Scanning device, driving condition setting method and scanning display module

Abstract

This application discloses a scanning device, a driving condition setting method, and a scanning display module. By configuring the frequency characteristics of the scanning device, the nonlinear characteristics caused by the combined influence of the resonant frequency on the actual response are effectively mitigated, and the scanning trajectory is made closer to the ideal motion trajectory, ensuring that the image display is orderly and accurate.

Description

Technical Field

[0001] This application relates to the field of scanning display technology, specifically to a scanning device, a driving condition setting method, and a scanning display module. Background Technology

[0002] Laser scanning display, as an emerging display imaging technology, can achieve scanning display using scanning devices such as micro-electro-mechanical systems (MEMS) scanning mirrors and fiber scanning displays (FSD). This technology can be applied to various display scenarios such as projection displays and near-eye displays.

[0003] In practical applications, in order to achieve better display results, the scanning device will be in a state of high-frequency vibration, and it will become a complex vibration system. Therefore, it is necessary to improve the design of the scanning device's own characteristics and driving conditions. Summary of the Invention

[0004] Therefore, the purpose of this application is to provide a scanning device, a driving condition setting method, and a scanning display module to improve the performance of the scanning device.

[0005] Based on one aspect of this application, embodiments of this application provide a scanning device, comprising at least: performing grid scanning when in an operating state, the scanning device comprising at least two scanning axes capable of vibration in a first direction and a second direction, the two scanning axes having different frequency characteristics, and the frequency characteristics of the two scanning axes satisfying:

[0006] Within the set frequency range, the number of significant peaks on the frequency response curve shall not exceed the set number.

[0007] Optionally, the set frequency range is determined based on the drive frequency applied to the scanning axis.

[0008] Optionally, the driving frequency includes: the frequency in the spectrum of the driving signal applied to the scanning axis whose amplitude meets the set conditions.

[0009] Optionally, the driving frequency includes: the frequency in the scan trajectory response spectrum of the scan axis whose amplitude meets the set conditions.

[0010] Optionally, the drive frequencies applied to different scan axes are different.

[0011] Optionally, the frequency response curve includes at least one of the following: impedance curve, phase curve, and frequency amplitude response curve.

[0012] Optionally, the scanning device includes: a fiber optic scanner and / or a MEMS scanning mirror.

[0013] Based on another aspect of this application, embodiments of this application provide a method for setting driving conditions for a scanning device, comprising at least:

[0014] At least determine the natural frequency corresponding to the scanning axis in the scanning device;

[0015] Based on the determined inherent frequency, a drive signal is applied to the scanning axis, and the amplitude pole frequency is determined according to the drive signal;

[0016] Based on the amplitude pole frequency and the preset frequency characteristic constraints, the driving frequency range of the driving signal used to drive the scanning axis is determined.

[0017] The driving conditions are set by using a defined driving frequency range, amplitude pole frequency, and frequency characteristic constraints.

[0018] Based on another aspect of this application, an embodiment of this application provides a scanning display module, which includes at least the aforementioned scanning device, light source, and control circuit;

[0019] Under the control of the control circuit, the light source outputs image light, which is then output via the scanning device to achieve scanning display.

[0020] Optionally, the scanning device includes: a fiber optic scanner and / or a MEMS scanning mirror.

[0021] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the technical solutions of this application. The objectives and other advantages of this application may be realized and obtained by means of the structures and / or processes particularly pointed out in the description, claims and drawings. Attached Figure Description

[0022] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0023] Figure 1a This is a schematic diagram of the structure of a scanning device called a fiber optic scanner provided in an embodiment of this application;

[0024] Figure 1b This is a schematic diagram of another fiber optic scanner provided in an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of a raster-based scanning trajectory affected by nonlinearity;

[0026] Figure 3 This is a schematic diagram of another type of raster-based scanning trajectory affected by nonlinearity;

[0027] Figure 4a This is a configured frequency response curve corresponding to the fast axis actuator and fiber cantilever of the fiber scanner provided in the embodiments of this application;

[0028] Figure 4b It is a schematic diagram of a frequency response curve with specific values;

[0029] Figure 4c This is another schematic diagram of frequency response curves with specific values;

[0030] Figure 5 This is a configured frequency response curve corresponding to the fast axis actuator and fiber cantilever of the fiber scanner provided in the embodiments of this application;

[0031] Figure 6 This is a configured frequency response curve corresponding to the fast axis actuator and fiber cantilever of the fiber scanner provided in the embodiments of this application;

[0032] Figure 7 This is a configured frequency response curve corresponding to the fast axis actuator and fiber cantilever of the fiber scanner provided in the embodiments of this application;

[0033] Figure 8 This is a configured frequency response curve corresponding to the slow axis actuator and fiber cantilever of the fiber scanner provided in this application embodiment;

[0034] Figure 9 This is a schematic diagram of the grid-format scanning trajectory of a fiber optic scanner based on its configured frequency characteristics;

[0035] Figure 10 This is a schematic diagram illustrating the steps of a method for setting driving conditions for a scanning device according to an embodiment of this application;

[0036] Figure 11 This is a frequency response curve of a configured Lissajous scan provided in an embodiment of this application;

[0037] Figure 12 This is a Lissajous scanning trajectory provided in an embodiment of this application;

[0038] Figure 13 This is a schematic diagram of the bending vibration of the piezoelectric ceramic tube provided in the embodiments of this application;

[0039] Figure 14 This is another fiber optic scanner provided in the embodiments of this application;

