coil and the elastic linear member are close to each other, they are easily affected by heat generated from the coil. As a result, the spring constant of the elastic linear member changes and the resonance frequency also changes.

  Therefore, the present invention has an object to realize a stable torsion drive by reducing the influence of the external environment.

The present invention is, for example,
A torsion beam formed of a metal alloy;
A vibrator attached to a part amount of the torsion beam,
A drive unit that drives the vibrating body so that the vibrating body vibrates;
A heat relaxation member that relaxes heat generated from the drive unit from being transmitted to the outer periphery of the shaft of the torsion beam,
The vibrator is constituted by the first vibrator and the second vibrator sandwiching a part component of said torsion beam,
It said heat relaxation member has an insertion hole through which the torsion bar is inserted protruding from the vibrating body, other than the first portion sandwiched between the first vibrator and the second vibrator of the torsion beam And is inserted into the other part through the insertion hole so as to alleviate the transfer of heat generated from the driving unit to the other part that protrudes toward the support end side of the torsion beam , and the vibrator Provided is a vibration device characterized in that the vibration device is installed close to the device.

  In the present invention, by providing a heat relaxation member for relaxing the heat generated by the drive unit that drives the vibrating body to be transmitted to the outer periphery of the shaft of the torsion beam, it is possible to suppress the temperature rise in the vicinity of the torsion beam. it can. Thereby, the resonance frequency shift that occurs when the vibrating body shifts from a stationary state to a vibrating state is reduced, and stabilization of vibration is achieved.

The perspective view which shows an example of the vibration apparatus concerning this embodiment Schematic which shows an example of the vibration apparatus concerning this embodiment. Schematic which shows the vibration part concerning embodiment. Schematic which shows an example of the vibration apparatus concerning a comparative example (A) is a figure which shows the fluctuation amount of the frequency immediately after a drive start, (B) is a figure which shows the relationship between atmospheric temperature and a frequency. Diagram showing temperature change near torsion beam due to heat generated from drive unit Schematic diagram of image forming apparatus Schematic diagram of video projector Schematic which shows an example of the vibration apparatus concerning this embodiment.

<Configuration of vibration device>
FIG. 1 is a perspective view illustrating the vibration device according to the embodiment. The vibration device 1 includes a vibration unit 10 and a drive unit 20 that drives the vibration unit 10. The vibrating body 12 and the magnet 31 of the vibrating unit 10 are cantilevered by the torsion beam 11. The vibrating body 12 is made of a nonmagnetic member. The direction of the magnetic field generated by the magnet 31 is substantially orthogonal to the direction of the alternating magnetic field generated by the drive unit 20 when the vibration unit 10 is stationary. When a current having the same frequency as the natural frequency of the vibration unit 10 flows through the coil 25 (FIG. 4B) of the drive unit 20, the vibrating body 12 of the vibration unit 10 vibrates due to a resonance phenomenon.

  When a current flows through the coil 25 (FIG. 4B) of the drive unit 20, heat is generated. When this heat is transmitted to the outer periphery of the shaft of the torsion beam 11, the natural frequency (resonance frequency) fluctuates, and the vibration unit 10 does not vibrate at a constant frequency. Therefore, in the present embodiment, the whole or a part of the torsion beam 11 is surrounded by the heat relaxation member 41. The heat relaxation member 41 relaxes the heat generated by the drive unit 20 from being transmitted to the outer periphery of the shaft of the torsion beam.

  FIG. 2 is a perspective view showing a vibration device according to an embodiment different from FIG. The heat relaxation member 41 is attached to the two support members 3 extending from the base 2. The heat relaxation member 41 is provided with an insertion hole 24 through which at least a part of the torsion beam 11 is inserted. One end of the torsion beam 11 is inserted into and supported by the insertion hole 24. The other end of the torsion beam 11 is attached to the vibrating body 12. By making the difference between the outer diameter of the torsion beam 11 and the inner diameter of the insertion hole 24 the minimum necessary difference, the effect of mitigating the heat generated by the drive unit 20 can be further enhanced. A bearing may be provided in the insertion hole 24, and the torsion beam 11 may be inserted into the bearing. Thereby, the torsion beam 11 can be rotatably supported while further enhancing the effect of mitigating the heat generated by the drive unit 20. That is, the vibration of the torsion beam 11 becomes smooth and the durability is improved.

