Optical path controller, display device, and optical path control method

Abstract

To provide an optical path controller, a display device, and an optical path control method with which it is possible to appropriately drive an oscillating unit.SOLUTION: An optical path controller according to the present disclosure comprises: an oscillating unit that has an optical member which light enters; an actuator for oscillating the oscillating unit; and a drive circuit for applying a drive signal to the actuator that includes a first period and a second period continuous to the first period, with a current value switched from a first current value to a second current value at a start timing of the first period, and changed a current value to the first current value linearly immediately thereafter in accordance with the passage of time till the termination timing of the first period, then switched from the first current value to the second current value at a start timing of the second period, and held at the second current value immediately thereafter till a termination timing of the second period, thereby causing the actuator to oscillate the oscillating unit so as to control the optical path.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a light path control device, a display device, and a light path control method. [Background technology]

[0002] Optical devices that shift the optical axis by swinging the optical unit into which light enters are known. For example, Patent Documents 1 and 2 listed below describe techniques that swing the optical unit to shift the optical path of light passing through the optical unit, thereby making it possible to increase the resolution of a projected image beyond that of a light modulation device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2016-071232 [Patent Document 2] Japanese Patent Application Publication No. 2020-077911 Summary of the Invention [Problem to be solved by the invention]

[0004] Such optical devices have a drive unit that mechanically swings the optical unit, and therefore there is a need to suppress noise generated by the swinging of the drive unit.

[0005] In view of the above-mentioned problems, an object of the present disclosure is to provide a light path control device, a display device, and a light path control method that can appropriately drive an oscillating portion. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the light path control device of the present disclosure comprises: an oscillating unit having an optical element onto which light is incident; an actuator that oscillates the oscillating unit; and a drive circuit that includes a first period and a second period that is continuous with the first period, and that applies to the actuator a drive signal having a waveform that switches the current value from a first current value to a second current value at the start of the first period, and immediately thereafter changes the current value linearly to the first current value over time until the end of the first period, and switches the current value from the first current value to the second current value at the start of the second period, and maintains the current value at the second current value from immediately thereafter until the end of the second period, thereby causing the actuator to oscillate the oscillating unit and control the light path.

[0007] In order to solve the above-mentioned problems and achieve the object, a display device according to the present disclosure includes a light path control device and an irradiation device that irradiates the optical member with light.

[0008] In order to solve the above-mentioned problems and achieve the object, the optical path control method according to the present disclosure is an optical path control method that controls an optical path by applying a drive signal to an actuator that oscillates an oscillating unit including an optical element into which light is incident, and includes a first period and a second period that is continuous with the first period, and includes a step of applying to the actuator a drive signal having a waveform that switches the current value from a first current value to a second current value at the start of the first period, and immediately thereafter changes the current value linearly to the first current value over time until the end of the first period, and switches the current value from the first current value to the second current value at the start of the second period, and holds the current value at the second current value from immediately thereafter until the end of the second period, thereby causing the actuator to oscillate the oscillating unit and control the optical path. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a light path control device, a display device, and a light path control method that can appropriately drive an oscillation part. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a display device according to the present disclosure. [Figure 2] FIG. 2 is a block diagram schematically showing the circuit configuration of the display device. [Figure 3] FIG. 3 is a schematic diagram of the optical path control mechanism. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 5 is a graph illustrating the waveform of the drive signal of the drive unit. [Figure 6] FIG. 6 is a graph illustrating the oscillation pattern of the optical part. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the embodiments described below.

[0012] (display device) Fig. 1 is a schematic diagram of a display device according to the present disclosure. As shown in Fig. 1, the display device 1 according to the first embodiment 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, and the light path control device 10 is a device that controls the optical path of the light L. In this embodiment, the light path control device 10 shifts the optical axis of the light L to shift the position of the image displayed by the light L, thereby increasing the resolution of the projected image compared to the resolution of the image generated by the irradiation device 100 (i.e., the number of pixels of a display element 106, which will be described later).

[0013] 1, 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 to 145, a polarization conversion element 150, and a video signal processing circuit 160. When there is no need to distinguish between the display elements 106R, 106G, and 106B, they will be referred to as display elements 106.

[0014] The light source 101 is a light source that generates and irradiates light. The light source 101 irradiates incident light L0. In this embodiment, an example is shown in which one light source 101 is used as the light source that irradiates the incident light L0, but other optical devices may be included to generate the incident light L0.

