JP2016051095A - Optical scanning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize an influence arising from a change in amount of light in accordance with a location where light is scanned.SOLUTION: A movable electrode 120 is configured to rotate centering around a rotation axis, and reflect incident light. A control unit 200 is configured to control an amount of rotation of the movable electrode 120. A light-amount control unit is configured to control at least one of an amount of light of the incident light before reflected by the movable electrode 120 and an amount of light of the incident light after reflected by the movable electrode 120 on the basis of the amount of rotation of the movable electrode 120. In an example as shown in Fig. 1, the light-amount control unit is a light source control unit 520, which controls the amount of light of incident light before reflected by the movable electrode 120 on the basis of the amount of rotation of the movable electrode 120.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical scanning device.

  In recent years, development of MEMS (Micro ElectroMechanical Systems) technology has progressed. One of apparatuses using MEMS technology is an optical scanning apparatus that scans light. Optical scanning devices are used in various devices such as laser printers, bar code readers, and endoscopes.

  In such an optical scanning device, a rotary actuator may be used. Such actuators include those described in Patent Documents 1 and 2, for example. The actuators described in these documents have a movable electrode, a fixed electrode, a frame, and a support shaft that attaches the movable electrode to the frame. By using the movable electrode as a light reflecting surface, Scan.

JP 2004-219889 A JP 2008-40228 A

  In the optical scanning device described above, the movable electrode is irradiated with the scanned light. However, when the inclination of the movable electrode increases, a part of the irradiated light may come off the movable electrode. In this case, there is a possibility that the amount of light changes depending on the inclination of the movable electrode, that is, the position where the light is scanned.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the influence caused by the change in the amount of light depending on the position where the light is scanned.

  In the present invention, the optical scanning device includes a movable electrode, a control unit, and a light amount control unit. The movable electrode rotates about the rotation axis and reflects incident light. The control unit controls the amount of rotation of the movable electrode. The light quantity control unit controls at least one of the quantity of incident light before being reflected by the movable electrode and the quantity of incident light after being reflected by the movable electrode, based on the rotation amount of the movable electrode.

  Further, when the optical scanning device irradiates the irradiated body with light, and has a detection unit for detecting light from the irradiated body and an amplification unit for amplifying the output of the detection unit, amplification is performed. The amplification factor of the part may be determined based on the rotation amount of the movable electrode.

  According to the present invention, it is possible to reduce the influence caused by the amount of light changing depending on the position where light is scanned.

1 is a diagram illustrating a configuration of an optical scanning device according to a first embodiment. It is a figure which shows an example of a structure of a rotary actuator with a control part and a detection part. It is a figure for demonstrating the relationship between the rotation amount of a movable electrode, and the quantity of the light reflected by a movable electrode. It is a figure which shows the structure of the optical scanning device which concerns on 2nd Embodiment. It is a figure which shows the structure of the optical scanning device concerning 3rd Embodiment. It is a figure explaining the in-plane distribution of the light transmittance of a transmissive member. It is a figure which shows the 1st example of a permeable member. It is a figure which shows the 2nd example of a permeable member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

  In the following description, the control unit 200, the detection unit 300, and the light source control unit 520 indicate functional unit blocks instead of hardware units. The control unit 200, the detection unit 300, and the light source control unit 520 are a CPU, a memory of any computer, a program that realizes the components shown in the figure loaded in the memory, a storage medium such as a hard disk that stores the program, and a network It is realized by any combination of hardware and software, centering on the connection interface. There are various modifications to the implementation method.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of an optical scanning device 10 according to the first embodiment. The optical scanning device 10 according to the present embodiment includes a movable electrode 120, a control unit 200, and a light amount control unit. The movable electrode 120 rotates around the rotation axis and reflects incident light. The control unit 200 controls the amount of rotation of the movable electrode 120. The light quantity control unit controls at least one of the quantity of incident light before being reflected by the movable electrode 120 and the quantity of incident light after being reflected by the movable electrode 120 based on the rotation amount of the movable electrode 120. In the example shown in this figure, the light amount control unit is a light source control unit 520 and controls the amount of incident light before being reflected by the movable electrode 120 based on the amount of rotation of the movable electrode 120. Details will be described below.

