Patent Description:
There are known optical devices shifting an optical axis by oscillating an optical part on which light is made incident. <CIT> and <CIT>, for example, describe a technique that can make the resolution of a projected image higher than the resolution of an optical modulation apparatus by oscillating the optical part to shift the optical path of light passing through the optical part.

There are known optical devices shifting the optical path of the light passing through the optical part by oscillating the optical part about each of a first axis and a second axis crossing each other. In such optical devices, there is a problem in that an image may be displayed during the oscillation of the optical part, and if the oscillation time of the optical part by the first axis and the oscillation time of the optical part by the second axis are different from each other, the image output during the oscillation of the optical part by the first axis and the image output during the oscillation of the optical part by the second axis are different from each other in appearance, thus degrading image quality.

In view of the above problem, an object of the present invention is to provide an optical path control apparatus and a display apparatus making an image output during the oscillation of the optical part by first shaft parts and an image output during the oscillation of the optical part by second shaft parts uniform in appearance to suppress degradation of image quality.

<CIT> discloses torsion bars for pivotally supporting an outer moving plate formed of a polyimide having low rigidity and low resonance frequency and inner torsion bars for pivotally supporting an inner moving plate formed of silicon having a rigidity and resonance frequency higher than those formed of polyimide.

An optical path control apparatus according to the invention is defined in claim <NUM> and a display apparatus comprising the optical path control apparatus of claim <NUM> is defined in claim <NUM>.

The following describes embodiments of the present invention in detail based on the accompanying drawings. The embodiments described below do not limit the present invention.

<FIG> is a schematic diagram of a display apparatus according to a first embodiment.

In the first embodiment, as illustrated in <FIG>, the display apparatus <NUM> has an optical path control apparatus <NUM> and an irradiation apparatus <NUM>. The irradiation apparatus <NUM> is an apparatus emitting light L for images. The optical path control apparatus <NUM> is an apparatus controlling an optical path of the light L. The optical path control apparatus <NUM> shifts the optical axis of the light L to shift the position of an image displayed by the light L and to make the resolution of a projected image higher than the resolution of an image by the irradiation apparatus <NUM> (that is, the number of pixels of a display element <NUM> described below).

The irradiation apparatus <NUM> includes a light source <NUM>, polarizing plates 105R, <NUM>, and 105B, display elements 106R, <NUM>, and 106B, polarizing plates 107R, <NUM>, and 107B, a color combining prism <NUM>, a projection lens <NUM>, dichroic mirrors <NUM> and <NUM>, reflective mirrors <NUM> and <NUM>, lenses <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, a polarization conversion element <NUM>, and an image signal processing circuit <NUM>. When the display element 106R, the display element <NUM>, and the display element 106B are not distinguished from each other, they are referred to as the display element <NUM>.

The light source <NUM> is a light source generating and emitting light. The light source <NUM> emits incident light L0. The following description takes using one light source <NUM> as the light source emitting the incident light L0 as an example; another optical apparatus for generating the incident light L0 may be included.

The incident light L0 from the light source <NUM> is made incident on the lens <NUM>. The lens <NUM> and the lens <NUM> are, for example, fly-eye lenses. The incident light L0 is made uniform in illumination distribution by the lenses <NUM> and <NUM> and is made incident on the polarization conversion element <NUM>. The polarization conversion element <NUM> is an element aligning the polarization of the incident light L0 and has, for example, a polarization beam splitter and a retardation plate. For example, the polarization conversion element <NUM> aligns the incident light L0 to the p-polarized light.

The incident light L0, the polarization of which has been aligned by the polarization conversion element <NUM>, is applied to the dichroic mirror <NUM> through the lens <NUM>. The lens <NUM> is, for example, a condenser lens.

The dichroic mirror <NUM> separates the incident light L0 made incident thereon into yellow light LRG and blue light LB, which contains blue band components. The yellow illumination light LRG separated by the dichroic mirror <NUM> reflects off the reflective mirror <NUM> and is made incident on the dichroic mirror <NUM>.

The dichroic mirror <NUM> separates the yellow light LRG made incident thereon into red light LR, which contains red band components, and green light LG, which contains green band components.

The red light LR separated by the dichroic mirror <NUM> is applied to the polarizing plate 105R through the lens <NUM>. The green light LG separated by the dichroic mirror <NUM> is applied to the polarizing plate <NUM> through the lens <NUM>. The blue light LB separated by the dichroic mirror <NUM> reflects off the reflective mirror <NUM> and is applied to the polarizing plate 105B through the lens <NUM>.

The polarizing plates 105R, <NUM>, and 105B have the property of reflecting either the s-polarized light or the p-polarized light and passing the other. For example, the polarizing plates 105R, <NUM>, and 105B reflect the s-polarized light and pass the p-polarized light. The polarizing plates 105R, <NUM>, and 105B are also referred to as reflective polarizing plates.

The red light LR, which is the p-polarized light, passes through the polarizing plate 105R and is applied to the display element 106R. The green light LG, which is the p-polarized light, passes through the polarizing plate <NUM> and is applied to the display element <NUM>. The blue light LB, which is the p-polarized light, passes through the polarizing plate 105B and is applied to the display element 106B.

The display element 106R, the display element <NUM>, and the display element 106B are, for example, reflective liquid crystal display elements. The following description describes a case in which the display element 106R, the display element <NUM>, and the display element 106B are reflective liquid crystal display elements as an example; not limited to the reflective type, transmissive liquid crystal display elements may also be used. They can also be applied in various ways to configurations including other display elements in place of the liquid crystal display elements.

The display element 106R is controlled by the image signal processing circuit <NUM>. The image signal processing circuit <NUM> drives and controls the display element 106R based on red component image data. The display element 106R optically modulates the red light LR as the p-polarized light in accordance with the control of the image signal processing circuit <NUM> to generate the red light LR as the s-polarized light. The display element <NUM> is controlled by the image signal processing circuit <NUM>. The image signal processing circuit <NUM> drives and controls the display element <NUM> based on green component image data. The display element <NUM> optically modulates the green light LG as the p-polarized light in accordance with the control of the image signal processing circuit <NUM> to generate the green light LG as the s-polarized light. The display element 106B is controlled by the image signal processing circuit <NUM>. The image signal processing circuit <NUM> drives and controls the display element 106B based on blue component image data. The display element 106B optically modulates the blue light LB as the p-polarized light based on the blue component image data in accordance with the control of the image signal processing circuit <NUM> to generate the blue light LB as the s-polarized light.

The polarizing plates 107R, <NUM>, and 107B have the property of passing either the s-polarized light or the p-polarized light and reflecting or absorbing the other. For example, the polarizing plates 107R, <NUM>, and 107B pass the s-polarized light and absorb the p-polarized light, which is unnecessary.

The red light LR as the s-polarized light generated by the display element 106R is reflected by the polarizing plate 105R, passes through the polarizing plate 107R, and is applied to the color combining prism <NUM>. The green light LG as the s-polarized light generated by the display element <NUM> is reflected by the polarizing plate <NUM>, passes through the polarizing plate <NUM>, and is applied to the color combining prism <NUM>. The blue light LB as the s-polarized light generated by the display element 106B is reflected by the polarizing plate 105B, passes through the polarizing plate 107B, and is applied to the color combining prism <NUM>.

The color combining prism <NUM> combines the red light LR, the green light LG, and the blue light LB made incident and applies them as the light L for image display to the projection lens <NUM>. The light L is projected onto a screen or the like, not illustrated, through the projection lens <NUM>.

