English:
[0002] Examples are disclosed that relate to scanning display systems. One example provides a display device comprising a controller, a light source, and a scanning mirror system. The scanning mirror system comprises a scanning mirror configured to scan light from the light source in at least one direction at a resonant frequency of the scanning mirror, and also comprises an electromechanical actuator system coupled with the scanning mirror and being controllable by the controller to adjust the resonant frequency of the scanning mirror.
[0004] FIG. 1 schematically shows an example display device.
[0005] FIG. 2 shows an example scanning mirror system including a first example electromechanical actuator system.
[0006] FIG. 3 shows a second example electromechanical actuator system.
[0007] FIGS. 4A-4B show a third example electromechanical actuator system.
[0008] FIG. 5 schematically shows an example circuit for adjusting the resonant frequency of a scanning mirror in a scanning mirror system.
[0009] FIG. 6 shows a flowchart illustrating an example method of adjusting the resonant frequency of a scanning mirror in a scanning mirror system.
[0010] FIGS. 7A-7B show an example of adjusting the mass of a scanning mirror during manufacturing to adjust the resonant frequency of the scanning mirror.
[0011] FIG. 8 shows a flowchart illustrating an example method of manufacturing a scanning display system.
[0012] Some scanning display systems may scan light from a light source in a first direction at a slower rate and a second direction at a faster rate to raster scan an image for display. In some examples, separate mirrors may be used for the different scan directions, while in other examples a same mirror may be used to scan in both directions. Various types of scanning mirrors may be used, including but not limited to microelectromechanical system (MEMS) mirrors.
[0013] Video data may have an associated line rate at which pixels are to be displayed in a horizontal direction, and a refresh or frame rate at which whole images or frames are to be displayed in a vertical direction. To achieve relatively fast line rates (e.g., greater than 20 kHz) for high resolution image display, a MEMS-based scanning mirror may be driven at its resonant frequency. To facilitate image display, such a mirror may be designed to have a resonant frequency that is a multiple (e.g. 400) of a desired frame rate so that scanning of each new image data frame begins at a consistent pixel location. However, as the resonant frequency is a function of the structure of the mirror (e.g. shape, mass, etc.), the actual harmonic frequency of a MEMS-based mirror may be somewhat different than the target harmonic frequency for which them mirror was designed, for example, due to manufacturing variances and to usage over time. This may lead to variances in the location at which scanning starts between frames, as the oscillating frequency of the mirror may not be an exact multiple of the frame rate. Further, different video data may have differing frame rates. A data buffer may be used as one possible mitigation strategy for such issues. However, this may add cost, complexity, and display latency, which may make this strategy untenable for display contexts where low display latency is desirable, such as in virtual or mixed reality head-mounted displays. Other mechanisms for compensating, such as a frame locking mechanism, may introduce similar undesirable issues.
[0014] Thus, examples are disclosed that relate to adjusting the resonant frequency of a scanning mirror in a display device to allow a harmonically oscillating scanning mirror to be synchronized with a video data frame rate. As described in more detail below, the disclosed examples may allow a display device to dynamically adapt operation to compensate for manufacturing variances in resonant frequency, variances in video data, and/or to adjust to changes in resonant frequency that may occur over time due to factors such as ageing, temperature, etc. In this way, proper frame display may be achieved without the inclusion of large buffers and/or frame locking mechanisms.
[0015] FIG. 1 schematically shows an example display device 100 in communication with a video source 102. Display device 100 includes a controller 104 operatively coupled to a scanning mirror system 106 and to a light source 108. Controller 104 is configured to control light source 108 to emit light based on video image data received from video source 102. Light source 108 may include any suitable light-emitting elements, such as one or more lasers. Light source 108 may output light in any suitable wavelength ranges - e.g., red, green, and blue wavelength ranges that enable the production of color images. In other examples, light source 108 may output substantially monochromatic light.
[0016] Scanning mirror system 106 comprises one or more scanning mirrors 110 controllable to vary an angle at which light from the light source is reflected to thereby scan an image. As mentioned above, scanning mirror system 106 may include a single mirror configured to scan light in horizontal and vertical directions, or separate mirrors for scanning in the horizontal and vertical directions. In other examples, scanning mirror system 106 may scan light in any other suitable manner via any suitable number of mirrors.
[0018] As mentioned above, scanning mirror system 106 may be configured to scan light in a horizontal direction via harmonic oscillation of a MEMS mirror. However, due to manufacturing tolerances and use-based factors, the actual resonant frequency of a MEMS- based scanning mirror may vary from a target scan rate. Accordingly, scanning mirror system 106 comprises an electromechanical actuator system 114 comprising one or more actuators 116 controllable to adjust the resonant frequency to synchronize the horizontal scan rate of scanning mirror(s) 110 to the line rate of received video. As described in more detail below, electromechanical actuator system 114 may be configured to change a tension in supports (flexures) that support the harmonically oscillating mirror 110, and/or change a distribution of mass in the mirror, to thereby adjust the resonant frequency at which the mirror oscillates.