[0040] Figure 15This is a schematic diagram of a scanning display module provided in an embodiment of this application;

[0041] Figure 16 yes Figure 15 A detailed structural diagram;

[0042] Figure 17 This is a frequency response curve corresponding to the frequency multiplication of a fast shaft actuator provided in an embodiment of this application;

[0043] Figure 18 This is a frequency response curve of a MEMS scanning mirror provided in an embodiment of this application. Detailed Implementation

[0044] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0045] refer to Figure 1a This illustration shows a scanning device 10 according to an embodiment of this application, mainly including: an actuator 11 and an optical fiber 12. This scanning device 10 is also referred to as an optical fiber scanner. Figure 1a In this example, the actuator 11 is cylindrical in shape, and its specific structure can be a cylindrical tube or a cylindrical rod. When it is a cylindrical tube, the entire tube wall is made of piezoelectric material, and the inside of the tube can be filled with a filling material (such as epoxy resin). When it is a cylindrical rod, the entire rod body can be made of piezoelectric material. In this example, the actuator 11 has a through channel along the axial direction for mounting the optical fiber 12. One end of the actuator 11 is fixed to the fixing part 13 (this end can be referred to as the rear end), and the other end is free in space and not connected to the external fixing structure (this end can be referred to as the front end / free end). Of course, the cylindrical shape of the actuator 11 is only one possible structure, and in different embodiments, the overall shape of the actuator 11 is not limited to this. Figure 1a The cylindrical shape shown can also be square prism (the specific structure can be a square tube or square rod), triangular prism (the specific structure can be a triangular tube or triangular rod), sheet, etc.

[0046] The actuator 11 includes a first actuating part 110 and a second actuating part 112 in a rear-to-front direction. Electrodes are respectively arranged on the surfaces of the first actuating part 110 and the second actuating part 112 (not shown). Figure 1aAs shown in the figure, the piezoelectric material generates an actuating force based on the inverse piezoelectric effect. In this example, the actuator 11 can be manufactured using a one-piece molding process, while in other embodiments, the actuator 11 can also be a non-one-piece structure. For example, the first actuating part 110 and the second actuating part 112 are manufactured separately and connected together by means of bonding, welding, precision welding or connecting structures (such as threads, snaps) to form the actuator 11.

[0047] In some embodiments, the actuator 11 may also be provided with an isolation section 114, such as Figure 1b As shown, the isolation part 114 is located between the first actuation part 110 and the second actuation part 112. No electrodes are provided on the surface of the isolation part 114 and the isolation part 114 may not use piezoelectric material. In other words, the isolation part 114 does not vibrate autonomously.

[0048] exist Figure 1a In the example shown, the optical fiber 12 passes through the actuator 11 along its length axis and extends at the front end of the actuator 11 to form a cantilever structure 121, i.e., an optical fiber cantilever 121. Of course, in some embodiments, the optical fiber 12 may be bonded to the surface of the actuator 11 and extend at the front end of the actuator 11 to form an optical fiber cantilever, rather than being a through-type fiber.

[0049] In some examples, the actuator 11 is made of a piezoelectric material, enabling piezoelectric actuation. In other examples, the actuator 11 may be made of a non-piezoelectric material, actuating by means such as electromagnetic actuation, thermal actuation, or electrostatic actuation. When in operation, under the actuation of the actuator 11, the cantilever portion 121 of the optical fiber 12 extending beyond the actuator 11 can scan according to a set grid pattern trajectory. Of course, the scanning device 10 may also include a housing, lens, and mounting base, and in actual operation, the scanning device 10 needs to cooperate with other components, such as a light source and driving circuit, to achieve scanning display. For details, please refer to [reference needed]. Figure 15 , 16 The corresponding content will not be described in detail here. It should be understood that... Figure 1a and Figure 1b The shape and size of the scanning device 10 shown are exemplary; actual scanning devices may differ to some extent, for example: Figure 1a and Figure 1b The length of the first actuator 110 is greater than the length of the second actuator 112. In actual scanning devices, their lengths may be the same; for example, Figure 1a and... Figure 1bThe fixing part 13 in the figure is rectangular, but the fixing part in the actual scanning device may not be this shape, or it may not exist independently, but as part of the packaging structure. That is to say, the structural drawings shown in the embodiments of this application are for the purpose of understanding the solution and should not be construed as limiting the application.

[0050] For the actuator 11 in operation, the first actuating part 110 vibrates at a first frequency in a first direction (i.e., the Y-axis direction of the reference coordinate system in FIG1a), and the second actuating part 112 vibrates at a first frequency in a second direction (i.e., the Y-axis direction of the reference coordinate system in FIG1a). Figure 1a The first actuation unit 110 (in the X-axis direction of the reference coordinate system) vibrates at a second frequency. Generally, for raster scanning, the first frequency is less than the second frequency; therefore, in some examples, the first actuation unit 110 can also be called the slow-axis actuator 110, and the second actuation unit 112 can also be called the fast-axis actuator 112. Under the synergistic effect of the vibrations generated by the first actuation unit 110 and the second actuation unit 112, the fiber cantilever is driven to sweep along the raster pattern trajectory. Therefore, in the embodiments of this application, the first actuation unit 110 and the second actuation unit 112 can also be regarded as the two scanning axes of the fiber scanner.