Although the irradiation apparatus <NUM> is configured as described above, its configuration is not limited to the above description; any configuration may be employed.

The optical path control apparatus <NUM> has an optical path control mechanism <NUM>, a control circuit (a controller) <NUM>, and a drive circuit (a drive unit) <NUM>. The optical path control mechanism <NUM> is a mechanism oscillating by being driven by the drive circuit <NUM>. The optical path control mechanism <NUM> is provided between the color combining prism <NUM> and the projection lens <NUM> in a direction along the optical path of the light L. The optical path control mechanism <NUM> oscillates while the light L from the color combining prism <NUM> is made incident thereon, thereby shifting the travel direction (the optical path) of the light L and emitting it toward the projection lens <NUM>. Thus, the optical path control apparatus <NUM> controls the optical path of the light L so as to shift the optical path of the light L. The position in which the optical path control mechanism <NUM> is provided is not limited to between the color combining prism <NUM> and the projection lens <NUM> but may be any position.

<FIG> is a block diagram schematically illustrating a circuit configuration of the display apparatus.

As illustrated in <FIG>, the image signal processing circuit <NUM> controls the display elements 106R, 106B, and <NUM>. An image signal including image data for controlling the display elements 106R, 106B, and <NUM> and a synchronization signal is input to the image signal processing circuit <NUM>. The image signal processing circuit <NUM> controls the display elements 106R, 106B, and <NUM> based on the image data while synchronizing timing based on the synchronization signal. A control circuit <NUM> has a digital circuit 14A and a converter 14B. The synchronization signal from the image signal processing circuit <NUM> is input to the digital circuit 14A. The digital circuit 14A generates a digital drive signal to drive the optical path control mechanism <NUM> while synchronizing timing based on the synchronization signal. The converter 14B is a digital-to-analog (DA) converter converting a digital signal to 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 <NUM> receives input of the analog drive signal from the converter 14B, amplifies the analog drive signal, and outputs it to actuators 12B of the optical path control mechanism <NUM> described below. The actuators 12B are driven in response to the drive signal to oscillate an oscillating part 12A described below (refer to <FIG>).

<FIG> is a plan view of the optical path control mechanism, <FIG> is a IV-IV sectional view of <FIG>, and <FIG> is a V-V sectional view of <FIG>.

As illustrated in <FIG>, the optical path control mechanism <NUM> has the oscillating part 12A including an optical member <NUM> (an optical part) on which the light L is made incident and the actuators 12B oscillating the oscillating part 12A.

The actuators 12B oscillate the oscillating part 12A about a first oscillation axis AX and a second oscillation axis BX along two directions crossing (preferably orthogonal to) the direction in which the light L is made incident on the optical member <NUM>. The first oscillation axis AX and the second oscillation axis BX are preferably orthogonal to each other. Thus, the optical path control mechanism <NUM> has a first oscillating part <NUM> and a second oscillating part <NUM> as the oscillating part 12A, first shaft parts <NUM> and second shaft parts <NUM> along the first oscillation axis AX and the second oscillation axis BX, respectively, first actuators <NUM> and second actuators <NUM> as the actuators 12B, and a support part <NUM>.

The optical member <NUM> is a member passing the light L made incident thereon. The optical member <NUM> makes the light L incident on one surface, passes the light L made incident thereon, and emits the light L from the other surface. The optical member <NUM> is a glass plate; any material and shape may be employed.

The first oscillating part <NUM> has the optical member <NUM> and a first movable part <NUM>. The first movable part <NUM> is a member supporting the optical member <NUM>. The first movable part <NUM> is fixed to the optical member <NUM>. Specifically, the first movable part <NUM> is a plate frame-shaped member formed with a through hole 31a at the center. The optical member <NUM> is fixed to the first movable part <NUM> fit into the through hole 31a of the first movable part <NUM>. The optical member <NUM> is fixed to the first movable part <NUM> via a fixing member or adhesive to be fixed to the first movable part <NUM>; any method for fixing the optical member <NUM> to the first movable part <NUM> may be employed.

The second oscillating part <NUM> is placed outside the first oscillating part <NUM>. The second oscillating part <NUM> has a second movable part <NUM>. The second movable part <NUM> is a member supporting the first movable part <NUM>. The first movable part <NUM> is supported in an oscillatable manner about the first oscillation axis AX with respect to the second movable part <NUM>. Specifically, the second movable part <NUM> is a plate frame-shaped member formed with a through hole 32a at the center. The first movable part <NUM> is supported on the second movable part <NUM> in an oscillatable manner placed spaced apart from the through hole 32a of the second movable part <NUM> by a certain gap. The first movable part <NUM> and the second movable part <NUM> are coupled to each other by a pair of first shaft parts <NUM> along the first oscillation axis AX. The first movable part <NUM> oscillates about the first oscillation axis AX by the pair of first shaft parts <NUM> becoming elastically deformed so as to be twisted with respect to the second movable part <NUM>.

The support part <NUM> is placed outside the second oscillating part <NUM>. The support part <NUM> is a member supporting the second movable part <NUM>. The second movable part <NUM> is supported in an oscillatable manner about the second oscillation axis BX with respect to the support part <NUM>. Specifically, the support part <NUM> is a plate frame-shaped member formed with a through hole 27a at the center. The second movable part <NUM> is supported on the support part <NUM> in an oscillatable manner placed spaced apart from the through hole 27a of the support part <NUM> by a certain gap. The second movable part <NUM> and the support part <NUM> are coupled to each other by a pair of second shaft parts <NUM> along the second oscillation axis BX. The second movable part <NUM> oscillates about the second oscillation axis BX by the pair of second shaft parts <NUM> becoming elastically deformed so as to be twisted with respect to the support part <NUM>.

The second movable part <NUM> (the second oscillating part <NUM>) oscillates about the second oscillation axis BX with respect to the support part <NUM> with the pair of second shaft parts <NUM> as supports. The first movable part <NUM> (the first oscillating part <NUM>) oscillates about the first oscillation axis AX with respect to the second movable part <NUM> with the pair of first shaft parts <NUM> as supports. Thus, the optical member <NUM> fixed to the second movable part <NUM> can oscillate about the first oscillation axis AX and the second oscillation axis BX. The optical member <NUM> oscillates about the first oscillation axis AX and the second oscillation axis BX, whereby the optical path of the light L passing through the optical member <NUM> can be shifted by a change in the attitude of the optical member <NUM>.

In the first embodiment, the first movable part <NUM>, the second movable part <NUM>, the first shaft parts <NUM>, and the second shaft parts <NUM> are integrally formed. Thus, the first movable part <NUM> oscillates with respect to the second movable part <NUM> by the first shaft parts <NUM> becoming elastically deformed so as to be twisted in a circumferential direction. However, the first movable part <NUM>, the second movable part <NUM>, and the first shaft parts <NUM> may be separately formed and coupled to each other. One end and the other end of the second movable part <NUM> in the axial direction of the second oscillation axis BX are coupled to the support part <NUM> to be fixed, and the second shaft parts <NUM> are formed at the respective ends of the second movable part <NUM>. However, the second shaft parts <NUM> may be provided at the respective ends of the second movable part <NUM>, and the second shaft parts <NUM> may be directly coupled to the support part <NUM> to be fixed. Furthermore, the second movable part <NUM>, the second shaft parts <NUM>, and the support part <NUM> may be integrally formed.

The first actuators <NUM> oscillate the first movable part <NUM> (the first oscillating part <NUM>) about the first oscillation axis AX with respect to the support part <NUM> with the pair of first shaft parts <NUM> as supports. The first actuators <NUM> are placed both on one side and the other side in a radial direction (the axial direction in the second oscillation axis BX) from the first oscillation axis AX. The first actuators <NUM> each have a coil <NUM>, a yoke <NUM>, and a magnet <NUM>.

