JP7725977B2 - Optical path control device, display device, and optical path control method - Google Patents

Description

The present invention relates to an optical path control device, a display device, and an optical path control method.

Optical devices that shift the optical axis by oscillating the optical section into which light enters are known. For example, Patent Document 1 below describes a technology that can increase the resolution of a projected image beyond that of a light modulation device by oscillating the optical section to shift the optical path of light passing through the optical section.

Japanese Patent Application Laid-Open No. 2020-091343

Optical devices are known that shift the optical path of light passing through an optical unit by swinging the optical unit around intersecting first and second axes. Such optical devices have a first actuator that swings the optical unit around the first axis and a second actuator that swings the optical unit around the second axis. Driving the two actuators simultaneously tilts the optical unit in a specific direction by a specific angle, thereby changing the optical path. In this case, driving two actuators simultaneously increases power consumption. Furthermore, it is necessary to adjust the balance between the drive amounts of the two actuators, i.e., the respective displacement amounts for tilting the optical unit, which creates the problem of complex adjustment control of each actuator.

In view of the above-mentioned problems, the present invention aims to provide an optical path control device, a display device, and an optical path control method that reduce the power consumption of the actuator and simplify the control of the actuator.

An optical path control device according to one aspect of the present invention comprises an oscillating unit having an optical unit onto which light is incident, an actuator that oscillates the oscillating unit, and a drive unit that applies a drive signal of a current value to the actuator, wherein the drive unit applies a current value that is half the peak current value for a period that is half the period of the natural vibration of the oscillating unit, and then maintains the current value at the peak current value or at 0.

A display device according to one aspect of the present invention includes the light path control device and an illumination device that illuminates the optical section with light.

An optical path control method according to one aspect of the present invention controls an optical path by applying a drive signal to an actuator that oscillates an oscillating unit having an optical unit onto which light is incident. The method applies a current value that is half the peak current value to the actuator for a period that is half the period of the natural frequency of the oscillating unit, and then maintains the current value at the peak current value or at zero.

This invention makes it possible to reduce the power consumption of the actuator and simplify the control of the actuator.

FIG. 1 is a schematic diagram showing a display device according to this embodiment. FIG. 2 is a block diagram schematically showing the circuit configuration of the display device. FIG. 3 is a plan view showing the optical path control mechanism. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is a graph illustrating the waveform of the drive signal of the drive unit. FIG. 7 is a graph illustrating the oscillation pattern of the optical part. FIG. 8 is an explanatory diagram illustrating a two-axis swing pattern of the optical unit. FIG. 9 is a graph illustrating the relationship between the waveform of the drive signal of the drive unit and the oscillation pattern of the optical unit. FIG. 10 is a schematic diagram illustrating power consumption in a trapezoidal wave drive signal. FIG. 11 is a schematic diagram illustrating power consumption in a step wave of a drive signal.

Embodiments of the present invention are described in detail below with reference to the drawings. Note that the present invention is not limited to the embodiments described below.

First Embodiment
[Schematic configuration of display device]
FIG. 1 is a schematic diagram of a display device according to the first embodiment.

In the first embodiment, as shown in FIG. 1, the display device 1 has a light path control device 10 and an irradiation device 100. The irradiation device 100 is a device that irradiates light L for an image. The light path control device 10 is a device that controls the optical path of the light L. The light path control device 10 shifts the optical axis of the light L, thereby shifting the position of the image displayed by the light L and increasing the resolution of the projected image compared to the image resolution generated by the irradiation device 100 (i.e., the number of pixels of the display element 106, described below).

The irradiation device 100 includes a light source 101, polarizing plates 105R, 105G, and 105B, display elements 106R, 106G, and 106B, polarizing plates 107R, 107G, and 107B, a color synthesis prism 108, a projection lens 109, dichroic mirrors 120 and 121, reflecting mirrors 130 and 131, lenses 140, 141, 142, 143, 144, and 145, a polarization conversion element 150, and a video signal processing circuit 160. When display elements 106R, 106G, and 106B are not distinguished from one another, they are referred to as display elements 106.

Light source 101 is a light source that generates and irradiates light. Light source 101 irradiates incident light L0. In the following explanation, an example will be given in which one light source 101 is used as the light source that irradiates incident light L0, but other optical devices may be included to generate incident light L0.

Incoming light L0 from light source 101 is incident on lens 140. Lenses 140 and 141 are, for example, fly's eye lenses. The illumination distribution of incident light L0 is homogenized by lenses 140 and 141, and the incident light is then incident on polarization conversion element 150. Polarization conversion element 150 is an element that aligns the polarization of incident light L0, and includes, for example, a polarizing beam splitter and a retardation plate. Polarization conversion element 150 aligns incident light L0 to p-polarized light, for example.

Incoming light L0, whose polarization has been aligned by the polarization conversion element 150, is irradiated onto the dichroic mirror 120 via the lens 142. The lens 142 is, for example, a condenser lens.

Dichroic mirror 120 separates incident light L0 into yellow light LRG and blue light LB containing blue band components. The yellow illumination light LRG separated by dichroic mirror 120 is reflected by reflecting mirror 130 and enters dichroic mirror 121.

The dichroic mirror 121 separates the incident yellow light LRG into red light LR containing red band components and green light LG containing green band components.

The red light LR separated by the dichroic mirror 121 is irradiated onto the polarizing plate 105R via the lens 143. The green light LG separated by the dichroic mirror 121 is irradiated onto the polarizing plate 105G via the lens 144. The blue light LB separated by the dichroic mirror 120 is reflected by the reflecting mirror 131 and irradiated onto the polarizing plate 105B via the lens 145.

Polarizing plates 105R, 105G, and 105B have the property of reflecting either s-polarized light or p-polarized light and transmitting the other. For example, polarizing plates 105R, 105G, and 105B reflect s-polarized light and transmit p-polarized light. Polarizing plates 105R, 105G, and 105B are also called reflective polarizing plates.

P-polarized red light LR passes through polarizer 105R and is irradiated onto display element 106R. P-polarized green light LG passes through polarizer 105G and is irradiated onto display element 106G. P-polarized blue light LB passes through polarizer 105B and is irradiated onto display element 106B.

Display element 106R, display element 106G, and display element 106B are, for example, reflective liquid crystal display elements. In the following explanation, we will use an example in which display element 106R, display element 106G, and display element 106B are reflective liquid crystal display elements, but they are not limited to reflective types and may also be configured to use transmissive liquid crystal display elements. Various applications are also possible for configurations that use other display elements instead of liquid crystal display elements.

Display element 106R is controlled by video signal processing circuit 160. Video signal processing circuit 160 drives and controls display element 106R based on image data for the red component. Display element 106R optically modulates p-polarized red light LR in accordance with the control of video signal processing circuit 160 to generate s-polarized red light LR. Display element 106G is controlled by video signal processing circuit 160. Video signal processing circuit 160 drives and controls display element 106G in accordance with image data for the green component. Display element 106G optically modulates p-polarized green light LG in accordance with the control of video signal processing circuit 160 to generate s-polarized green light LG. Display element 106B is controlled by video signal processing circuit 160. Video signal processing circuit 160 drives and controls display element 106B in accordance with image data for the blue component. Display element 106B optically modulates p-polarized blue light LB based on image data of the blue component under the control of video signal processing circuit 160, generating s-polarized blue light LB.

