JP6520614B2 - Optical scanner - Google Patents

Description

  The present invention relates to an optical scanner using MEMS (Micro Electro Mechanical System) technology.

  A light scanner (light deflector) is used for a projection type image display apparatus such as a projector or a head mounted display.

  When a laser beam is irradiated to a mirror of the light scanner which is driven to be deflected, the laser beam is reflected by the mirror and scanned in the deflection direction of the mirror.

  An image can be displayed on a screen by scanning laser light in the horizontal direction and the vertical direction by two light scanners. A color image can be displayed by superimposing each of the three primary colors of light, red, green and blue, on the screen.

  Patent Document 1 describes an optical scanner that scans laser light using a permanent magnet and a drive coil.

JP, 2015-87444, A

  Generally, in an image display apparatus using an optical scanner as described in Patent Document 1, a mirror is driven at high speed in the horizontal direction by applying a drive voltage of a sinusoidal waveform to a drive coil. Further, the mirror is driven at low speed in the vertical direction by applying a sawtooth lamp voltage drive voltage to the drive coil.

  In general, the optical scanner has a variation for each optical scanner with respect to mechanical characteristics of components, magnetic force of permanent magnet, resistance value of driving coil, and the like. Therefore, the drive sensitivity of the optical scanner, specifically, the deflection angle of the mirror varies, and the displayed image varies among the optical scanners. In particular, the variation in the drive sensitivity of the light scanner driven at low speed in the vertical direction causes the deterioration of the image quality.

  By controlling the drive voltage of the optical scanner for each optical scanner by a servo circuit or the like, it is possible to reduce the variation in the drive sensitivity of the optical scanner.

  However, when controlling the drive voltage for each optical scanner, it is difficult to control an optical scanner whose drive sensitivity largely deviates from the set value because the range of the drive voltage that can be controlled is limited. Further, when replacing the optical scanner for maintenance or the like, it is necessary to newly set the control condition of the drive voltage for the replaced optical scanner.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical scanner adjusted with a simple configuration so as to reduce variations in drive sensitivity for each optical scanner.

  The present invention comprises a magnet, a mirror portion disposed in a magnetic gap to which a magnetic field is applied by the magnet, and having a drive coil, and a magnetic flux density adjusting member for adjusting the magnetic flux density of the magnetic gap; The unit is driven by a magnetic field generated by applying a driving voltage to the driving coil and a magnetic field applied to the magnetic gap by the magnet, and the magnetic flux of the magnet is adjusted by the magnetic flux density adjusting member. The magnetic flux is divided into a magnetic flux through the magnetic gap and a magnetic flux through the magnetic flux density adjusting member, and the magnetic flux density of the magnetic gap is adjusted by the ratio of the magnetic flux through the magnetic gap and the magnetic flux through the magnetic flux density adjusting member. To provide an optical scanner characterized by

  According to the optical scanner of the present invention, the variation in drive sensitivity of each optical scanner is reduced with a simple configuration.

It is a perspective view which shows the state which looked at the optical scanner of 1st Embodiment from the mirror side. It is sectional drawing of the part cut | disconnected by AA of FIG. It is a perspective view which shows the state which looked at the mirror drive unit in the optical scanner of 1st Embodiment from the other side of a mirror. It is a conceptual diagram for demonstrating the relationship between the thickness of a magnetic flux density adjustment member, and the magnetic flux density of the magnetic gap JG. It is a conceptual diagram for demonstrating the relationship between the space | interval of a magnetic flux density adjustment member and a permanent magnet, and the magnetic flux density of the magnetic gap JG. It is sectional drawing of the optical scanner of 2nd Embodiment. It is a conceptual diagram for demonstrating the magnetic flux density of the magnetic gap in the state to which the magnetic flux density adjustment member is being fixed to one yoke side. It is a flowchart for demonstrating the adjustment method of the drive sensitivity of the optical scanner of 1st and 2nd embodiment.

First Embodiment
The optical scanner 1 of the first embodiment will be described with reference to FIGS. 1 to 5.

  FIG. 1 is a perspective view showing the optical scanner 1 of the first embodiment as viewed from the mirror 21 side. FIG. 2 is a perspective view showing a cross section taken along the line A-A of FIG. FIG. 3 is a perspective view showing the mirror driving unit 10 of the optical scanner 1 as viewed from the opposite side of the mirror 21. As shown in FIG.