[0051] In the embodiments of this application, both slow-axis and fast-axis actuators can have a natural frequency based on one or more properties. Generally, the natural frequency is the frequency characteristic of the device itself. In some examples, the natural frequency and the resonant frequency (or resonance frequency) are equivalent. The one or more properties mentioned include, but are not limited to: material, Young's modulus, cross-sectional second distance, density, cross-sectional area, length, and / or mode constant, etc. Typically, the natural frequencies of fast-axis and slow-axis actuators are different. It should also be noted that the natural frequency of the actuator in this application is not just a single frequency point, but a series of multiple frequency points distributed according to a certain pattern, that is, there are multiple orders.

[0052] Optical fibers can also possess inherent frequencies based on one or more properties, including but not limited to: fiber cantilever length, fiber cross-sectional shape, fiber cross-sectional dimensions, material, and refractive index. Similarly, the inherent frequencies of optical fibers also have multiple orders. Of course, the inherent frequencies of optical fibers mentioned in this application mainly refer to the inherent frequencies of the fiber cantilever.

[0053] Ideally, when the natural frequencies of the slow-axis actuator, the fast-axis actuator, and the fiber optic cable are matched, the fiber optic cantilever can achieve a larger swing amplitude during operation. For example, in some examples, the matching means that the natural frequency of the fast-axis actuator is equal to or close to the natural frequency of the fiber optic cable; in other embodiments, the matching means that at the same order, there is a difference between the natural frequencies of the fast-axis actuator and the fiber optic cable, such as a difference of tens to thousands of Hz; or, for example, a difference close to an integer multiple of their natural frequencies.

[0054] Some existing technologies often utilize the natural frequency of the actuator and / or the natural frequency of the optical fiber to obtain a larger fiber swing amplitude, thereby increasing the screen size or field of view. For example, Chinese Patent (CN102525384, A Two-Dimensional Raster Scanning Method for a Fiber Optic Cantilever Resonant Scanner) uses the natural frequency of the optical fiber to drive the scanner to obtain the maximum fiber swing amplitude. However, the inventors of this application have discovered that an optical fiber scanner operating at the resonant frequency point becomes a complex nonlinear vibration system, with both the actuator and the optical fiber responding nonlinearly. Nonlinear vibration will cause the optical fiber to vibrate instably, making it susceptible to interference and difficult to control. It may even cause the scanning trajectory to deviate from the ideal raster trajectory, potentially leading to issues such as… Figure 2 or Figure 3 As shown, such abnormal trajectories will severely affect the display effect of the image during image display.

[0055] The inventors of this application further discovered that not only does operating at the resonant frequency point cause strong nonlinear phenomena in the fiber optic scanner, but the frequency characteristics of the fiber optic scanner itself (such as the degree of closeness between the actuator's natural frequency and the fiber's natural frequency) also affect the overall nonlinear performance of the fiber optic scanner, and even amplify the influence of the actuator's nonlinearity on the whole, leading to abnormal scanning trajectories.

[0056] The natural frequencies of the actuators and optical fibers in a fiber optic scanner are affected by one or more of the aforementioned properties. Therefore, reasonable frequency characteristics can be configured during the design and manufacturing process to enable the fiber optic scanner to achieve good scanning and display effects. For a raster-type scanning fiber optic scanner, the fast and slow axis actuators have different frequency characteristics. When in a vibrating state, the excitation generated on the fiber optic cantilever is also different. Correspondingly, the response characteristics of the fiber optic cantilever to the two excitations are also different. Therefore, different frequency characteristics can be configured for the sub-vibration systems composed of the fast axis actuator and fiber optic cantilever, and the slow axis actuator and fiber optic cantilever.

[0057] Specifically, based on the aforementioned Figure 1a The fiber optic scanner shown is a reference. Figure 4aThis illustrates a configured frequency response curve corresponding to the fast-axis actuator 112 and fiber cantilever 121 of the fiber optic scanner, including impedance curve 41 and phase curve 42. Figure 4a The horizontal axis represents frequency; impedance curve 41 shows the change in impedance with frequency; phase curve 42 shows the change in phase with frequency. F1 to F4 are the resonant frequency points, and the driving frequency F... x 0 represents the frequency with the largest amplitude in the spectrum of the drive (voltage) signal applied to the fast-axis actuator 112, or in the spectrum of the scan trajectory response. The scan trajectory response spectrum can be considered as the spectrum of the response signal generated by the corresponding instrument or device, which is obtained from the response of the sub-vibration system composed of the fast-axis actuator 112 and the fiber optic cantilever 121 to the drive (voltage) signal.

[0058] Impedance curve 41 and phase curve 42 can both be measured using appropriate testing equipment (such as an impedance analyzer). Of course, Figure 4a The curve shown is within a specific frequency range. In actual operation, by setting frequency boundaries, curves within a larger or smaller frequency range can be measured.

[0059] for Figure 4a As shown, the impedance curve 41 and the phase curve 42 have similar line shapes, i.e., they are correlated. The peak on the impedance curve 41 (also called the impedance peak) can characterize the response characteristics or filtering characteristics of the excitation frequency within that frequency range; the peak on the phase curve 42 (also called the phase peak) can characterize the natural frequency of the fast-axis actuator and / or optical fiber. The peaks mentioned in the embodiments of this application generally refer to the line shape that bulges in the positive direction of the vertical axis.