[0019] FIG. 2 shows an example scanning mirror system 200 comprising a first example electromechanical actuator. Scanning mirror system 200 includes a MEMS mirror 202 attached to a frame 204 via a first flexure 206 and a second flexure 208. First and second flexures 206 and 208 may provide respective pivots via which mirror 202 can rotate and thereby change its angular orientation to vary the angle at which light from a light source is reflected. Mirror 202 may scan in a horizontal or vertical direction, depending upon an orientation in which scanning mirror system 200 is incorporated into a display device.
[0020] Scanning mirror system 200 further includes an electromechanical actuator system comprising a first actuator 212 coupled to frame 204 adjacent to first flexure 206, and a second actuator 214 coupled to the frame adjacent to second flexure 208. First and second actuators 212 and 214 are actuatable to adjust respective tensions in first and second flexures 206 and 208 in response to electrical signals. In the example depicted in FIG. 2, actuators 212 and 214 span respective gaps 215 in frame 204. Actuators 212 and 214 may apply respective forces across the gaps 215 that may be varied to adjust the tensions in flexures 206 and 208, and thereby adjust the resonant frequency of mirror 202. For example, upon receiving an electrical signal having a first polarity (e.g., positive), actuators 212 and 214 may apply a contractive force across gaps 215, thereby increasing the tensions in flexures 206 and 208 and the resonant frequency of mirror 202. An electrical signal having a second, different polarity (e.g., negative) may cause actuators 212 and 214 to apply a dilative force across gaps 215, thereby decreasing the tensions in flexures 206 and 208 and the resonant frequency of mirror 202. Further, the magnitude of force applied by actuators 212 and 214 to flexures 206 and 208 - and thus the magnitude of adjustment to the resonant frequency of mirror 202 - may be controlled by controlling the magnitude of an electrical signal applied to the actuators.
[0021] A controller (e.g., controller 104 of FIG. 1) may generate control signals for controlling the electromechanical actuator system of mirror system 200 to adjust the resonant frequency of mirror 202. To allow the controller to achieve and maintain a desired resonant frequency, the scanning mirror system 200 may comprise a feedback device 216 configured to sense the mirror motion (e.g. by sensing strain in flexure 208). Feedback device 216 may provide positive output in response to torsion of flexure 208 in a first direction, and negative output in response to torsion of the flexure in a second, opposite direction, wherein the degree of mirror motion may be indicated by the magnitude of the output signal from feedback device 216. While the depicted example shows a single feedback device 216 arranged on flexure 208, any other suitable number and arrangement of feedback devices may be used. Moreover, while described above as sensing strain, any other suitable sensor than a strain gauge may be used in other examples.
[0022] FIG. 3 shows another example scanning mirror system 300 comprising an electromechanical actuator system configured to adjust a resonant frequency of the scanning mirror system. Scanning mirror system 300 comprises a scanning mirror 302 coupled to a frame 304 via first and second flexures 306 and 308. In this example, the electromechanical actuator system includes a first actuator pair 310 coupled to frame 304 adjacent to first flexure 306, and a second actuator pair 312 coupled to the frame adjacent to second flexure 308. Each actuator of actuator pairs 310 and 312 spans respective gaps 314 in frame 304. The spacing of individual actuators away from flexures 306 and 308 on each side of flexures 306 and 308 may provide mechanical advantage, thereby enabling a greater range within which the flexure tensions and resonant frequency of mirror 302 can be adjusted.
[0023] The electromechanical actuator system of mirror systems 200 and 300 may utilize any suitable type of actuators. In some examples, each actuator may comprise a piezoelectric material that changes dimension based upon an applied voltage. In other examples, each actuator may comprise magnetic actuators, wherein a magnetic force between magnetic elements can be varied via electrical signal. In yet other examples, each actuator may comprise an electrostatic actuator, where an electric field between electrodes can be varied to adjust flexure tensions. As a further example, each electromechanical actuator may utilize one or more bimetallic strips, where differing coefficients of thermal expansion of different materials can be leveraged to vary the flexure tensions. Further, actuator(s) of an electromechanical actuator system may be arranged at any suitable location in a scanning mirror system. In some examples, frames 204 and 304 may be formed from micromachined silicon dies, and electromechanical actuators may be positioned on the same die surface as mirror 202 or 302, or on an opposing die surface.