Polarizing plates 107R, 107G, and 107B have the property of transmitting either s-polarized light or p-polarized light and reflecting or absorbing the other. For example, polarizing plates 107R, 107G, and 107B transmit s-polarized light and absorb unwanted p-polarized light.

S-polarized red light LR generated by display element 106R is reflected by polarizing plate 105R, passes through polarizing plate 107R, and is irradiated onto color synthesis prism 108. S-polarized green light LG generated by display element 106G is reflected by polarizing plate 105G, passes through polarizing plate 107G, and is irradiated onto color synthesis prism 108. S-polarized blue light LB generated by display element 106B is reflected by polarizing plate 105B, passes through polarizing plate 107B, and is irradiated onto color synthesis prism 108.

The color synthesis prism 108 synthesizes the incident red light LR, green light LG, and blue light LB, and irradiates the projection lens 109 with the resulting light L for image display. The light L is projected via the projection lens 109 onto a screen (not shown) or the like.

Although the irradiation device 100 has the configuration described above, its configuration is not limited to the above description and may be any configuration.

The light path control device 10 has a light path control mechanism 12, a control circuit (controller) 14, and a drive circuit (driver) 16. The light path control mechanism 12 is a mechanism that oscillates when driven by the drive circuit 16. The light path control mechanism 12 is provided between the color synthesis prism 108 and the projection lens 109 in a direction along the optical path of the light L. The light path control mechanism 12 oscillates while receiving the light L from the color synthesis prism 108, thereby shifting the traveling direction (optical path) of the light L and outputting it toward the projection lens 109. In this way, the light path control device 10 controls the optical path of the light L so that the optical path of the light L shifts. Note that the position at which the light path control mechanism 12 is provided is not limited to between the color synthesis prism 108 and the projection lens 109, and may be any position.

[Functional configuration of the display device]
FIG. 2 is a block diagram showing a schematic circuit configuration of the display device.

As shown in FIG. 2, the video signal processing circuit 160 controls the display elements 106R, 106B, and 106G. The video signal processing circuit 160 receives image data for controlling the display elements 106R, 106B, and 106G, as well as a video signal including a synchronization signal. The video signal processing circuit 160 controls the display elements 106R, 106B, and 106G based on the image data while synchronizing the timing based on the synchronization signal. The control circuit 14 includes a digital circuit 14A. The synchronization signal from the video signal processing circuit 160 is input to the digital circuit 14A. The digital circuit 14A generates a digital drive signal for driving the optical path control mechanism 12 while synchronizing the timing based on the synchronization signal. The drive circuit 16 receives the digital drive signal generated by the digital circuit 14A, amplifies the digital drive signal, and outputs it to the actuator 12B of the optical path control mechanism 12, which will be described later. The actuator 12B is driven in response to a drive signal to oscillate the oscillating portion 12A (see Figure 3), which will be described later.

[Optical path control mechanism]
3 is a plan view showing the optical path control mechanism, FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a cross-sectional view taken along line VV in FIG.

As shown in Figures 3 to 5, the optical path control mechanism 12 has a swinging unit 12A that includes an optical member (optical unit) 20 onto which light L is incident, and an actuator 12B that swings the swinging unit 12A.

Actuator 12B oscillates oscillating unit 12A around first and second oscillation axes AX and BX, which are aligned along two directions that intersect (preferably perpendicular) with the direction in which light L is incident on optical element 20. The first and second oscillation axes AX and BX are preferably perpendicular to each other. Therefore, optical path control mechanism 12 includes first and second oscillation units 21 and 22 as oscillating unit 12A, first and second axes 23 and 24 aligned along first and second oscillation axes AX and BX, first and second actuators 25 and 26 as actuator 12B, and support unit 27.

In Figure 3, the AY direction is the horizontal arrangement direction of the pixels of the optical element 20, and the BY direction is the vertical arrangement direction of the pixels of the optical element 20. The AY direction and the BY direction intersect at right angles. The first oscillation axis AX direction and the second oscillation axis BX direction have the same center O and intersect at an angle of 45 degrees with the AY direction and the BY direction. The first oscillation axis AX direction is offset 45 degrees counterclockwise from the AY direction, and the second oscillation axis BX direction is offset 45 degrees counterclockwise from the BY direction. In other words, the first oscillation axis AX direction and the second oscillation axis BX direction are offset 45 degrees from the horizontal and vertical arrangement directions of the pixels.

The optical element 20 is a member that transmits incident light L. Light L is incident on one surface of the optical element 20, the optical element 20 transmits the incident light L, and the light L is emitted from the other surface. The optical element 20 is a glass plate, but the material and shape may be arbitrary.

The first oscillating part 21 has an optical element 20 and a first movable part 31. The first movable part 31 is a member that supports the optical element 20. The first movable part 31 is fixed to the optical element 20. Specifically, the first movable part 31 is a frame-shaped plate member with a through hole 31a formed in the center. The optical element 20 is fixed to the first movable part 31 by being fitted into the through hole 31a of the first movable part 31. The optical element 20 is fixed to the first movable part 31 via a fixing member or adhesive for fixing it to the first movable part 31, but the method of fixing the optical element 20 to the first movable part 31 may be arbitrary.

The second oscillating part 22 is disposed outside the first oscillating part 21. The second oscillating part 22 has a second movable part 32. The second movable part 32 is a member that supports the first movable part 31. The first movable part 31 is supported by the second movable part 32 so that it can oscillate freely around the first oscillation axis AX. Specifically, the second movable part 32 is a frame-shaped plate member with a through hole 32a formed in its center. The first movable part 31 is supported by the second movable part 32 so that it can oscillate freely, with a predetermined gap between them in the through hole 32a of the second movable part 32. The first movable part 31 and the second movable part 32 are connected by a pair of first shafts 23 that extend along the first oscillation axis AX. The first movable part 31 oscillates around the first oscillation axis AX as the pair of first shafts 23 elastically deform so as to be twisted relative to the second movable part 32.

The support portion 27 is disposed outside the second oscillating portion 22. The support portion 27 is a member that supports the second movable portion 32. The second movable portion 32 is supported relative to the support portion 27 so that it can oscillate freely around the second oscillating axis BX. Specifically, the support portion 27 is a frame-shaped plate member with a through hole 27a formed in its center. The second movable portion 32 is supported by the support portion 27 so that it can oscillate freely, with a predetermined gap between them in the through hole 27a of the support portion 27. The second movable portion 32 and the support portion 27 are connected by a pair of second shaft portions 24 that extend along the second oscillating axis BX. The second movable portion 32 oscillates around the second oscillating axis BX as the pair of second shaft portions 24 elastically deform so as to be twisted relative to the support portion 27.