  FIG. 3 is a diagram illustrating components of the vibration unit 10. The torsion beam 11 is made of a metal alloy or the like. The other end of the torsion beam 11 has a bowl-shaped flat portion. A magnet 32 and a vibrating body 13 are attached to the surface of the flat portion. The magnet 31 and the vibrating body 12 are attached to the back surface of the flat portion. As described above, the vibrating bodies 12 and 13 function as an oscillating body attached to a part of the torsion beam 11. A mirror may be attached to or formed on the vibrating bodies 12 and 13. Here, the magnets 31 and 32 are attached to the torsion beam 11, but may be attached on the vibrating bodies 12 and 13.

  As described above, in the present embodiment, the thermal relaxation member 41 can suppress the temperature change in the vicinity of the torsion beam 11 due to the heat generated by the drive unit 20 to vibrate the vibrating bodies 12 and 13. Therefore, it is not necessary to select a material that is insensitive to temperature changes, and the selection range of the material of the torsion beam 11 is widened. Moreover, in this embodiment, it is only necessary to add the heat relaxation member 41 to the vibration device 1, and no configuration change of the drive unit 20 is necessary. Therefore, there is little concern that the vibration device 1 will be enlarged.

  Further, in this embodiment, the heat relaxation member 41 has a configuration that surrounds the entire torsion beam 11, and has an insertion hole 24, and minimizes the difference between the outer diameter of the torsion beam 11 and the inner diameter of the insertion hole 24. It is set as the difference. Therefore, the heat relaxation member 41 also has a function of restricting the displacement of the torsion beam 11 and can be expected to have an excellent impact resistance by damping the torsion beam 11 from a plurality of directions.

  Thus, since the phenomenon that the heat generated from the drive unit 20 is transmitted to the torsion beam 11 is suppressed, the drive of the vibration unit 10 can be stably controlled.

  In the present embodiment, the vibrating bodies 12 and 13 are cantilevered by the torsion beam 11, but as shown in FIGS. 9A to 9C, the two torsion beams 11a and 11b are supported. May be supported at both ends. A mirror is formed on the front surface of the vibration unit 10, and a magnet is attached to the back surface. Moreover, the drive part 20 is arrange | positioned so that this magnet may be opposed. The heat relaxation members 41a and 41b are attached to the support members 3a and 3b. The heat relaxation members 41a and 41b prevent the heat generated from the drive unit 20 from being transmitted to the two torsion beams 11a and 11b. Instead of at least one of the heat relaxation members 41a and 41b, the heat relaxation member 41 as shown in FIG. 1 may be employed. That is, one or both of the torsion beams 11a and 11b may be surrounded by the heat relaxation member 41 around the axis.

<Configuration of Comparative Example>
FIG. 4A and FIG. 4B are side views of a vibration device 1 ′ as a comparative example. It should be noted that the same reference numerals are given to the portions already described. A vibration device 1 ′ as a comparative example is obtained by excluding the heat relaxation member 41 from the vibration device 1 of the present embodiment. In the following, the dependency between the temperature change near the torsion beam 11 and the resonance frequency is clarified, and the necessity of the thermal relaxation member 41 is proved.

  When a current is passed through the coil 25 of the drive unit 20 while the vibration device 1 'is stationary, an electromagnetic force is generated between the magnets 31 and 32 and the drive unit 20, and the vibration unit 10 starts to vibrate. . The drive circuit of the drive unit 20 controls the deflection angle of the vibration unit 10 by changing the magnitude of the current. When the drive circuit keeps the current constant, the deflection angle is also kept constant.

  As a comparative example, an experiment was performed with the frequency f0 of the natural vibration mode of the vibration unit 10 set to 2 kHz. As shown in FIG. 5A, it was found that the resonance frequency fluctuates up to around 0.5 Hz at the maximum for the first few minutes after the vibration unit 10 starts to vibrate. When such a phenomenon occurs in a vibration device (optical scanning device) mounted on a video projection device or an image forming device, the scanning lines vary. As a result, the image projected on the screen is disturbed, or the image on the image carrier is disturbed.

  About the comparative example, it experimented in each temperature atmosphere of 25 degreeC, 45 degreeC, and 60 degreeC, and verified the resonant frequency. As shown in FIG. 5B, the resonance frequency was 2226 Hz at 25 ° C., 2221 Hz at 45 ° C., and 2217 Hz at 60 ° C. Therefore, it was confirmed that there was a relationship of −0.26 Hz / ° C. in the comparative example. Further, when an experiment was performed under the condition of 25 ° C., it was found that there was a frequency variation of −0.52 Hz after the vibration device 1 ′ started to be driven from a stationary state until the resonance frequency did not vary. (FIG. 5A). From this result, it can be estimated that the temperature rise of about 2 ° C. occurs in the torsion beam 11 of the comparative example (−0.52 / −0.26 = 2.00).