  As shown in FIGS. 1 and 2, the optical scanner 1 includes a housing 2, magnets 3, yokes 4 and 5, a mirror drive unit 10, and a magnetic flux density adjusting member 30. The magnet 3 is, for example, a permanent magnet. The magnet 3, the yokes 4 and 5, the mirror drive unit 10, and the magnetic flux density adjustment member 30 are fixed to the housing 2.

  As shown in FIG. 3, the mirror driving unit 10 includes a frame 11, a base 12, torsion bars 13 and 14, a terminal group 15, terminals 16 a and 16 b, a wiring group 17, wirings 18 a and 18 b, and an elastic member having conductivity. It has 19, 20.

  One end side of the torsion bars 13 and 14 is connected to the frame 11, and the other end side is connected to the base 12 to connect the frame 11 and the base 12.

  A mirror 21 (shown in FIG. 1) for reflecting the laser light is formed on one surface side (the back side in FIG. 3) of the base 12. A driving coil 22 for driving the mirror 21 and a magnetic sensor 23 for detecting a deflection angle of the mirror 21 are fixed on the other surface side (front side in FIG. 3) of the base 12.

  A mirror unit 25 is configured by the mirror 21, the drive coil 22, the magnetic sensor 23, and the base 12.

  The terminal group 15 and the terminals 16 a and 16 b are formed in the frame 11. The wiring group 17 is formed in a range from the frame 11 to the base 12 via the torsion bars 13 and 14. The wires 18 a and 18 b are formed in the frame 11.

  The terminal group 15 is electrically connected to the magnetic sensor 23 through the wiring group 17.

  The terminal 16a is electrically connected to one end of the elastic member 19 via the wiring 18a. The other end of the elastic member 19 is electrically connected to one end of the drive coil 22. Accordingly, the terminal 16 a is electrically connected to one end side of the drive coil 22 through the wiring 18 a and the elastic member 19.

  The terminal 16 b is electrically connected to one end of the elastic member 20 via the wiring 18 b. The other end of the elastic member 20 is electrically connected to the other end of the drive coil 22. Accordingly, the terminal 16 b is electrically connected to the other end of the drive coil 22 via the wiring 18 b and the elastic member 20.

  The frame 11, the base 12, and the torsion bars 13 and 14 are integrally formed. The frame 11, the base 12, the torsion bars 13 and 14, the terminal group 15, the terminals 16a and 16b, the wiring group 17 and the wirings 18a and 18b can be manufactured as, for example, a flexible printed circuit (FPC) substrate.

  The elastic members 19 and 20 have one end fixed to the frame 11 and the other end fixed to the base 12 so as to be parallel to the torsion bars 13 and 14. The elastic members 19 and 20 together with the torsion bars 13 and 14 have the function of a torsion spring. For example, wire springs made of a conductive member such as copper can be used as the elastic members 19 and 20.

  A driving voltage for deflecting and driving the mirror unit 25 is applied to the driving coil 22 through the terminals 16a and 16b, the wirings 18a and 18b, and the elastic members 19 and 20.

  For example, in an optical scanner used for an image display device, when a laser beam is scanned at low speed in the vertical direction, a sawtooth lamp voltage drive voltage is applied to the drive coil 22. When the laser beam is scanned in the horizontal direction at high speed, a drive voltage of a sinusoidal waveform is applied to the drive coil 22.

  As shown in FIG. 1 and FIG. 2, the mirror portion 25 is disposed in the magnetic gap JG which is the gap between the yoke 4 and the yoke 5. A magnetic field is applied to the magnetic gap JG by the magnet 3 via the yokes 4 and 5. The mirror portion 25 is driven to reciprocate and rotate around the rotation center axis C25 by the magnetic field applied by the magnet 3 and the magnetic field generated by the drive coil 22 when the drive voltage is applied to the drive coil 22. .

  The mirror 21 is driven to be deflected as the mirror unit 25 is driven to reciprocate. By irradiating the laser beam which is a form of light to the mirror 21 driven to be deflected, the laser beam is reflected by the mirror 21 and scanned in the deflection direction of the mirror 21.