[0060] The response characteristics of the fast-axis actuator 112 and the fiber optic cantilever 121 can be reflected by the impedance curve 41. Generally, in F... x Within a certain frequency range (representing the driving frequency applied to the fast-axis actuator 112), the fast-axis actuator 112 and the fiber optic cantilever 121 will respond to this F... x A frequency response is generated, which is reflected in the impedance curve 41 as a peak. However, for the sub-vibration system composed of the fast-axis actuator 112 and the optical fiber 12, the actual nonlinear process of the frequency response is more complex. As the fast-axis actuator 112 vibrates, the optical fiber cantilever 121, as the load of the fast-axis actuator 112, follows the vibration and generates an interaction force, which may affect the response characteristics of the fast-axis actuator 112 and change the inherent frequency characteristics of the device. This altered response characteristic will also be reflected in the impedance curve 41, causing a corresponding peak on the impedance curve 41.

[0061] Typically, the significance of the peaks on the impedance curve 41 (which may include peak size, sharpness, width, and other line shape characteristics) reflects the greater the interaction between the optical fiber and the actuator, and the greater their mutual influence. Therefore, in this embodiment, for the sub-vibration system composed of the fast-axis actuator 112 and the optical fiber cantilever 121, in order to minimize the impact of complex nonlinear vibration processes, the configured frequency characteristics must satisfy the following: within a set frequency range, the number of significant peaks on the impedance curve does not exceed a set number.

[0062] In some preferred embodiments of this application, the frequency characteristics of the configured fast-axis actuator 112 and fiber optic cantilever 121 satisfy the following: within the frequency range [0.6*F... x 0, 1.3*F x Within 0], the number of significant peaks on impedance curve 41 does not exceed 5.

[0063] To determine the significant peak, the resonance peak on phase curve 42 will be identified first, specifically based on the following formula:

[0064]

[0065] Among them, P i i represents the maximum value of the phase on the phase curve 42 within the aforementioned frequency range (i.e., the phase peak), where i is a positive integer.

[0066] P max This represents the maximum phase value of phase curve 42 within the aforementioned frequency range;

[0067] P min This represents the minimum phase value of phase curve 42 within the aforementioned frequency range;

[0068] D Pi For each phase maximum P within the above frequency range i The difference relative to the minimum phase value;

[0069] d Pi D within the above frequency range Pi The relative magnitude of the maximum phase difference.

[0070] Based on the above formula, if d Pi If P > 0.1, then P i The corresponding frequency is the resonant frequency that may have an impact; accordingly, this P i The corresponding peak can be considered as a resonance peak; if d Pi If P < 0.1, then P i The corresponding frequency is the resonant frequency whose influence can be ignored; accordingly, this P i The corresponding peak can be considered a non-resonance peak.

[0071] Based on the identified resonance peaks, significant peaks can then be further determined. Specifically, this can be based on the following formula:

[0072]

[0073] Among them, Z mxi The resonant frequency point F i With the next resonant frequency point F i+1 The maximum value on the impedance curve between;

[0074] Z mni The resonant frequency point F i With the previous resonant frequency point F i-1 The minimum value on the impedance curve between;

[0075] D i The resonant frequency point F i The corresponding impedance difference;

[0076] D max For all D within the aforementioned frequency range i The maximum value in;

[0077] d i The resonant frequency point F i The corresponding impedance difference and D max The relative size.

[0078] In this example, if d i ≥0.2, then the resonant frequency point F i The peak corresponding to the impedance curve is a significant peak; otherwise, it is not a significant peak.

[0079] refer to Figure 4b The figure shows a configured frequency response curve for the fast-axis actuator 112 and the fiber cantilever 121 within the frequency range [12000Hz, 25500Hz]. On the phase curve 42, there are five phase maxima, P1 to P5, with specific values ​​shown in the figure. Therefore, based on the aforementioned formula (1), in this example, the phase peaks P1 to P4 on the phase curve 42 are resonance peaks, and correspondingly, the frequencies corresponding to the phase peaks P1 to P4 are the resonance frequencies.

[0080] Taking a resonant frequency of 13700Hz as an example, at a resonant frequency of 13700Hz and the previous resonant frequency (which was not in...), Figure 4b Within the frequency range shown (i.e., to the left of the resonant frequency of 13700Hz and to the right of the previous resonant frequency), a minimum impedance value close to 13700Hz can be found on impedance curve 41. Figure 4bThe value is Z1 = 1209.0 Ω. Similarly, at the resonant frequency of 13700 Hz and the subsequent resonant frequency (i.e.,... Figure 4b Within the frequency range defined by 16825Hz, a maximum impedance value close to 13700Hz can be found on impedance curve 41. Figure 4b Given Z2 = 1936.2Ω, it is clear that Z2 > Z1. Based on the aforementioned formula (2), the impedance difference D1 = Z2 - Z1 corresponding to the resonant frequency of 13700Hz can be calculated. The impedance differences D2 to D4 corresponding to the other resonant frequencies are calculated in the same way, thus determining the maximum value D. max ( Figure 4b Let D1 be the integer part of the equation, and calculate d. i , i = 1 to 4. Therefore, it can be determined whether the peaks corresponding to the above four resonant frequencies on impedance curve 41 are significant peaks. In this example, after calculation, Figure 4b The resonant frequencies of 13700Hz, 21323Hz, and 24318Hz correspond to significant peaks on impedance curve 41. That is, the aforementioned frequency characteristics are satisfied.

[0081] refer to Figure 4c The figure shows another configured frequency response curve for the fast-axis actuator 112 and the fiber cantilever 121 in the frequency range [12000Hz, 25500Hz]. On the phase curve 44, there are 5 phase maxima, namely P1 to P5, and their specific values ​​are shown in the figure. Therefore, based on the aforementioned formula (1), in this example, the phase peaks P1 to P4 on the phase curve 44 are resonance peaks, and correspondingly, the frequencies corresponding to the phase peaks P1 to P4 are the resonance frequencies.