[0015] Incident light L0 from the light source 101 is incident on the lens 140. The lenses 140 and 141 are, for example, fly-eye lenses. The illumination distribution of the incident light L0 is homogenized by the lenses 140 and 141, and the incident light L0 is incident on the polarization conversion element 150. The polarization conversion element 150 is an element that aligns the polarization of the incident light L0, and includes, for example, a polarizing beam splitter and a retardation plate. For example, the polarization conversion element 150 aligns the incident light L0 to p-polarized light.

[0016] The incident light L0, the polarization of which 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.

[0017] The dichroic mirror 120 separates the incident light L0 into yellow light LRG and blue light LB containing a blue band component. The yellow illumination light LRG separated by the dichroic mirror 120 is reflected by the reflecting mirror 130 and enters the dichroic mirror 121.

[0018] The dichroic mirror 121 separates the incident yellow light LRG into red light LR containing a component in the red wavelength range and green light LG containing a component in the green wavelength range.

[0019] 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.

[0020] The 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, the polarizing plates 105R, 105G, and 105B reflect s-polarized light and transmit p-polarized light. The polarizing plates 105R, 105G, and 105B are also called reflective polarizing plates.

[0021] The p-polarized red light LR is transmitted through polarizer 105R and is irradiated onto display element 106R. The p-polarized green light LG is transmitted through polarizer 105G and is irradiated onto display element 106G. The p-polarized blue light LB is transmitted through polarizer 105B and is irradiated onto display element 106B.

[0022] The display elements 106R, 106G, and 106B are, for example, reflective liquid crystal display elements. In this embodiment, the display elements 106R, 106G, and 106B are reflective liquid crystal display elements, but they are not limited to reflective types and may 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.

[0023] The display element 106R is controlled by the video signal processing circuit 160. The video signal processing circuit 160 drives and controls the display element 106R based on image data for the red component. The display element 106R optically modulates p-polarized red light LR in accordance with the control of the video signal processing circuit 160 to generate s-polarized red light LR. The display element 106G is controlled by the video signal processing circuit 160. The video signal processing circuit 160 drives and controls the display element 106G in accordance with image data for the green component. The display element 106G optically modulates p-polarized green light LG in accordance with the control of the video signal processing circuit 160 to generate s-polarized green light LG. The display element 106B is controlled by the video signal processing circuit 160. The video signal processing circuit 160 drives and controls the 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, and generates s-polarized blue light LB.

[0024] The polarizers 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, the polarizers 107R, 107G, and 107B transmit s-polarized light and absorb unwanted p-polarized light.

[0025] 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 combining 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 combining 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 combining prism 108.

[0026] The color synthesis prism 108 synthesizes the incident red light LR, green light LG, and blue light LB, and irradiates the resulting light L for image display onto a projection lens 109. The light L is projected via the projection lens 109 onto a screen or the like (not shown).

[0027] The irradiation device 100 has the above-described configuration, but the configuration is not limited to the above description and may have any configuration.

[0028] 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 is shifted. 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.

[0029] FIG. 2 is a block diagram illustrating a schematic circuit configuration of the display device. As shown in FIG. 2, a video signal processing circuit 160 controls the display elements 106R, 106B, and 106G. A video signal including image data for controlling the display elements 106R, 106B, and 106G and a synchronization signal is input to the video signal processing circuit 160. 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 and a converter 14B. 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 converter 14B is a DA converter that converts a digital signal into an analog signal. The converter 14B converts the digital drive signal generated by the digital circuit 14A into an analog drive signal. The drive circuit 16 receives the analog drive signal from the converter 14B, amplifies the analog drive signal, and outputs it to an actuator 12B of the optical path control mechanism 12, which will be described later. The actuator 12B is driven in response to the drive signal to oscillate an oscillating portion 12A, which will be described later.

[0030] (Optical path control mechanism) The configuration of the light path control mechanism 12 will be described in more detail. Fig. 3 is a schematic diagram of the light path control mechanism, and Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. As shown in Figs. 3 and 4, the light path control mechanism 12 has an oscillating unit 12A including an optical member 20 onto which light L is incident, and an actuator 12B that oscillates the oscillating unit 12A. More specifically, the light path control mechanism 12 has the optical member 20, a movable unit 22, a support unit 24, a shaft unit 25, a coil 26, a yoke 27, and a magnet 28.