  The magnetic sensor 23 detects the magnetic field strength of the magnet 3. The deflection angle of the mirror 21 can be detected from the detected magnetic field strength. For example, a Hall element can be used as the magnetic sensor 23.

  As shown in FIG. 2, in the optical scanner 1 according to the first embodiment, the magnetic flux density adjusting member 30 is fixed at a position opposite to the magnetic gap JG of the housing 2.

  The magnetic flux density adjusting member 30 is a member for adjusting the magnetic flux density of the magnetic gap JG acting on the mirror portion 25, more specifically, the drive coil 22 of the mirror portion 25. The magnetic flux density adjusting member 30 is formed of, for example, a soft magnetic material such as soft iron, galvanized steel sheet, silicon steel sheet, or permalloy.

  Usually, the optical scanner 1 has variations in mechanical characteristics of components such as the torsion bars 13 and 14 and the elastic members 19 and 20, the magnetic force of the magnet 3, the resistance value of the drive coil 22, and the like. Therefore, the drive sensitivity of the light scanner 1, specifically, the deflection angle of the mirror 21 varies, and the displayed image varies from one light scanner 1 to another.

  Therefore, a specific embodiment for reducing the variation of the drive sensitivity for each light scanner 1 by adjusting the magnetic flux density of the magnetic gap JG with the magnetic flux density adjusting member 30 will be described using FIGS. 4 and 5. Do.

Example 1
For example, by thickening the magnetic flux density adjusting member 30, the magnetic flux density of the magnetic gap JG can be adjusted in the direction to be reduced.

  The relationship between the thickness of the magnetic flux density adjusting member 30 and the magnetic flux density of the magnetic gap JG will be described with reference to FIGS. 4 (a) to 4 (c).

  FIG. 4A to FIG. 4C are conceptual diagrams schematically showing the magnetic flux density of the magnetic gap JG by the number of magnetic flux lines. FIG. 4A shows a state in which the magnetic flux density adjusting member 30 is not fixed. FIG. 4B shows a state in which the magnetic flux density adjusting member 30 of thickness t1 is fixed. FIG. 4C shows a state in which the magnetic flux density adjusting member 30 of thickness t2 (t1 <t2) is fixed. In FIGS. 4A to 4C, the magnetic flux of the magnet 3 is schematically shown by eight magnetic flux lines JS.

  As shown in FIG. 4A, in the state where the magnetic flux density adjusting member 30 is not fixed, the magnetic flux of the magnet 3 is concentrated in the magnetic gap JG in which the driving coil 22 is disposed. Therefore, the magnetic flux density of the magnetic gap JG is indicated by eight magnetic flux lines JS.

  On the other hand, as shown in FIG. 4B and FIG. 4C, the magnetic flux of the magnet 3 is converted by the magnetic flux density adjusting member 30 to the magnetic flux through the magnetic gap JG and the magnetic flux through the magnetic flux density adjusting member 30. I'm divided. Therefore, the magnetic flux density of the magnetic gap JG can be adjusted in the direction to be reduced by the magnetic flux density adjusting member 30.

  In order to make the explanation easy to understand, in FIG. 4B, the magnetic flux density of the magnetic gap JG is schematically represented by five magnetic flux lines JS, and the magnetic flux density of the magnetic flux density adjusting member 30 of thickness t1 by three magnetic flux lines JS. Is shown. In FIG. 4C, the magnetic flux density of the magnetic gap JG is schematically indicated by four magnetic flux lines JS, and the magnetic flux density of the magnetic flux density adjusting member 30 with a thickness t2 is indicated by four magnetic flux lines JS.

  The thicker the magnetic flux density adjustment member 30, the higher the ratio of the magnetic flux through the magnetic flux density adjustment member 30 to the magnetic flux through the magnetic gap JG. Therefore, by thickening the magnetic flux density adjusting member 30, the magnetic flux density of the magnetic gap JG can be reduced.

  The magnetic flux density adjusting member 30 is a soft magnetic material having a length L1 of 7.2 mm, a width (length in the front of the sheet in FIG. 4B) of 5 mm, and a relative permeability of 10000. The thickness t3 of the yoke 4 and the thickness t4 of the yoke 5 are each 1.2 mm.