[0024] In the above examples, a resonant frequency of a scanning mirror is adjusted by changing a tension in flexures supporting the mirror. In other examples, the resonant frequency may be adjusted by moving a mass coupled to the scanning mirror. FIGS. 4A-4B show an example scanning mirror system 400 including a mirror 402 coupled to a frame 404 via first and second flexures 406 and 408, and also including one or more movable masses 410A, 410B coupled to scanning mirror 402. Masses 410 may be of substantially equal mass and arranged on opposite sides of flexures 406 and 408 in a balanced configuration. FIG. 4A schematically shows a first state of mirror system 400 in which movable masses 410 are arranged in first respective positions (e.g. orientation and/or relative location) relative to mirror 402, while FIG. 4B shows a second state of the mirror system in which movable masses 410A, 410B are arranged at second respective positions relative to the mirror. In the second positions, movable masses 410A, 410B are moved farther away from an oscillation axis of the mirror relative to the mass distribution in the first position. Moving mass away from the oscillation axis may decrease the resonant frequency, while moving mass closer to the oscillation axis may increase the resonant frequency. In some examples, a spring arm may couple movable masses 410 to mirror 402 (or another suitable location in mirror system 400), enabling adjustment of the relative position of the movable masses and thus the resonant frequency of the mirror with suitable respective actuators 412A, 412B. Actuators 412 may assume any suitable form. For example, the masses coupled to mirror 402 may comprise a magnetic material, and actuators 412 may comprise an electromagnet configured for magnetic actuation of the masses. In other examples, actuators 412 may attract moveable masses 410 with electrostatic force. While FIG. 4B depicts movement of both moveable masses 410A, 410B, in other examples a single moveable mass may undergo actuation to adjust the resonant frequency of mirror 402. Further, while shown as comprising two movable masses coupled to mirror 402, any suitable implementation of a movable mass-based electromechanical actuator system is possible, which may include any other suitable number of movable mass(es) and/or coupling of movable mass(es) to other locations in mirror system 400.
[0025] FIG. 5 schematically shows an example circuit 500 for adjusting the resonant frequency of a scanning mirror in a scanning mirror system. Circuit 500 may be used to adjust the resonant frequency of the mirrors in mirror systems 110, 200, 300, and/or 400, for example. Circuit 500 may be at least partially implemented in controller 104 of FIG. 1, for example.
[0026] Circuit 500 interfaces with a scanning mirror system 502 that includes a scanning mirror having a resonant frequency at which the scanning mirror is driven by an oscillator driver 504. Mirror system 502 outputs a signal indicative of the resonant frequency of the mirror, which is amplified by an amplifier 506 and fed back into oscillator driver 504.
[0027] The amplified feedback signal indicating the resonant frequency of the scanning mirror of scanning mirror system 502 is received by a divider 507, which divides the resonant frequency by an integer (e.g., a number of horizontal lines in images scanned by mirror system 502), thereby producing a signal indicating a frame rate or vertical scan rate of the mirror system. This mirror frame rate is received by a phase detector 508, which also receives a signal indicative of the frame rate of video image data being displayed. Detector 508 compares the mirror frame rate with the video frame rate, and in response generates a signal that is fed to a tuning driver 510 to thereby generate a control signal for controlling an electromechanical actuator system of the scanning mirror system 502. The control signal may cause the electromechanical actuator to adjust the resonant frequency of the scanning mirror of scanning mirror system 502 such that the vertical scan rate of the mirror is synchronized with the frame rate of the video image data. In some examples, the control signal may cause the horizontal scan rate of the mirror to be synchronized with a line rate of the video image data. In other examples, a vertical scanning mirror, or other suitable scanning mirror, may be adjusted.
[0028] FIG. 6 shows a flowchart illustrating a method 600 of adjusting the resonant frequency of a scanning mirror in a scanning display device. At 602, method 600 includes receiving video image data from a video source. At 604, method 600 includes adjusting, via an electromechanical actuator system coupled with the scanning mirror, a resonant frequency of the scanning mirror based on a frame rate of the video image data. As indicated at 606, in some examples adjusting the resonant frequency may include synchronizing a horizontal scan rate of the scanning mirror with a multiple of the frame rate (e.g., the line rate of the video image data). In some examples, the scanning mirror may include a mirror attached to a frame via a first flexure and a second flexure, and adjusting the resonant frequency may include adjusting tensions of the first and second flexures. In such examples, as the resonant frequency may be adjusted via one or more piezoelectric actuators 608, via one or more bimetallic strips 610, via one or more magnetic actuators 612, and/or via one or more electrostatic actuators 614. Alternatively or additionally, as indicated at 616, the resonant frequency may be adjusted by redistributing a mass of the mirror via one or more movable masses.
[0029] As mentioned above, variances in manufacturing scanning mirrors for scanning mirror systems may result in mirrors having resonant frequencies that are slightly off a target resonant frequency. Thus, a process for manufacturing scanning mirrors may account for such variance by providing for the adjustment of the resonant frequency of a mirror during manufacture. For example, FIG. 7A shows a scanning mirror 700 formed with an initial mass corresponding to an initial resonant frequency. As the initial resonant frequency of mirrors formed via the manufacturing process may differ from a desired target resonant frequency, mirror 700 is formed with one or more sacrificial regions 702 configured as an area where a portion of mirror mass may be removed to adjust the resonant frequency to a target resonant frequency corresponding to the reduced mass. Sacrificial region 702 is shown as occupying a perimeter of mirror 700, but may be arranged at any other suitable location in the mirror.
[0030] The resonant frequency of the mirror may be initially measured, e.g. via a strain gauge or other suitable gauge, to determine a resonant frequency of the mirror. If the resonant frequency differs from the target resonant frequency, then an amount of, and location of, mass to be removed to achieve the target resonant frequency may be determined. In the example depicted in FIG. 7B, the measured resonant frequency of mirror 700 is less than the target resonant frequency, and a computed portion of mass is removed from sacrificial region 702 in the form of a notch 704. The resonant frequency again may be measured. In other examples, the measured resonant frequency of mirror 700 may be greater than the target resonant frequency, and a computed portion of mass may be added to the mirror in region 702 or another suitable location. Any suitable method of increasing or reducing the mass of mirror 700 may be used, including but not limited to material deposition or laser ablation. In this manner, mass may be added or removed until the target resonant frequency is reached or within a desired range.