[0031] The optical member 20 is a member that transmits incident light L. The light L is incident on one surface of the optical member 20, the optical member 20 transmits the incident light L, and the light L is emitted from the other surface. In this embodiment, the optical member 20 is a glass plate, but the material and shape of the optical member 20 may be any desired one.

[0032] The movable part 22 is a member that supports the optical element 20. The movable part 22 is fixed to the optical element 20. Specifically, the movable part 22 in this embodiment is a plate-shaped member with a through-hole formed in the center. The optical element 20 is fixed to the movable part 22 in a state where it is fitted into the through-hole of the movable part 22. Note that the optical element 20 is fixed to the movable part 22 via a fixing member or adhesive for fixing it to the movable part 22, but the method of fixing the optical element 20 to the movable part 22 may be arbitrary.

[0033] The support part 24 is a member that swingably supports the movable part 22 on which the optical element 20 is provided. In this embodiment, the support part 24 is a frame-shaped member that is provided so as to surround the outer periphery of the movable part 22. The shaft part 25 is a member that swingably connects the movable part 22 to the support part 24. In this embodiment, two shaft parts 25 are provided. Each shaft part 25 is provided at a position near a vertex of the rectangular optical element 20 that faces each other. The movable part 22 swings around a swing axis AX that is an axis connecting the shaft parts 25. When the movable part 22 swings around the swing axis AX, the posture of the optical element 20 provided on the movable part 22 changes, and the optical path of the light L that passes through the optical element 20 is shifted.

[0034] The coils 26 are attached to the movable part 22 and fixed relative to the movable part 22. The coils 26 are provided at both ends of the movable part 22. The yokes 27 are members that form a magnetic path. The yokes 27 are attached to the support part 24 and fixed relative to the support part 24. The yokes 27 are provided at both ends of the movable part 22 corresponding to the coils 26. The magnets 28 are permanent magnets. The magnets 28 are attached to the yokes 27 and fixed relative to the yokes 24. The magnets 28 are disposed adjacent to the respective coils 26. A drive signal is input to the coils 26 from the drive circuit 16. In the example of FIG. 4 , the magnets 28 are bonded to one side of the U-shaped yoke 27, and an air gap is formed between the unbonded surface of the magnet 28 and the opposing U-shaped side of the yoke 27. The coils 26 are disposed within this air gap. A drive signal is input to the coils 26. As a result, a current flows through coil 26, which is a conductor located within the magnetic field of magnet 28, generating a force that causes movable part 22 (oscillating part 12A) fixed to coil 26 to oscillate. In other words, actuator 12B according to this embodiment can be said to be an electromagnetic actuator composed of coil 26, yoke 27, and magnet 28.

[0035] In this embodiment, the movable part 22 provided with the optical element 20 oscillates in this manner, and therefore the optical element 20, the movable part 22, and the coil 26 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 24 can be said to refer to the oscillating part 12A. Note that, if a fixing member or adhesive for fixing the optical element 20 to the movable part 22, or a substrate or lead wire for passing a current through the coil 26, is provided, these also oscillate relative to the support part 24 and are therefore included in the oscillating part 12A.

[0036] The actuator of this embodiment is a so-called moving coil type in which the coil 26 is arranged in the movable part 22, but is not limited to this and may be, for example, a so-called moving magnet type in which the magnet 28 is arranged in the movable part 22 and the coil 26 is arranged in the support part 24. In this case, the magnet 28 is swung together with the optical member 20, and therefore the magnet 28 is included in the swiveling part 12A instead of the coil 26.

[0037] The optical path control mechanism 12 has the above-described 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.

[0038] In the optical path control mechanism 12, the actuator 12B swings the swinging unit 12A in response to a drive signal. That is, in response to the drive signal, the actuator 12B swings the swinging unit 12A so that the swinging unit 12A repeatedly changes its position around the swing axis AX from a first angle D1 to a second angle D2 and then from the second angle D2 to the first angle D1. As the swinging unit 12A repeatedly swings between the first angle D1 and the second angle D2, the optical axis of the light L repeatedly shifts from the first position to the second position and from the second position to the first position. In this embodiment, the image projected onto the screen by the light L when the optical axis is at the first position is shifted by half a pixel from the image projected onto the screen by the light L when the optical axis is at the second position. That is, the image projected onto the screen repeatedly shifts by half a pixel and then moves back by half a pixel. This increases the apparent number of pixels, thereby increasing the resolution of the image projected onto the screen. As described above, since the shift amount of the optical axis in this embodiment 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 half a pixel. Note that the shift amount of the image is not limited to half a pixel and may be any amount, such as 1 / 4 or 1 / 8 of a pixel. The first angle D1 and the second angle D2 may also be set appropriately according to the shift amount of the image.