The second movable part 32 (second oscillating part 22) oscillates around the second oscillating axis BX with respect to the support part 27, with a pair of second shafts 24 as fulcrums. The first movable part 31 (first oscillating part 21) oscillates around the first oscillating axis AX with respect to the second movable part 32, with a pair of first shafts 23 as fulcrums. Therefore, the optical element 20 fixed to the first movable part 31 can oscillate around the first oscillating axis AX and the second oscillating axis BX. When the optical element 20 oscillates around the first oscillating axis AX and the second oscillating axis BX, the posture of the optical element 20 changes, shifting the optical path of the light L passing through the optical element 20.

In this embodiment, the first movable part 31, the second movable part 32, the first shaft part 23, and the second shaft part 24 are integrally formed. Therefore, the first movable part 31 swings relative to the second movable part 32 as the first shaft part 23 elastically deforms so as to be twisted circumferentially. However, the first movable part 31, the second movable part 32, and the first shaft part 23 may be formed separately and then connected. Alternatively, one end and the other end of the axial direction of the second swing axis BX of the second movable part 32 are fixed so as to be connected to the support part 27, and the second shaft parts 24 are formed at each end of the second movable part 32. However, the second shaft parts 24 may be provided at each end of the second movable part 32, and each second shaft part 24 may be fixed so as to be directly connected to the support part 27. Furthermore, the second movable part 32, the second shaft part 24, and the support part 27 may be formed integrally.

The first actuator 25 swings the first movable part 31 (first swing part 21) around the first swing axis AX, with the pair of first shaft parts 23 as fulcrums relative to the support part 27. The first actuator 25 is disposed on both sides of the first swing axis AX in the radial direction (axial direction of the second swing axis BX). The first actuator 25 has a coil 41, a yoke 42, and a magnet 43.

The coil 41 is attached to the first movable part 31 and fixed to the coil attachment part 31b provided on the first movable part 31. The coil 41 is provided at both ends of the first movable part 31 in the radial direction of the first oscillation axis AX (one side and the other side in the axial direction of the second oscillation axis BX). The yoke 42 is a member that forms a magnetic path. The yoke 42 is attached to the support part 27 and fixed to the support part 27. The yoke 42 is arranged at both ends of the first movable part 31 corresponding to the coil 41. The magnet 43 is a permanent magnet. The magnet 43 is attached to the yoke 42 and fixed to the yoke 42. The magnets 43 are arranged in positions adjacent to their respective coils 41.

A drive signal is input to the coil 41 from the drive circuit 16 (see Figure 2). In the example shown in Figure 5, a magnet 43 is attached to one side of a U-shaped yoke 42, and an air gap is formed between the unattached surface of the magnet 43 and the opposing U-shaped surface of the yoke 42. The coil 41 is disposed within the air gap. When a drive signal is input to the coil 41, a current flows through the coil 41, which is a conductor located within the air gap (magnetic field) formed by the magnet 43 and the yoke 42, generating a force in the coil 41. This force causes the first movable part 31 (first oscillating part 21) fixed to the coil 41 to oscillate. In other words, the first actuator 25 can be considered an electromagnetic actuator composed of the coil 41, the yoke 42, and the magnet 43.

The second actuator 26 swings the second movable portion 32 (second oscillating portion 22) about the second oscillating axis BX with respect to the support portion 27, using the pair of second shaft portions 24 as fulcrums. The second actuator 26 is disposed on both sides of the second oscillating axis BX in the radial direction (axial direction of the first oscillating axis AX). The second actuator 26 has a coil 44, a yoke 45, and a magnet 46.

The coil 44 is attached to the second movable part 32 and fixed to the coil attachment part 32b provided on the second movable part 32. The coil 44 is provided at both ends of the second movable part 32 in the radial direction of the second oscillation axis BX (one side and the other side in the axial direction of the first oscillation axis AX). The yoke 45 is a member that forms a magnetic path. The yoke 45 is attached to the support part 27 and fixed to the support part 27. The yoke 45 is arranged at both ends of the second movable part 32 corresponding to the coil 44. The magnet 46 is a permanent magnet. The magnet 46 is attached to the yoke 45 and fixed to the yoke 45. The magnets 46 are arranged in positions adjacent to the respective coils 44.

A drive signal is input to the coil 44 from the drive circuit 16 (see Figure 2). In the example shown in Figure 4, a magnet 46 is attached to one side of a U-shaped yoke 45, and an air gap is formed between the unattached surface of the magnet 46 and the opposing U-shaped surface of the yoke 45. The coil 44 is disposed within the air gap. When a drive signal is input to the coil 44, a current flows through the coil 44, which is a conductor located within the air gap (magnetic field) formed by the magnet 46 and the yoke 45, generating a force in the coil 44. This force causes the second movable part 32 (second oscillating part 22) fixed to the coil 44 to oscillate. In other words, the second actuator 26 can be considered an electromagnetic actuator composed of the coil 44, yoke 45, and magnet 46.

In the optical path control mechanism 12, the first movable part 31 on which the optical element 20 is mounted oscillates, and the second movable part 32 supporting the first movable part 31 oscillates as well. Therefore, the optical element 20, the first movable part 31, the second movable part 32, and the coils 41 and 44 can be said to constitute the oscillating part 12A. In other words, the part of the optical path control mechanism 12 that oscillates relative to the support part 27 can be said to be the oscillating part 12A. Note that the first shaft part 23 also oscillates together with the second movable part 32, and is therefore included in the oscillating part 12A. Furthermore, if a fixing member or adhesive for fixing the optical element 20 to the first movable part 31, or a substrate or lead wire for passing current through the coils 41 and 44, is provided, these also oscillate relative to the support part 27 and are therefore included in the oscillating part 12A.

In this embodiment, the first movable part 31 is oscillated by the first actuator 25, and the second movable part 32 is oscillated by the second actuator 26. In this case, the yokes 42, 45 that constitute each actuator 25, 26 are fixed to the support part 27. Therefore, when the second movable part 32 is oscillated by the second actuator 26, a gap is secured between the first actuator 25 and the second movable part 32 to prevent interference between them.

In the above, the actuators 25, 26 are of the so-called moving coil type, in which the coils 41, 44 are arranged on the movable parts 31, 32. However, this is not limited to this. For example, the actuators may be of the so-called moving magnet type, in which the magnets 43, 46 are arranged on the movable parts 31, 32 and the coils 41, 44 are arranged on the support part 27. In this case, the magnets 43, 46 are oscillated together with the optical element 20, and therefore the magnets 43, 46 are included in the oscillating part 12A instead of the coils 41, 44.

The optical path control mechanism 12 has the above configuration, but is not limited to this and may have any configuration in which the optical part can shift the optical path of light L by oscillating the optical part using an actuator to which a drive signal is applied.