[0031] FIG. 8 shows a flowchart illustrating a method 800 of manufacturing a scanning display system. At 802, method 800 includes forming a mirror having an initial mass and having an initial resonant frequency. Any suitable method of forming the mirror may be used, such as suitable photolithographic processes. At 804, method 800 includes measuring the resonant frequency. At 806, method 800 includes, when the resonant frequency is different than a target resonant frequency, then adjusting a mass of the mirror from the initial mass to an adjusted mass to achieve the target resonant frequency. Adjusting the mass of the mirror may include reducing the mass 808 by ablating a portion of the mass via a laser, or increasing the mass 810 by depositing a portion of added mass (e.g., via a suitable lithographic process). In some examples, the resonant frequency may be measured continuously during mass adjustment, while in other examples mass may be adjusted stepwise, with resonant frequency measurements performed between mass adjustment steps, until the target resonant frequency is reached or within a desired range. Since mirror manufacturing techniques, and techniques for adding mass to or removing mass from a mirror, may exhibit some degree of tolerance,“target resonant frequency” as used herein may refer in some examples to a range of target resonant frequencies (e.g., a desired target resonant frequency +1- 2 Hz). In these examples, configuring a mirror with a target resonant frequency may including configuring the mirror with a resonant frequency within the range of resonant frequencies referred to by the target resonant frequency.
[0032] Another example provides a display device comprising a controller, a light source, and a scanning mirror system comprising a scanning mirror configured to scan light from the light source in at least one direction at a resonant frequency of the scanning mirror, and an electromechanical actuator system coupled with the scanning mirror and being controllable by the controller to adjust the resonant frequency of the scanning mirror. In such an example, the display device alternatively or additionally may comprise an electronic circuit configured to generate a control signal to control the electromechanical actuator system by comparing the resonant frequency to a framerate of video received by the display device. In such an example, the electronic circuit alternatively or additionally may be configured to synchronize a scan rate of the scanning mirror with a multiple of a framerate of video received by the display device. In such an example, the scan rate may be a horizontal scan rate. In such an example, the scanning mirror may comprise a mirror attached to a frame via a first flexure and a second flexure. In such an example, the electromechanical actuator system may comprise a first actuator coupled to the frame adjacent to the first flexure and a second actuator coupled to the frame adjacent to the second flexure such that actuation of the first actuator and the second actuator adjusts tensions of the first flexure and the second flexure. In such an example, the first actuator and the second actuator alternatively or additionally may span respective gaps in the frame. In such an example, the electromechanical actuator system alternatively or additionally may comprise a first actuator pair coupled to the frame adjacent to the first flexure and a second actuator pair coupled to the frame adjacent to the second flexure. In such an example, the electromechanical actuator system alternatively or additionally may comprise a piezoelectric actuator. In such an example, the electromechanical actuator system alternatively or additionally may comprise a magnetic actuator. In such an example, the electromechanical actuator system alternatively or additionally may comprise an electrostatic actuator. In such an example, the electromechanical actuator system alternatively or additionally may comprise a movable mass coupled with the scanning mirror. In such an example, the electromechanical actuator system alternatively or additionally may comprise a bimetallic strip.
[0033] Another example provides, enacted on a scanning display device, a method comprising receiving video image data from a video source, adjusting, via an electromechanical actuator system, a resonant frequency of a scanning mirror coupled with the electromechanical actuator system based on a framerate of the video image data, and scanning, via the scanning mirror, light from a light source at the resonant frequency. In such an example, adjusting the resonant frequency may comprise synchronizing a horizontal scan rate of the scanning mirror with a multiple of the framerate. In such an example, the scanning mirror may comprise a mirror attached to a frame via a first flexure and a second flexure, and adjusting the resonant frequency may comprise adjusting tensions of the first flexure and the second flexure. In such an example, the tensions of the first flexure and the second flexure may be adjusted via a piezoelectric actuator. In such an example, adjusting the resonant frequency alternatively or additionally may comprise adjusting a position of a mass coupled with the scanning mirror.
[0034] Another example provides a method of manufacturing a scanning display system comprising forming a mirror with an initial mass corresponding to an initial resonant frequency, determining a resonant frequency of the mirror with the initial mass, and when the resonant frequency is different than a target resonant frequency, then adjusting a mass of the mirror from the initial mass to an adjusted mass such that the mirror has the target resonant frequency. In such an example, adjusting the mass of the mirror may comprise one or more of depositing a portion of added mass via a deposition process and ablating a portion of the mass via laser light.
[0035] It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and/or described may be performed in the sequence illustrated and/or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed.