[0082] Furthermore, for the resonant frequencies corresponding to phase peaks P1 to P4, the impedance difference D on the impedance curve 43 can be calculated using the above formula (2). i And determine the maximum value D among them. max And calculate d i , i = 1 to 4. In this example, after calculation, Figure 4c The resonant frequencies of 13700Hz, 16825Hz, 21323Hz, and 24318Hz correspond to significant peaks on impedance curve 43. That is, the aforementioned frequency characteristics are satisfied.

[0083] On the impedance curve 41 mentioned above, the more significant the impedance peak corresponding to the fiber cantilever 121, the more significant the interaction between the fiber and the actuator, and the greater their mutual influence. This results in a relatively smaller voltage requirement for the corresponding piezoelectric actuator. Therefore, in this example, the resonant frequency of the fiber cantilever 121 can be configured approximately at the resonant frequency F2 or F3. It should be understood that the frequency characteristics of the fiber cantilever 121 can be designed or configured using finite element tools based on modeling and simulation of one or more of the aforementioned properties, which will not be elaborated upon here.

[0084] By configuring the frequency characteristics of the fiber optic scanner described above, a better scanning display effect can be achieved. This is because, for a vibration system like a grating-type scanning fiber optic scanner, the responses of the actuator and the fiber are nonlinear. The closer the response is to the resonant frequency of the actuator or fiber, the stronger the nonlinearity. This causes the fiber's motion trajectory to deviate further from the ideal vibration, making trajectory control difficult and leading to image display errors and inaccuracies, thus affecting the scanning display quality. If multiple resonant frequencies exist within the frequency range near the operating frequency, the actual response is the result of the combined effect of these frequencies, making the nonlinear process complex. Therefore, the number of significant resonant peaks on the impedance curve within the set frequency range should be minimized. Thus, in this example, by configuring the frequency characteristics of the sub-vibration system composed of the fast-axis actuator 112 and the fiber optic cable 12, the number of significant peaks within the set frequency range near the operating frequency is controlled below a set number. This effectively mitigates the nonlinear characteristics caused by the combined influence of the resonant frequencies corresponding to the significant peaks on the actual response, further making the fiber's motion trajectory closer to the ideal grating-type motion trajectory, ensuring orderly and accurate image display.

[0085] refer to Figure 5 The diagram shows another configured frequency response curve corresponding to the fast axis actuator 112 and fiber cantilever 121 of the fiber scanner. Figure 5 Impedance curve 51 and phase curve 52 are shown in the figure. F1 and F2 are the resonant frequency points. x 0 represents the frequency with the largest amplitude in the drive (voltage) signal spectrum applied to the fast axis actuator 112, or in the timing spectrum of the scan trajectory. The resonant frequency points F1 and F2 correspond to two impedance peaks Z2 and Z4 on the impedance curve 51, and two phase peaks P1 and P2 on the phase curve 52, respectively.

[0086] As a preferred example, the frequency characteristics of the configured fast-axis actuator 112 and fiber optic cantilever 121 satisfy the following: within the frequency range [0.6*F... x 0, 1.2*F x 0] within (i.e., Figure 5 (In the frequency range shown), the number of significant peaks on impedance curve 51 is 2. Figure 5 The intermediate impedance peaks Z2 and Z4 are significant peaks.

[0087] refer to Figure 6 The diagram shows another configured frequency response curve corresponding to the fast axis actuator 112 and fiber cantilever 121 of the fiber scanner. Figure 6 Impedance curve 61 and phase curve 62 are shown in the figure. F1 and F2 are the resonant frequency points. x 0 represents the frequency with the largest amplitude in the drive (voltage) signal spectrum applied to the fast-axis actuator 112, or in the timing spectrum of the scan trajectory. The resonant frequency point F1 corresponds to an impedance peak Z2 on the impedance curve 61 and a phase peak P1 on the phase curve 62. The peak shape of frequency point F2 on the impedance curve 61 is not obvious, and similarly, the peak shape on the phase curve 62 is also not obvious.

[0088] As a preferred example, the frequency characteristics of the configured fast-axis actuator 112 and fiber optic cantilever 121 satisfy the following: within the frequency range [0.6*F... x 0, 1.1*F x 0] within (i.e., Figure 6 In the frequency range shown, the impedance curve 61 has one significant peak, which is the impedance peak Z2.

[0089] refer to Figure 7 The diagram shows another configured frequency response curve corresponding to the fast axis actuator 112 and fiber cantilever 121 of the fiber scanner. Figure 7 Impedance curve 71 and phase curve 72 are shown in the figure. F1 to F5 are the resonant frequency points. x 0 represents the frequency with the largest amplitude in the drive (voltage) signal spectrum applied to the fast-axis actuator 112, or in the timing spectrum of the scan trajectory. The resonant frequency points F1 to F5 correspond to five impedance peaks Z2 to Z5 on the impedance curve 71. 10 There are five phase peaks P1 to P5 on phase curve 72.

[0090] As a preferred example, the frequency characteristics of the configured fast-axis actuator 112 and fiber optic cantilever 121 satisfy the following: within the frequency range [0.6*F... x 0, 1.3*F x 0] within (i.e., Figure 7 (In the frequency range shown), the number of significant peaks on impedance curve 71 is 5. Figure 5 Intermediate impedance peaks Z2~Z 10 All were significant peaks.