  The optical scanning device 10 includes a light source 500, a rotary actuator 100, a control unit 200, and a detection unit 300.

  The light source 500 includes a light emitting element such as a laser diode. Light (incident light) emitted from the light source 500 is irradiated to the irradiated object 20. A movable electrode 120 of the rotary actuator 100 is provided between the light source 500 and the irradiated object 20. By changing the rotation amount (angle) of the movable electrode 120, the scanning position of the incident light in the irradiated body 20 changes.

  The amount of rotation of the movable electrode 120 is controlled by the control unit 200. A signal (control signal) indicating the rotation amount of the movable electrode 120 is input to the control unit 200. The control unit 200 controls the amount of rotation of the movable electrode 120 according to the control signal. Further, the rotation amount of the movable electrode 120 is detected by the detection unit 300. The control unit 200 uses the rotation amount of the movable electrode 120 detected by the detection unit 300 so that the rotation amount of the movable electrode 120 becomes a desired value (specifically, a value indicated by the control signal). Control the amount of rotation. In addition, the light source control unit 520 controls the output of the light source 500 using the rotation amount of the movable electrode 120 detected by the detection unit 300. Note that the light source control unit 520 may receive the rotation amount of the movable electrode 120 from the control unit 200.

  The optical scanning device 10 further includes a light detection unit 540. The light detection unit 540 receives the light from the irradiated body 20 and photoelectrically converts the light to generate an electrical signal indicating the received light amount. This electrical signal is output to the outside of the optical scanning device 10 as a detection signal. Note that the wavelength of light photoelectrically converted by the light detection unit 540 may be the same as or different from the wavelength of light emitted from the light source 500. In the latter case, the light detection unit 540 photoelectrically converts, for example, light emitted from a phosphor included in the irradiated body 20. The phosphor emits fluorescence when irradiated with light from the light source 500.

  FIG. 2 is a diagram illustrating an example of the configuration of the rotary actuator 100 together with the control unit 200 and the detection unit 300. The rotary actuator 100 includes a support 110, a movable electrode 120, a fixed member 130, a first fixed electrode 142, a second fixed electrode 144, a first detection electrode 152, and a second detection electrode 154. The fixed electrode 140 of the rotary actuator 100 is configured by the first fixed electrode 142 and the second fixed electrode 144, and the detection electrode 150 of the rotary actuator 100 is configured by the first detection electrode 152 and the second detection electrode 154. It is configured.

  The fixed member 130 becomes a rotation axis of the movable electrode 120 by attaching the movable electrode 120 to the support 110. The first fixed electrode 142 faces the first side of the movable electrode 120. The second fixed electrode 144 faces the second side of the movable electrode 120. The second side is the side opposite to the first side of the movable electrode 120. The first detection electrode 152 is insulated from the movable electrode 120 and the first fixed electrode 142, and faces the first side of the movable electrode 120. The second detection electrode 154 is insulated from the movable electrode 120 and the second fixed electrode 144, and faces the second side of the movable electrode 120. Then, the control unit 200 inputs the first signal, which is a signal obtained by superimposing the DC voltage on the AC voltage, to the first fixed electrode 142, and the second fixed electrode 144 has a phase opposite to that of the first signal. 2 signals are input. The second signal is, for example, a signal obtained by inverting the phase of the first signal, and the voltage at the phase 0 is equal to the first signal. In this case, the amplitude of the second signal is approximately equal to the amplitude of the first signal.

  In the example shown in the figure, the planar shape of the movable electrode 120 is a rectangle. A first fixed electrode 142 is disposed at the center of the first side of the movable electrode 120. And the 1st electrode 152 for a detection is each arrange | positioned at the both ends of a 1st edge | side. In addition, a second fixed electrode 144 is disposed at the center of the side (second side) of the movable electrode 120 that faces the first side. And the 2nd electrode 154 for a detection is each arrange | positioned at the both ends of a 2nd edge | side. The first fixed electrode 142 and the second fixed electrode 144 are arranged at positions that are symmetrical with respect to each other with respect to a line obtained by extending the fixing member 130. Further, the first detection electrode 152 and the second detection electrode 154 are also arranged at positions that are symmetrical with respect to each other with respect to a line extending from the fixing member 130.