中文:
[0002]公开了涉及扫描显示系统的示例。一个示例提供了包括控制器、光源和扫描镜系统的显示设备。扫描镜系统包括扫描镜,其被配置为以扫描镜的谐振频率在至少一个方向上扫描来自光源的光,并且扫描镜还包括机电致动器系统,机电致动器系统与扫描镜耦合,并且由控制器可控制以调整扫描镜的谐振频率。
[0004]图1示意性地示出了示例显示设备。
[0005]图2示出了包括第一示例机电致动器系统的示例扫描镜系统。
[0006]图3示出了第二示例机电致动器系统。
[0007]图4A-图4B示出了第三示例机电致动器系统。
[0008]图5示意性地示出了用于调整扫描镜系统中的扫描镜的谐振频率的示例电路。
[0009]图6示出了图示调整扫描镜系统中的扫描镜的谐振频率的示例方法的流程图。
[0010]图7A-图7B示出了在制造期间调整扫描镜的质量以调整扫描镜的谐振频率的示例。
[0011]图8示出了图示制造扫描显示系统的示例方法的流程图。
[0012]一些扫描显示系统可以以较慢的速率在第一方向上、并且以较快的速率在第二方向上扫描来自光源的光,以对用于显示的图像进行光栅扫描。在一些示例中,分开的反射镜可以用于不同的扫描方向,而在其他的一些示例中,同一反射镜可以用于在两个方向上扫描。各种类型的扫描镜可以被使用,包括但不限于微机电系统(MEMS)反射镜。
[0013]视频数据可以具有像素将以此在水平方向上被显示的相关联的行速率,并且具有整个图像或帧将以此在垂直方向上被显示的刷新速率或帧速率。为实现用于高分辨率图像显示器的相对快的行速率(例如,大于20kHz),基于MEMS的扫描镜可以以其谐振频率被驱动。为促进图像显示,这样的反射镜可以被设计为具有是期望的帧速率的倍数(例如,400)的谐振速率,使得每个新的图像数据帧的扫描在一致的像素位置处开始。然而,由于谐振频率根据反射镜的结构(例如,形状、质量等)而变化,基于MEMS的反射镜的实际谐波频率可以与反射镜针对其而被设计的目标频率稍微不同,例如,由于制造差异和随着时间的使用。这可以导致扫描开始的位置在帧之间的差异,因为反射镜的振荡频率可以不是帧速率的确切倍数。此外,不同的视频数据可以具有相异的帧速率。数据缓冲可以用作针对这样的问题的一个可能的缓解策略。然而,这可能增加成本、复杂性和显示延时,其可能使该策略对于期望低显示时延的显示情况(诸如在虚拟现实或混合现实头戴式显示器中)不成立。用于补偿的其他机制(诸如帧锁定机制)可能引入类似的不期望的问题。
[0014]因此,公开了涉及调整显示设备中的扫描镜的谐振频率以允许谐波振荡的扫描镜与视频数据帧速率同步的示例。如下面更详细地描述的,所公开的示例可以允许显示设备动态地使操作适于补偿谐振频率中的制造差异、视频数据中的差异,和/或适于为由于诸如老化、温度等因素可能随着时间发生的谐振频率的改变而调整。以这种方式,适当的帧显示可以在不包括大型缓冲和/或帧锁定机制的情况下实现。
[0015]图1示意性地示出了与视频源102通信的示例显示设备100。显示设备100包括操作地耦合到扫描镜系统106和光源108的控制器104。控制器104被配置为控制光源108基于从视频源102接收到的视频图像数据发射光。光源108可以包括任何合适的发光元件,诸如一个或多个激光器。光源108可以输出在支持彩色图像的产生的任何合适波长范围内的光,例如,红、绿和蓝波长范围。在其他的一些示例中,光源108可以输出大体上单色的光。
[0016]扫描镜系统106包括一个或多个扫描镜110,其可控制以使来自光源的光被反射的角度变化,以从而扫描图像。如上面所提及的,扫描镜系统106可以包括被配置为在水平方向和垂直方向上扫描光的单个反射镜,或者用于在水平方向和垂直方向上扫描的分开的反射镜。在其他的一些示例中,扫描镜系统106可以经由任何合适数目的反射镜以任何其他合适的方式来扫描光。
[0018]如上面所提到的,扫描镜系统106可以被配置为经由MEMS反射镜的谐波振荡在水平方向上扫描光。然而,由于制造公差和基于使用的因素,基于MEMS的扫描镜的实际谐振频率可以从目标扫描速率变化。相应地,扫描镜系统106包括机电致动器系统114,其包括一个或多个致动器116,一个或多个致动器116可控制以调整谐振频率,以将(多个)扫描镜116的水平扫描速率同步到接收到的视频的行速率。如下面更详细地描述的,机电致动器系统114可以被配置为改变支撑谐波振荡反射镜110的支撑件(挠曲件)中的张力,和/或改变反射镜中的质量分布,以从而调整反射镜振荡所处于的谐振频率。
