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

Abstract

This invention relates to an optical path control device, a display device, and an optical path control method. The problem solved by this invention is to stably oscillate an optical component. The technical means to solve this problem is an optical path control device comprising: an oscillating component including an optical element into which light is incident; an actuator for oscillating the oscillating component; and a driving unit that controls the optical path by applying a driving signal comprising a waveform including a first period TA1 and a second period TA2 to the actuator, thereby causing the actuator to oscillate the oscillating component. The first period is a period during which a current value changes from a first current value to a second current value, and the second period is a period continuous with the first period during which the current value remains at the second current value. The driving unit applies the driving signal to the driving unit such that the length of the first period TA1 corresponds to the inherent frequency of the oscillating component.

Description

Technical Field

[0001] This invention relates to an optical path control device, a display device, and an optical path control method. Background Technology

[0002] For example, as shown in Patent Document 1, there is a known optical device that shifts the optical axis by oscillating the optical section into which light is incident. Patent Document 1 describes that by oscillating the optical section to shift the optical path of the light passing through the optical section, the resolution of the projected image can be higher than the resolution of the optical modulation device.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6451187. Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In cases where such a shift causes the optical path to deviate, it is required that the optical components swing rapidly and remain stationary.

[0008] 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 can make the optical part swing rapidly and remain stably stationary.

[0009] means for solving problems

[0010] One aspect of the present invention relates to an optical path control device comprising: a swinging part having an optical component for light incidence; an actuator for swinging the swinging part; and a driving part for controlling the optical path by applying a driving signal of a waveform to the actuator to swing the swinging part, wherein the driving signal of the waveform includes a first period and a second period, the first period being a period during which a current value changes from a first current value to a second current value, and the second period being a period continuous with the first period and during which the current value remains at the second current value, the driving part applying the driving signal in such a way that the length of the first period is a value corresponding to the inherent frequency of the swinging part.

[0011] One aspect of the present invention is a display device comprising the above-described optical path control device and an irradiation device for irradiating light onto the above-described optical components.

[0012] One aspect of the present invention relates to an optical path control method that controls an optical path by applying a drive signal to an actuator that causes a oscillating portion to oscillate. The oscillating portion includes an optical component for light incident. The method comprises the following steps: causing the actuator to oscillate the oscillating portion by applying a waveform drive signal to the actuator, the waveform drive signal including a first period and a second period, the first period being a period during which a current value changes from a first current value to a second current value, and the second period being a period continuous with the first period and during which the current value remains at the second current value, wherein the length of the first period is set to a value corresponding to the inherent frequency of the oscillating portion.

[0013] One aspect of the present invention relates to an optical path control device comprising: a oscillating part including an optical component for light incidence; an actuator for oscillating the oscillating part; and a driving part for controlling the optical path by applying a driving signal of a waveform to the actuator to oscillate the oscillating part, wherein the driving signal of the waveform includes a first period and a second period, the first period being a period in which the current value is zero, and the second period being a period following and continuous with the first period, wherein the current value is maintained at a first current value, and the driving part applies the driving signal in such a way that the length of the first period is a value corresponding to the inherent frequency of the oscillating part.

[0014] One aspect of the present invention is a display device comprising the above-described optical path control device and an irradiation device for irradiating light onto the above-described optical components.

[0015] One aspect of the present invention relates to an optical path control method that controls an optical path by applying a drive signal to an actuator, the actuator causing a swinging part to swing, the swinging part including an optical component for light incidence, the method comprising the steps of: applying a waveform drive signal to the actuator, the actuator causing the swinging part to swing, the waveform drive signal including a first period and a second period, the first period being a period in which the current value is zero, the second period being a period following and continuous with the first period, and the current value maintaining a first current value, wherein the length of the first period is set to a value corresponding to the inherent frequency of the swinging part.

[0016] An optical path control device according to one aspect of the present invention includes: a swinging part comprising an optical component for light incident; an actuator for swinging the swinging part; and a driving part for controlling the optical path by applying a wave-shaped driving signal to the actuator, thereby causing the actuator to swing the swinging part, the wave-shaped driving signal comprising a first period and a second period, the first period being a period in which a current value is held at a first current value and then held at a second current value opposite to the first current value, the second period being a period continuous with the first period and holding the current value at the first current value, the driving part applying the driving signal such that the length of the first period is a value corresponding to the inherent frequency of the swinging part.

[0017] One aspect of the present invention is a display device comprising the above-described optical path control device and an irradiation device for irradiating light onto the above-described optical components.

[0018] One aspect of the present invention relates to an optical path control method that controls an optical path by applying a drive signal to an actuator that causes a oscillating part to oscillate. The oscillating part includes an optical component for light incident. The method comprises the following steps: applying a waveform drive signal to the actuator, which causes the oscillating part to oscillate. The waveform drive signal includes a first period and a second period. The first period is a period in which a current value is held at a first current value and then held at a second current value that is opposite in sign to the first current value. The second period is a period that is continuous with the first period and holds the current value at the first current value. The length of the first period is set to a value corresponding to the natural frequency of the oscillating part.

[0019] Invention Effects

[0020] According to the present invention, the optical part can be made to swing rapidly and remain stationary stably. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the display device according to the first embodiment;

[0022] Figure 2 It is a block diagram schematically showing the circuit structure of the display device;

[0023] Figure 3 This is a schematic diagram of the optical path control mechanism;

[0024] Figure 4 yes Figure 3 AA cross-section view;

[0025] Figure 5 It is a graph illustrating the waveform of the drive signal in the first embodiment;

[0026] Figure 6It is a graph illustrating the swing mode of the optical unit in the first embodiment;

[0027] Figure 7 This is a block diagram schematically showing the circuit structure of the display device in the second embodiment;

[0028] Figure 8 It is a graph illustrating the waveform of the driving signal in the second embodiment;

[0029] Figure 9 This is a graph illustrating the oscillation mode of the optical unit in the second embodiment;

[0030] Figure 10 It is a graph illustrating the waveform of the drive signal in the third embodiment;

[0031] Figure 11 This is a graph illustrating the oscillation mode of the optical unit in the third embodiment. Detailed Implementation

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below.

[0033] (First Implementation)

[0034] (Display device)

[0035] Figure 1 This is a schematic diagram of the display device according to the first embodiment. Figure 1 As shown, the display device 1 of the first embodiment includes a light path control device 10 and an illumination device 100. The illumination device 100 is a device for illuminating light L for an image, and the light path control device 10 is a device for controlling the light path of light L. In this embodiment, the light path control device 10 shifts the position of the image displayed by light L by shifting the optical axis of light L, so that the resolution of the projected image is higher than the resolution of the image of the illumination device 100 (i.e., the number of pixels of the display element 106 described later).