  For example, when the thickness t1 of the magnetic flux density adjusting member 30 is 1 mm, the magnetic flux density of the magnetic gap JG may be adjusted to about 74% of the magnetic flux density adjusting member 30 not fixed. it can.

  When the thickness t2 of the magnetic flux density adjusting member 30 is 2 mm, the magnetic flux density of the magnetic gap JG can be adjusted to about 61% of the magnetic flux density relative to the state where the magnetic flux density adjusting member 30 is not fixed.

  The magnetic flux density of the magnetic gap JG can be accurately adjusted by using the magnetic flux density adjusting members 30 having different thicknesses or by overlapping the magnetic flux density adjusting members 30 in the thickness direction.

  Further, the ratio of the magnetic flux passing through the magnetic flux density adjusting member 30 to the magnetic flux passing through the magnetic gap JG is also increased by lengthening the magnetic flux density adjusting member 30 or widening the width of the magnetic flux density adjusting member 30. be able to. That is, the magnetic flux density of the magnetic gap JG can be adjusted in the direction to be reduced also by lengthening the magnetic flux density adjusting member 30 or widening the width of the magnetic flux density adjusting member 30.

  That is, by increasing the size of the magnetic flux density adjusting member 30, the magnetic flux density of the magnetic gap JG can be adjusted in the direction to be reduced.

  Further, by using a soft magnetic material having a high magnetic permeability (relative magnetic permeability) as the material of the magnetic flux density adjusting member 30, the ratio of the magnetic flux passing through the magnetic flux density adjusting member 30 to the magnetic flux passing through the magnetic gap JG is increased. be able to. That is, the magnetic flux density of the magnetic gap JG can be adjusted in the direction to be reduced also by using a soft magnetic material having high permeability.

Example 2
For example, by widening the distance between the magnetic flux density adjusting member 30 and the magnet 3, the magnetic flux density of the magnetic gap JG can be adjusted in the direction to be increased.

  The relationship between the distance between the magnetic flux density adjusting member 30 and the magnet 3 and the magnetic flux density of the magnetic gap JG will be described with reference to FIGS. 5 (a) to 5 (c).

  FIG. 5A to FIG. 5C are conceptual diagrams schematically showing the magnetic flux density of the magnetic gap JG by the number of magnetic flux lines. FIG. 5A shows a state in which the distance between the magnetic flux density adjusting member 30 and the magnet 3 is zero. FIG. 5 (a) corresponds to FIG. 4 (b). FIG. 5B shows a state in which the interval is d1 (0 <d1). FIG. 5C shows a state in which the distance is d2 (d1 <d2). In FIGS. 5A to 5C, the magnetic flux of the magnet 3 is schematically indicated by eight magnetic flux lines JS.

  In FIG. 5A, the magnetic flux density of the magnetic gap JG is schematically shown by five magnetic flux lines JS, and the magnetic flux density of the magnetic flux density adjusting member 30 is schematically indicated by three magnetic flux lines JS in FIG. . In FIG. 5B, the magnetic flux density of the magnetic gap JG is schematically shown by six magnetic flux lines JS, and the magnetic flux density of the magnetic flux density adjusting member 30 is schematically indicated by two magnetic flux lines JS. In FIG. 5C, the magnetic flux density of the magnetic gap JG is schematically shown by seven magnetic flux lines JS, and the magnetic flux density of the magnetic flux density adjusting member 30 is schematically indicated by one magnetic flux line JS.

  As the distance between the magnetic flux density adjusting member 30 and the magnet 3 is wider, the ratio of the magnetic flux through the magnetic flux density adjusting member 30 to the magnetic flux through the magnetic gap JG decreases. Therefore, the magnetic flux density of the magnetic gap JG can be increased by widening the distance between the magnetic flux density adjusting member 30 and the magnet 3.

  The magnetic flux density adjusting member 30 has a thickness t5 of 1 mm, a length L2 of 7.2 mm, and a width (the length in the direction toward the back of the sheet in FIGS. 5A to 5C) of 5 mm. It is a soft magnetic substance of 10000. The thickness t3 of the yoke 4 and the thickness t4 of the yoke 5 are each 1.2 mm.