The coil <NUM> is mounted on the first movable part <NUM> and is fixed to a coil mounting part 31b provided in the first movable part <NUM>. The coils <NUM> are provided at the respective ends of the first movable part <NUM> in the radial direction of the first oscillation axis AX (one side and the other side of the second oscillation axis BX in the axial direction). The yokes <NUM> are members forming a magnetic path. The yokes <NUM> are mounted on the support part <NUM> and are fixed to the support part <NUM>. The yokes <NUM> are provided at the respective ends of the first movable part <NUM> in correspondence with the coils <NUM>. The magnets <NUM> are permanent magnets. The magnets <NUM> are mounted on the respective yokes <NUM> and are fixed to the respective yokes <NUM>. The magnets <NUM> are placed at positions adjacent to the respective coils <NUM>.

The drive signal from the drive circuit <NUM> (refer to <FIG>) is input to the coils <NUM>. In the example illustrated in <FIG>, the magnet <NUM> is bonded to one side of the U-shaped yoke <NUM>, forming an air gap between the face of the magnet <NUM> that is not bonded and the U-shaped opposing face of the yoke <NUM>. The coil <NUM> is placed within the air gap. When the drive signal is input to the coils <NUM>, a current flows through the coils <NUM>, which are conductors within the air gaps (magnetic fields) caused by the magnets <NUM> and the yokes <NUM> to generate a force in the coils <NUM>, and this force causes the first movable part <NUM> (the first oscillating part <NUM>) fixed to the coils <NUM> to oscillate. That is to say, it can be said that the first actuator <NUM> is an electromagnetic actuator including the coil <NUM>, the yoke <NUM>, and the magnet <NUM>.

The second actuators <NUM> oscillate the second movable part <NUM> (the second oscillating part <NUM>) about the second oscillation axis BX with respect to the support part <NUM> with the pair of second shaft parts <NUM> as supports. The second actuators <NUM> are placed both on one side and the other side in a radial direction (the axial direction in the first oscillation axis AX) from the second oscillation axis BX. The second actuators <NUM> each have a coil <NUM>, a yoke <NUM>, and a magnet <NUM>.

The coil <NUM> is mounted on the second movable part <NUM> and is fixed to a coil mounting part 32b provided in the second movable part <NUM>. The coils <NUM> are provided at the respective ends of the second movable part <NUM> in the radial direction of the second oscillation axis BX (one side and the other side of the first oscillation axis AX in the axial direction). The yokes <NUM> are members forming a magnetic path. The yokes <NUM> are mounted on the support part <NUM> and are fixed to the support part <NUM>. The yokes <NUM> are provided at the respective ends of the second movable part <NUM> in correspondence with the coils <NUM>. The magnets <NUM> are permanent magnets. The magnets <NUM> are mounted on the respective yokes <NUM> and are fixed to the respective yokes <NUM>. The magnets <NUM> are placed at positions adjacent to the respective coils <NUM>.

The drive signal from the drive circuit <NUM> (refer to <FIG>) is input to the coils <NUM>. In the example illustrated in <FIG>, the magnet <NUM> is bonded to one side of the U-shaped yoke <NUM>, forming an air gap between the face of the magnet <NUM> that is not bonded and the U-shaped opposing face of the yoke <NUM>. The coil <NUM> is placed within the air gap. When the drive signal is input to the coils <NUM>, a current flows through the coils <NUM>, which are conductors within the air gaps (magnetic fields) caused by the magnets <NUM> and the yokes <NUM> to generate a force in the coils <NUM>, and this force causes the second movable part <NUM> (the second oscillating part <NUM>) fixed to the coils <NUM> to oscillate. That is to say, it can be said that the second actuator <NUM> is an electromagnetic actuator including the coil <NUM>, the yoke <NUM>, and the magnet <NUM>.

In the optical path control mechanism <NUM>, the first movable part <NUM> provided with the optical member <NUM> oscillates, and in addition, the second movable part <NUM> on which the first movable part <NUM> is supported oscillates, and thus it can be said that the optical member <NUM>, the first movable part <NUM>, the second movable part <NUM>, and the coils <NUM> and <NUM> form the oscillating part 12A. That is to say, it can be said that the part of the optical path control mechanism <NUM> oscillating with respect to the support part <NUM> refers to the oscillating part 12A. The first shaft parts <NUM> also oscillate together with the second movable part <NUM> and are thus included in the oscillating part 12A. When fixing members or adhesive for fixing the optical member <NUM> to the first movable part <NUM> or a substrate or lead wires for passing a current through the coils <NUM> and <NUM> are provided, they also oscillate with respect to the support part <NUM> and are thus also included in the oscillating part 12A.

In the first embodiment, the first actuators <NUM> oscillate the first movable part <NUM>, whereas the second actuators <NUM> oscillate the second movable part <NUM>. In this case, the yokes <NUM> and <NUM> forming the actuators <NUM> and <NUM>, respectively, are fixed to the support part <NUM>. Thus, when the second actuators <NUM> oscillate the second movable part <NUM>, in order for the first actuators <NUM> and the second movable part <NUM> not to interfere with each other, a gap is ensured between them. The first actuators <NUM> may be provided in the second movable part <NUM>.

Although the actuators <NUM> and <NUM> are of what is called a moving coil type, in which the coils <NUM> and <NUM> are placed in the movable parts <NUM> and <NUM>, respectively, this is not limiting; for example, they may be what is called a moving magnet type, in which the magnets <NUM> and <NUM> are placed in the movable parts <NUM> and <NUM>, respectively, whereas the coils <NUM> and <NUM> are placed in the support part <NUM>. In this case, the magnets <NUM> and <NUM> are oscillated together with the optical member <NUM>, and thus the magnets <NUM> and <NUM> are included in the oscillating part 12A in place of the coils <NUM> and <NUM>.

Although the optical path control mechanism <NUM> is configured as described above, this is not limiting; any configuration in which the optical part oscillates by the actuators to which the drive signal has been applied to enable the shift of the optical path of the light L by the optical part may be employed.

<FIG> is a perspective view of the oscillating part of the optical path control mechanism.

As illustrated in <FIG>, the first movable part <NUM> forming the first oscillating part <NUM> and the second movable part <NUM> forming the second oscillating part <NUM> are coupled to each other by the first shaft parts <NUM> along the first oscillation axis AX, whereas the second movable part <NUM> and the support part <NUM> are coupled to each other by the second shaft parts <NUM> along the second oscillation axis BX. Here, the mass of the first oscillating part <NUM> and the distance from the first oscillation axis AX to the outer peripheral part of the first movable part <NUM> and the mass of the second oscillating part <NUM> and the distance from the second oscillation axis BX to the outer peripheral part of the second movable part <NUM> are different from each other. Thus, the moment of inertia when the first actuators <NUM> oscillate the first movable part <NUM> with the first shaft parts <NUM> as supports and the moment of inertia when the second actuators <NUM> oscillate the second movable part <NUM> with the second shaft parts <NUM> as supports are different from each other.

That is to say, the moment of inertia I<NUM> of the first movable part <NUM> when the first actuators <NUM> oscillate the first movable part <NUM> about the first oscillation axis AX with the first shaft parts <NUM> as supports can be considered as follows. Considering the first movable part <NUM> as a collection of a particle with a mass m1 and the distance of the particle from the first oscillation axis AX (the radius of rotation of the particle) as r1, the moment of inertia of the rotating particle is expressed by the following formula.