[0036] like Figure 1 As shown, the illumination 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 combining prism 108, a projection lens 109, dichroic mirrors 120 and 121, a reflector 130 and 131, lenses 140 to 145, a polarization conversion element 150, and an image signal processing circuit 160. Display elements 106R, 106G, and 106B are referred to as display element 106 without distinction.

[0037] Light source 101 is a light source that generates and illuminates light. Light source 101 illuminates incident light L0. In this embodiment, one light source 101 is used as an example to illuminate incident light L0, but other optical devices for generating incident light L0 may also be used.

[0038] Incident light L0 from light source 101 is incident on lens 140. Lenses 140 and 141 are, for example, compound eye lenses. The incident light L0 is homogenized in illumination distribution by passing through lenses 140 and 141 and is then incident on polarization conversion element 150. Polarization conversion element 150 is an element that makes the polarization of the incident light L0 consistent, for example, having a polarization beam splitter and a phase retardation plate. For example, polarization conversion element 150 makes the incident light L0 consistent with p-polarized light.

[0039] The incident light L0, after being polarized by the polarization conversion element 150, illuminates the dichroic mirror 120 via the lens 142. The lens 142 is, for example, a condenser lens.

[0040] Dichroic mirror 120 separates the incident light L0 into yellow light LRG and blue light LB, which contains a blue band component. The yellow illumination light LRG, separated by dichroic mirror 120, is reflected by mirror 130 and incident on dichroic mirror 121.

[0041] Dichroic mirror 121 separates the incident yellow light LRG into red light LR containing a red band component and green light LG containing a green band component.

[0042] The red light LR, separated by dichroic mirror 121, shines on polarizer 105R through lens 143. The green light LG, separated by dichroic mirror 121, shines on polarizer 105G through lens 144. The blue light LB, separated by dichroic mirror 120, is reflected by mirror 131 and shines on polarizer 105B through lens 145.

[0043] Polarizing plates 105R, 105G, and 105B have the property of reflecting either s-polarized light or p-polarized light while allowing the other to pass through. For example, polarizing plates 105R, 105G, and 105B reflect s-polarized light while allowing p-polarized light to pass through. Polarizing plates 105R, 105G, and 105B are also called reflective polarizing plates.

[0044] Red light LR, which is p-polarized light, passes through polarizer 105R and illuminates display element 106R. Green light LG, which is p-polarized light, passes through polarizer 105G and illuminates display element 106G. Blue light LB, which is p-polarized light, passes through polarizer 105B and illuminates display element 106B.

[0045] Display elements 106R, 106G, and 106B are, for example, reflective liquid crystal display elements. In this embodiment, the case where display elements 106R, 106G, and 106B are reflective liquid crystal display elements will be used as an example, but the method is not limited to reflective; a transmissive liquid crystal display element may also be used. Furthermore, this method can also be applied to structures that use other display elements instead of liquid crystal display elements.

[0046] Display element 106R is controlled by image signal processing circuit 160. Image signal processing circuit 160 drives display element 106R based on image data of the red component. Display element 106R, under the control of image signal processing circuit 160, modulates the p-polarized red light LR to generate s-polarized red light LR. Display element 106G is controlled by image signal processing circuit 160. Image signal processing circuit 160 drives display element 106G based on image data of the green component. Display element 106G, under the control of image signal processing circuit 160, modulates the p-polarized green light LG to generate s-polarized green light LG. Display element 106B is controlled by video signal processing circuit 160. Image signal processing circuit 160 drives display element 106B based on image data of the blue component. Display element 106B, under the control of image signal processing circuit 160, modulates the p-polarized blue light LB based on image data of the blue component to generate s-polarized blue light LB.

[0047] 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.

[0048] The red light LR of the s-polarized light generated by display element 106R is reflected by polarizer 105R, passes through polarizer 107R, and illuminates color combining prism 108. The green light LG of the s-polarized light generated by display element 106G is reflected by polarizer 105G, passes through polarizer 107G, and illuminates color combining prism 108. The blue light LB of the s-polarized light generated by display element 106B is reflected by polarizer 105B, passes through polarizer 107B, and illuminates color combining prism 108.

[0049] The color combining prism 108 combines incident red light (LR), green light (LG), and blue light (LB) into light (L) for image display, which is then projected onto the projection lens 109. The light (L) is then projected through the projection lens 109 onto a screen (not shown) or similar object.

[0050] Although the irradiation device 100 has the structure described above, its structure is not limited to the above description and can be any structure.

[0051] The optical path control device 10 includes an optical path control mechanism 12, a control circuit (control unit) 14, and a drive circuit (drive unit) 16. The optical path control mechanism 12 is a mechanism that oscillates by being driven by the drive circuit 16. The optical path control mechanism 12 is disposed between the color combining prism 108 and the projection lens 109 along the direction of the optical path of light L. The optical path control mechanism 12 receives incident light L from the color combining prism 108 and oscillates, thereby shifting the travel direction (optical path) of light L so that it is emitted towards the projection lens 109. In this way, the optical path control device 10 controls the optical path of light L to move the optical path of light L. Furthermore, the position of the optical path control mechanism 12 is not limited to between the color combining prism 108 and the projection lens 109, and can be arbitrary.

[0052] Figure 2 It is a block diagram schematically showing the circuit structure of a display device. For example... Figure 2 As shown, the image signal processing circuit 160 controls display elements 106R, 106B, and 106G. The image signal processing circuit 160 receives an image signal as input, which includes image data and a synchronization signal for controlling the display elements 106R, 106B, and 106G. The image signal processing circuit 160 synchronizes timing based on the synchronization signal and controls the display elements 106R, 106B, and 106G based on the image data. The control circuit 14 has a digital circuit 14A and a converter 14B. The digital circuit 14A receives the synchronization signal from the video signal processing circuit 160. The digital circuit 14A synchronizes timing based on the synchronization signal and generates a digital drive signal for driving the optical path control mechanism 12. The converter 14B is a DA converter that converts digital signals to analog signals. The converter 14B converts the digital drive signal generated by the digital circuit 14A into an analog drive signal. The drive circuit 16 receives an analog drive signal from the converter 14B, amplifies the analog drive signal, and outputs it to the actuator 12B of the optical path control mechanism 12 (described later). The actuator 12B is driven according to the drive signal, causing the swinging part 12A (described later) to swing.