[Drive signal]
Here, the drive signal applied from the drive circuit 16 to the actuator 12B will be described. FIG. 6 is a graph illustrating the waveform of the drive signal of the drive unit. T1 is one frame period of the input video signal, and by displaying one frame in four subframes, the resolution of the projected image can be made higher than the resolution of the light modulation device. For example, if one frame period is 60 Hz, the first subframe period is 1/240 seconds, and the same applies to the second, third, and fourth subframes. In FIG. 6, the waveform of the drive signal applied to the first actuator 25 is represented by a solid line, and the waveform of the drive signal applied to the second actuator 26 is represented by a dotted line.

As shown in FIG. 6 , the digital drive signal applied from the drive circuit 16 to the first actuator 25 is an electrical signal whose current value changes over time. Hereinafter, the waveform representing the change in the current value of the drive signal over time is referred to as the drive signal waveform. Here, the current value varies between the first current value A1 and the fourth current value A4, with the current value A0 at the midpoint between the first current value A1 and the fourth current value A4 being 0. Furthermore, the first current value A1 and the fourth current value A4 are current values whose positive and negative polarities are opposite, and their absolute values may be equal. In FIG. 6 , the first current value A1 and the second current value A2 are negative, and the third current value A3 and the fourth current value A4 are positive. In this embodiment, since the digital circuit 14A and the like include digital switching circuits, the supply of current to the first actuator 25 and the second actuator 26 can be stopped, and the current value A0 is maintained during the period during which the current supply is stopped.

The waveform of the drive signal applied to the first actuator 25 is shown by a solid line in Figure 6. The same waveform of the drive signal is repeated every cycle T1. Cycle T1 includes periods T1A, T1B, T1C, and T1D. Periods T1A, T1B, T1C, and T1D are continuous over time. Period T1A corresponds to the period during which the first oscillation unit 21 displaces from the reference angle D0 to the second angle D2 and the period during which the first oscillation unit 21 is maintained at the second angle D2. With respect to the optical axis of light L, this corresponds to the period during which the first oscillation unit 21 displaces from the D operating position to the A operating position and the period during which an image (an image shifted by 1/4 pixel to one side in the direction of the second oscillation axis BX) is displayed when the optical axis is in the A operating position. Period T1C corresponds to the period during which the first oscillation shaft 21 is displaced from the reference angle D0 to the first angle D1 and the period during which the first oscillation unit 21 is maintained at the first angle D1. With respect to the optical axis of light L, this corresponds to the period during which it is displaced from the B operating position to the C operating position and the period during which an image when the optical axis is in the C operating position (an image shifted by 1/4 pixel in the other direction along the second oscillation axis BX) is displayed. Period T1B corresponds to the period during which the first oscillation unit 21 is displaced from the second angle D2 to the reference angle D0 and the period during which the first oscillation unit 21 is maintained at the reference angle D0, and period T1D corresponds to the period during which the first oscillation unit 21 is displaced from the first angle D1 to the reference angle D0 and the period during which the first oscillation unit 21 is maintained at the reference angle D0.

The period T1A includes a first period T1A-1 and a second period T1A-2. First, at the start of the first period T1A-1, the current value of the drive signal switches from current value A0 to third current value A3, and is maintained at the third current value A3 until the end of the first period T1A-1. As a result, the displacement angle of the first oscillation unit 21 changes from the reference angle D0 to the second angle D2 during the first period T1A-1. Next, at the start of the second period T1A-2, the current value of the drive signal switches from the third current value A3 to a fourth current value A4, and is maintained at the fourth current value A4 until the end of the second period T1A-2. As a result, the displacement angle of the first oscillation unit 21 is maintained at the second angle D2 during the second period T1A-2. The length of the first period T1A-1 corresponds to the natural frequency of the first oscillation part 21.

Period T1B includes a first period T1B-1 and a second period T1B-2. First, at the start of the first period T1B-1, the current value of the drive signal switches from the fourth current value A4 to the third current value A3, and is maintained at the third current value A3 until the end of the first period T1B-1. As a result, the displacement angle of the first oscillation unit 21 changes from the second angle D2 to the reference angle D0 and returns to it during the first period T1B-1. Next, at the start of the second period T1B-2, the current value of the drive signal switches from the third current value A3 to the current value A0, and is maintained at the current value A0 until the end of the second period T1B-2. As a result, the displacement angle of the first oscillation unit 21 is maintained at the reference angle D0 during the second period T1B-2. The length of the first period T1B-1 corresponds to the natural frequency of the first oscillation part 21.

The first oscillator 21 refers to the portion of the optical path control mechanism 12 that oscillates relative to the second oscillator 22 (in this embodiment, the optical element 20, the first movable portion 31, and the coil 41). In other words, the length of the first period T1A-1 and the length of the first period T1B-1 correspond to the natural frequency of the portion that oscillates relative to the second oscillator 22. More specifically, the length of the first period T1A-1 and the length of the first period T1B-1 are each preferably approximately the same as half the natural period, which is the reciprocal of the natural frequency of the first oscillator 21, and more preferably are the same as half the natural period.

The period T1C includes a first period T1C-1 and a second period T1C-2. First, at the start of the first period T1C-1, the current value of the drive signal switches from current value A0 to second current value A2, and is maintained at second current value A2 until the end of the first period T1C-1. As a result, the displacement angle of the first oscillation unit 21 changes from reference angle D0 to first angle D1 during the first period T1C-1. Next, at the start of the second period T1C-2, the current value of the drive signal switches from second current value A2 to first current value A1, and is maintained at first current value A1 until the end of the second period T1C-2. As a result, the displacement angle of the first oscillation unit 21 is maintained at first angle D1 during the second period T1C-2. The length of the first period T1C-1 corresponds to the natural frequency of the first oscillation part 21.

The period T1D includes a first period T1D-1 and a second period T1D-2. First, at the start of the first period T1D-1, the current value of the drive signal switches from the first current value A1 to the second current value A2, and is maintained at the second current value A2 until the end of the first period T1D-1. As a result, the displacement angle of the first oscillation unit 21 changes from the first angle D1 to the reference angle D0 and returns to it during the first period T1D-1. Next, at the start of the second period T1D-2, the current value of the drive signal switches from the second current value A2 to the current value A0, and is maintained at the current value A0 until the end of the second period T1D-2. As a result, the displacement angle of the first oscillation unit 21 is maintained at the reference angle D0 during the second period T1D-2. The length of the first period T1D-1 corresponds to the natural frequency of the first oscillation part 21.

The first oscillator 21 refers to the portion of the optical path control mechanism 12 that oscillates relative to the second oscillator 22 (in this embodiment, the optical element 20, the first movable portion 31, and the coil 41). In other words, the length of the first period T1C-1 and the length of the first period T1D-1 correspond to the natural frequency of the portion that oscillates relative to the second oscillator 22. More specifically, the length of the first period T1C-1 and the length of the first period T1D-1 are each preferably approximately the same as half the natural period, which is the reciprocal of the natural frequency of the first oscillator 21, and more preferably are the same as half the natural period.