The first movable part <NUM> is considered to be a collection of the particle, and thus the moment of inertia I of the first movable part <NUM> about the first oscillation axis AX is expressed as the sum of the product of the mass m1 of an infinitesimal part, which is the particle of the first movable part <NUM>, and the square of the distance from the first oscillation axis AX (the radius of rotation r1).

Similarly, the moment of inertia I<NUM> of the second movable part <NUM> when the second actuators <NUM> oscillate the second movable part <NUM> about the second oscillation axis BX with the second shaft parts <NUM> as supports is expressed as the sum of the product of a mass m2 of an infinitesimal part, which is the particle of the second movable part <NUM>, and the square of the distance from the second oscillation axis BX (the radius of rotation r2). Thus, the moment of inertia when the first movable part <NUM> is oscillated about the first oscillation axis AX and the moment of inertia when the second movable part <NUM> is oscillated about the second oscillation axis BX are different from each other.

Then, the natural frequency when the first movable part <NUM> oscillates and the natural frequency when the second movable part <NUM> oscillates are different from each other, making the displacement times of the two parts different from each other. In the display apparatus <NUM>, an image may be displayed during the oscillation of the optical member <NUM>, and if the displacement time of the first movable part <NUM> and the displacement time of the second movable part <NUM> are different from each other, the images output during the oscillation of the respective parts are different from each other in appearance, thus degrading image quality.

In the first embodiment, the torsional rigidity of the second shaft parts <NUM> is set to be higher than the torsional rigidity of the first shaft parts <NUM>. The first shaft parts <NUM> and the second shaft parts <NUM> are made different from each other in at least one of a cross-sectional area, a length, and a material to make the torsional rigidity of the second shaft parts <NUM> higher than the torsional rigidity of the first shaft parts <NUM>.

The natural frequency of the first movable part <NUM> and the second movable part <NUM> is determined by the moment of inertia about the axes and the torsional rigidity of the shafts. The moment of inertia about the axes is determined by the mass of the first oscillating part <NUM> and the mass of the second oscillating part <NUM> and the distance from the first oscillation axis AX to the first movable part <NUM> and the distance from the second oscillation axis BX to the second movable part <NUM>. The torsional rigidity of the shafts is determined by the cross-sectional area, the length, and the material of the first shaft parts <NUM> and the second shaft parts <NUM>. The distance from the second oscillation axis BX to the second movable part <NUM> is longer than the distance from the first oscillation axis AX to the first movable part <NUM>, and thus the second movable part <NUM> has a larger moment of inertia and a lower natural frequency than those of the first movable part <NUM>. Thus, by making the torsional rigidity of the second shaft parts <NUM> higher than the torsional rigidity of the first shaft parts <NUM>, the second movable part <NUM> is reduced in the moment of inertia and is increased in the natural frequency. Then, the natural frequency of the first movable part <NUM> and the natural frequency of the second movable part <NUM> are approximated to each other or, preferably, equal to each other.

When the natural frequency of the first movable part <NUM> and the natural frequency of the second movable part <NUM> are the same, the displacement time of the first movable part <NUM> and the displacement time of the second movable part <NUM> are the same, thus making the images output during the oscillation of the respective parts the same in appearance and suppressing degradation of image quality.

In the first embodiment, the first shaft parts <NUM> and the second shaft parts <NUM> are made of the same material. The first shaft parts <NUM> and the second shaft parts <NUM> have the same radial lengths L1 and L2. The first shaft parts <NUM> and the second shaft parts <NUM> have different cross-sectional areas. The cross-sectional area of the first shaft parts <NUM> is a width W1 × a thickness T1, whereas the cross-sectional area of the second shaft parts <NUM> is a width W2 × a thickness T2. The height of the torsional rigidity is proportional to the cross-sectional area, and thus the cross-sectional area of the first shaft parts <NUM> (the width W1 × the thickness T1) < the cross-sectional area of the second shaft parts <NUM> (the width W2 × the thickness T2) is set. The height of the torsional rigidity is inversely proportional to the axial length, and thus the length L1 of the first shaft parts <NUM> > the length L2 of the second shaft parts <NUM> may be set. The first shaft parts <NUM> and the second shaft parts <NUM> are made different from each other in at least one of the cross-sectional area, the length, and the material to make the torsional rigidity of the second shaft parts <NUM> higher than the torsional rigidity of the first shaft parts <NUM>. For example, when the thicknesses T1 and T2 of the first shaft parts <NUM> and the second shaft parts <NUM> are the same and the axial lengths L1 and L2 of the first shaft parts <NUM> and the second shaft parts <NUM> are the same, by making the width W2 of the second shaft parts <NUM> larger than the width W1 of the first shaft parts <NUM>, difference can be made so as to give the torsional rigidity of the second shaft parts > the torsional rigidity of the first shaft parts.

The following describes the drive signal applied from the drive circuit <NUM> to the actuators 12B. <FIG> is a graph illustrating a waveform of a drive signal of the drive unit.

As illustrated in <FIG>, the drive signal applied from the drive circuit <NUM> to the first actuators <NUM> is an electric signal, and the current value changes with the passage of time. In the following, the waveform representing a change in the current value with time of the drive signal is referred to as the waveform of the drive signal. The waveform of the drive signal is illustrated by a solid line in <FIG>. The drive signal has the same waveform repeated every cycle T. The cycle T includes a period T1 and a period T2, which is after the period T1 and is continuous with the period T1. The period T1 corresponds to a period in which an image when the optical axis of the light L is in a first position (an image not shifted by half a pixel) is displayed, whereas the period T2 corresponds to a period in which an image when the optical axis of the light L is in a second position (an image shifted by half a pixel) is displayed.

In a first period TA1 of the period T1, the drive signal changes the current value from a first current value A1 to a second current value A2. Here, the middle position <NUM> between the first current value A1 and the second current value A2 is a position at which the current value is <NUM>. In the first period TA1, the drive signal changes the current value linearly from the first current value A1 to the second current value A2 with the passage of time. That is to say, the drive signal has a current value of the first current value A1 at the start timing of the first period TA1, then changes the current value linearly from the first current value A1, and has a current value of the second current value A2 at the end timing of the first period TA1. The first current value A1 is a current value that can hold the first oscillating part <NUM> at a first angle D1 and is set in accordance with the value of the first angle D1. The second current value A2 is a current value that can hold the first oscillating part <NUM> at a second angle D2 and is set in accordance with the value of the second angle D2. The first current value A1 and the second current value A2 are current values opposite to each other in polarity, and their absolute values may be equal. <FIG> exemplifies that the first current value A1 is negative, whereas the second current value A2 is positive.

The length of the first period TA1 is a value corresponding to the natural frequency of the first oscillating part <NUM>. The first oscillating part <NUM> refers to the part of the optical path control mechanism <NUM> oscillating with respect to the support part <NUM> (the optical member <NUM>, the first movable part <NUM>, and the coils <NUM> in the first embodiment). That is to say, the length of the first period TA1 can be said to be a value corresponding to the natural frequency of the part oscillating with respect to the support part <NUM>. More specifically, the length of the first period TA1 is preferably substantially the same value as the natural period of the first oscillating part <NUM> and more preferably the same value as the natural period. The natural period is the inverse of the natural frequency. The term "substantially the same value" means that values that deviate from the natural period by about an error range are also acceptable. For example, when the deviation with respect to the natural period is within <NUM>% of the value of the natural period, it may also be "substantially the same value. " In the following, too, the description "substantially the same value" refers to the same meaning. The value of the natural period (the inverse of the natural frequency) is expressed as "<NUM>/f" [s] when the natural frequency is f [Hz].