[0091] Regarding the frequency characteristics of the fast-axis actuator 112 and the fiber cantilever 121 of the fiber scanner as described above, generally speaking, the resonant frequency F1 corresponds to the resonant frequency of the fast-axis actuator 112, and the resonant frequency F2 corresponds to the resonant frequency of the fiber cantilever 121.

[0092] Therefore, in a preferred example, the frequency difference between the resonant frequencies F1 and F2 is greater than 1.2 kHz.

[0093] In another preferred example, the frequency difference between the resonant frequencies F1 and F2 is less than 5 kHz.

[0094] In a preferred example, the driving frequency F x The frequency difference between 0 and the resonant frequency F2 is less than 100Hz.

[0095] In some practical use cases, there may be scenarios where it is necessary to increase the drive frequency of the fast-axis actuator 112. The increased drive frequency may reach a multiple of the resonant frequency F2 of the fast-axis actuator 112, i.e., a frequency multiplication. (Reference) Figure 17 The diagram shows the frequency response curves of a fast-axis actuator 112 at its harmonics, including impedance curve 01 and phase curve 02. Figure 17 The diagram shows three octave points corresponding to the fast-axis actuator 112: 2kHz, 4kHz, and 6kHz. These three frequency points exhibit corresponding peaks on both the impedance curve 01 and the phase curve 02. This frequency characteristic can affect the operating state of the fast-axis actuator 112, easily leading to undesirable nonlinear responses.

[0096] Therefore, in a preferred example, the resonant frequency F2 of the fast-axis actuator 112 satisfies the frequency characteristics: within the frequency range (n*F2-200, n*F2+200), there is no significant peak on the impedance curve. Here, n represents a multiple, n = 2, 3, 4, 5...

[0097] It should be noted that since both the actuator and the optical fiber have multiple orders of natural frequencies, the frequency range mentioned above may include the natural frequencies of the actuator and / or the optical fiber of the corresponding orders. In this embodiment, the natural frequency of the fast-axis actuator 112 can be denoted as Fk. i The natural frequency of the fiber optic cantilever can be denoted as Ff. j Where i and j are both positive integers, corresponding to different orders of the natural frequency, such as: Fk2 represents the second natural frequency of the fast axis and Ff1 represents the first natural frequency of the fiber cantilever.

[0098] The i-th natural frequency Fp of the fast-axis actuator 112 i The j-th natural frequency Ff of fiber cantilever 121 jand driving frequency F x Between 0 and 0, the following situations may exist in terms of spectral position relationship:

[0099] F x 0>Fk i >Ff j ;Fk i >F x 0>Ff j ;Fk i >Ff j >F x 0;

[0100] F x 0>Ff j >Fk i ;Ff j >F x 0>Fk i ;Ff j >Fk i >F x 0.

[0101] Typically, the driving frequency F x The j-th natural frequency Ff of 0 and fiber cantilever 121 j The frequency difference between them does not exceed 1000Hz.

[0102] The above example describes the frequency characteristics of a sub-vibration system configuration consisting of fast-axis actuator 112 and fiber optic cantilever 121.

[0103] Based on the foregoing Figure 1a The fiber optic scanner shown is a reference. Figure 8 The diagram shows a configured frequency response curve corresponding to the slow-axis actuator 110 and fiber cantilever 121 of the fiber optic scanner. It includes impedance curve 81 and phase curve 82.

[0104] It should be noted that, for Figure 1a In the integrated fast and slow axis structure shown, the vibrations of the fast and slow axis actuators will couple to a certain extent when in operation. That is, the lower frequency vibration of the slow axis actuator is transmitted to the fast axis actuator, and correspondingly, the higher frequency vibration of the fast axis actuator is also transmitted to the slow axis actuator. Due to this coupling phenomenon, the slow axis actuator will also exhibit a certain degree of high-frequency response, which can be measured using the aforementioned testing equipment during actual testing. However, in practical applications, due to deviations in various process steps, strong coupling may occur between the fast and slow axis actuators, with the slow axis actuator exhibiting a frequency range [0.6*F]. x 0, 1.3*F xThe peaks within 0 correspond to the positions of each significant peak, indicating a strong coupling characteristic between the fast and slow axes. This characteristic will lead to a more complex fiber scanning trajectory, which should be avoided as much as possible.

[0105] Therefore, for the sub-vibration system composed of the slow-axis actuator 110 and the fiber optic cantilever 121, corresponding frequency characteristics can be configured:

[0106] In some examples, the relatively significant peaks measured on the frequency response curves corresponding to the aforementioned fast-axis actuator 112 and fiber cantilever 121 are relatively insignificant on the frequency response curves corresponding to the slow-axis actuator 110 and fiber cantilever 121, i.e., as shown... Figure 8 As shown, the peaks on impedance curve 81 are not significant, and phase curve 82 presents messy information similar to noise signals, with no obvious bulges.

[0107] In some examples, Figure 8 In the frequency range corresponding to the frequency response curve shown, the frequency is related to F. x Peaks within 500Hz of each other are not significant. If a peak is the most significant peak in this frequency range, then it satisfies: (Z mx - Z mn ) / (Z mx +Z mn )≤5%; of which, Z mx Z represents the impedance maximum corresponding to the most significant peak. mn This is the impedance minimum value adjacent to the most significant peak on impedance curve 81.

[0108] In some examples, the frequency response curves corresponding to the fast and slow axis actuators are closest to F. x The peaks of 0 (not necessarily significant peaks, but mainly those with obvious bulges on the phase curve) are offset from each other by a distance greater than 80Hz.