[0053] (Optical path control mechanism)

[0054] The structure of the optical path control mechanism 12 will be explained in more detail. Figure 3 This is a schematic diagram of the optical path control mechanism. Figure 4 yes Figure 3 AA sectional view. For example... Figure 3 and Figure 4As shown, the optical path control mechanism 12 includes: a swinging part 12A, which includes an optical component 20 into which light L is incident; and an actuator 12B that causes the swinging part 12A to swing. More specifically, the optical path control mechanism 12 includes an optical component 20, a movable part 22, a support part 24, a shaft part 25, a coil 26, a magnetic yoke 27, and a magnet 28.

[0055] Optical component 20 is a component that allows incident light L to pass through. Optical component 20 receives incident light L from one surface and allows the incident light L to pass through, while emitting light L from another surface. In this embodiment, optical component 20 is a glass plate, but the material and shape can be arbitrary.

[0056] The movable part 22 is a component that supports the optical component 20. The movable part 22 is fixed relative to the optical component 20. Specifically, in this embodiment, the movable part 22 is a plate-shaped component with a through hole formed in the center. The optical component 20 is fixed to the movable part 22 in a state where it is inserted into the through hole of the movable part 22. Alternatively, the optical component 20 is fixed to the movable part 22 via a fixing member or an adhesive for fixing to the movable part 22; however, the method of fixing the optical component 20 to the movable part 22 can be arbitrary.

[0057] The support portion 24 is a component that supports the movable portion 22, on which the optical component 20 is mounted, in a swingable manner. In this embodiment, the support portion 24 is a frame-shaped component that surrounds the outer periphery of the movable portion 22. The shaft portion 25 is a component that connects the movable portion 22 to the support portion 24 in a swingable manner. In this embodiment, two shaft portions 25 are provided. Each shaft portion 25 is located near the opposite vertices of the rectangular optical component 20. The movable portion 22 swings about a swing axis AX, which connects the shaft portions 25. By swinging the movable portion 22 about the swing axis AX, the posture of the optical component 20 mounted on the movable portion 22 changes, causing the light path of the light L transmitted through the optical component 20 to shift.

[0058] Coils 26 are mounted on and fixed relative to movable part 22. Coils 26 are respectively disposed at both ends of movable part 22. Magnetic yoke 27 is a component forming a magnetic circuit. Magnetic yoke 27 is mounted on support part 24 and fixed relative to support part 24. Corresponding to coils 26, magnets 28 are respectively disposed at both ends of movable part 22. Magnets 28 are permanent magnets. Magnets 28 are mounted on and fixed relative to magnetic yoke 27. Magnets 28 are positioned adjacent to each coil 26. Coils 26 are input with drive signals from drive circuit 16. Figure 4In this example, a magnet 28 is attached to one side of the "ko"-shaped yoke 27, and an air gap is formed between the unattached surface of the magnet 28 and the opposite side of the "ko"-shaped yoke 27. A coil 26 is disposed within this air gap. A drive signal is input to the coil 26. As a result, current flows through the coil 26, which is a conductor within the magnetic field generated by the magnet 28, generating a force that causes the movable part 22 (oscillating part 12A) fixed to the coil 26 to oscillate. In other words, the actuator 12B of this embodiment can be described as an electromagnetic actuator composed of the coil 26, the yoke 27, and the magnet 28.

[0059] In this embodiment, since the movable part 22 of the optical component 20 is provided to swing as described above, it can be said that the optical component 20, the movable part 22, and the coil 26 constitute the swing part 12A. That is, it can be said that the part of the optical path control mechanism 12 that swings relative to the support part 24 is the swing part 12A. Furthermore, when a fixing member for fixing the optical component 20 to the movable part 22, an adhesive, a substrate for allowing current to flow through the coil 26, wires, etc. are provided, these members also swing relative to the support part 24, and are therefore included in the swing part 12A.

[0060] Furthermore, the actuator in this embodiment is a so-called moving coil type in which the coil 26 is arranged in the movable part 22, but it is not limited to this. For example, it can also be 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, since the magnet 28 swings together with the optical component 20, the magnet 28 is included in the swing part 12A instead of the coil 26.

[0061] Although the optical path control mechanism 12 has the structure described above, it is not limited to this. It can also be any structure in which the optical unit is oscillated by an actuator that is given a drive signal, thereby enabling the optical unit to shift the optical path of the light L.

[0062] In the optical path control mechanism 12, the actuator 12B causes the swinging part 12A to swing according to the drive signal. That is, the actuator 12B causes the swinging part 12A to swing according to the drive signal, so that the swinging part 12A repeatedly changes its posture around the swing axis AX from a first angle D1 to a second angle D2 and from a second angle D2 to a first angle D1. By the swinging part 12A repeatedly swinging between the first angle D1 and the second angle D2, the optical axis of the light L repeatedly shifts from a first position to a second position and from a second position to a first position. In this embodiment, the image projected onto the screen by the light L when the optical axis is in the first position is offset by half a pixel from the image projected onto the screen by the light L when the optical axis is in the second position. That is, the image projected onto the screen is repeatedly offset by half a pixel and then returns to half a pixel. As a result, the apparent number of pixels increases, and the image projected onto the screen can be made higher resolution. Thus, in this embodiment, the optical axis shift is half a pixel of the image. Therefore, the first angle D1 and the second angle D2 are set to angles capable of shifting the image by half a pixel. Furthermore, the image shift is not limited to half a pixel; for example, it can be any value such as 1 / 4 or 1 / 8 of a pixel. The first angle D1 and the second angle D2 can also be appropriately set according to the image shift.

[0063] (Drive signal)

[0064] Next, the drive signal applied from the drive circuit 16 to the actuator 12B will be explained.

[0065] Figure 5 This is a graph illustrating the waveform of the drive signal in the first embodiment. The drive signal applied from the drive circuit 16 to the actuator 12B is an electrical signal, such as... Figure 5 As shown, the current value changes over time. The waveform representing the change in current value of the drive signal over time will be described below as the waveform of the drive signal. Figure 5 In the diagram, the waveform of the drive signal is represented by a solid line. In the first embodiment, the drive signal repeats the same waveform in each period T. Period T includes a period T1 and a period T2 that follows and is continuous with period T1. Period T1 corresponds to the period of the image when the optical axis of the display light L is in the first position (here, the image without offset by half a pixel), and period T2 corresponds to the period of the image when the optical axis of the display light L is in the second position (here, the image with offset by half a pixel).

[0066] During the first period TA1 of period T1, the current value of the drive signal changes from a first current value A1 to a second current value A2. More specifically, during the first period TA1, the current value changes linearly from the first current value A1 to the second current value A2 over time. That is, at the beginning of the first period TA1, the current value is the first current value A1, then changes linearly from the first current value A1, and at the end of the first period TA1, the current value becomes the second current value A2. The first current value A1 is the current value that can maintain the oscillating part 12A at a first angle D1, and is set according to the value of the first angle D1. The second current value A2 is the current value that can maintain the oscillating part 12A at a 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 ​​with opposite signs, and their absolute values ​​can be equal. Figure 5 The example illustrates the case where the first current value A1 is negative and the second current value A2 is positive.