[0039] (drive signal) Here, a description will be given of the drive signal applied to actuator 12B from drive circuit 16. Fig. 5 is a graph illustrating the waveform of the drive signal of the drive unit.

[0040] As shown in FIG. 5, the drive signal applied from the drive circuit 16 to the actuator 12B is an electric signal, and the current value changes over time. The waveform of the drive signal is shown by a solid line in FIG. 5. The same waveform of the drive signal is repeated every cycle T. The cycle T includes a period T1 and a period T2 that follows and continues after the period T1. The period T1 corresponds to the period during which an image (an image not shifted by half a pixel) is displayed when the optical axis of the light L is at a first position, and the period T2 corresponds to the period during which an image (an image shifted by half a pixel) is displayed when the optical axis of the light L is at a second position.

[0041] The drive signal changes its current value from a first current value A1 to a second current value A2 at the start of the first period TA1. The drive signal changes its current value discontinuously in a stepwise manner by switching from the first current value A1 to the second current value A2 at the start of the first period TA1. That is, the drive signal has a current value of the first current value A1 at the start of the first period TA1, and then changes stepwise from the first current value A1 to the second current value A2.

[0042] The first current value A1 is a current value that can maintain the oscillation part 12A at the first angle D1 and is set according to the value of the first angle D1. The second current value A2 is a current value that can maintain the oscillation part 12A at the second angle D2 and is set according to the value of the second angle D2. The first current value A1 and the second current value A2 are current values ​​that have opposite positive and negative signs, and their absolute values ​​may be equal. FIG. 5 illustrates an example in which the first current value A1 is negative and the second current value A2 is positive.

[0043] 5, in the period immediately following the change from the first current value A1 to the second current value A2 due to switching at the start of the first period TA1, the current value of the drive signal changes from the second current value A2 to the first current value A1. Specifically, the current value of the drive signal changes linearly over time from the second current value A2 to the first current value A1. That is, from immediately after the start of the first period TA1 to the end of the first period TA1, the current value of the drive signal changes linearly from the second current value A2, and at the end of the first period TA1, the current value becomes the first current value A1.

[0044] 5, the current value of the drive signal changes from a first current value A1 to a second current value A2 at the start of the second period TB1. The current value of the drive signal changes discontinuously in a stepwise manner by switching from the first current value A1 to the second current value A2 at the start of the second period TB1. That is, the current value of the drive signal is the first current value A1 at the start of the second period TB1, and then the current value changes stepwise from the first current value A1 to the second current value A2.

[0045] Next, as shown in FIG. 5, during a second period TB1, the current value of the drive signal is maintained at a second current value A2. The second period TB1 is a period that follows the first period TA1 and is continuous with the first period TA1. Increasing the natural frequency of the oscillating portion 12A is preferable because it shortens the first period TA1 and lengthens the second period TB1 (for example, makes the second period TB1 longer than the first period TA1). Maintaining the current value at the second current value A2 does not necessarily mean that the current value does not strictly change from the second current value A2, but may also mean that the current value deviates from the second current value A2 by a predetermined value. The predetermined value by which the current value deviates from the second current value A2 may be, for example, 10% of the second current value A2.

[0046] In this way, during period T1, the current value of the drive signal changes discontinuously in a stepwise manner from the first current value A1 to the second current value A2, and once the current value reaches the second current value A2, it changes continuously over time to the first current value A1, and once the current value reaches the first current value A1, it again changes discontinuously in a stepwise manner from the first current value A1 to the second current value A2, and thereafter the current value is maintained at the second current value A2.