[0019]图2示出了包括第一示例机电致动器的示例扫描镜系统200。扫描镜系统200包括经由第一挠曲件206和第二挠曲件208而附接到框架204的MEMS反射镜202。第一挠曲件206和第二挠曲件208可以提供相应的枢轴,反射镜可以经由枢轴旋转并且从而改变其角度定向,以使来自光源的光被反射的角度变化。取决于扫描镜系统200被并入到显示设备中的定向,反射镜202可以在水平方向或垂直方向上扫描。
[0020]扫描镜系统200还包括机电致动器系统,其包括与第一挠曲件206邻近地耦合到框架204的第一致动器212,以及与第二挠曲件208邻近地耦合到框架的第二致动器214。第一致动器212和第二致动器214可致动以响应于电信号来调整第一挠曲件206和第二挠曲件208中的相应张力。在图2中所描绘的示例中,致动器212和致动器214跨越框架204中的相应间隙215。致动器212和致动器214可以跨间隙215施加相应的力,其可以被变化以调整挠曲件206和挠曲件208中的张力,并且从而调整反射镜202的谐振频率。例如,在接收到具有第一极性(例如,正)的电信号时,致动器212和致动器214可以跨间隙215施加收缩力,从而增大挠曲件206和挠曲件208中的张力和反射镜202的谐振频率。具有不同的第二极性(例如,负)的电信号可以使致动器212和致动器214跨间隙215施加扩张力,从而减小挠曲件206和挠曲件208中的张力和反射镜202的谐振频率。此外,由致动器212和致动器214施加到挠曲件206和挠曲件208的力的幅度以及因此的对反射镜202的谐振频率的调整的幅度可以通过控制被施加到致动器的电信号的幅度而被控制。
[0021]控制器(例如,图1的控制器104)可以生成控制信号,控制信号用于控制镜系统200的机电致动器系统以调整反射镜202的谐振频率。为允许控制器实现并且维持期望的谐振频率,扫描镜系统200可以包括被配置为感测镜运动(例如,通过感测挠曲件208中的应变)的反馈设备216。反馈设备216可以响应于挠曲件208在第一方向上的扭转提供正输出,并且响应于挠曲件在相反的第二方向上的扭转提供负输出,其中镜运动的程度可以由来自反馈设备216的输出信号的幅度指示。虽然所描绘的示例示出了被布置在挠曲件208上的单个反馈设备216,但是任何其他合适数目和布置的反馈设备可以被使用。此外,虽然上面被描述为感测应变,但是不同于应变计的任何其他合适的传感器可以在其他示例中被使用。
[0022]图3示出了另一示例扫描镜系统300,其包括被配置为调整扫描镜系统的谐振频率的机电致动器系统。扫描镜系统300包括经由第一挠曲件306和第二挠曲件308而附接到框架304的扫描镜302。在该示例中,机电致动器系统包括与第一挠曲件306邻近地耦合到框架304的第一致动器对312,以及与第二挠曲件308邻近地耦合到框架的第二致动器对314。致动器对310和致动器对312中的每个致动器跨越框架304中的相应间隙314。个体致动器在挠曲件306和挠曲件308的每一侧离开挠曲件306和挠曲件308的间隔可以提供机械优势,从而支持挠曲件张力和反射镜302的谐振频率能够在其中被调整的更大范围。
[0023]镜系统200和镜系统300的机电致动器系统可以利用任何合适类型的致动器。在一些示例中,每个致动器可以包括基于所施加的电压改变尺寸的压电材料。在其他的一些示例中,每个致动器可以包括磁性致动器,其中磁性元件之间的磁力可以经由电信号而变化。在又一些其他实例中,每个致动器可以包括静电致动器,其中电极之间的电场可以被变化以调整挠曲件张力。作为另一的示例,每个机电致动器可以利用一个或多个双金属条,其中不同材料的相异的热膨胀系数可以被利用以使挠曲件张力变化。此外,机电致动器系统的(多个)致动器可以被布置在扫描镜系统中的任何合适的位置处。在一些示例中,框架204和框架304可以从微加工硅裸片形成,并且机电致动器可以与反射镜202或反射镜302被定位在同一裸片表面上,或者被定位在相对的裸片表面上。
[0024]在上面的示例中,扫描镜的谐振频率通过改变支撑反射镜的挠曲件中的张力而被调整。在其他的一些示例中,谐振频率可以通过移动耦合到扫描镜的质量块而被调整。图4A-图4B示出了示例扫描镜系统400,其包括经由第一挠曲件406和第二挠曲件408而附接到框架404的反射镜402,并且还包括耦合到扫描镜402的一个或多个可移动质量块410A、可移动质量块410B。在平衡的配置中,质量块410可以具有大致相等的质量并且被布置在挠曲件406和挠曲件408的相对侧上。图4A示意性地示出了镜系统400的第一状态,其中可移动质量块410被布置在相对于反射镜402的第一相应定位(例如,定向和/或相对位置)中,而图4B示出了镜系统的第二状态,其中可移动质量块410A、可移动质量块410B被布置在相对于反射镜的第二相应定位处。