[0067] The length of the first period TA1 is a value corresponding to the natural frequency of the swing portion 12A. As described above, the swing portion 12A refers to the part of the optical path control mechanism 12 that swings relative to the support portion 24 (in this embodiment, it is the optical component 20, the movable portion 22, and the coil 26). That is, the length of the first period TA1 can be said to be a value corresponding to the natural frequency of the part that swings relative to the support portion 24. More specifically, the length of the first period TA1 is preferably a value that is approximately the same as the natural period of the swing portion 12A, and more preferably a value that is the same as the natural period. Here, the natural period is the reciprocal of the natural frequency. In addition, "approximately the same value" means a value that allows for a deviation from the error range relative to the natural period. For example, if the deviation relative to the natural period is within 5% of the value of the natural period, it can also be set to "approximately the same value". Hereinafter, the description of "approximately the same value" also means the same thing. Furthermore, when the natural frequency is set to f [Hz], the value of the natural period (the reciprocal of the natural frequency) is expressed as "1 / f" [s].

[0068] Furthermore, the natural frequency of the oscillating part 12A can be predetermined. For example, a sine wave can be applied to the actuator 12B while gradually increasing the frequency from 0Hz, and the vibration of the oscillating part 12A can be measured. The frequency at which the oscillating part 12A vibrates most is then set as the natural frequency of the oscillating part 12A. Furthermore, a micro-displacement meter can be used in the vibration measurement. In this embodiment, based on the naturally occurring frequency of the oscillating part 12A measured in this way, the length of the first period TA1 is set, and the waveform of the drive signal is set such that it changes from a first current value A1 to a second current value A2 within the first period TA1 of the set length.

[0069] During the second period TB1 of period T1, the current value of the drive signal is maintained at the second current value A2. The second period TB1 is a period following and continuous with the first period TA1. Furthermore, by increasing the inherent frequency of the oscillating section 12A, the first period TA1 can be shortened, and the second period TB1 can be lengthened (for example, it can be made longer than the first period TA1), which is therefore preferred. Moreover, maintaining the second current value A2 means not limited to the current value strictly not changing from the second current value A2; it can also include cases where the current value deviates from the second current value A2 within a specified range. This specified value can be arbitrarily set, for example, it can be a value of 10% of the second current value A2.

[0070] In this way, the current value of the drive signal gradually changes from the first current value A1 to the second current value A2 during the period T1. If the current value reaches the second current value A2, the current value is maintained at the second current value A2.

[0071] During the third period TA2 within 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 can be considered as the period following and continuing from the second period TB1. More specifically, during the third period TA2, the current value of the drive signal changes linearly from the second current value A2 to the first current value A1 over time. That is, at the beginning of the third period TA2, the current value is the second current value A2, then changes linearly from the second current value A2, and at the end of the third period TA2, the current value becomes the first current value A1.

[0072] The length of the third period TA2 is a value corresponding to the natural frequency of the oscillating part 12A. More specifically, the length of the third period TA2 is preferably approximately the same as the natural period (the reciprocal of the natural frequency) of the oscillating part 12A, and more preferably the same as the natural period. In this embodiment, the length of the third period TA2 is equal to the length of the first period TA1.

[0073] During the fourth period TB2 of period T2, the current value of the drive signal is maintained at the first current value A1. The fourth period TB2 is a period following and continuous with the third period TA2. Furthermore, the fourth period TB2 is a period preceding and continuous with the first period TA1. In this embodiment, the fourth period TB2 is equal to the second period TB1. By increasing the inherent frequency of the oscillating section 12A, the third period TA2 can be shortened, and the fourth period TB2 can be lengthened (for example, it can be made longer than the third period TA2), which is therefore preferred. Furthermore, maintaining the first current value A1 means not limited to the current value strictly not changing from the first current value A1, but may also include cases where the current value deviates from the first current value A1 within a predetermined range. This predetermined value can be arbitrarily set, for example, it could be 10% of the first current value A1.

[0074] In this way, the current value of the drive signal gradually changes from the second current value A2 to the first current value A1 during the period T2. If the current value reaches the first current value A1, the current value is maintained at the first current value A1.

[0075] As described above, in the first embodiment, the waveform of the drive signal is trapezoidal, and the first periods during which the current value changes, TA1 and TA2, are values ​​corresponding to the inherent frequency of the swing section 12A.

[0076] in addition, Figure 5 The dashed lines indicate the periods of illumination L. The illumination device 100 preferably does not illuminate L during the first period TA1, but illuminates L during the second period TB1. Furthermore, the illumination device 100 preferably does not illuminate L during the third period TA2, but illuminates L during the fourth period TB2.

[0077] (Oscillating Pattern)

[0078] Next, the swing mode of the swing unit 12A based on the application of the drive signal will be explained. Figure 6 This is a graph illustrating the oscillation pattern of the optical unit in the first embodiment. The oscillation pattern of the oscillating unit 12A refers to the displacement angle (angle about the oscillation axis AX) of the oscillating unit 12A at each time when a drive signal is applied to the actuator 12B. Figure 6 In the middle, the oscillation pattern is represented by a solid line.

[0079] During the first period TA1, the current value of the drive signal changes from a first current value A1 to a second current value A2. Consequently, during the first period TA1, the displacement angle of the swing part 12A changes from a first angle D1 to a second angle D2.

[0080] During the second period TB1, the current value of the drive signal is maintained at the second current value A2. Therefore, during the second period TB1, the displacement angle of the swing unit 12A is maintained at the second angle D2. Furthermore, maintaining it at the second angle D2 means that it is not limited to the displacement angle strictly not changing from the second angle D2; it can also include cases where the displacement angle deviates from the second angle D2 within a specified range. This specified value can be arbitrarily set, for example, it could be 10% of the second angle D2.

[0081] During the third period TA2, the current value of the drive signal changes from the second current value A2 to the first current value A1. As a result, the displacement angle of the swing unit 12A changes from the second angle D2 to the first angle D1 during the third period TA2.

[0082] During the fourth period TB2, the current value of the drive signal is maintained at the first current value A1. Therefore, during the fourth period TB2, the displacement angle of the swing unit 12A is maintained at the first angle D1. Furthermore, maintaining it at the first angle D1 means that it is not limited to the displacement angle strictly not changing from the first angle D1; it can also include cases where the displacement angle deviates from the first angle D1 within a specified range. This specified value can be arbitrarily set, for example, it could be 10% of the first angle D1.