On the other hand, the waveform of the drive signal applied to the second actuator 26 is shown by a dotted line in Figure 6. The same waveform of the drive signal is repeated every cycle T2. Cycle T2 includes periods T2A, T2B, T2C, and T2D. Periods T2A, T2B, T2C, and T2D are continuous over time. Period T2A corresponds to the period during which the second oscillation unit 22 is displaced from the reference angle D0 to the second angle D2 and the period during which the second oscillation unit 22 is maintained at the second angle D2. With respect to the optical axis of light L, this corresponds to the period during which the second oscillation unit 22 is displaced from the A operating position to the B operating position and the period during which an image (an image shifted by 1/4 pixel to one side in the direction of the first oscillation axis AX) is displayed when the optical axis of light L is in the B operating position. Period T1D corresponds to the period during which the second oscillation unit 22 is displaced from the reference angle D0 to the first angle D1 and the period during which the second oscillation unit 22 is maintained at the first angle D1. With respect to the optical axis of light L, this corresponds to the period during which the optical axis is displaced from the C operating position to the D operating position and the period during which an image is displayed when the optical axis is in the D operating position (an image shifted by 1/4 pixel in the other direction along the first oscillation axis AX). Period T2B corresponds to the period during which the second oscillation unit 22 is displaced from the second angle D2 to the reference angle D0 and the period during which the second oscillation unit 22 is maintained at the reference angle D0, and period T2D corresponds to the period during which the second oscillation unit 22 is displaced from the first angle D1 to the reference angle D0 and the period during which the second oscillation unit 22 is maintained at the reference angle D0.

The period T2A includes a first period T2A-1 and a second period T2A-2. First, at the start of the first period T2A-1, the current value of the drive signal switches from current value A0 to third current value A3 and is maintained at the third current value A3 until the end of the first period T2A-1. As a result, the displacement angle of the second oscillation unit 22 changes from the reference angle D0 to the second angle D2 during the first period T2A-1. Next, at the start of the second period T2A-2, the current value of the drive signal switches from the third current value A3 to a fourth current value A4 and is maintained at the fourth current value A4 until the end of the second period T2A-2. As a result, the displacement angle of the second oscillation unit 22 is maintained at the second angle D2 during the second period T2A-2. The length of the first period T2A-1 corresponds to the natural frequency of the second oscillation part 22.

The period T2B includes a first period T2B-1 and a second period T2B-2. First, at the start of the first period T2B-1, the current value of the drive signal switches from the fourth current value A4 to the third current value A3 and is maintained at the third current value A3 until the end of the first period T2B-1. As a result, the displacement angle of the second oscillation part 22 changes from the second angle D2 to the reference angle D0 and returns to it during the first period T2B-1. Next, at the start of the second period T2B-2, the current value of the drive signal switches from the third current value A3 to the current value A0 and is maintained at the current value A0 until the end of the second period T2B-2. As a result, the second oscillation part 22 is maintained at the reference angle D0 during the second period T2B-2. The length of the first period T2B-1 corresponds to the natural frequency of the second oscillation part 22.

The second oscillating part 22 refers to the part of the optical path control mechanism 12 that oscillates relative to the support part 27 (in this embodiment, the optical element 20, the second movable part 32, and the coil 44). In other words, the length of the first period T2A-1 and the length of the first period T2B-1 correspond to the natural frequency of the part that oscillates relative to the support part 27. More specifically, the length of the first period T2A-1 and the length of the first period T2B-1 are each preferably approximately the same as half the natural period, which is the reciprocal of the natural frequency of the second oscillating part 22, and more preferably are the same as half the natural period.

The period T2C includes a first period T2C-1 and a second period T2C-2. First, at the start of the first period T2C-1, the current value of the drive signal switches from current value A0 to second current value A2, and is maintained at the second current value A2 until the end of the first period T2C-1. As a result, the displacement angle of the second oscillation portion 22 changes from the reference angle D0 to the first angle D1 during the first period T2C-1. Next, at the start of the second period T2C-2, the current value of the drive signal switches from the second current value A2 to the first current value A1, and is maintained at the first current value A1 until the end of the second period T2C-2. As a result, the displacement angle of the second oscillation portion 22 is maintained at the first angle D1 during the second period T2C-2. The length of the first period T2C-1 corresponds to the natural frequency of the second oscillation part 22.

The period T2D includes a first period T2D-1 and a second period T2D-2. First, at the start of the first period T2D-1, the current value of the drive signal switches from the first current value A1 to the second current value A2 and is maintained at the second current value A2 until the end of the first period T2D-1. As a result, the displacement angle of the second oscillation part 22 changes from the first angle D1 to the reference angle D0 and returns during the first period T2D-1. Next, at the start of the second period T2D-2, the current value of the drive signal switches from the second current value A2 to the current value A0 and is maintained at the current value A0 until the end of the second period T2D-2. As a result, the second oscillation part 22 is maintained at the reference angle D0 during the second period T2D-2. The length of the first period T2D-1 corresponds to the natural frequency of the second oscillation part 22.

The second oscillating part 22 refers to the part of the optical path control mechanism 12 that oscillates relative to the support part 27 (in this embodiment, the optical element 20, the second movable part 32, and the coil 44). In other words, the length of the first period T2C-1 and the length of the first period T2D-1 correspond to the natural frequency of the part that oscillates relative to the support part 27. More specifically, the length of the first period T2C-1 and the length of the first period T2D-1 are each preferably approximately the same as half the natural period, which is the reciprocal of the natural frequency of the second oscillating part 22, and more preferably are the same as half the natural period.

The waveform of the drive signal applied to the first actuator 25 (solid line in Figure 6) and the waveform of the drive signal applied to the second actuator 26 (dotted line in Figure 6) are shifted by a predetermined period T12. For example, the start timing of the first period T1A-1 of the waveform of the drive signal applied to the first actuator 25 and the start timing of the first period T2A-1 of the waveform of the drive signal applied to the second actuator 26 are shifted by a predetermined period T12. Therefore, the second period T1A-2, in which the current value in the waveform of the drive signal applied to the first actuator 25 is held at the fourth current value A4, becomes the second period T2D-2, in which the current value in the waveform of the drive signal applied to the second actuator 26 is held at the current value A0 (current value 0). Similarly, the second period T1C-2, during which the current value in the waveform of the drive signal applied to the first actuator 25 is held at the first current value A1, is followed by the second period T2D-2, during which the current value in the waveform of the drive signal applied to the second actuator 26 is held at the current value A0 (current value 0).

Furthermore, the second period T2A-2, during which the current value in the waveform of the drive signal applied to the second actuator 26 is held at the fourth current value A4, becomes the second period T2B-2, during which the current value in the waveform of the drive signal applied to the first actuator 25 is held at the current value A0 (current value 0). Similarly, the second period T2C-2, during which the current value in the waveform of the drive signal applied to the second actuator 26 is held at the first current value A1, becomes the second period T2D-2, period T1D, during which the current value in the waveform of the drive signal applied to the first actuator 25 is held at the current value A0 (current value 0).