The drive signal holds the current value at the second current value A2 in a second period TB1 of the period T1. The second period TB1 is a period that is after the first period TA1 and is continuous with the first period TA1. Increasing the natural frequency of the first oscillating part <NUM> is desirable, because doing so can shorten the first period TA1 and lengthen the second period TB1 (can lengthen it than the first period TA1, for example). Holding at the second current value A2 is not limited to the current value not changing strictly from the second current value A2 but may also include the current value shifting from the second current value A2 within the range of a certain value. The certain value here may be set to any value and may be a value <NUM>% of the second current value A2, for example.

Thus, in the period T1, the drive signal gradually changes the current value from the first current value A1 to the second current value A2 and, when the current value reaches the second current value A2, holds the current value at the second current value A2.

In a third period TA2 of the period T2, the drive signal changes the current value from the second current value A2 to the first current value A1. The third period TA2 can be said to be a period that is after the second period TB1 and is continuous with the second period TB1. More specifically, in the third period TA2, the drive signal changes the current value linearly from the second current value A2 to the first current value A1 with the passage of time. That is to say, the drive signal has a current value of the second current value A2 at the start timing of the third period TA2, then changes the current value linearly from the second current value A2, and has a current value of the first current value A1 at the end timing of the third period TA2.

The length of the third period TA2 is the value corresponding to the natural frequency of the first oscillating part <NUM>. More specifically, the length of the third period TA2 is preferably substantially the same value as the natural period (the inverse of the natural frequency) of the first oscillating part <NUM> and more preferably the same value as the natural period. In the third period TA2, the length of the third period TA2 is equal to the length of the first period TA1.

In a fourth period TB2 of the period T2, the drive signal holds the current value at the first current value A1. The fourth period TB2 is a period that is after the third period TA2 and is continuous with the third period TA2. The fourth period TB2 is a period that is before the first period TA1 and is continuous with the first period TA1. The fourth period TB2 is equal to the second period TB1. Increasing the natural frequency of the first oscillating part <NUM> is desirable, because doing so can shorten the third period TA2 and lengthen the fourth period TB2 (can lengthen it than the third period TA2, for example). Holding at the first current value A1 is not limited to the current value not changing strictly from the first current value A1 but may also include the current value shifting from the first current value A1 within the range of a certain value. The certain value here may be set to any value and may be a value <NUM>% of the first current value A1, for example.

Thus, in the period T2, the drive signal gradually changes the current value from the second current value A2 to the first current value A1 and, when the current value reaches the first current value A1, holds the current value at the first current value A1.

As described above, in the first embodiment, the waveform of the drive signal is trapezoidal, and the first period TA1 and the third period TA2, in which the current value changes, are the value corresponding to the natural frequency of the oscillating part 12A.

The broken line illustrated in <FIG> illustrates periods during which the light L is applied. It is preferable that the irradiation apparatus <NUM> do not apply the light L in the first period TA1 and apply the light L in the second period TB1. It is preferable that the irradiation apparatus <NUM> do not apply the light L in the third period TA2 and apply the light L in the fourth period TB2.

The following describes an oscillation pattern of the first oscillating part <NUM> by the application of the drive signal. <FIG> is a graph illustrating a one-axis oscillation pattern of the optical part.

As illustrated in <FIG>, the oscillation pattern of the first oscillating part <NUM> refers to the displacement angle (an angle about the first oscillation axis AX) of the first oscillating part <NUM> with time when the drive signal is applied to the first actuators <NUM>. In <FIG>, the oscillation pattern is illustrated by a solid line.

In the first period TA1, the drive signal changes the current value from the first current value A1 to the second current value A2. Thus, the first oscillating part <NUM> changes the displacement angle from the first angle D1 to the second angle D2 in the first period TA1. Here, the middle position <NUM> between the first current value D1 and the second current value D2 is a position at which the displacement angle of the first oscillating part <NUM> is zero.

In the second period TB1, the drive signal holds the current value at the second current value A2. Thus, the first oscillating part <NUM> holds the displacement angle at the second angle D2 in the second period TB1. Holding at the second angle D2 is not limited to the displacement angle not changing strictly from the second angle D2 but may also include the displacement angle shifting from the second angle D2 within the range of a certain value. The certain value here may be set to any value and may be a value <NUM>% of the second angle D2, for example.

In the third period TA2, the drive signal changes the current value from the second current value A2 to the first current value A1. Thus, the first oscillating part <NUM> changes the displacement angle from the second angle D2 to the first angle D1 in the third period TA2.

In the fourth period TB2, the drive signal holds the current value at the first current value A1. Thus, the first oscillating part <NUM> holds the displacement angle at the first angle D1 in the fourth period TB2. Holding at the first angle D1 is not limited to the displacement angle not changing strictly from the first angle D1 but may also include the displacement angle shifting from the first angle D1 within the range of a certain value. The certain value here may be set to any value and may be a value <NUM>% of the first angle D1, for example.

The light L is applied in the second period TB1 and the fourth period TB2. Thus, in the second period TB1, the light L is applied to the first oscillating part <NUM> held at the second angle D2, making the optical path of the light L the first position. In the fourth period TB2, the light L is applied to the first oscillating part <NUM> held at the first angle D1, shifting the optical path of the light L to the second position, and shifting the image by half a pixel.

In the optical path control apparatus <NUM> shifting the optical path by oscillating the optical member <NUM>, the optical member <NUM> is required to be stably oscillated. In the first embodiment, by setting the lengths of the first period TA1 and the third period TA2 to the value corresponding to the natural frequency of the first oscillating part <NUM>, the first oscillating part <NUM> is suppressed from vibrating in the second period TB1 and the fourth period TB2, and the first oscillating part <NUM> can be oscillated stably. That is to say, the lengths of the first period TA1 and the third period TA2 are the value corresponding to the natural frequency of the first oscillating part <NUM>, and thus the vibration of the first oscillating part <NUM> in the second period TB1 and the fourth period TB2 is suppressed, and the first oscillating part <NUM> can be oscillated stably. Thus, the first oscillating part <NUM> is oscillated at high speed and is stopped stably, and image degradation can be suppressed.

The drive signal applied to the first actuators <NUM> has been described as the drive signal applied from the drive circuit <NUM> to the actuators 12B. The drive signal applied to the second actuators <NUM> is the same, and a description thereof is omitted.

The following describes an action when the first oscillating part <NUM> and the second oscillating part <NUM> are oscillated. <FIG> is an illustrative diagram illustrating a two-axis oscillation pattern of the optical part.

In the optical path control mechanism <NUM> of the first embodiment, the first actuators <NUM> and the second actuators <NUM> forming the actuators 12B oscillate the first oscillating part <NUM> and the second oscillating part <NUM>, respectively, so as to repeat an attitude change from the first angle D1 to the second angle D2 and an attitude change from the second angle D2 to the first angle D1 about the first oscillation axis AX and the second oscillation axis BX each in accordance with the drive signal. The first oscillating part <NUM> and the second oscillating part <NUM> each repeat the oscillation between the first angle D1 and the second angle D2, whereby the optical axis of the light L repeats a shift from the first position to the second position and a shift from the second position to the first position.