  A current was passed through the coil 25 of the drive unit 20 from the state where the vibration device 1 ′ was stationary, and the temperature change in the vicinity of the torsion beam 11 was measured for several minutes after the vibration of the vibration unit 10 was started. FIG. 6 shows the measurement results. The temperature in the vicinity of the torsion beam 11 increased by 2 ° C. from 25 ° C. to 27 ° C. At the same time, as shown in FIGS. 5A and 5B, the resonance frequency fluctuation result is also −0.52 Hz (temperature rise of about 2 ° C.). It can be explained that it is involved in the fluctuation of Therefore, if the thermal relaxation member 41 is provided as in the present embodiment, the temperature rise near the torsion beam 11 can be suppressed, so that it can be said that the fluctuation of the resonance frequency can be suppressed.

<Effect of heat relaxation member 41>
The frequency f0 of the natural vibration mode has a property of decreasing as the temperature of the torsion beam 11 increases. At the start of driving, the temperature of the torsion beam 11 is equal to the ambient temperature, but the temperature in the vicinity of the torsion beam 11 rises due to heat generated by the driving unit 20. Thereby, the drive frequency of the vibration part 10 comes away from the target drive frequency fc.

  For each of the present embodiments shown in FIGS. 1 and 2, an experiment was performed under the same conditions as those applied to the comparative example. That is, the change in the resonance frequency in the present embodiment from the stop state to the elapsed drive time in a temperature atmosphere of 25 ° C. was 0.00 Hz. Therefore, in this embodiment, it has confirmed that the fluctuation | variation was improved significantly with respect to the comparative example. The temperature atmosphere range is not limited to 25 ° C.

<Material of vibration part>
As a material constituting the torsion beam 11, for example, a work hardening and age hardening type cobalt (Co) -nickel (Ni) based alloy subjected to work hardening treatment and age hardening treatment can be adopted. The Co—Ni-based alloy mentioned here is an alloy containing Co and Ni. This alloy includes, for example, chromium (Cr), which reduces stacking fault energy, and molybdenum (Mo) as a solute element that contributes to improvement of aging and work hardening ability by fixing dislocations by solid solution strengthening and segregation of the matrix. , Iron (Fe), and the like may be included. More specific examples of the alloy include a Co—Ni—Cr—Mo alloy and a Co—Ni—Fe—Cr alloy. In addition, these alloys can further include niobium (Nb), manganese (Mn), tungsten (W), titanium (Ti), boron (B), magnesium (Mg), carbon (C), and the like. Nb functions as a solute element similar to Mo and iron described above. Mn has the function of stabilizing the face-centered cubic lattice phase and reducing the stacking fault energy. W contributes to strengthening the matrix and lowering stacking fault energy. Ti contributes to refinement of the ingot structure and strength improvement. B and Mg improve hot workability. C dissolves in the matrix to form carbides with Cr, Mo, Nb, etc., and exhibits the function of strengthening the grain boundaries. When the previous Co—Ni—Cr—Mo alloy is used, the weight ratio of the main composition is, for example, Co: 20.0 to 50.0%, Ni: 20.0 to 45.0%, Cr / Mo : 20.0 to 40.0% (Cr: 18 to 26%, Mo: 3 to 11%). In particular, Co: 31.0 to 37.3%, Ni: 31.4 to 33.4%, Cr: 19.5 to 20.5%, and Mo: 9.5 to 10.5% may be used.

  More specifically, work hardening by cold rolling is performed from a starting raw material containing a substitutional solute element in a matrix containing at least Co and Ni obtained through processes such as hot forging and homogenization heat treatment after melting. A Co—Ni—Cr—Mo alloy material is obtained through the treatment. In this alloy material, a texture is usually formed in the rolling direction, and a texture is formed in a direction orthogonal to the rolling direction. For this reason, when using as the torsion beam 11 of this embodiment, it cuts out so that the direction orthogonal to a rolling direction may become the longitudinal direction of the torsion beam 11 by press work, laser processing, wire cut processing, etc. Alternatively, a desired torsion beam 11 is formed by processing into a product shape by superplastic processing, applying a curing process along with these processes to give an internal residual strain, and then performing an age hardening process in vacuum or in a reducing atmosphere. Can be obtained. The age hardening treatment is optimally performed at a temperature of 400 ° C. to 700 ° C. for several tens of minutes to several hours (for example, 550 ° C. for 2 hours). In order to shorten the processing time, for example, in a strong magnetic field. It is also effective to use heat treatment.