[Swing pattern]
Next, the oscillation patterns of the first oscillation unit 21 and the second oscillation unit 22 due to the application of the drive signal will be described. Fig. 7 is a graph illustrating the oscillation patterns of the optical unit. In Fig. 7, the oscillation pattern of the first oscillation unit 21 is represented by a solid line, and the oscillation pattern of the second oscillation unit 22 is represented by a dotted line.

As shown in Figure 7, the oscillation pattern (solid line) of the first oscillation unit 21 refers to the displacement angle (angle around the first oscillation axis AX) of the first oscillation unit 21 per unit time when a drive signal is applied to the first actuator 25. The oscillation pattern (dotted line) of the second oscillation unit 22 refers to the displacement angle (angle around the second oscillation axis BX) of the second oscillation unit 22 per unit time when a drive signal is applied to the second actuator 26.

As shown in FIG. 9, in the first oscillation unit 21, during the first period T1A-1, the current value of the drive signal switches from current value A0 to third current value A3 and is maintained at third current value A3 until the end of the first period T1A-1. As a result, the displacement angle of the first oscillation unit 21 changes from the reference angle D0 to the second angle D2 during the first period T1A-1.

During the second period T1A-2, the drive signal maintains a current value at the fourth current value A4. As a result, the displacement angle of the first oscillation member 21 is maintained at the second angle D2 during the second period T1A-2. Note that in the following description, "maintaining the current value or displacement angle" does not necessarily mean that the current value or displacement angle does not change strictly, but may also mean that the current value or displacement angle deviates within a predetermined range. The predetermined value here may be set arbitrarily, and may be, for example, 10% of the current value or displacement angle.

During the first period T1B-1, the current value of the drive signal switches from the fourth current value A4 to the third current value A3, and is maintained at the third current value A3 until the end of the first period T1B-1. As a result, the displacement angle of the first oscillation unit 21 changes from the second angle D2 to the reference angle D0 during the first period T1B-1. During the second period T1B-2, the drive signal switches to the current value A0, and the current value is maintained at the current value A0 until the end of the second period T1B-2. As a result, the displacement angle of the first oscillation unit 21 is maintained at the reference angle D0 during the second period T1B-2.

During the first period T1C-1, the current value of the drive signal switches from current value A0 to second current value A2 and is maintained at second current value A2 until the end of the first period T1C-1. As a result, the displacement angle of the first oscillation unit 21 changes from reference angle D0 to first angle D1 during the first period T1C-1. During the second period T1C-2, the current value of the drive signal is maintained at first current value A1. As a result, the displacement angle of the first oscillation unit 21 is maintained at first angle D1 during the second period T1C-2.

During the first period T1D-1, the current value of the drive signal switches from the first current value A1 to the second current value A2, and is maintained at the second current value A2 until the end of the first period T1D-1. As a result, the displacement angle of the first oscillation unit 21 changes from the first angle D1 to the reference angle D0 during the first period T1D-1. During the second period T1D-2, the drive signal switches to the current value A0, and the current value is maintained at the current value A0 until the end of the second period T1D-2. As a result, the displacement angle of the first oscillation unit 21 is maintained at the reference angle D0 during the second period T1D-2.

Note that light L is irradiated during periods T1A-2 and T1C-2. Therefore, during period T1A-2, light L is irradiated onto the first oscillation unit 21 held at the second angle D2, the optical path of light L shifts to the A operating position, and the image shifts by 1/4 pixel. Also, during period T1C-2, light L is irradiated onto the first oscillation unit 21 held at the first angle D1, the optical path of light L shifts to the D operating position, and the image shifts by 1/4 pixel. Therefore, there is a shift of half a pixel from the A operating position to the C operating position.

Meanwhile, in the second oscillation unit 22, during the first period T2A-1, the current value of the drive signal switches from current value A0 to third current value A3, and is maintained at third current value A3 until the end of the first period T2A-1. It then changes to fourth current value A4. As a result, the displacement angle of the second oscillation unit 22 changes from reference angle D0 to second angle D2 during the first period T2A-1.

During the second period T2A-2, the current value of the drive signal is maintained at the fourth current value A4. As a result, the displacement angle of the second oscillation portion 22 is maintained at the second angle D2 during the second period T2A-2.

During the first period T2B-1, the current value of the drive signal switches from the fourth current value A4 to the third current value A3 and is maintained at the third current value A3 until the end of the first period T2B-1. As a result, the displacement angle of the second oscillation unit 22 changes from the second angle D2 to the reference angle D0 during the first period T2B-1. During the second period T2B-2, the current value of the drive signal is maintained at the current value A0. As a result, the displacement angle of the second oscillation unit 22 is maintained at the reference angle D0 during the second period T2B-2.

During the first period T2C-1, the current value of the drive signal switches from current value A0 to second current value A2 and is maintained at second current value A2 until the end of the first period T2C-1. As a result, the displacement angle of the second oscillation unit 22 changes from reference angle D0 to first angle D1 during the first period T2C-1. During the second period T2C-2, the current value of the drive signal is maintained at first current value A1. As a result, the displacement angle of the second oscillation unit 22 is maintained at first angle D1 during the second period T2C-2.

During the first period T2D-1, the current value of the drive signal switches from the first current value A1 to the second current value A2 and is maintained at the second current value A2 until the end of the first period T2D-1. As a result, the displacement angle of the second oscillation unit 22 changes from the first angle D1 to the reference angle D0 during the first period T2D-1. During the second period T2D-2, the drive signal switches to the current value A0 and the current value is maintained at the current value A0 until the end of the second period T2D-2. As a result, the displacement angle of the second oscillation unit 22 is maintained at the reference angle D0 during the second period T2D-2.

Note that light L is irradiated during periods T2A-2 and T2C-2. Therefore, during period T2A-2, light L is irradiated onto the second oscillation unit 22 held at the second angle D2, shifting the optical path of light L to the A operating position and shifting the image by 1/4 pixel. Also, during period T2C-2, light L is irradiated onto the first oscillation unit 21 held at the first angle D1, shifting the optical path of light L to the C operating position and shifting the image by 1/4 pixel. Therefore, there is a shift of half a pixel from the A operating position to the C operating position.

As shown in Figure 6, the waveform of the drive signal applied to the first actuator 25 (solid line in Figure 6) and the waveform of the drive signal applied to the second actuator 26 (dotted line) are shifted by a predetermined period T12. Therefore, the periods T1A-2 and T1C-2 during which the first oscillation portion 21 oscillates and irradiates light L and the periods T2A-2 and T2C-2 during which the second oscillation portion 22 oscillates and irradiates light L are shifted by the predetermined period T12. At this time, the second period T1A-2 during which the current value of the first actuator 25 is maintained at the fourth current value A4 overlaps with the neutral period T2D-2 during which the current value of the second actuator 26 is maintained at the current value A0, i.e., the current value is maintained at 0. Similarly, the second period T1C-2, during which the current value of the first actuator 25 is maintained at the first current value A1, overlaps with the neutral period T2B-2, during which the current value of the second actuator 26 is maintained at the current value A0, i.e., the current value is maintained at 0.