[0083] Furthermore, light L is irradiated during the second periods TB1 and TB2. Therefore, during the second period TB1, light L is irradiated onto the swing portion 12A, which is held at the second angle D2, and the optical path of light L becomes the first position. During the fourth period TB2, light L is irradiated onto the swing portion 12A, which is held at the first angle D1, and the optical path of light L shifts to the second position, causing the image to shift by half a pixel.

[0084] In optical path control devices that shift the optical path by oscillating the optical section, it is required that the optical section oscillate stably. The inventors conducted in-depth research and discovered that by setting the lengths of the first periods TA1 and TA2 to values ​​corresponding to the natural frequency of the oscillating section 12A, vibration of the oscillating section 12A during the second periods TB1 and TB2 can be suppressed, thereby ensuring stable oscillation of the oscillating section 12A. That is, in this embodiment, by setting the lengths of the first periods TA1 and TA2 to values ​​corresponding to the natural frequency of the oscillating section 12A, vibration of the oscillating section 12A during the second periods TB1 and TB2 can be suppressed, allowing the oscillating section 12A to oscillate stably. Therefore, according to this embodiment, the oscillating section 12A can oscillate rapidly and then remain stably stationary, suppressing image degradation.

[0085] (Effect)

[0086] As described above, the optical path control device 10 according to this embodiment includes: a swinging part 12A, comprising an optical component 20 into which light L is incident; an actuator 12B, which swings the swinging part 12A; and a drive circuit 16 (drive unit), which controls the optical path by applying a drive signal to the actuator 12B, which in turn swings the swinging part 12A. The drive circuit 16 applies a drive signal to the actuator 12B, comprising a waveform including a first period TA1 and a second period TB1, wherein the first period TA1 causes the current value to change from a first current value A1 to a second current value A2, and the second period TB1 is continuous with the first period TA1 and the current value remains at the second current value A2. The drive circuit 16 applies the drive signal in such a way that the length of the first period TA1 corresponds to the inherent frequency of the swinging part 12A.

[0087] Thus, in the first embodiment, by setting the length of the first period TA1 to a value corresponding to the natural frequency of the oscillating part 12A, the vibration of the oscillating part 12A in the second period TB1 can be suppressed, thereby enabling the oscillating part 12A to oscillate stably. Furthermore, by setting the waveform so that the current value changes during the first period TA1, which is the length corresponding to the natural frequency of the oscillating part 12A, and then maintains the current value during the subsequent second period TB1, the waveform setting does not become complicated, and a waveform that enables the oscillating part 12A to oscillate stably can be easily set.

[0088] Furthermore, the drive circuit 16 applies a drive signal such that the length of the first period TA1 is the reciprocal of the natural frequency of the swing section 12A. By setting the length of the first period TA1 to the reciprocal of the natural frequency of the swing section 12A, the swing section 12A can swing more stably.

[0089] Furthermore, during the first period TA1, the drive circuit 16 applies a drive signal in such a way that the current value changes linearly from the first current value A1 to the second current value A2. By making the change in the current value during the first period TA1 linear, the oscillating part 12A can oscillate more stably.

[0090] Furthermore, the display device 1 of this embodiment includes a light path control device 10 and an illumination device 100 for irradiating the swing portion 12A with light L. By including the light path control device 10, the display device 1 of this embodiment can stably swing the swing portion 12A and suppress image degradation.

[0091] In addition, the irradiation device 100 irradiates the swing section 12A with light L during the second period TB1. By irradiating the swing section 12A with light L during the second period TB1, the light path can be appropriately shifted.

[0092] Furthermore, the optical path control method of this embodiment controls the optical path by applying a drive signal to the actuator 12B that oscillates the swing section 12A, wherein light L is incident on the swing section 12A. This method includes the following steps: applying a drive signal containing a waveform comprising a first period TA1 and a second period TB1 to the actuator 12B, thereby causing the swing section 12A to oscillate, wherein during the first period TA1, the current value changes from a first current value A1 to a second current value A2, and during the second period TB1, the current value remains continuous with the first period TA1 and is maintained at the second current value A2. In this method, the length of the first period TA1 is set to a value corresponding to the natural frequency of the swing section 12A. According to this method, the swing section 12A can be made to oscillate stably.

[0093] (Second Implementation)

[0094] Next, the second embodiment will be described. In the second embodiment, the waveform of the drive signal is different from that in the first embodiment. In the second embodiment, the description of the parts that are the same as those in the first embodiment is omitted.

[0095] Figure 7 This is a block diagram schematically illustrating the circuit structure of the display device in the second embodiment. For example... Figure 7 As shown, the control circuit 14 of the second embodiment includes a digital circuit 14A and does not have a DA converter (converter 14B) as in the first embodiment. In the second embodiment, the digital drive signal generated by the digital circuit 14A is input to the drive circuit 16, which amplifies the digital drive signal and outputs it to the actuator 12B. The actuator 12B is driven according to the drive signal, causing the oscillating part 12A to oscillate. As described above, in the second embodiment, a digital drive signal is input to the drive circuit 16, but it is not limited to this; a drive signal that has undergone analog conversion by the converter 14B can also be input, just as in the first embodiment.

[0096] (Drive waveform)

[0097] Figure 8 This is a graph illustrating the waveform of the drive signal in the second embodiment. For example... Figure 8 As shown, in the second embodiment, the current value is kept at zero during the first period TA1. In this embodiment, since the digital circuit 14A and other digital switching circuits include digital circuits, the current supply to the actuator 12B can be stopped, and the period during which the current supply is stopped becomes the period during which the current value is zero.

[0098] The length of the first period TA1 is a value corresponding to the natural frequency of the swing section 12A. More specifically, the length of the first period TA1 is preferably approximately the same as half the value of the natural period (the reciprocal of the natural frequency) of the swing section 12A, and more preferably the same as half the value of the natural period (the reciprocal of the natural frequency). Furthermore, when the natural frequency is set to f [Hz], half the value of the natural period is expressed as "1 / (2·f)" [s].

[0099] During the second period TB1, the current value of the drive signal is maintained at the second current value A2. The second period TB1 is the period following and continuing from the first period TA1. That is, at the beginning timing of the second period TB1 (the timing of the switch from the first period TA1 to the second period TB1), the current value switches from zero to the second current value A2, and the current value is maintained at the second current value A2 until the end timing of the second period TB1.

[0100] Thus, in the second embodiment, the current value of the drive signal in period T1 is kept at zero in the first period TA1, the timing current value at the beginning of the second period TB1 is switched to the second current value A2, and the current value in the second period TB1 is kept at the second current value A2.