  Further, the first side and the second side of the movable electrode 120 are both comb-like. Of the first fixed electrode 142 and the first detection electrode 152, the side facing the movable electrode 120 is also comb-shaped and meshes with the first side of the movable electrode 120. Further, the sides of the second fixed electrode 144 and the first detection electrode 152 that face the movable electrode 120 are also comb-like and mesh with the second side of the movable electrode 120. For this reason, the first fixed electrode 142, the second fixed electrode 144, and the movable electrode 120 have a large area of the portions facing each other, and as a result, the driving force of the movable electrode 120 increases. Further, the first detection electrode 152, the second detection electrode 154, and the movable electrode 120 have a large area of the portions facing each other. As a result, the detection values by the first detection electrode 152 and the second detection electrode 154 are detected. Will grow.

  The support 110 faces each of two sides other than the first side and the second side among the four sides of the movable electrode 120. The fixed member 130 is provided for each of the two sides of the movable electrode 120 facing the support 110. Specifically, the fixed member 130 is connected to the center of the side of the movable electrode 120 facing the support 110. A line connecting the two fixed members 130 serves as the rotation axis of the movable electrode 120. In the present embodiment, the support 110, the movable electrode 120, and the fixed member 130 are integrally formed.

  The movable electrode 120 of the rotary actuator 100 has, for example, a mirror surface on the upper surface. This mirror surface is formed, for example, by forming a metal film (for example, an Al film) on the upper surface of the movable electrode 120. Then, by changing the rotation amount (angle) of the movable electrode 120, the reflection angle of the light incident on the movable electrode 120 is changed.

  Note that a DC voltage predetermined by the DC voltage source 400 is applied to the movable electrode 120. The magnitude of the DC voltage is larger than both twice the amplitude of the first signal and twice the amplitude of the second signal.

  In addition, the detection unit 300 determines the amount of rotation of the movable electrode 120 based on the sum or average fluctuation of the potential of the first detection electrode 152 and the potential of the second detection electrode 154. The detection result of the detection unit 300 is output to the control unit 200. The control unit 200 generates a first signal and a second signal using the output from the detection unit 300.

  In the above example, a fixed voltage is applied to the movable electrode 120 and a voltage (signal) from the control unit 200 is input to the fixed electrode 140, but a voltage from the control unit 200 is applied to the movable electrode 120. A fixed voltage may be applied to the fixed electrode 140.

  FIG. 3 is a diagram for explaining the relationship between the amount of rotation of the movable electrode 120 and the amount of light reflected by the movable electrode 120. As shown in FIG. 3A, when the amount of rotation of the movable electrode 120 is small and the incident angle of light with respect to the movable electrode 120 is small, most of the light incident from the light source 500 hits the reflecting surface of the movable electrode 120 and is covered. Reflected toward the irradiation body 20. On the other hand, as shown in FIG. 3B, when the rotation amount of the movable electrode 120 becomes larger than the reference value, that is, when the incident angle of the light with respect to the movable electrode 120 becomes larger than the reference value, a part of the light. Is no longer reflected by the movable electrode 120, and the amount of light irradiated on the irradiated body 20 is reduced. In this case, since the intensity of the detection signal output from the light detection unit 540 is reduced, the reliability of the detection signal is reduced.

  On the other hand, in this embodiment, the light source control unit 520 controls the output of the light source 500 based on the rotation amount of the movable electrode 120. Specifically, the output of the light source 500 when the incident angle of light from the light source 500 with respect to the movable electrode 120 is larger than the reference value (that is, when the rotation amount of the movable electrode 120 is larger than the reference value) is The output angle of the light source 500 is larger than the output of the light source 500 when the incident angle of the light is smaller than the reference value. Thereby, when the amount of rotations of movable electrode 120 is large, it can control that the quantity of the light irradiated to to-be-irradiated body 20 changes. As a result, the search range of light by the optical scanning device 10 can be expanded without reducing the reliability of the detection signal output from the light detection unit 540.