Furthermore, the second period TA-2, during which the current value of the second actuator 26 is maintained at the fourth current value A4, overlaps with the neutral period T1B-2, during which the current value of the first actuator 25 is maintained at the current value A0, i.e., the current value is 0. Similarly, the second period T2C-2, during which the current value of the second actuator 26 is maintained at the first current value A1, overlaps with the neutral period T1D-2, during which the current value of the first actuator 25 is maintained at the current value A0, i.e., the current value is 0.

In FIG. 6, the natural frequency of the first oscillator 21 and the natural frequency of the second oscillator 22 are not necessarily the same, and the torsional rigidity of the first oscillator 21 and the torsional rigidity of the second oscillator 22 are not necessarily the same. Therefore, the current values A1 to A4 of the first oscillator (solid line) 21 and the current values A1 to A4 of the second oscillator (dotted line) 22 do not necessarily have to be the same, and the lengths of periods T1A-1 and T2A-1, and periods T1B-1 and T2B-1 do not necessarily have to be the same. The same is true for periods T1C and T2C, and periods T1D and T2D.

[Pixel operation by optical path control mechanism]
The following describes the operation when the first swinging unit 21 and the second swinging unit 22 are swung. Fig. 8 is an explanatory diagram for explaining the two-axis swing pattern of the optical unit.

As shown in Figures 3 and 8, when the horizontal arrangement direction of the pixels of the optical element 20 in the optical path control mechanism 12 is the AY direction and the vertical arrangement direction of the pixels of the optical element 20 is the BY direction, the first oscillation axis AX direction and the second oscillation axis BX direction are arranged at an angle of 45 degrees relative to the AY direction and the BY direction.

The first actuator 25 swings the first swinging unit 21 in response to the drive signal, so as to repeatedly change its position around the first axis AX from the reference angle D0 to the second angle D2 and from the reference angle D0 to the first angle D1. As the first swinging unit 21 repeatedly swings between the first angle D1 and the second angle D2, the optical axis of the light L repeatedly shifts from the reference position to the operating position A and from the reference position to the operating position C.

In other words, the image projected onto the screen by light L when the optical axis is in operating position A and the image projected onto the screen by light L when the optical axis is in operating position C are shifted by half a pixel. That is, the image projected onto the screen is shifted by a quarter pixel from the reference position, but the shift is half a pixel between operating positions A and C. In this way, the image shifts from the reference position by a quarter pixel, then moves back by a quarter pixel, then moves back by a quarter pixel in the opposite direction, and repeats this process. This increases the apparent number of pixels, thereby increasing the resolution of the image projected onto the screen. Because the shift amount of the optical axis is half a pixel of the image, the first angle D1 and the second angle D2 are set to angles that allow the image to be shifted by a quarter pixel. Note that the image shift amount is not limited to half a pixel and may be any amount, such as half or one-eighth of a pixel. The first angle D1 and the second angle D2 may also be set appropriately according to the amount of image shift.

The second actuator 26, in response to the drive signal, swings the second swinging unit 22 so as to repeatedly change its position around the first axis BX from the reference angle D0 to the second angle D2 and from the reference angle D0 to the first angle D1. As the second swinging unit 22 repeatedly swings between the first angle D1 and the second angle D2, the optical axis of the light L repeatedly shifts from the reference position to the B operating position and from the reference position to the D operating position.

In other words, the image projected onto the screen by light L when the optical axis is in the B operating position and the image projected onto the screen by light L when the optical axis is in the D operating position are shifted by half a pixel. That is, the image projected onto the screen is shifted by a quarter pixel from the reference position, but the shift is half a pixel between the B operating position and the D operating position. In this way, the image shifts from the reference position by a quarter pixel, then moves back by a quarter pixel, then moves back by a quarter pixel in the opposite direction, and repeats this process. This increases the apparent number of pixels, thereby increasing the resolution of the image projected onto the screen. Because the shift amount of the optical axis is half a pixel of the image, the first angle D1 and the second angle D2 are set to angles that allow the image to be shifted by a quarter pixel. Note that the image shift amount is not limited to a half pixel and may be any amount, such as half or one-eighth of a pixel. The first angle D1 and the second angle D2 may also be set appropriately according to the image shift amount.

The following provides a more detailed explanation. Image position P0 is the display position when the current value applied to the first actuator 25 and the second actuator 26 is 0, i.e., when the displacement angle of the optical element 20 is 0. Operation state A is a state in which the first actuator 25 has swung the optical element 20 a predetermined angle around the first oscillation axis AX, shifting image position P0 by 1/4 pixel in the direction of the second oscillation axis BX. In other words, operation state A is a state in which an image is displayed at image position P1.

Operation state B is a state in which the second actuator 26 swings the optical element 20 a predetermined angle around the second swing axis BX, shifting the image position P0 by 1/4 pixel in the direction of the first swing axis AX. In other words, operation state B is a state in which an image is displayed at image position P2. Similarly, operation state C is a state in which an image is displayed at image position P3. Similarly, operation state D is a state in which an image is displayed at image position P4.

[Drive waveform]
9 is a graph illustrating the relationship between the waveform of the drive signal of the drive unit and the oscillation pattern of the optical unit. Note that, in the following explanation, the waveform of the drive signal applied to the first actuator 25 and the oscillation pattern of the first oscillation unit 21 will be explained, but the same applies to the second actuator 26 and the second oscillation unit 22.

As shown in FIG. 9, the current value A0 applied to the first actuator 25 switches the first actuator 25 from a reference position (displacement angle 0) to a third current value A3 at the start of the first period T1A-1, and is maintained until the end of the first period T1A-1. Here, the length of the first period T1A-1 corresponds to half the period of the natural frequency of the first actuator 25, and the third current value A3 is half the peak current value, or fourth current value A4. Then, during the first period T1A-1, the displacement angle of the first actuator 25 changes from the reference angle D0 to the second angle D2. Then, at the start of the second period T1A-2, the current value is switched to a fourth current value A4, and is maintained until the end of the second period T1A-2. As a result, the first oscillation part 21 is maintained at the second angle D2 during the second period T1A-2.

Next, at the start of the first period T1B-1, the current value is switched to the third current value A3, which is maintained until the end of the first period T1B-1. Here, the length of the first period T1B-1 corresponds to 1/2 of the natural vibration period of the first oscillation part 21. Then, during the first period T1B-1, the displacement angle of the first oscillation part 21 changes from the second angle D2 to the reference angle D0. Then, at the start of the second period T1B-2, the current value is switched to the current value A0, which is maintained until the end of the second period T1B-2. Then, during the second period T1B-2, the first oscillation part 21 is maintained at the reference angle D0.