[0101] In the second embodiment, the current value is kept at zero during the third period TA2. The third period TA2 can be said to be the period following and continuing from the second period TB1. That is, at the beginning timing of the third period TA2 (the timing of switching from the second period TB1 to the third period TA2), the current value switches from the second current value A2 to zero, and the current value is kept at zero until the end timing of the third period TA2.

[0102] The length of the third period TA2 is a value corresponding to the natural frequency of the oscillating part 12A. More specifically, the length of the third period TA2 is preferably approximately the same as half the natural period (the reciprocal of the natural frequency) of the oscillating part 12A, and more preferably the same as half the natural period (the reciprocal of the natural frequency). In this embodiment, the length of the third period TA2 is equal to the length of the first period TA1.

[0103] During the fourth period TB2, the current value is maintained at the first current value A1. The fourth period TB2 is the period following and continuing from the third period TA2. That is, at the beginning timing of the fourth period TB2 (the timing of the switch from the third period TA2 to the fourth period TB2), the current value switches from zero to the first current value A1, and is maintained at the first current value A1 until the end timing of the fourth period TB2.

[0104] Thus, in the second embodiment, the current value of the drive signal in period T2 is kept at zero in the third period TA2, and the timing current value at the beginning of the fourth period TB2 is switched to the first current value A1, and the current value in the fourth period TB2 is kept at the first current value A1.

[0105] Furthermore, in the subsequent first period TA1 of the fourth period TB2, the current value is kept at zero as described above. That is, at the beginning timing of the first period TA1 (the timing of switching from the fourth period TB2 to the first period TA1), the current value switches from the first current value A1 to zero, and the current value is kept at zero until the end timing of the first period TA1.

[0106] Figure 8 The dashed lines indicate the periods of illumination L. The illumination device 100 preferably does not illuminate L during the first period TA1, but illuminates L during the second period TB1. Furthermore, the illumination device 100 preferably does not illuminate L during the third period TA2, but illuminates L during the fourth period TB2.

[0107] (Oscillating Pattern)

[0108] Next, the swing mode of the swing unit 12A based on the application of the drive signal will be explained. Figure 9 This is a graph illustrating the oscillation mode of the optical section in the second embodiment.

[0109] At the beginning of the first period TA1, the current value of the drive signal switches from the first current value A1 to zero, and remains zero until the end of the first period TA1. Thus, during the first period TA1, the displacement angle of the swing section 12A changes from the first angle D1 to the second angle D2. More specifically, the current of the swing section 12A, which was previously twisted to the first angle D1 and maintained the first current value A1, becomes zero, thereby releasing the twist and returning to the neutral position. Then, inertial force takes effect, and it is twisted to the opposite side to the second angle D2, thus reaching the second angle D2.

[0110] At the beginning of the second period TB1, the current value of the drive signal switches from zero to the second current value A2, and remains at the second current value A2 until the end of the second period TB1. Therefore, during the second period TB1, the displacement angle of the swing unit 12A is maintained at the second angle D2. That is, the swing unit 12A, twisted to the second angle D2, is maintained at the second angle D2 because the force to return to neutral is balanced by the force generated by the second current value A2.

[0111] At the beginning of the third period TA2, the current value of the drive signal switches from the second current value A2 to zero, and remains zero until the end of the third period TA2. As a result, the displacement angle of the swing unit 12A changes from the second angle D2 to the first angle D1 during the third period TA2.

[0112] At the beginning of the fourth period TB2, the current value of the drive signal switches from zero to a first current value A1, and remains at the first current value A1 until the end of the fourth period TB2. Therefore, during the fourth period TB2, the displacement angle of the swing unit 12A is maintained at a first angle D1.

[0113] In the second embodiment, the lengths of the first periods TA1 and TA2, in which the current value is switched to zero and held at zero, are values ​​corresponding to the natural frequency of the oscillating part 12A. This suppresses the vibration of the oscillating part 12A during the second periods TB1 and TB2, allowing the oscillating part 12A to oscillate stably. Therefore, according to this embodiment, image degradation can be suppressed. Furthermore, by keeping the current value zero during the first periods TA1 and TA2, for example, compared to gradually switching the current value as in the first embodiment, the lengths of the first periods TA1 and TA2 can be shortened, and the lengths of the second periods TB1 and TB2 can be lengthened. This extends the duration of the illumination light L, more appropriately suppressing image degradation.

[0114] (Effect)

[0115] As explained above, the optical path control device 10 according to the second embodiment includes: a swinging part 12A for light L incident; an actuator 12B for swinging the swinging part 12A; and a drive circuit 16 (drive unit). By applying a drive signal to the actuator 12B, the actuator 12B causes the swinging part 12A to swing, thereby controlling the optical path. The drive circuit 16 applies a drive signal to the actuator 12B containing a waveform of a first period TA1 and a second period TB1. The current value of the first period TA1 is zero, and the second period TB1 is after and continuous with the first period TA1, and the current value is maintained at a second current value A2. The drive circuit 16 applies the drive signal in such a way that the length of the first period TA1 corresponds to the inherent frequency of the swinging part 12A.

[0116] Thus, in the second embodiment, by setting the length of the first period TA1 to a value corresponding to the natural frequency of the oscillating part 12A, the vibration of the oscillating part 12A during the second period TB1 can be suppressed, thereby enabling the oscillating part 12A to oscillate stably. Furthermore, by setting the current value to zero during the first period TA1, which corresponds to the natural frequency of the oscillating part 12A, and then switching to and maintaining the second current value A2 during the subsequent second period TB1, the waveform setting does not become complicated, and a waveform that enables the oscillating part 12A to oscillate stably can be easily set.

[0117] Furthermore, the drive circuit 16 applies a drive signal such that the length of the first period TA1 is approximately the same as half the natural period (the reciprocal of the natural frequency) of the oscillating part 12A. By setting the length of the first period TA1 to the reciprocal of the natural frequency of the oscillating part 12A, the oscillating part 12A can oscillate more stably.

[0118] Furthermore, during the fourth period TB2 (third period) preceding and continuing the first period TA1, the drive circuit 16 applies a drive signal while maintaining a first current value A1, the sign of which is opposite to that of the second current value A2. In this way, by applying opposite current values ​​before and after the first period TA1, the oscillating section 12A can be made to oscillate stably and appropriately.

[0119] (Third Implementation)

[0120] Next, the third embodiment will be described. In the third embodiment, the waveform of the drive signal is different from that of the first embodiment. In the third embodiment, the description of the parts that are the same as those in the first embodiment is omitted.