  The light source control unit 520 may control the output of the light source 500 according to a table indicating the relationship between the rotation amount of the movable electrode 120 and the output of the light source 500, or the rotation amount of the movable electrode 120 and the output of the light source 500. You may control the output of the light source 500 using the function which shows a relationship.

(Second Embodiment)
FIG. 4 is a diagram illustrating a configuration of the optical scanning device 10 according to the second embodiment, and corresponds to FIG. 1 in the first embodiment. The optical scanning device 10 according to the present embodiment has the same configuration as the optical scanning device 10 according to the first embodiment except for the following points.

  First, the light source control unit 520 does not control the light source 500 based on the detection value of the detection unit 300, and causes the light source 500 to emit light with a certain intensity.

  In addition, the optical scanning device 10 includes an amplification unit 542. The amplification unit 542 amplifies the output from the light detection unit 540. The amplification unit 542 controls the amplification factor based on the rotation amount of the movable electrode 120 (for example, the detection value of the detection unit 300 or the control signal from the control unit 200). Specifically, the amplification unit 542 calculates the amplification factor when the incident angle of the light from the light source 500 with respect to the movable electrode 120 is larger than the reference value (that is, when the rotation amount of the movable electrode 120 is larger than the reference value). The gain is set larger than the amplification factor when the incident angle of light from the light source 500 is smaller than the reference value.

  The amplification unit 542 may control the amplification factor of the amplification unit 542 according to a table indicating the relationship between the rotation amount of the movable electrode 120 and the amplification factor of the amplification unit 542, or the rotation amount of the movable electrode 120 and the amplification unit. The amplification factor of the amplification unit 542 may be controlled using a function indicating the relationship between the amplification factors 542.

  According to this embodiment, even if the incident angle of the light from the light source 500 with respect to the movable electrode 120 is larger than the reference value and the amount of light reflected toward the irradiated body 20 by the movable electrode 120 is reduced, Since the amplification factor in the amplification unit 542 increases, the intensity of the detection signal output from the light detection unit 540 does not decrease. Therefore, the search range of light by the optical scanning device 10 can be expanded without reducing the reliability of the detection signal output from the light detection unit 540.

(Third embodiment)
FIG. 5 is a diagram showing a configuration of the optical scanning device 10 according to the third embodiment, and corresponds to FIG. 1 in the first embodiment. The optical scanning device 10 according to the present embodiment has the same configuration as the optical scanning device 10 according to the first embodiment except for the following points.

  First, the light source control unit 520 does not control the light source 500 based on the detection value of the detection unit 300, and causes the light source 500 to emit light with a certain intensity.

  Further, the optical scanning device 10 includes a transmissive member 560. The transmissive member 560 is located between the movable electrode 120 and the irradiated object 20, and has an in-plane distribution in the transmittance of light from the light source 500.

  As described with reference to FIG. 3 in the first embodiment, when the rotation amount of the movable electrode 120 becomes larger than the reference value, a part of the light is not reflected by the movable electrode 120, and thus the irradiated object 20. This reduces the amount of light irradiated on the surface. For this reason, the amount of light irradiated to the irradiated body 20 changes depending on the rotation amount of the movable electrode 120. The in-plane distribution of the light posting rate in the transmissive member 560 is set so as to cancel this influence.

  Specifically, the region of the transmissive member 560 where the reflected light from the movable electrode 120 is transmitted varies depending on the rotation amount (angle) of the movable electrode 120. Then, as shown in FIG. 6, in the transmissive member 560, a region where the reflected light is transmitted when the amount of rotation of the movable electrode 120 is equal to or less than a reference value (that is, the condition that the movable electrode 120 reflects almost all the light from the light source 500). The light transmittance is relatively low. On the other hand, in the transmission member 560, the transmittance of light in a region where the reflected light is transmitted when the rotation amount of the movable electrode 120 exceeds the reference value (that is, the condition that the movable electrode 120 reflects only part of the light from the light source 500). Is relatively high.