That is to say, an image projected onto the screen by the light L when the optical axis is in the first position and an image projected onto the screen by the light L when the optical axis is in the second position are shifted by half a pixel. That is to say, the image projected on the screen repeats shifts by half a pixel and returns by half a pixel. This increases an apparent number of pixels and enables images projected onto the screen to have a higher resolution. The optical axis shift amount is equivalent to half a pixel of the image, and thus the first angle D1 and the second angle D2 are set to angles that can shift the image by half a pixel. The image shift amount is not limited to being equivalent to half a pixel but may be any amount such as <NUM>/<NUM> or <NUM>/<NUM> of a pixel, for example. The first angle D1 and the second angles D2 may be set as appropriate in line with the image shift amount.

The following gives a specific description. Here, the first oscillation axis AX direction and the second oscillation axis BX direction cross each other in an orthogonal direction and are parallel to a pixel arrangement direction. As illustrated in <FIG> and <FIG>, the image position P0 is a display position when the current value applied to the first actuators <NUM> and the second actuators <NUM> is zero, that is, when the displacement angle of the optical member <NUM> is zero. The A operating state is a state in which the optical member <NUM> has been oscillated by a certain angle about the first oscillation axis AX by the first actuators <NUM> to shift the image position P0 by <NUM>/<NUM> pixel in the second oscillation axis BX direction, and the optical member <NUM> has been oscillated by a certain angle about the second oscillation axis BX by the second actuators <NUM> to shift the image position P0 by <NUM>/<NUM> pixel in the first oscillation axis AX direction. That is to say, the A operating state is a state in which an image is displayed at an image position P1, in which the image position P0 has been shifted to ABXa, which is one of an ABX direction, which is a composite of a vector toward one side in the first oscillation axis AX direction and a vector toward one side in the second oscillation axis BX direction.

Similarly, the B operating state is a state in which an image is displayed at an image position P2, in which the image position P0 has been shifted to ABXb, which is one of the ABX direction, which is a composite of a vector toward one side in the first oscillation axis AX direction and a vector toward one side in the second oscillation axis BX direction. Similarly, the C operating state is a state in which an image is displayed at an image position P3, in which the image position P0 has been shifted to ABXc, which is one of the ABX direction, which is a composite of a vector toward one side in the first oscillation axis AX direction and a vector toward one side in the second oscillation axis BX direction. Similarly, the D operating state is a state in which an image is displayed at an image position P4, in which the image position P0 has been shifted to ABXd, which is one of the ABX direction, which is a composite of a vector toward one side in the first oscillation axis AX direction and a vector toward one side in the second oscillation axis BX direction.

The following describes oscillation patterns of the first oscillating part <NUM> and the second oscillating part <NUM> in the pixel operating state described above. <FIG> is a graph illustrating a two-axis oscillation pattern when the natural frequencies of the first shaft parts and the second shaft parts are different from each other, whereas <FIG> is a graph illustrating a two-axis oscillation pattern when the natural frequencies of the first shaft parts and the second shaft parts are the same.

In the following description, the oscillation pattern of the first oscillating part <NUM> refers to the displacement angle (an angle about the first oscillation axis AX) of the first oscillating part <NUM> with time when the drive signal is applied to the first actuators <NUM> and is illustrated by a solid line. The oscillation pattern of the second oscillating part <NUM> refers to the displacement angle (an angle about the second oscillation axis BX) of the second oscillating part <NUM> with time when the drive signal is applied to the second actuators <NUM> and is illustrated by a dotted line.

As illustrated in <FIG>, in the displacement period TA2-A, the drive signal changes the current value from the second current value A2 to the first current value A1 (refer to <FIG>). Thus, the first oscillating part <NUM> changes the displacement angle from the second angle D2 to the first angle D1 in the displacement period TA2-A. In the displacement period TA2-B, the drive signal changes the current value from the second current value A2 to the first current value A1. Thus, the second oscillating part <NUM> changes the displacement angle from the second angle D2 to the first angle D1 in the displacement period TA2-B.

In the displacement period TA1-C, the drive signal changes the current value from the first current value A1 to the second current value A2. Thus, the first oscillating part <NUM> changes the displacement angle from the first angle D1 to the second angle D2 in the displacement period TAL-C. In the displacement period TA1-D, the drive signal changes the current value from the first current value A1 to the second current value A2. Thus, the second oscillating part <NUM> changes the displacement angle from the first angle D1 to the second angle D2 in the displacement period TAL-D.

The displacement period TA2-A, the displacement period TA2-B, the displacement period TA1-C, and the displacement period TA1-D represent the periods of transition to the A operating state, the B operating state, the C operating state, and the D operating state described in <FIG>, respectively. When the natural frequencies of the first shaft parts <NUM> and the second shaft parts <NUM> are different from each other, the lengths of the displacement period TA2-A and the displacement period TA2-B are different from each other, for example, and thus the lengths of a display period TB2-A and a display period TB2-B, in which the current is maintained, are different from each other, thus making the A operating state and the B operating state different from each other in image appearance, and degrading image quality. The same is true for the C operating state and the D operating state. On the other hand, as illustrated in <FIG>, when the natural frequencies of the first shaft parts <NUM> and the second shaft parts <NUM> are the same, the lengths of the displacement period TA2-A and the displacement period TA2-B are the same, and thus the lengths of the display period TB2-A and the display period TB2-B, in which the current is maintained, are the same, thus making the A operating state and the B operating state the same in image appearance and suppressing degradation of image quality.

In the first embodiment, when the optical member <NUM> is oscillated in two axes, the torsional rigidity of the second shaft parts <NUM> as the center of the oscillation axis with a larger moment of inertia of the optical member <NUM> is set to be higher than the torsional rigidity of the first shaft parts <NUM> as the center of the oscillation axis with a smaller moment of inertia of the optical member <NUM>. Then, the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> approximate each other (are the same), and the lengths of the displacement periods TA1-C and TA2-A of the first oscillating part <NUM> and the lengths of the displacement periods TA1-D and TA2-B of the second oscillating part <NUM> become the same, and image degradation can be suppressed.

According to the invention, in the optical path control mechanism <NUM> oscillating the optical member <NUM> in a secondary manner, the lengths of the displacement periods TA1-C and TA2-A of the first oscillating part <NUM> and the lengths of the displacement periods TA1-D and TA2-B of the second oscillating part <NUM> are made the same to suppress image degradation. In this case, the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> are the same. This displacement time is proportional to the natural frequency of each of the oscillating parts <NUM> and <NUM>; as the natural frequency increases, the displacement time becomes shorter (the displacement speed increases), whereas as the natural frequency decreases, the displacement time becomes longer (the displacement speed decreases). When the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> correspond with an integer multiple (odd number) of the frame rate, the oscillating parts <NUM> and <NUM> cause unwanted vibration due to resonance, and the optical member <NUM> cannot be stopped stably.

Given these circumstances, in the optical path control apparatus <NUM> of the first embodiment, the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> are set to a value shifting from odd multiple values of the corresponding frame rate.

Specifically, according to the invention, the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> are set to a value within a range larger than an odd (n) multiple of the corresponding frame rate and smaller than an odd (n + <NUM>) multiple of the corresponding frame rate.

The optical path control mechanism <NUM> applies a drive signal with a trapezoidal waveform (a trapezoidal wave) to the first actuators <NUM> and the second actuators <NUM> by the drive circuit <NUM> to oscillate the first oscillating part <NUM> and the second oscillating part <NUM>. This trapezoidal wave can be expressed as the sum of trigonometric functions by Fourier series expansion. This equation of trigonometric functions can be expressed by fundamental and odd-order harmonics as described below and can be an approximation of the trapezoidal wave illustrated in <FIG>.

Thus, when odd-order harmonic components and the natural frequency correspond with each other, the vibration of the first oscillating part <NUM> and the second oscillating part <NUM> becomes larger. This phenomenon has been demonstrated in a case of being actually operated and measured.