[0047] At the start of a third period TA2 of period T2, the current value of the drive signal changes from the second current value A2 to the first current value A1. The third period TA2 is a period that follows the second period TB1 and is continuous with the second period TB1. At the start of the third period TA2, the current value of the drive signal changes in a stepwise manner by switching from the second current value A2 to the first current value A1. That is, at the start of the third period TA2, the current value of the drive signal is the second current value A2, and then the current value changes in a stepwise manner from the second current value A2 to the first current value A1.

[0048] The length of the third period TA2 corresponds to the natural frequency of the oscillating part 12A. More specifically, the length of the third period TA2 is preferably 10 / 27 of the natural period (the reciprocal of the natural frequency) of the oscillating part 12A. In this embodiment, the length of the third period TA2 is equal to the length of the first period TA1.

[0049] 5, the current value of the drive signal changes from a first current value A1 to a second current value A2 during a third period TA2. During the third period TA2, the current value of the drive signal changes linearly over time from the first current value A1 to the second current value A2. That is, the current value of the drive signal changes linearly from the first current value A1 immediately after the start of the third period TA2 to the end of the third period TA2, and becomes the second current value A2 at the end of the third period TA2.

[0050] 5, the current value of the drive signal changes from the second current value A2 to the first current value A1 at the start of the fourth period TB2. The current value of the drive signal changes discontinuously in a stepwise manner by switching from the second current value A2 to the first current value A1 at the start of the fourth period TB2. That is, the current value of the drive signal is the second current value A2 at the start of the fourth period TB2, and then the current value changes stepwise from the second current value A2 to the first current value A1.

[0051] Next, as shown in FIG. 5, the current value of the drive signal is maintained at the first current value A1 during a fourth period TB2. The fourth period TB2 is a period following the third period TA2 and continuing therefrom. Note that maintaining the current value at the first current value A1 does not necessarily mean that the current value does not strictly change from the first current value A1, but may also mean that the current value deviates from the first current value A1 by a predetermined amount. The predetermined amount by which the current value deviates from the first current value A1 may be, for example, 10% of the first current value A1.

[0052] In this way, during period T2, the current value of the drive signal changes discontinuously in a stepwise manner from the second current value A2 to the first current value A1, and once the current value reaches the first current value A1, it changes continuously over time to the second current value A2, and once the current value reaches the second current value A2, it again changes discontinuously in a stepwise manner from the second current value A2 to the first current value A1, and thereafter the current value is maintained at the first current value A1.

[0053] As described above, the waveform of the drive signal is a triangular waveform, and the first period TA1 during which the current value changes has a value corresponding to the natural frequency of the oscillating part 12A.

[0054] The length of the first period TA1 corresponds to the natural frequency of the oscillating unit 12A. As described above, the oscillating unit 12A refers to the portion of the optical path control mechanism 12 that oscillates relative to the support unit 24 (in this embodiment, the optical member 20, the movable unit 22, and the coil 26). In other words, the length of the first period TA1 corresponds to the natural frequency of the portion that oscillates relative to the support unit 24. More specifically, the length of the first period TA1 is preferably approximately equal to 10 / 27 of the natural period of the oscillating unit 12A. Here, the natural period is the reciprocal of the natural frequency. Furthermore, "approximately the same value" means that a value that deviates from the natural period by an amount within the error range is acceptable. For example, a deviation from the natural period within 5% of the value of the natural period may also be considered "approximately the same value." Hereinafter, the term "approximately the same value" will have the same meaning. The value of the natural vibration (the reciprocal of the natural frequency) is expressed as "1 / f" [s], where f [Hz] is the natural frequency.

[0055] The natural frequency can be determined by applying (sweeping) a sine wave to the actuator while gradually increasing the frequency from 0 Hz, and finding the frequency at which the actuator vibrates (resonates) most strongly. A micro-displacement meter such as a laser displacement meter can be used to measure the vibration.

[0056] (swing pattern) Next, the oscillation pattern of the oscillating unit 12A due to application of a drive signal will be described. Fig. 6 is a graph illustrating the oscillation pattern of the optical unit. The oscillation pattern of the oscillating unit 12A refers to the change in the displacement angle (angle around the oscillation axis AX) of the oscillating unit 12A over time when a drive signal is applied to the actuator 12B. In Fig. 6, the oscillation pattern is shown by a solid line.