[0109] Similarly, in some practical use cases, there may be scenarios where it is necessary to increase the driving frequency of the slow-axis actuator 110, which will also be affected by the harmonics. Therefore, in some preferred examples, the resonant frequency Fm of the slow-axis actuator 110 satisfies the following frequency characteristics: within the frequency range (n*Fm-20, n*Fm+20), there is no significant peak on the impedance curve. Here, n represents the multiple, n = 2, 3, 4, 5...

[0110] Additionally, in some superior examples, within the frequency range (0.9*n*F) y ,1.1*n*F y (This frequency range is not within) Figure 8 (As shown in the figure), there is no resonance peak. Among them, F yIt is the driving frequency applied to the slow axis actuator 110; n = 2, 3, 4, 5...

[0111] Based on the frequency characteristics of the fiber optic scanner configured as described above, both the slow-axis actuator and fiber optic cantilever sub-vibration system and the fast-axis actuator and fiber optic cantilever sub-vibration system can reduce nonlinear response during operation under the effect of the configured frequency characteristics. On the one hand, by configuring the frequency characteristics of the slow-axis actuator and fiber optic cantilever sub-vibration system, strong coupling between the vibrations of the slow-axis actuator and the fast-axis actuator is avoided when the fiber optic scanner is in operation, reducing the complexity of the nonlinear process. On the other hand, by configuring the frequency characteristics of the fast-axis actuator and fiber optic cantilever sub-vibration system, the nonlinear characteristics caused by the combined influence of the resonant frequencies corresponding to significant peaks within the frequency range on the actual response are effectively mitigated, further making the fiber optic motion trajectory closer to the ideal grid-like motion trajectory. It is precisely because of the reasonable frequency characteristics that not only is the tolerance to deviations in the actual manufacturing process of the fiber optic scanner improved, but the fiber optic scanner is also more stable and controllable during operation, and the grid-like scanning trajectory is closer to the ideal trajectory, thereby ensuring the image display effect.

[0112] Based on the frequency characteristics of the configured fiber optic scanner, the grating pattern of the fiber optic scan during operation is as follows: Figure 9 As shown, it can be seen that, relative to Figure 2 , Figure 3 The scan trajectory shown is closer to the ideal trajectory using the grid-format scan trajectory of the fiber optic scanner with the configured frequency characteristics.

[0113] Based on the aforementioned frequency characteristics, appropriate driving conditions can be reasonably set for fiber optic scanners employing grating-based scanning trajectories. In this application embodiment, a method for setting driving conditions for a fiber optic scanner is provided, referencing... Figure 10 Here is a flowchart of the method, in which the structure described can be based on the aforementioned fiber optic scanner content, and specifically includes the following steps:

[0114] Step S1001: Determine the actuator natural frequency corresponding to the actuator in the fiber scanner and the fiber natural frequency corresponding to the fiber cantilever.

[0115] As mentioned earlier, both the actuator and the cantilever structure of the optical fiber in a fiber optic scanner have their own natural frequencies, namely, the actuator natural frequency and the optical fiber natural frequency. It should also be noted that for a raster-scanning fiber optic scanner, the fast and slow axes of the actuator have different natural frequencies. Therefore, the actuator natural frequencies mentioned here further include the slow axis natural frequency and the fast axis natural frequency. Both the actuator natural frequency and the optical fiber natural frequency can be determined based on one or more of their respective properties through methods such as finite element simulation and theoretical calculation. Of course, the specific simulation and calculation processes will not be described in detail here.

[0116] It should also be noted that the actuator natural frequency mentioned in step S1001 can be considered as the i-th natural frequency of the actuator, and correspondingly, the optical fiber natural frequency can be considered as the j-th natural frequency of the optical fiber. Here, the values ​​of i and j are both positive integers.

[0117] Step S1003: Based on the determined actuator natural frequency and fiber natural frequency, apply a driving signal to the actuator, and determine the amplitude pole frequency according to the applied driving signal.

[0118] In this embodiment, the amplitude pole frequency can be considered as the frequency with the largest amplitude in the spectrum of the driving (voltage) signal. In practical applications, the aforementioned amplitude pole frequency can be acquired by instruments with frequency acquisition and measurement functions, such as an impedance analyzer. As a feasible approach, the frequency of the driving voltage signal applied to the actuator can be continuously changed by adjusting the driving circuit, thereby determining the frequency with the largest amplitude (i.e., the amplitude pole frequency). Specifically, the frequency of the continuously changing driving voltage signal is within the safe operating frequency range of the actuator, so as not to damage the actuator. While adjusting the frequency of the driving voltage signal, the spectrum of the driving voltage signal is acquired and detected using appropriate instruments (such as the aforementioned impedance analyzer) to find the frequency point with the largest amplitude in the spectrum, which is then used as the amplitude pole frequency. The specific acquisition process will not be elaborated further here.

[0119] Step S1005: Determine the driving frequency range of the driving signal used to drive the actuator based on the amplitude pole frequency and the preset frequency characteristic constraint conditions.

[0120] Step S1007: The determined driving frequency range, amplitude pole frequency, and frequency characteristic constraints are used as driving conditions to complete the driving condition setting.

[0121] For the aforementioned step S1001, the method for determining the actuator's inherent frequency and the fiber's inherent frequency is as follows: obtain the actuator attributes corresponding to the actuator in the fiber scanner and the fiber attributes corresponding to the fiber; determine the actuator's inherent frequency through the actuator attributes; and determine the fiber's inherent frequency through the fiber attributes.

[0122] The actuator properties described herein may include one or more properties, including but not limited to: material, Young's modulus, cross-sectional second distance, density, cross-sectional area, length and / or mode constant, etc.