The displacement time of the first oscillating part <NUM> and the second oscillating part <NUM> is proportional to the natural frequency of the first oscillating part <NUM> and the second oscillating part <NUM>. When the natural frequency of the first oscillating part <NUM> and the second oscillating part <NUM> corresponds with an odd multiple of the frame rate, the first oscillating part <NUM> and the second oscillating part <NUM> cause unwanted vibration due to resonance, and the optical member <NUM> cannot be stopped stably. Thus, in the first embodiment, the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> are set to be a frequency as large as possible and shifting from the frequency of an odd multiple of the frame rate.

That is to say, the natural frequency of the first oscillating part <NUM> and the second oscillating part <NUM> is set between the same frame rate × n (odd number) and the frame rate × (n + <NUM>), which is satisfied for all corresponding frame rates.

A plurality of frame rates are set in the display apparatus <NUM>. Thus, it is preferable to set the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> shifting from odd multiple values of the corresponding frame rates.

For example, when three frame rates, or <NUM>, <NUM>, and <NUM>, are corresponded, the natural frequency of the first oscillating part <NUM> and the second oscillating part <NUM> is set to a frequency satisfying the following three conditions. <MAT> <MAT> <MAT>.

That is to say, the natural frequency of the first oscillating part <NUM> and the second oscillating part <NUM> is in the following range.

Thus, in the optical path control apparatus <NUM> of the first embodiment, the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> are set to a value shifting from the odd multiple values of the corresponding frame rates.

Thus, the unwanted vibration of the first oscillating part <NUM> and the second oscillating part <NUM> due to resonance can be suppressed, and the optical member <NUM> can be stopped stably.

<FIG> is a sectional view of the optical path control mechanism according to a second embodiment, and <FIG> is a block diagram schematically illustrating a circuit configuration of the display apparatus. Members having the same functions as those of the first embodiment described above are denoted by the same symbols, and detailed descriptions thereof are omitted.

In the second embodiment, as illustrated in <FIG>, the optical path control apparatus <NUM> has the optical path control mechanism <NUM>, the control circuit <NUM>, and the drive circuit <NUM>.

The optical path control mechanism <NUM> has the oscillating part 12A including the optical member <NUM> and the actuators 12B oscillating the oscillating part 12A. The oscillating part 12A has the first oscillating part <NUM> and the second oscillating part <NUM>. The first oscillating part <NUM> oscillates by the first shaft parts <NUM> along the first oscillation axis AX with respect to the second oscillating part <NUM>. The second oscillating part <NUM> oscillates by the second shaft parts <NUM> along the second oscillation axis BX with respect to the support part <NUM>. The actuators 12B have the first actuators <NUM> and the second actuators <NUM>. The first actuators <NUM> oscillate the first oscillating part <NUM>, whereas the second actuators <NUM> oscillates the second oscillating part <NUM>.

The optical path control mechanism <NUM> oscillates the first oscillating part <NUM> and the second oscillating part <NUM> by the first actuators <NUM> and the second actuators <NUM> being driven by the drive circuit <NUM>. The drive circuit <NUM> applies a drive signal with a trapezoidal wave to the first actuators <NUM> and the second actuators <NUM> to oscillate the first oscillating part <NUM> and the second oscillating part <NUM>.

The natural frequency of the first oscillating part <NUM> and the second oscillating part <NUM> is set to a certain value as described in the first embodiment. The optical path control apparatus <NUM> sets the length of each displacement period based on the natural frequency of the first oscillating part <NUM> and the second oscillating part <NUM> and sets the trapezoidal wave of the drive signal in such a manner that the current value changes in the displacement period of the set length.

Incidentally, the parameters of the drive circuit <NUM>, including the trapezoidal wave of the drive signal, are adjusted in advance before being mounted on products. However, the natural frequency of a vibrating part may change due to, for example, variations and changes over time in the mounting of the optical path control mechanism <NUM>, the optical path control apparatus <NUM>, or the like on the display apparatus <NUM>, environmental changes, or the like. In this case, it is difficult to readjust the trapezoidal wave of the drive signal.

Given these circumstances, in the second embodiment, a vibration sensor is mounted on the optical path control apparatus <NUM>, and the trapezoidal wave of the drive signal is adjusted and set based on the frequency of the first oscillating part <NUM> and the second oscillating part <NUM> detected by the vibration sensor. The waveform of the drive signal is not limited to the trapezoidal shape but may be a staircase shape, a rectangular shape, or the like.

That is to say, the optical path control apparatus <NUM> has a vibration sensor <NUM> and a parameter setting unit <NUM> in addition to the optical path control mechanism <NUM>, the control circuit <NUM>, and the drive circuit <NUM>.

The vibration sensor <NUM> is mounted on the support part <NUM>. The vibration sensor <NUM> can detect the frequency of the first oscillating part <NUM> and the second oscillating part <NUM> as the oscillating part 12A. The parameter setting unit <NUM> adjusts and sets the trapezoidal wave of the drive signal applied to the first actuators <NUM> and the second actuators <NUM> by the drive circuit <NUM> based on the frequency of the first oscillating part <NUM> and the second oscillating part <NUM> detected by the vibration sensor <NUM>.

That is to say, a sine wave is applied (swept) to the first actuators <NUM> by the drive circuit <NUM> while gradually increasing its frequency from <NUM>. In this process, the vibration sensor <NUM> placed in the support part <NUM> measures the vibration of the first oscillating part <NUM>. The parameter setting unit <NUM> sets a frequency at which the first oscillating part <NUM> vibrates most significantly (resonates) as the natural frequency of the first oscillating part <NUM> based on the vibration of the first oscillating part <NUM> detected by the vibration sensor <NUM>.

Similarly, a sine wave is applied (swept) to the second actuator <NUM> by the drive circuit <NUM> while gradually increasing its frequency from <NUM>. In this process, the vibration sensor <NUM> placed in the support part <NUM> measures the vibration of the second oscillating part <NUM>. The parameter setting unit <NUM> sets a frequency at which the second oscillating part <NUM> vibrates most significantly (resonates) as the natural frequency of the second oscillating part <NUM> based on the vibration of the second oscillating part <NUM> detected by the vibration sensor <NUM>.

The control circuit <NUM> sets the trapezoidal wave of the drive signal, that is, the length of the displacement period based on the natural frequency of the oscillating parts <NUM> and <NUM> set by the parameter setting unit <NUM>. The control circuit <NUM> then sets the trapezoidal wave of the drive signal in such a manner that the current value changes in the displacement period of the set length.

Thus, in the optical path control apparatus <NUM> of the second embodiment, the vibration sensor <NUM> is mounted on the optical path control apparatus <NUM>, the vibration sensor <NUM> detects the natural frequency of the first oscillating part <NUM> and the second oscillating part <NUM>, and the parameter setting unit <NUM> adjusts and sets the waveform of the drive signal based on the frequency of the first oscillating part <NUM> and the second oscillating part <NUM> detected by the vibration sensor <NUM>. Thus, even if the natural frequency of the vibrating part changes due to variations and changes over time in the mounting of the optical path control mechanism <NUM>, the optical path control apparatus <NUM>, or the like on the display apparatus <NUM>, environmental changes, or the like, the drive waveform (the trapezoidal wave) for oscillating the first oscillating part <NUM> and the second oscillating part <NUM> can be easily adjusted when the display apparatus <NUM> is shipped. Even if the natural frequency deviates due to age-related deterioration of the components after shipment of the display apparatus <NUM>, the drive waveform (the trapezoidal waves) of the first oscillating part <NUM> and the second oscillating part <NUM> can be adjusted when necessary.