[0121] The control circuit 14 in the third embodiment, like that in the second embodiment, includes a digital circuit 14A, but may not have a DA converter (converter 14B) as in the first embodiment. That is, in the third embodiment, the digital drive signal generated by the digital circuit 14A is input to the drive circuit 16, which switches the current of the drive signal between positive and negative values ​​via a switching circuit (not shown), i.e., switching the current in opposite directions with the same current value, and outputs it to the actuator 12B. As described above, although a digital drive signal is input to the drive circuit 16 in the third embodiment, it is not limited to this; a drive signal that has undergone analog conversion by the converter 14B may also be input, similar to the first embodiment.

[0122] (Drive waveform)

[0123] Figure 10 This is a graph illustrating the waveform of the drive signal in the third embodiment. For example... Figure 10As shown, in the third embodiment, during the first period TA1, after the current value is maintained at the second current value A2, the current value is maintained at the first current value A1. That is, during period TA1a of the first period TA1, the current value is maintained at the second current value A2, and during period TA1b of the first period TA1, the current value is maintained at the first current value A1. Period TA1b is a period that follows and is continuous with period TA1a. That is, at the start timing of period TA1b (the timing of switching from period TA1a to period TA1b), the current value switches from the second current value A2 to the first current value A1, and until the end timing of period TA1b, the current value is maintained at the first current value A1.

[0124] The length of the first period TA1 is a value corresponding to the natural frequency of the swing section 12A. The length of the first period TA1 is preferably approximately the same as one-third of the natural period (the reciprocal of the natural frequency) of the swing section 12A, and more preferably the same as one-third of the natural period. Furthermore, when the natural frequency is set to f [Hz], one-third of the natural period (the reciprocal of the natural frequency) is expressed as "1 / (3·f)" [s].

[0125] Furthermore, the lengths of periods TA1a and TA1b in the first period TA1 are values ​​corresponding to the natural frequency of the oscillating section 12A. Preferably, the lengths of periods TA1a and TA1b are the same. More specifically, the lengths of periods TA1a and TA1b are preferably approximately the same as one-sixth of the natural period (the reciprocal of the natural frequency) of the oscillating section 12A, and more preferably the same as one-sixth of the natural period. Furthermore, when the natural frequency is set to f [Hz], one-sixth of the reciprocal of the natural frequency is expressed as "1 / (6·f)" [s].

[0126] During the second period TB1, the current value of the drive signal is maintained at the second current value A2. The second period TB1 is the period following and continuing from the first period TA1 (period TA1b). That is, at the beginning timing of the second period TB1 (the timing of the switch from period TA1b to the second period TB1), the current value switches from the first current value A1 to the second current value A2, and the current value is maintained at the second current value A2 until the end timing of the second period TB1.

[0127] Thus, in the third embodiment, the current value of the drive signal in period T1 is maintained at the second current value A2 in period TA1a, the current value is switched to the first current value A1 and maintained in period TA1b, and the current value is switched to the second current value A2 and maintained in the second period TB1.

[0128] In the third embodiment, during the third period TA2, after the current value is maintained at the first current value A1, the current value is maintained at the second current value A2. That is, at the start timing of period TA2a in the third period TA2 (the timing for switching from the second period TB1 to period TA2a), the current value is switched from the second current value A2 to the first current value A1, and is maintained at the first current value A1 until the end timing of period TA2a. Period TA2b is a period that follows period TA2a and is continuous with period TA2a. That is, at the start timing of period TA2b (the timing for switching from period TA2a to period TA2b), the current value is switched from the first current value A1 to the second current value A2, and is maintained at the second current value A2 until the end timing of period TA2b.

[0129] The length of the third period TA2 is a value corresponding to the natural frequency of the oscillating part 12A. Preferably, the length of the third period TA2 is approximately the same as one-third of the natural period (the reciprocal of the natural frequency) of the oscillating part 12A, and more preferably, it is the same as one-third of the natural period. In this embodiment, the length of the third period TA2 is equal to the length of the first period TA1.

[0130] Furthermore, the lengths of period TA2a and period TA2b in the third period TA2 are values ​​corresponding to the natural frequency of the oscillating part 12A. The length of period TA2a is preferably the same as the length of period TA1a. More specifically, the lengths of period TA2a and period TA2b are preferably approximately the same as one-sixth of the reciprocal of the natural frequency of the oscillating part 12A, and more preferably the same as one-sixth of the natural period. In this embodiment, the length of period TA2a is equal to the length of period TA1a, and the length of period TA2b is equal to the length of period TA1b.

[0131] During the fourth period TB2, the current value of the drive signal is maintained at the first current value A1. The fourth period TB2 is the period following and continuing with the third period TA2 (period TA2b). That is, at the beginning timing of the fourth period TB2 (the timing of the switch from period TA2b to the fourth period TB2), the current value is switched from the second current value A2 to the first current value A1, and the current value is maintained at the first current value A1 until the end timing of the fourth period TB2.

[0132] Thus, in the third embodiment, the current value of the drive signal in period T2 is maintained at the first current value A1 in period TA2a, the current value is switched to the second current value A2 and maintained in period TA2b, and the current value is switched to the first current value A1 and maintained in the fourth period TB2.

[0133] Furthermore, in the subsequent period TA1a of the fourth period TB2, the current value is maintained at the second current value A2 as described above. That is, at the beginning timing of period TA1a (the timing of switching from the fourth period TB2 to period TA1a), the current value is switched from the first current value A1 to the second current value A2, and the current value is maintained at the second current value A2 until the end timing of period TA1a.

[0134] Figure 10 The dashed lines indicate the periods of illumination L. The illumination device 100 preferably does not illuminate L during the first period TA1, but illuminates L during the second period TB1. Furthermore, the illumination device 100 preferably does not illuminate L during the third period TA2, but illuminates L during the fourth period TB2.

[0135] (Oscillating Pattern)

[0136] Next, the swing mode of the swing unit 12A based on the application of the drive signal will be explained. Figure 11 This is a graph illustrating the oscillation mode of the optical unit in the third embodiment.

[0137] During the initial timing of period TA1a, the current value is switched from a first current value A1 to a second current value A2, and remains at the second current value A2 until the end of period TA1a. Similarly, during the initial timing of period TA1b, the current value is switched from the second current value A2 to the first current value A1, and remains at the first current value A1 until the end of period TA1b. Thus, during the first period TA1 (periods TA1a and TA1b), the displacement angle of the swinging part 12A changes from a first angle D1 to a second angle D2. More specifically, for the force intended to twist back from the first angle D1, a further force is applied in the direction of return with the second current value A2, causing the swinging part 12A to accelerate towards the second angle D2. If the original trend continues, it will twist further beyond the second angle D2 due to inertia; therefore, in this embodiment, braking is applied by flowing through the first current value A1. Therefore, compared to the second embodiment, the swinging motion can be accelerated even faster.