在第二定位中,可移动质量块410A、可移动质量块410B相对于第一定位中的质量分布,被移动而更加远离反射镜的振荡轴线。将质量块移动远离振荡轴线可以减小谐振频率,而将质量移动靠近振荡轴线可以增大谐振频率。在一些示例中,弹簧臂可以将可移动质量块410耦合到反射镜402(或者镜系统400中的另一合适位置),从而支持可移动质量块的相对位置的调整,并且因此支持利用合适的相应致动器412A、致动器412B对反射镜的谐振频率的调整。致动器412可以采取任何合适的形式。例如,耦合到反射镜402的质量块可以包括磁性材料,并且致动器412可以包括被配置用于质量块的磁性致动的电磁体。在其他的一些示例中,致动器412可以利用静电力吸引可移动质量块410。虽然图4B描绘了可移动质量块410A、可移动质量块410B两者的移动,但是在其他的一些实施例中,单个可移动质量块可以经历致动以调整反射镜402的谐振频率。此外,虽然被示出为包括耦合到反射镜402的两个可移动质量块,但是基于可移动质量块的机电致动器系统的任何合适的实现是可能的,其可以包括任何其他合适数目的(多个)可移动质量块和/或(多个)可移动质量块到镜系统400中的其他位置的耦合。
[0025]图5示意性地示出了用于调整扫描镜系统中的扫描镜的谐振频率的示例电路500。例如,电路500可以用于调整镜系统110、镜系统200、镜系统300、和/或镜系统400中的反射镜的谐振频率。例如,电路500可以至少部分地在图1的控制器104中被实现。
[0026]电路500与扫描镜系统502接合,扫描镜系统502包括具有谐振频率的扫描镜,扫描镜由振荡器驱动器504以谐振频率驱动。镜系统502输出指示反射镜的谐振频率的信号,其由放大器506放大并且被反馈到振荡器驱动器504中。
[0027]指示扫描镜系统502的扫描镜的谐振频率的经放大的反馈信号由除法器507接收,除法器507将谐振频率除以整数(例如,由镜系统502扫瞄的图像中的水平行的数目),从而产生指示镜系统的帧速率或垂直扫描速率的信号。该反射镜帧速率由相位检测器508接收,相位检测器508还接收指示被显示的视频图像数据的帧速率的信号。检测器508将反射镜帧速率与视频帧速率进行比较,并且作为响应生成馈送到调谐驱动器510的信号,以从而生成用于控制扫描镜系统502的机电致动器系统的控制信号。控制信号可以使机电致动器调整扫描镜系统502的扫描镜的谐振频率,使得反射镜的垂直扫描速率与视频图像数据的帧速率同步。在一些示例中,控制信号可以使反射镜的水平扫描速率与视频图像数据的行速率同步。在其他的一些示例中,垂直扫描镜或其他合适的扫描镜可以被调整。
[0028]图6示出了图示调整扫描显示设备中的扫描镜的谐振频率的方法600的流程图。在602处,方法600包括从视频源接收视频图像数据。在604处,方法600包括经由与扫描镜耦合的机电致动器系统,基于视频图像数据的帧速率调整扫描镜的谐振频率。如606处所指示的,在一些示例中,调整谐振频率可以包括将扫描镜的水平扫描速率与帧速率的倍数同步(例如,视频图像数据的行速率)。在一些示例中,扫描镜可以包括经由第一挠曲件和第二挠曲件而附接到框架的反射镜,并且调整谐振频率可以包括调整第一挠曲件和第二挠曲件的张力。在这样的示例中,如谐振频率可以经由一个或多个压电致动器608、经由一个或多个双金属条610、经由一个或多个磁性致动器、和/或经由一个或多个静电致动器被调整。备选地或者附加地,如在616处所指示的,谐振频率可以通过经由一个或多个可移动质量块重新分布反射镜的质量被调整。
[0029]如上面所提到的,制造用于扫描镜系统的扫描镜的差异可以导致反射镜具有稍微偏离目标谐振频率的谐振频率。因此,用于制造扫描镜的过程可以通过提供在制造期间对反射镜的谐振频率的调整而解决这样的差异。例如,图7A示出了扫描镜700,其被形成为具有对应于初始谐振频率的初始质量。由于经由制造过程而形成的扫描镜的初始谐振频率可能与期望的目标谐振频率不同,反射镜700被形成为具有一个或多个牺牲区域702,一个或多个牺牲区域702被配置为其中反射镜质量的一部分可以被移除以将谐振频率调整到对应于减少的质量的目标谐振频率的区。牺牲区域702被示出为占据反射镜700的周界,但是可以被布置在反射镜中的任何其他合适的位置处。
[0030]反射镜的谐振频率可以例如经由应变计或其他合适计量器被初始地测量,以确定反射镜的谐振频率。如果谐振频率与目标谐振频率不同,则将被移除以实现目标谐振频率的质量的量和位置可以被确定。在图7B中所描绘的示例中,反射镜700的所测量的谐振频率小于目标谐振频率,并且所计算的质量部分以缺口704的形式从牺牲区域702被移除。谐振频率可以再次被测量。在其他的一些示例中,反射镜700的所测量的谐振频率大于目标谐振频率,并且所计算的质量部分可以在区域702或另一合适的位置中被添加到反射镜。可以使用增大或减少反射镜700的质量的任何方法,包括但不限于材料沉积或激光烧灼。以这种方式,质量可以被添加或移除,直到目标谐振频率被达到或在期望的范围内为止。