  As a result, it is possible to obtain the torsion beam 11 having good vibration characteristics with high strength, low vibration damping capability, and high elastic limit. As an example of such a non-magnetic, work-hardening and age-hardening type Co—Ni—Cr—Mo alloy, there can be mentioned SPRON 510 (trade name: SPRON is a registered trademark) of Seiko Instruments Inc. This SPRON 510 has a composition of Co: 35%, Ni: 32%, Cr: 20%, Mo: 10%.

  In this way, the torsion beam 11 having a sharp resonance frequency and a characteristic in which the vibration is line symmetric with respect to the resonance frequency, that is, a high Q value (for example, 1000 or more) and a very small nonlinearity of the spring characteristic is obtained. be able to. Such a torsion beam 11 does not become unstable even when the maximum strain due to vibration deformation increases to about 3 × 10 −3 mm, and the vibration device 1 with low power consumption can be realized.

  In the present embodiment, the torsion beam 11 is formed of a non-magnetic Co—Ni based alloy. This is because stable driving can be realized when the magnets 31 and 32 and the alternating magnetic field are used as means for swinging the vibrating bodies 12 and 13 together with the torsion beam 11. Therefore, when a means other than an alternating magnetic field, such as a piezoelectric element, is used as the element driving unit, a general spring material other than a nonmagnetic metal can be used as the material of the torsion beam 11. More specifically, stainless steel such as SUS301, 302, 304, 316, 631, 632, spring steel (SUP), piano wire (SWP), oil tempered wire (SWO) of spring carbon steel can be employed. . In addition, silicon chrome steel oil tempered wire (SWOSC), beryllium copper alloys for springs (C1700, C1720), titanium copper alloys for springs (C1990), phosphor bronze for springs (C5210), spring white (C7701) ) Etc. can also be adopted.

  The magnets 31 and 32 attached to the torsion beam 11 together with the vibrating bodies 12 and 13 are preferably as small and light as possible and have a high coercive force. For example, Nd—Fe—B or Sm—Co rare earth magnets are suitable as the magnets 31 and 32. Alnico magnets, Fe-Co-V alloy magnets, Cu-Ni-Fe alloy magnets, Cu-Ni-Co alloy magnets, Fe-Cr-Co magnets, Pt-Co magnets, hard ferrites (Ba ferrite and Sr ferrite) A sintered magnet such as may be used. In addition, it may be a thin film magnet formed by a bond magnet or a sputtering method, and is not particularly limited by a material, a manufacturing method or a shape.

  As a material of the vibrators 12 and 13, nonmagnetic materials such as alumina, zirconia, beryllium, silicon nitride, aluminum nitride, sapphire, silicon carbide, silicon dioxide, glass, and resin can be used. Moreover, these surfaces can be used as light reflecting surfaces (mirror surfaces) by making them mirror surfaces.

<Image forming apparatus>
FIG. 7 is a schematic diagram of an image forming apparatus 200 including the optical scanning device 30 configured by the vibration device 1 of the present embodiment. The image forming apparatus 200 forms an image on the photoconductor 204 that is an image carrier by the light scanned by the optical scanning device 30. The optical scanning device 30 is an application of the vibration device 1 described above, and a mirror surface is formed on at least one of the vibration bodies 12 and 13. The image forming apparatus 200 is a so-called laser beam printer (LBP). Note that the image forming apparatus 200 may be a printer, a copier, a multifunction peripheral, a facsimile machine, or the like.

  Light is applied to a mirror surface of a light source 201 such as a laser. Specifically, the light emitted from the light source 201 passes through the emission optical system 202, is reflected by the mirror surface of the optical scanning device 30, passes through the imaging optical system 203, and exposes the photosensitive member 204, which is an image carrier. . As the mirror surface swings, the light reflection direction changes continuously. Thereby, light scanning is realized. Beam detection sensors 205 are provided at both ends of the photoconductor 204. When the beam detection sensor 205 detects light, it outputs a detection signal to the control circuit 206. The control circuit 206 feeds back a control signal corresponding to the detection signal from the beam detection sensor 205 to the drive circuit 207 of the optical scanning device 30. That is, the drive circuit 207 has the coil 25 so that the time from the timing when the first beam detection sensor 205 outputs the detection signal to the timing when the second beam detection sensor 205 outputs the detection signal is constant. Adjust the frequency of the current applied to the. Thereby, the scanning cycle (drive frequency) of the optical scanning device 30 is maintained at a desired target value.

  The image forming apparatus 200 according to this embodiment includes an optical scanning device 30 to which the above-described vibration device 1 is applied. For this reason, it is possible to suppress the deviation of the scanning line even with respect to the temperature variation, and it is possible to maintain the image quality. Further, since the vibration device 1 is more advantageous than the related art in terms of manufacturing cost and space efficiency, the optical scanning device 30 and the image forming apparatus 200 are also more advantageous than the related art in terms of manufacturing cost and space efficiency. Further, the downsizing of the vibration device 1 facilitates miniaturization of the optical scanning device 30 and the image forming apparatus 200.