  For example, when the distance d1 between the magnetic flux density adjusting member 30 and the magnet 3 is 0.5 mm, the magnetic flux density of the magnetic gap JG can be adjusted to a magnetic flux density of about 114% with respect to the state of 0 mm. .

  The distance between the magnetic flux density adjusting member 30 and the magnet 3 can be adjusted by rotating a screw or the like or interposing a spacer.

  Therefore, according to the optical scanner 1 of the first embodiment, even when variation in drive sensitivity occurs for each optical scanner, by using the magnetic flux density adjusting member 30 having a different size and permeability, it is possible to Variations in drive sensitivity can be reduced.

  Further, according to the optical scanner 1 of the first embodiment, even when the drive sensitivity varies from one optical scanner to another, the distance between the magnetic flux density adjusting member 30 and the magnet 3 is made different to allow each optical scanner to It is possible to reduce the variation in drive sensitivity of

Second Embodiment
The optical scanner 50 of the second embodiment will be described with reference to FIGS. 6 and 7.

  FIG. 6 is a perspective view showing an optical scanner 50 of the second embodiment. FIG. 6 corresponds to FIG.

  The optical scanner 50 of the second embodiment is different from the optical scanner 1 of the first embodiment in that the magnetic flux density adjusting member 30 is fixed to one yoke 4 side of the housing 2, The other components are the same as those of the optical scanner 1 of the first embodiment. Therefore, in order to make the description easy to understand, the same components are denoted by the same reference numerals.

  The magnetic flux density of the magnetic gap JG in a state in which the magnetic flux density adjusting member 30 is fixed to the one yoke 4 side will be described with reference to FIGS. 7A to 7C.

  FIGS. 7A to 7C are conceptual diagrams schematically showing the magnetic flux density of the magnetic gap JG in terms of the number of magnetic flux lines. FIG. 7A shows a state in which the magnetic flux density adjusting member 30 is not fixed. FIG. 7 (a) corresponds to FIG. 4 (a). FIG. 7B shows a state in which the magnetic flux density adjusting member 30 of length L3 is fixed. FIG. 7C shows a state in which the magnetic flux density adjusting member 30 having the length L4 (L3 <L4) is fixed. 7A to 7C, the magnetic flux of the magnet 3 is schematically indicated by eight magnetic flux lines JS.

  As shown in FIG. 7A, in the state where the magnetic flux density adjusting member 30 is not fixed, the magnetic flux of the magnet 3 acts on the magnetic gap JG via the yoke 4. Therefore, the magnetic flux density of the yoke 4 is indicated by eight magnetic flux lines JS.

  On the other hand, as shown in FIGS. 7B and 7C, in the state where the magnetic flux density adjusting member 30 is fixed to the one yoke 4 side, the magnetic flux of the magnet 3 is a magnetic flux passing through the yoke 4 And the magnetic flux through the magnetic flux density adjusting member 30. As a result, the magnetic resistance can be increased, and the magnetic flux density of the magnetic gap JG can be adjusted to be reduced.

  7B, the magnetic flux density of the yoke 4 is schematically shown by seven magnetic flux lines JS, and the magnetic flux density of the magnetic flux density adjusting member 30 is schematically indicated by one magnetic flux line JS. In FIG. 7C, the magnetic flux density of the yoke 4 is schematically shown by six magnetic flux lines JS, and the magnetic flux density of the magnetic flux density adjusting member 30 is schematically indicated by two magnetic flux lines JS.

  The magnetic flux density adjusting member 30 is a soft magnetic material having a thickness t6 of 1 mm, a width (length in the front and back direction in FIG. 7B and FIG. 7C) of 5 mm, and a relative permeability of 10000. The thickness t3 of the yoke 4 and the thickness t4 of the yoke 5 are each 1.2 mm.

  For example, when the length L3 of the magnetic flux density adjusting member 30 is 2.5 mm, the magnetic flux density of the magnetic gap JG is adjusted to about 98% of the magnetic flux density with respect to the state where the magnetic flux density adjusting member 30 is not fixed. be able to.

  When the length L4 of the magnetic flux density adjusting member 30 is 5 mm, the magnetic flux density of the magnetic gap JG can be adjusted to about 96% of the magnetic flux density with respect to the state where the magnetic flux density adjusting member 30 is not fixed.