[0031]图8示出了图示制造扫描显示系统的方法800的流程图。在802处,方法800包括形成具有初始质量和具有初始谐振频率的反射镜。可以使用形成反射镜的任何合适方法,诸如合适的光刻过程。在804处,方法800包括测量谐振频率。在806处,方法800包括,当谐振频率与目标谐振频率不同时,则将反射镜的质量从初始质量调整到经调整的质量以实现目标谐振频率。调整反射镜的质量可以包括通过经由激光烧蚀质量的一部分来减少质量808,或通过沉积添加质量的一部分来增加质量810(例如,经由合适的光刻过程)。在一些示例中,谐振频率可以在质量调整期间持续地被测量,而在其他的一些实例中,在谐振频率测量在质量调整步骤之间被测量的情况下,质量可以逐步地被调整,直到目标谐振频率被达到或者在期望的范围内为止。因为反射镜制造技术、以及用于将质量添加到反射镜或将质量从反射镜移除的技术可能表现出某种程度的公差,如本文中所使用的“目标谐振频率”在一些示例中可以指的是目标谐振频率的范围(例如,期望的目标谐振频率+/-2Hz)。在这些示例中,将反射镜配置为具有目标谐振频率可以包括将反射镜配置为具有由目标谐振频率所指的谐振频率的范围内的谐振频率。
[0032]另一示例提供了显示设备,其包括控制器、光源和扫描镜系统,扫描镜系统包括扫描镜和机电致动器系统,扫描镜被配置为以扫描镜的谐振频率在至少一个方向上扫描来自光源的光,机电致动器系统与扫描镜耦合,并且由控制器可控制以调整扫描镜的谐振频率。在这样的示例中,显示设备备选地或附加地可以包括电子电路,其被配置为通过将谐振频率与由显示设备接收到的视频的帧速率进行比较,来生成控制信号以控制机电致动器系统。在这样的示例中,电子电路备选地或附加地可以被配置为将扫描镜的扫描速率与由显示设备接收到的视频的帧速率的倍数同步。在这样的示例中,扫描速率可以是水平扫描速率。在这样的示例中,扫描镜可以包括经由第一挠曲件和第二挠曲件而附接到框架的反射镜。在这样的示例中,机电致动器系统可以包括与第一挠曲件邻近地耦合到框架的第一致动器和与第二挠曲件邻近地耦合到框架的第二致动器,使得第一致动器的致动和第二致动器的致动调整第一挠曲件的张力和第二挠曲件的张力。在这样的示例中,第一致动器和第二致动器备选地或附加地可以跨越框架中的相应间隙。在这样的示例中,机电致动器系统备选地或附加地可以包括与第一挠曲件邻近地耦合到框架的第一致动器对和与第二挠曲件邻近地耦合到框架的第二致动器对。在这样的示例中,机电致动器系统备选地或附加地可以包括压电致动器。在这样的示例中,机电致动器系统备选地或附加地可以包括磁性致动器。在这样的示例中,机电致动器系统备选地或附加地可以包括静电致动器。在这样的示例中,机电致动器系统备选地或附加地可以包括与扫描镜耦合的可移动质量块。在这样的示例中,机电致动器系统备选地或附加地可以包括双金属条。
[0033]另一示例提供了在扫描显示设备上进行的方法,其包括:从视频源接收视频图像数据;经由机电致动器系统,基于视频图像数据的帧速率,调整与机电致动器系统耦合的扫描镜的谐振频率;以及经由扫描镜,以谐振频率扫描来自光源的光。在这样的示例中,调整谐振频率可以包括将扫描镜的水平扫描速率与帧速率的倍数同步。在这样的示例中,扫描镜可以包括经由第一挠曲件和第二挠曲件而附接到框架的反射镜,并且调整谐振频率可以包括调整第一挠曲件的张力和第二挠曲件的张力。在这样的示例中,第一挠曲件的张力和第二挠曲件的张力可以经由压电致动器被调整。在这样的示例中,调整谐振频率备选地或附加地可以包括调整与扫描镜耦合的质量块的定位。
[0034]另一示例提供了制造扫描显示系统的方法,其包括:形成具有对应于初始谐振频率的初始质量的反射镜;确定具有初始质量的反射镜的谐振频率;以及当谐振频率与目标谐振频率不同时,则将反射镜的质量从初始质量调整到经调整的质量,使得反射镜具有目标谐振频率。在这样的示例中,调整反射镜的质量可以包括以下中的一项或多项:经由沉积过程沉积添加质量的一部分,以及经由激光烧蚀质量的一部分。
[0035]将理解,本文中所描述的配置和/或方法在本质上是示例性的,并且这些具体实施例或示例不以限制性的意义被考虑,因为诸多的变化是可能的。本文中所描述的例程和方法可以表示任何数目的处理策略中的一个或多个处理策略。如此,所图示和/或所描述的各种动作可以以所图示和/或所描述的序列、以其他序列、并行地被执行,或者被省略。同样地,上面所描述的过程的顺序可以被改变。