[0138] At the beginning of the second period TB1, the current value of the drive signal is switched from the first current value A1 to the second current value A2, and the current value is maintained at the second current value A2 until the end of the second period TB1. As a result, during the second period TB1, the displacement angle of the swing part 12A is maintained at the second angle D2.

[0139] During the initial timing of period TA2a, the current value is switched from the second current value A2 to the first current value A1, and remains at the first current value A1 until the end of period TA2a. Similarly, during the initial timing of period TA2b, the current value is switched from the first current value A1 to the second current value A2, and remains at the second current value A2 until the end of period TA2b. Consequently, during the third period TA2 (periods TA2a and TA2b), the displacement angle of the oscillating unit 12A changes from the second angle D2 to the first angle D1.

[0140] At the beginning of the fourth period TB2, the current value of the drive signal is switched from the second current value A2 to the first current value A1, and the current value is maintained at the first current value A1 until the end of the fourth period TB2. Thus, during the fourth period TB2, the displacement angle of the swing unit 12A is maintained at the first angle D1.

[0141] In the third embodiment, by switching the sign of the current value in the first periods TA1 and TA2 to a value corresponding to the natural frequency of the oscillating part 12A, the vibration of the oscillating part 12A in the second periods TB1 and TB2 can be suppressed, allowing the oscillating part 12A to oscillate stably. Therefore, according to this embodiment, image degradation can be suppressed. Furthermore, by switching the sign of the current value in the first periods TA1 and TA2, for example, compared to the first and second embodiments, the length of the first periods TA1 and TA2 can be shortened, and the length of the second periods TB1 and TB2 can be lengthened. As a result, the duration of the illumination light L can be extended, and image degradation can be suppressed more appropriately.

[0142] (Effect)

[0143] As explained above, the optical path control device 10 according to the third embodiment includes: a swinging part 12A for light L incident; an actuator 12B for swinging the swinging part 12A; and a drive circuit 16 (drive unit). By applying a drive signal to the actuator 12B, the actuator 12B causes the swinging part 12A to swing, thereby controlling the optical path. The drive circuit 16 applies a drive signal containing a waveform of a first period TA1 and a second period TB1 to the actuator 12B. The first period TA1 is the period during which the current value is held at a second current value A2 and then at a first current value A1, which is opposite in sign to the second current value A2. The second period TB1 is the period during which the current value is held at the second current value A2, continuous with the first period TA1. The drive circuit 16 applies the drive signal in such a way that the length of the first period TA1 corresponds to the inherent frequency of the swinging part 12A.

[0144] As described above, in the third embodiment, by setting the length of the first period TA1 to a value corresponding to the natural frequency of the oscillating part 12A, the vibration of the oscillating part 12A in the second period TB1 can be suppressed, thereby enabling the oscillating part 12A to oscillate stably. Furthermore, by setting the waveform to switch the positive and negative current values ​​during the first period TA1 (a length corresponding to the natural frequency of the oscillating part 12A), and then switching to and maintaining the second current value A2 during the subsequent second period TB1, the waveform setting does not become complicated, and it is easy to set a waveform that allows the oscillating part 12A to oscillate stably.

[0145] Furthermore, the drive circuit 16 applies a drive signal such that the length of the period TA1a, which is maintained at the second current value A2 during the first period TA1, is the same as the length of the period TA1b, which is maintained at the first current value A1 during the first period TA1. By making the lengths of periods TA1a and TA1b equal, the swinging part 12A can swing more stably.

[0146] Furthermore, the drive circuit 16 applies a drive signal such that the length of the period TA1a, which is maintained at the second current value A2 during the first period TA1, and the length of the period TA1b, which is maintained at the first current value A1 during the first period TA1, are approximately the same as one-sixth of the reciprocal of the natural frequency of the oscillating part 12A. By setting the length of the first period TA1 to this range, the oscillating part 12A can oscillate more stably.

[0147] The embodiments of the present invention have been described above, but the embodiments are not limited to these embodiments. Furthermore, the aforementioned constituent elements include elements readily conceived by those skilled in the art, substantially the same elements, and elements of equivalent scope. Moreover, the aforementioned constituent elements can be appropriately combined, and the configurations of various embodiments can be combined. Furthermore, various omissions, substitutions, or modifications of the constituent elements can be made without departing from the spirit of the aforementioned embodiments.

[0148] Symbol Explanation

[0149] 1 Display device; 10 Optical path control device; 12 Optical path control mechanism; 12A Optical part; 12B Actuator; 16 Drive circuit (drive part); 100 Illumination device; A1 First current value; A2 Second current value; D1 First angle; D2 Second angle; L light; TA1, TA2 First period; TB1, TB2 Second period.

Claims

1. An optical path control device, comprising: A swinging part, which has an optical component for light incident; An actuator causes the swinging part to swing; and The driving unit controls the optical path by applying a waveform driving signal to the actuator, causing the actuator to oscillate the oscillating unit. The waveform driving signal periodically includes a first period, a second period, a third period, and a fourth period. The first period is a period in which the current value linearly changes from a first current value to a second current value. The second period is a period continuous with the first period in which the current value remains constant at the second current value. The third period is a period continuous with the second period in which the current value linearly changes from the second current value to the first current value. The fourth period is a period continuous with the third period in which the current value remains constant at the first current value. The driving unit applies the driving signal in such a way that the length of the first period is the same as the reciprocal of the inherent frequency of the oscillating unit. The first current value and the second current value are currents with opposite signs and the same absolute value. The first current value keeps the swinging part at a displacement angle of the first angle. The second current value keeps the swinging part at a displacement angle of a second angle, which is different from the first angle.

2. A display device, comprising: The optical path control device according to claim 1; as well as An irradiation device that irradiates light onto the optical components.

3. The display device according to claim 2, wherein, The irradiation device irradiates light onto the optical component during the second period.

4. A method for controlling an optical path, comprising controlling an optical path by applying a driving signal to an actuator, the actuator causing a oscillating part to oscillate, the oscillating part including an optical component for light incidence, the method comprising the following steps: A driving signal of a waveform is applied to the actuator to cause the actuator to oscillate the oscillating part. The driving signal of the waveform periodically includes a first period, a second period, a third period, and a fourth period. The first period is the period during which the current value linearly changes from a first current value to a second current value. The second period is continuous with the first period, and the current value remains constant at the second current value. The third period is continuous with the second period, and the current value linearly changes from the second current value to the first current value. The fourth period is continuous with the third period, and the current value remains constant at the first current value. The length of the first period is the same as the reciprocal of the natural frequency of the swinging part. The first current value and the second current value are currents with opposite signs and the same absolute value. The first current value keeps the swinging part at a displacement angle of the first angle. The second current value keeps the swinging part at a displacement angle of a second angle, which is different from the first angle.

Images