[0057] During the first period TA1, the current value of the drive signal changes discontinuously in a stepwise manner from a first current value A1 to a second current value A2, and when the current value reaches the second current value A2, it changes continuously over time back to the first current value A1, and when the current value reaches the first current value A1, it again changes discontinuously in a stepwise manner from the first current value A1 to the second current value A2. As a result, as shown in Fig. 6, the displacement angle of the oscillating part 12A changes from a first angle D1 to a second angle D2 during the first period TA1.

[0058] During the second period TB1, the current value of the drive signal is maintained at the second current value A2. As a result, the displacement angle of the oscillating part 12A is maintained at the second angle D2 during the second period TB1. Note that "maintained at the second angle D2" does not necessarily mean that the displacement angle does not strictly change from the second angle D2, but may also mean that the displacement angle deviates from the second angle D2 within a predetermined range. The predetermined value here may be set arbitrarily, and may be, for example, 10% of the second angle D2.

[0059] During the third period TA2, the current value of the drive signal changes discontinuously in a stepwise manner from the second current value A2 to the first current value A1, and when the current value reaches the first current value A1, the current value changes continuously over time to the second current value A2, and when the current value reaches the second current value A2, the current value again changes discontinuously in a stepwise manner from the second current value A2 to the first current value A1. As a result, the displacement angle of the oscillating part 12A changes from the second angle D2 to the first angle D1 during the third period TA2.

[0060] During the fourth period TB2, the current value of the drive signal is maintained at the first current value A1. As a result, the displacement angle of the oscillating part 12A is maintained at the first angle D1 during the fourth period TB2. Note that "maintained at the first angle D1" does not necessarily mean that the displacement angle does not change strictly from the first angle D1, but may also mean that the displacement angle deviates from the first angle D1 within a predetermined range. The predetermined value here may be set arbitrarily, and may be, for example, 10% of the first angle D1.

[0061] The light L is irradiated in the second period TB1 and the fourth period TB2. Therefore, in the second period TB1, the light L is irradiated onto the oscillating portion 12A held at the second angle D2, and the optical path of the light L is at the first position. In the fourth period TB2, the light L is irradiated onto the oscillating portion 12A held at the first angle D1, and the optical path of the light L is shifted to the second position, and the image is shifted by half a pixel.

[0062] (effect) As described above, the light path control device 10 according to this embodiment includes an oscillating unit 12A including an optical element 20 onto which light L is incident, an actuator 12B that oscillates the oscillating unit 12A, and a drive circuit 16 (drive unit) that applies a drive signal to the actuator 12B to cause the actuator 12B to oscillate the oscillating unit 12A and control the light path. The drive circuit 16 applies a drive signal to the actuator 12B, the drive signal having a waveform including a first period in which the current value is changed from a first current value to a second current value, then changed back to the first current value, and then further changed from the first current value to the second current value, and a second period following the first period in which the current value is maintained at the second current value. The drive circuit 16 applies the drive signal so that the length of the first period is approximately equal to 10 / 27 cycles of the natural frequency of the oscillating unit 12A.

[0063] In this embodiment, by setting the length of the first period TA1 to a value approximately equal to 10 / 27 of the natural frequency of the oscillating part 12A, the time required for displacement of the oscillating part 12A can be shortened and driving with less unnecessary vibration and drive noise can be easily performed. Also, by changing the current value during the first period TA1, which has a value approximately equal to 10 / 27 of the natural frequency of the oscillating part 12A, and then setting a waveform that maintains the current value during the subsequent second period TB1, stable oscillation without unnecessary vibration during the second period TB1 is possible, and a waveform that can stably oscillate the oscillating part 12A can be easily set.

[0064] (Composition and Effects) As described above, the light path control device 10 of this embodiment includes an oscillating unit 12A having an optical element 20 onto which light is incident, an actuator 12B that oscillates the oscillating unit 12A, and a drive circuit 16 that includes a first period and a second period that is continuous with the first period, and that applies to the actuator 12B a drive signal having a waveform that switches the current value from a first current value to a second current value at the start of the first period, and immediately thereafter changes the current value linearly to the first current value over time until the end of the first period, and switches the current value from the first current value to the second current value at the start of the second period, and maintains the current value at the second current value from immediately thereafter until the end of the second period, thereby causing the actuator 12B to oscillate the oscillating unit 12A and control the light path.

[0065] This configuration can shorten the time required for the displacement of the oscillating part 12A, and can easily perform driving with less unnecessary vibration and driving noise, thereby providing an optical path control device 10 that can appropriately drive the oscillating part.