As described above, the optical path control apparatus according to the present embodiment includes the oscillating part 12A having the optical member (the optical part) <NUM> on which light is made incident, the first oscillating part <NUM> supporting the optical member <NUM>, and the second oscillating part <NUM> supporting the first oscillating part <NUM> in an oscillatable manner by the first shaft parts <NUM> and supported on the support part <NUM> in an oscillatable manner by the second shaft parts <NUM>, the first actuators <NUM> oscillating the oscillating part 12A about the first oscillation axis AX including the first shaft parts <NUM> with the first shaft parts <NUM> as supports, and the second actuators <NUM> oscillating the oscillating part 12A about the second oscillation axis BX including the second shaft parts <NUM> with the second shaft parts <NUM> as supports, in which the first oscillation axis AX crosses the second oscillation axis BX, and the torsional rigidity of the second shaft parts <NUM> is higher than the torsional rigidity of the first shaft parts <NUM>.

According to the optical path control apparatus of the present embodiment, the torsional rigidity of the second shaft parts <NUM>, which are on the outer side, is set to be higher than the torsional rigidity of the first shaft parts <NUM>, which are on the inner side, whereby the natural frequencies of the optical member <NUM> oscillating with the first shaft parts <NUM> as supports and the optical member <NUM> oscillating with the second shaft parts <NUM> as supports can be made close to each other. Thus, the image output during the oscillation of the optical member <NUM> by the first shaft parts <NUM> and the image output during the oscillation of the optical member <NUM> by the second shaft parts <NUM> can be made uniform in appearance to suppress degradation of image quality.

The optical path control apparatus according to the present embodiment sets the torsional rigidity of the first shaft parts <NUM> and the torsional rigidity of the second shaft parts <NUM> in such a manner that the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> fall within the preset certain range. Thus, by setting the displacement times of the first oscillating part <NUM> and the second oscillating part <NUM> to the same length, degradation of image quality can be suppressed.

In the optical path control apparatus according to the present embodiment, the first shaft parts <NUM> and the second shaft parts <NUM> are made different from each other in at least one of the cross-sectional area, the length, and the material to make the torsional rigidity of the second shaft parts <NUM> higher than the torsional rigidity of the first shaft parts <NUM>. Thus, the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> can be easily made close to each other.

In the optical path control apparatus according to the present embodiment, the light is light for an image, and the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> are set shifting from the odd multiple values of the corresponding frame rate. Thus, the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> are set shifting from the odd multiple values of the frame rate, whereby the resonance (unwanted vibration) of the first oscillating part <NUM> and the second oscillating part <NUM> can be suppressed, and the optical member <NUM> can be stopped stably. Thus, the image output during the oscillation of the optical member <NUM> by the first shaft parts <NUM> and the image output during the oscillation of the optical member <NUM> by the second shaft parts <NUM> can be made uniform in appearance to suppress degradation of image quality.

The optical path control apparatus according to the present embodiment sets the natural frequency of the first oscillating part <NUM> and the natural frequency of the second oscillating part <NUM> to the value within a range larger than the odd (n) multiple of the corresponding frame rate and smaller than the odd (n + <NUM>) multiple of the corresponding frame rate. Thus, the resonance (unwanted vibration) of the first oscillating part <NUM> and the second oscillating part <NUM> can be properly suppressed.

The optical path control apparatus according to the present embodiment includes the oscillating part 12A having the optical member (the optical part) <NUM> on which light is made incident, the actuators 12B oscillating the oscillating part 12A, the drive circuit <NUM> applying the drive signal with a waveform including the first period, in which the current value is changed and the second period, in which the current value is held, to the actuators 12B to oscillate the oscillating part 12A and to control the optical path of light passing through the optical member <NUM>, the vibration sensor <NUM> detecting the frequency of the oscillating part 12A, and the parameter setting unit <NUM> setting the drive signal with the waveform based on the frequency of the oscillating part 12A detected by the vibration sensor <NUM>.

According to the optical path control apparatus of the present embodiment, the vibration sensor <NUM> detects the frequency of the oscillating part 12A, and the parameter setting unit <NUM> sets the drive signal with the waveform based on the frequency of the oscillating part 12A, whereby the deviation of the waveform of the drive signal corresponding to the mounting positions of the components such as the optical member <NUM>, the oscillating parts, and the actuators 12B can be adjusted at any time. Thus, the waveform of the drive signal for driving the actuators 12B can be automatically adjusted to reduce the number of man-hours.

The display apparatus according to the present embodiment includes the optical path control apparatus <NUM> and the irradiation apparatus <NUM> irradiating the oscillating part 12A with the light L. The display apparatus <NUM> includes the optical path control apparatus <NUM> and can thereby stably oscillate the oscillating part 12A and suppress image degradation.

Although in the embodiments described above, the optical member <NUM> is supported in an oscillatable manner by the first shaft parts <NUM> along the first oscillation axis AX and is supported in an oscillatable manner by the second shaft parts <NUM> along the second oscillation axis BX, this is not limiting.

The optical path control apparatus <NUM> according to the present invention has been described; it may be implemented in various different forms other than the embodiments described above.

The illustrated components of the optical path control apparatus <NUM> are functionally conceptual and do not necessarily have to be physically configured as illustrated. That is to say, the specific form of each apparatus is not limited to illustrated one but may be functionally or physically distributed or integrated in arbitrary units in whole or in part in accordance with the processing burden and the usage of each apparatus.

The configuration of the optical path control apparatus <NUM> is implemented, for example, as software by a computer program or the like loaded onto a memory. In the above embodiments, the configuration has been described as functional blocks implemented by the cooperation of these pieces of hardware or software. That is to say, these functional blocks can be implemented in various forms by hardware alone, software alone, or a combination of them.

The present invention can make the image output during the oscillation of the optical part by the first shaft parts and the image output during the oscillation of the optical part by the second shaft parts uniform in appearance to suppress degradation of image quality.

Claim 1:
An optical path control apparatus (<NUM>) comprising:
an oscillating part (12A), the oscillating part (12A) having an optical part (<NUM>) on which light for displaying an image is made incident with a frame rate of the image, a first oscillating part (<NUM>) for supporting the optical part (<NUM>), and a second oscillating part (<NUM>) for supporting the first oscillating part (<NUM>) in an oscillatable manner by a first shaft part (<NUM>), the second oscillating part (<NUM>) being supported on a support part (<NUM>) in an oscillatable manner by a second shaft part (<NUM>);
a first actuator (<NUM>) configured to oscillate the oscillating part (12A) about a first oscillation axis (AX) including the first shaft part (<NUM>) with the first shaft part (<NUM>) as a support; and
a second actuator (<NUM>) configured to oscillate the oscillating part (12A) about a second oscillation axis (BX) including the second shaft part (<NUM>) with the second shaft part (<NUM>) as a support, wherein
the first oscillation axis (AX) crosses the second oscillation axis (BX),
torsional rigidity of the second shaft part (<NUM>) is higher than torsional rigidity of the first shaft part (<NUM>),
a natural frequency of the first oscillating part (<NUM>) and a natural frequency of the second oscillating part (<NUM>) are set to a value within a range larger than an odd (n) multiple of the corresponding frame rate of the image and smaller than an odd (n + <NUM>) multiple of the corresponding frame rate, and
the natural frequencies of the first oscillating part( <NUM>) and the second oscillating part (<NUM>) are the same around the respective oscillation axes (AX, BX).