  FIG. 7 is a diagram illustrating a first example of the transmissive member 560. In the example shown in this drawing, the transmission member 560 has a slit 562. The width of the slit 562 has changed. The width on the center side of the slit 562 is narrower than the width on the end side of the slit 562. Then, under the condition that the movable electrode 120 reflects almost all of the light from the light source 500, the reflected light from the movable electrode 120 passes through the center side of the slit 562, and the movable electrode 120 is only a part of the light from the light source 500. The transmission member 560 is arranged so that the reflected light from the movable electrode 120 passes through the end side of the slit 562 under the condition of reflecting the light.

  FIG. 8 is a diagram illustrating a second example of the transmission member 560. In the example shown in this figure, the transmission member 560 is an optical filter. The light transmittance at the center of the transmissive member 560 is lower than the eaves efficiency at the end of the transmissive member 560. Also in the example shown in this figure, the reflected light from the movable electrode 120 passes through the center side of the slit 562 under the condition that the movable electrode 120 reflects almost all the light from the light source 500, and the movable electrode 120 is from the light source 500. The transmission member 560 is arranged so that the reflected light from the movable electrode 120 passes through the end portion side of the slit 562 under the condition that only a part of the light is reflected.

  According to this embodiment, the light transmittance of the transmissive member 560 has an in-plane distribution. For this reason, even if the intensity of the reflected light from the movable electrode 120 changes due to the amount of rotation of the movable electrode 120, this change is canceled when the light passes through the transmission member 560. Therefore, it is possible to suppress a change in the amount of light irradiated to the irradiation target 20. As a result, the search range of light by the optical scanning device 10 can be expanded without reducing the reliability of the detection signal output from the light detection unit 540.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

DESCRIPTION OF SYMBOLS 10 Optical scanning device 20 Subject to be irradiated 100 Rotary actuator 110 Support body 120 Movable electrode 130 Fixed member 140 Fixed electrode 142 First fixed electrode 144 Second fixed electrode 150 Detection electrode 152 First detection electrode 154 Second detection electrode 200 Control Unit 300 Detection Unit 400 DC Voltage Source 500 Light Source 520 Light Source Control Unit 540 Light Detection Unit 542 Amplification Unit 560 Transmission Member 562 Slit

Claims (6)

A movable electrode that rotates about a rotation axis and reflects incident light;
A control unit for controlling the amount of rotation of the movable electrode;
A light amount control unit that controls at least one of the light amount of the incident light before being reflected by the movable electrode and the light amount of the incident light after being reflected by the movable electrode, based on the rotation amount of the movable electrode; ,
An optical scanning device comprising: The optical scanning device according to claim 1,
A light source that emits the incident light;
The light quantity controller controls the quantity of incident light emitted from the light source based on the amount of rotation of the movable electrode. The optical scanning device according to claim 1,
The light amount control unit includes a transmission member that transmits the incident light reflected by the movable electrode,
The optical scanning device, wherein the transmission member has an in-plane distribution in the transmittance of the incident light. In the optical scanning device according to any one of claims 1 to 3,
The light amount control unit is an optical scanning device that makes the light amount when the incident angle of the incident light with respect to the movable electrode is larger than a reference value larger than the light amount when the incident angle is smaller than the reference value. An optical scanning device that scans light and irradiates the irradiated body with the light,
A movable electrode that rotates about a rotation axis and reflects the light to scan the light;
A control unit for controlling the amount of rotation of the movable electrode;
A detection unit for detecting light from the irradiated body;
An amplifier for amplifying the output of the detector;
With
The amplification unit is an optical scanning device that controls an amplification factor of the output based on a rotation amount of the movable electrode. The optical scanning device according to claim 5,
The optical scanning device, wherein the amplifying unit makes the amplification factor when the incident angle of the light with respect to the movable electrode is larger than a reference value larger than the amplification factor when the incident angle is smaller than the reference value.

Images