By applying a step-shaped waveform to the drive signal applied to the first actuator 25, the displacement angle of the first oscillation unit 21 can be maintained at the second angle D2 and the reference angle D0. The same applies to periods T1C and T1D.

[Actuator power consumption]
FIG. 10 is a schematic diagram illustrating the power consumption when the drive signal is a trapezoidal wave, and FIG. 11 is a schematic diagram illustrating the power consumption when the drive signal is a step wave.

As shown in Figure 10, when the waveform of the drive signal applied to the first actuator 25 and the second actuator 26 is trapezoidal, the power consumption, which is the area between the current value A0 and the trapezoidal wave (shaded area), is large. On the other hand, as shown in Figure 11, when the waveform of the drive signal applied to the first actuator 25 and the second actuator 26 is stepwise, the power consumption, which is the area between the current value A0 and the stepwise wave (shaded area), is smaller than that of the trapezoidal wave.

(effect)
As described above, the light path control device according to this embodiment comprises an oscillating unit 12A having an optical element (optical unit) 20 onto which light is incident, an actuator 12B that oscillates the oscillating unit 12A, and a drive circuit (drive unit) 16 that applies a drive signal of a current value to the actuator 12B, and the drive circuit 16 applies a current value that is half the peak current value for a period that is half the period of the natural vibration of the oscillating unit 12A, and then maintains the current value at the peak current value or at zero.

With the optical path control device of this embodiment, by applying a current value half the peak current value for a period half the natural vibration period of the oscillating unit 12A and then maintaining the current value at the peak current value or zero, the oscillating unit 12A can be easily stopped at a predetermined position, reducing the power consumption of the actuators 25 and 26. Furthermore, because the displacement of each axis for tilting the optical element is independent, there is no need to adjust the balance of the displacement amounts of each of the two axes, simplifying the control of the actuators 25 and 26. Because the A and C operating positions are determined by the displacement of the first oscillating unit, and the B and D operating positions are determined by the displacement of the second oscillating unit, adjustments are easier than when determining each operating position (A to D operating positions) by moving two axes simultaneously.

In addition, in the optical path control device according to this embodiment, the drive circuit 16 can stop the oscillating unit 12A at the first angle (first tilt angle) D1 or the second angle (second tilt angle) D2 by maintaining a positive or negative peak current value, and can stop the oscillating unit 12A at a reference angle D0 between the first angle D1 and the second angle D2 by maintaining a current value of 0. This simplifies the control of the actuators 25, 26.

In addition, in the optical path control device according to this embodiment, the drive signal of the current value applied by the drive circuit 16 to the first actuator 25 and the second actuator 26 has a staircase-shaped waveform. Therefore, because the first actuator 25 and the second actuator 26 are driven by a drive signal with a staircase-shaped waveform, the first oscillating unit 21 and the second oscillating unit 22 can be stopped at a predetermined position with high precision.

The display device according to this embodiment also includes an optical path control device 10 and an irradiation device 100 that irradiates light L onto the oscillating portion 12A. Therefore, by including the optical path control device 10, the display device 1 can reduce the power consumption of the actuators 25, 26 and simplify the control of the actuators 25, 26.

The optical path control method according to this embodiment controls the optical path by applying a drive signal to actuator 12B, which oscillates oscillating unit 12A having optical element 20 onto which light is incident. After applying a current value that is half the peak current value to actuator 12B for a period that is half the natural vibration period of oscillating unit 12A, the current value is maintained at the peak current value or at zero. This reduces the power consumption of actuators 25, 26 and simplifies the control of actuators 25, 26.

In the above-described embodiment, the optical element 20 is supported by the first oscillating portion 21, the first oscillating portion 21 is oscillably supported by the second oscillating portion 22, and the second oscillating portion 22 is oscillably supported by the support portion 27. However, this configuration is not limited to this. For example, a first optical path control device configured by supporting the first optical element on the first oscillating portion and oscillably supporting the first oscillating portion on the first support portion, and a second optical path control device configured by supporting the second optical element on the second oscillating portion and oscillably supporting the second oscillating portion on the second support portion may be configured to be stacked in the light irradiation direction. Furthermore, the optical element 20 is not limited to a two-axis oscillating configuration, and may also be a one-axis oscillating configuration.

So far, we have described the optical path control device 10 according to the present invention, but it may be implemented in a variety of different forms in addition to the above-described embodiment.

The components of the illustrated optical path control device 10 are conceptual and functional, and do not necessarily have to be physically configured as shown. In other words, the specific form of each device is not limited to that shown, and all or part of each device may be functionally or physically distributed or integrated in any unit depending on the processing load and usage status of each device.

The configuration of the optical path control device 10 is realized, for example, as software, such as a program loaded into memory. In the above embodiment, it has been described as a functional block realized by the cooperation of these hardware and software. In other words, these functional blocks can be realized in various ways, using only hardware, only software, or a combination of both.

The above-mentioned components include those that would be readily apparent to a person skilled in the art and those that are substantially identical. Furthermore, the above-mentioned configurations can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications to the configuration are possible without departing from the spirit of the present invention.

1 Display device 10 Light path control device 12 Light path control mechanism 12A Oscillating unit 12B Actuator 14 Control circuit 16 Drive circuit (drive unit)
20 Optical member (optical part)
21 First swinging portion 22 Second swinging portion 23 First shaft portion 24 Second shaft portion 25 First actuator 26 Second actuator 27 Support portion 31 First movable portion 32 Second movable portion 41, 44 Coil 42, 45 Yoke 43, 46 Magnet 100 Irradiation device AX First swinging axis BX Second swinging axis

Claims (5)

a swinging unit having an optical unit into which light is incident;
an actuator that swings the swinging portion;
a drive unit that applies a drive signal of a current value to the actuator;
Equipped with
the drive unit applies a current value that is half the peak current value for a period that is half the natural vibration period of the oscillation unit, and then maintains the current value at the peak current value or at 0;
the optical unit transmits light incident on one surface and emits it from the other surface,
The actuator includes a coil, a yoke, and a magnet.
Optical path control device. the drive unit can stop the oscillating unit at a first tilt angle or a second tilt angle by maintaining the peak current value at a positive or negative value, and can stop the oscillating unit at a reference position intermediate between the first tilt angle and the second tilt angle by maintaining the current value at 0.
The optical path control device according to claim 1 . the drive signal of the current value applied by the drive unit to the actuator has a waveform in the form of a staircase.
3. The optical path control device according to claim 1 or 2. The optical path control device according to any one of claims 1 to 3,
an irradiation device that irradiates the optical unit with light;
A display device comprising: An optical path control method for controlling an optical path by applying a drive signal to an actuator that oscillates an oscillating unit having an optical unit into which light is incident, comprising:
applying a current value that is half the peak current value to the actuator for a period that is half the natural vibration period of the oscillating portion, and then maintaining the current value at the peak current value or at 0;
the optical unit transmits light incident on one surface and emits it from the other surface,
The actuator includes a coil, a yoke, and a magnet.
Optical path control method.