  The optical scanner 50 of the second embodiment has a smaller amount of change in the magnetic flux density of the magnetic gap JG by the magnetic flux density adjusting member 30 than the optical scanner 1 of the first embodiment.

  Therefore, when variation in drive sensitivity occurs for each optical scanner, the first embodiment is suitable for an optical scanner with large variation, and the second embodiment is suitable for an optical scanner with small variation. It is.

  Also in the optical scanner 50 of the second embodiment, as in the optical scanner 1 of the first embodiment, the magnetic flux density adjusting member 30 having different sizes and magnetic permeability when variations in drive sensitivity occur among the optical scanners. By adjusting the distance between the magnetic flux density adjusting member 30 and the magnet 3 or by adjusting the distance between the magnetic flux density adjusting member 30 and the magnet 3, it is possible to reduce the variation in the drive sensitivity of each optical scanner.

  A method of adjusting the drive sensitivity of the optical scanners 1 and 50 according to the first and second embodiments will be described with reference to the flowchart of FIG.

  In step S1, in a state where the magnetic flux density adjustment member 30 is not fixed, a predetermined drive voltage is applied to the optical scanners 1 and 50 to drive the mirror unit 25.

  In step S2, the mirror 21 of the mirror unit 25 is irradiated with a laser beam.

  In step S3, the deflection angle of the mirror 21 is detected based on the reflection angle of the laser light from the mirror 21. The deflection angle of the mirror 21 may be detected by the magnetic sensor 23. When the magnetic sensor 23 is used, the irradiation of the laser beam is unnecessary.

  In step S4, the magnetic flux density adjusting member 30 having different size or permeability is used or the distance between the magnetic flux density adjusting member 30 and the magnet 3 is adjusted so that the detected deflection angle becomes a set value. , Adjust the magnetic flux density of the magnetic gap JG.

  Even when the variation in drive sensitivity occurs for each optical scanner according to the above-described procedure, the variation in drive sensitivity for each optical scanner is adjusted by adjusting the magnetic flux density of the magnetic gap JG using the magnetic flux density adjusting member 30. It can be reduced.

  The present invention is not limited to the above-described configuration, and various modifications can be made without departing from the scope of the present invention.

  For example, in the first embodiment, the magnetic flux density adjusting member 30 is fixed at a position opposite to the magnetic gap JG of the housing 2 and in the second embodiment is fixed to one yoke 4 side of the housing 2 Configuration. The position where the magnetic flux density adjusting member 30 is fixed to the housing 2 is not limited to the first and second embodiments as long as it is in a range that affects the magnetic flux of the magnet 3.

  With respect to the optical scanners 1 and 50 in which the magnetic flux density of the magnetic gap JG is adjusted by the magnetic flux density adjusting member 30, the drive voltage of the optical scanners 1 and 50 is controlled for each of the optical scanners 1 and 50 by a servo circuit or the like. It is also good. As a result, the variation in drive sensitivity of the optical scanner can be further reduced, and the adjustment range of the variation in drive sensitivity can be expanded.

  A temperature compensation element or the like for correcting an error caused by the temperature around the magnetic sensor 23 may be disposed in an area inside the drive coil 22 of the mirror unit 25. The arrangement position of the temperature compensation element is not limited to the region inside the drive coil 22.

1, 50 light scanner 3 magnet 22 drive coil 25 mirror unit 30 magnetic flux density adjusting member JG magnetic gap

Claims (2)

With a magnet,
A mirror portion disposed in a magnetic gap to which a magnetic field is applied by the magnet and having a drive coil;
A magnetic flux density adjusting member for adjusting the magnetic flux density of the magnetic gap;
Equipped with
The mirror unit is driven by a magnetic field generated by applying a drive voltage to the drive coil, and a magnetic field applied to the magnetic gap by the magnet.
The magnetic flux of the magnet is divided by the magnetic flux density adjusting member into a magnetic flux passing through the magnetic gap and a magnetic flux passing through the magnetic flux density adjusting member,
The magnetic flux density of the magnetic gap is adjusted by the ratio of the magnetic flux through the magnetic gap and the magnetic flux through the magnetic flux density adjusting member.
An optical scanner characterized by   The optical scanner according to claim 1, wherein the magnetic flux density adjustment member is formed of a soft magnetic material.

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