<Video projection device>
FIG. 8 is a schematic diagram of a video projection device 300 including the optical scanning device 30 configured by the vibration device 1 of the present embodiment. The image projection device 300 projects an image on the screen 303 with the light scanned by the optical scanning device 30.

  The light source 301 irradiates the mirror surface with light of three primary colors (RGB). The light scanned (deflected) in the horizontal direction by the optical scanning device 30 is further scanned in the vertical direction by the vertical scanning device 302 and projected onto the screen 303 as an image. The scanning speed of the vertical scanning device 302 is slower than the scanning speed of the optical scanning device 30. For the vertical scanning device 302, for example, a galvanometer mirror capable of highly accurate positioning by non-resonant driving may be used.

  The driving circuit 305 controls the scanning angle of the optical scanning device 30 based on a control signal output from the control circuit 304. Similarly, the scanning angle of the vertical scanning device 302 is controlled based on a control signal output from the control circuit 304. The control circuit 304 is set with a projection angle of view and a projection size from the input circuit 306. The distance measuring device 307 measures the distance from the image projection device 300 to the screen 303. The control circuit 304 determines the image size and aspect ratio based on the information, and controls the scanning angles of the optical scanning device 30 and the vertical scanning device 302 so that the determined image size and aspect ratio are realized. To do. The projection size of the image can be controlled by ON / OFF control of the light source 301 without changing the scanning angle. However, since the OFF time of the light source 301 can be reduced by changing the scanning angle, light can be used effectively.

  The image projection apparatus 300 according to the present embodiment includes an optical scanning device 30 to which the above-described vibration device 1 is applied. Therefore, it is possible to suppress the deviation of the scanning line even with respect to the temperature variation, and to maintain the quality of the projection image. In addition, since the vibration device 1 is more advantageous than the related art in terms of manufacturing cost and space efficiency, the image projection device 300 is also more advantageous than the conventional method regarding manufacturing cost and space efficiency. In addition, as the vibration device 1 is downsized, the video projection device 300 is easily downsized.

Claims (7)

A torsion beam formed of a metal alloy;
A vibrator attached to a part amount of the torsion beam,
A drive unit that drives the vibrating body so that the vibrating body vibrates;
A heat relaxation member that relaxes heat generated from the drive unit from being transmitted to the outer periphery of the shaft of the torsion beam,
The vibrator is constituted by the first vibrator and the second vibrator sandwiching a part component of said torsion beam,
It said heat relaxation member has an insertion hole through which the torsion bar is inserted protruding from the vibrating body, other than the first portion sandwiched between the first vibrator and the second vibrator of the torsion beam And is inserted into the other part through the insertion hole so as to alleviate the transfer of heat generated from the driving unit to the other part that protrudes toward the support end side of the torsion beam , and the vibrator Vibrating device characterized by being installed close to   The vibration device according to claim 1, wherein the torsion beam is entirely or partially surrounded by the heat relaxation member. The vibrating body is vibrating device according to claim 1 or 2, characterized in that it is cantilevered by said torsion beam. The vibrating body is vibrating device according to claim 1 or 2, characterized in that it is supported at both ends by a plurality of said torsion beam. A torsion beam formed of a metal alloy;
A vibrator attached to a part amount of the torsion beam,
A mirror surface provided on the vibrating body;
A light source for irradiating the mirror surface with light;
A driving unit that scans the light by the mirror surface by driving the vibrating body to vibrate the vibrating body;
A heat relaxation member that relaxes heat generated from the drive unit from being transmitted to the outer periphery of the shaft of the torsion beam,
The vibrator is constituted by the first vibrator and the second vibrator sandwiching a part component of said torsion beam,
It said heat relaxation member has an insertion hole through which the torsion bar is inserted protruding from the vibrating body, other than the first portion sandwiched between the first vibrator and the second vibrator of the torsion beam A part that is inserted into the other part through the insertion hole so as to alleviate the transfer of heat generated from the drive unit to the other part that protrudes toward the support end side of the torsion beam , and the vibrator An optical scanning device characterized by being installed close to An image projection apparatus comprising: the optical scanning device according to claim 5 , wherein an image is projected onto a screen by light scanned by the optical scanning device. An image forming apparatus comprising the optical scanning device according to claim 5 and an image carrier, and forming an image on the image carrier by light scanned by the optical scanning device.

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