[0066] The drive circuit 16 of the light path control device 10 according to this embodiment applies a drive signal so that the length of the first period has substantially the same value as 10 / 27 of the natural frequency of the oscillating part 12A.

[0067] According to this configuration, by determining the natural frequency of the oscillating part 12A and setting the time to be approximately equal to 10 / 27 of the natural frequency, it is possible to easily perform driving with less unnecessary vibration and driving noise. Therefore, it is possible to provide an optical path control device 10 that can appropriately drive the oscillating part.

[0068] The display device 1 according to this embodiment includes a light path control device 10 and an irradiation device 100 that irradiates an optical member 20 with light.

[0069] With this configuration, light can be emitted while the optical member 20 is oscillating, so the image projected on the screen repeatedly oscillates and moves. This increases the apparent number of pixels. Therefore, it is possible to provide a display device 1 that can appropriately drive the oscillating unit.

[0070] The optical path control method according to this embodiment is an optical path control method for controlling an optical path by applying a drive signal to an actuator 12B that oscillates an oscillating unit 12A that includes an optical element into which light is incident, and includes a first period and a second period that is continuous with the first period. The optical path control method includes the steps of: switching the current value from a first current value to a second current value at the start of the first period; immediately thereafter, changing the current value linearly to the first current value over time until the end of the first period; switching the current value from the first current value to the second current value at the start of the second period; and applying to the actuator 12B a drive signal having a waveform that maintains the current value at the second current value from immediately thereafter until the end of the second period, thereby causing the actuator 12B to oscillate the oscillating unit 12A and controlling the optical path.

[0071] This configuration can shorten the time required for the displacement of the oscillating part 12A, and can easily perform driving with less unnecessary vibration and driving noise, thereby providing an optical path control method that can appropriately drive the oscillating part.

[0072] The optical path control device 10 according to the present invention has been described above, but it may be embodied in various different forms other than the above-described embodiment.

[0073] Each component of the illustrated optical path control device 10 is a functional concept, and does not necessarily have to be physically configured as shown in the drawing. In other words, the specific form of each device is not limited to that shown in the drawing, and all or part of it may be functionally or physically distributed or integrated in any unit depending on the processing load and usage status of each device.

[0074] The configuration of the light path control device 10 is realized, for example, as software by a program loaded into memory. In the above embodiment, the functional blocks are described as being realized by the cooperation of these hardware and software. In other words, these functional blocks can be realized in various forms by hardware alone, software alone, or a combination of both.

[0075] The above-described components include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the above-described configurations can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0076] 1 Display device 10 Optical path control device 12 Optical path control mechanism 12A Swinging part 12B Actuator 16 Drive circuit (drive unit) 100 Irradiation device A1 First current value A2 Second current value D1 1st angle D2 2nd angle L light TA1 1st period TB1 2nd Period TA2 3rd period TB2 4th period

Claims

1. a swinging portion having an optical member onto which light is incident; an actuator that swings the swinging part; a drive circuit including a first period and a second period consecutive to the first period, which switches the current value from a first current value to a second current value at a start timing of the first period, and immediately thereafter changes the current value linearly to the first current value over time until an end timing of the first period, and switches the current value from the first current value to the second current value at a start timing of the second period, and maintains the current value at the second current value from immediately thereafter until an end timing of the second period, thereby causing the actuator to swing the swinging unit and control the optical path; Optical path control device.

2. the drive circuit applies the drive signal so that the length of the first period is approximately the same as 10 / 27 of a cycle of the natural frequency of the oscillator. The optical path control device according to claim 1 .

3. The optical path control device according to claim 1 or 2; an irradiation device that irradiates the optical member with light, Display device.

4. An optical path control method for controlling an optical path by applying a drive signal to an actuator that oscillates an oscillating unit including an optical member onto which light is incident, comprising: a drive signal having a waveform including a first period and a second period consecutive to the first period, in which the current value is switched from a first current value to a second current value at the start of the first period, and immediately thereafter the current value is changed linearly to the first current value over time until the end of the first period; the current value is switched from the first current value to the second current value at the start of the second period, and the current value is maintained at the second current value from immediately thereafter until the end of the second period; and applying a voltage to the actuator to cause the actuator to swing the swinging unit and control the optical path. Optical path control method.

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