[0123] The fiber properties described herein may also include one or more properties, including but not limited to: fiber cantilever length, core diameter, material, refractive index, etc.

[0124] In some implementations, the actuator properties and fiber properties in the fiber optic scanner can be measured using appropriate equipment (e.g., length measuring equipment, material testing equipment, etc.). Reference Figure 3 The figure shows the impedance characteristic curve of a fiber optic scanner, which characterizes the impedance characteristics of the actuator and the optical fiber. The impedance characteristic curve can reflect the vibration characteristics of the actuator and the optical fiber in the fiber optic scanner, and the peak on the impedance characteristic curve corresponds to a certain natural frequency of the actuator or the optical fiber.

[0125] In actual grid scanning, two different driving signals with different driving frequencies need to be applied to the two actuation parts of the actuator, which will result in differences in the driving conditions of the fast axis and the slow axis in the actuator.

[0126] By performing the above step S1003, the amplitude pole frequency F for the fast axis actuator can be determined. x 0. Typically, the amplitude pole frequency can be considered as the frequency with the largest amplitude in the acquired fiber optic scan trajectory timing spectrum or the drive signal spectrum applied to the fast axis actuator.

[0127] In this application, the i-th natural frequency Fk of the fast-axis actuator i The j-th natural frequency Ff of the fiber optic cantilever j and the amplitude pole frequency F applied to the fast axis actuator x Between 0 and 0, the spectral position relationship can be referred to the aforementioned content.

[0128] For step S1005, in this embodiment of the application, the pre-set frequency characteristic constraint conditions further include the frequency characteristic constraint conditions of the fast axis actuator and the frequency characteristic constraint conditions of the slow axis actuator.

[0129] The frequency characteristic constraint of the fast-axis actuator includes at least a frequency range constraint coefficient and a threshold number of significant frequency peaks contained within the frequency range. In some embodiments, the frequency characteristic constraint of the fast-axis actuator may be: the frequency range constraint coefficient includes 0.6*F x 0 and 1.3*F x 0, the threshold number of significant frequency peaks is no more than 5. In some embodiments, the frequency characteristic constraint of the fast-axis actuator may be: the frequency difference between resonant frequencies F1 and F2 is greater than 1.2 kHz. In some embodiments, the frequency characteristic constraint of the fast-axis actuator may be: the frequency difference between resonant frequencies F1 and F2 is less than 5 kHz. In some embodiments, the frequency characteristic constraint of the fast-axis actuator may be: the driving frequency F x The frequency difference between 0 and the resonant frequency F2 is less than 100Hz. In some embodiments,

[0130] The frequency characteristic constraints of the slow-axis actuator are related to those of the fast-axis actuator. In some embodiments, the frequency characteristic constraints of the slow-axis actuator may be: a frequency range constraint coefficient including 0.6*F. x 0 and 1.3*F x 0, the threshold number of significant frequency peaks is 0; the phase curve exhibits cluttered information resembling noise signals, with no clearly discernible convex line shape. Regarding the significance of peaks on the curve, please refer to the aforementioned section on significance judgment, so it will not be repeated here.

[0131] By setting the above driving conditions, not only can the tolerance for deviations in the actual process of manufacturing the fiber optic scanner be improved, but the fiber optic scanner can also be made more stable and controllable in operation. In operation, the grid scanning trajectory of the fiber optic scanner is closer to the ideal trajectory, thereby ensuring the image display effect.

[0132] The above content pertains to grating-type fiber optic scanners. In practical applications, Lissajous scanning tracks can also be used for scanning display. Unlike grating-type scanners, Lissajous scanning synthesizes periodic trajectory signals in two orthogonal directions (x-axis and y-axis). To balance the frequency characteristics of the fiber and scanning utilization, the operating frequencies of the two scanning axes are typically close, and both are relatively high. Therefore, due to the significant difference in operating mode compared to grating-type scanners, its frequency characteristics also differ.

[0133] It should be noted that in some embodiments of this application, the frequency ratio of the two scanning axes of the Lissajous scan is close to 1.

[0134] like Figure 11Shows the frequency characteristic curve of a configured Lissajous scan in an embodiment of the present application. Among them, Figure 11 The impedance curve 201 and the phase curve 202 are shown, and F1 to F5 are resonance frequency points. In the scanning trajectory time sequence of the optical fiber or the spectrum of the scanner drive voltage signal, the two main spectrum components are F1 and F2, where F1 < F2.

[0135] In a preferred example, the resonance frequency of the piezoelectric device and the optical fiber frequency are placed between the two drive frequencies F1 and F2, that is:

[0136] F1 < FPi ≤ FFj < F2 or F1 < FFj ≤ FPi < F2

[0137] Among them, FPi is the i-th order resonance frequency of the actuator, and Ffj is the j-th order resonance frequency of the optical fiber.

[0138] Furthermore, similar to the aforementioned raster scan, in the frequency range [F1, F2], the most prominent peak can be found. The frequency corresponding to this peak is denoted as Fmax. If the impedance differences corresponding to multiple peaks are close to each other and the difference is within 1%, then the peak with the largest phase at the resonance frequency point is used as the most prominent peak, and its frequency Fmax satisfies: F1 ≥ 0.7 * Fmax, F2 ≤ 1.3 * Fmax.

[0139] In a preferred example, in the frequency range [F1, F2], the number of prominent peaks is no more than 5.

[0140] It should be noted that, Figure 11 in, F3, F4, and F5 can all be the resonance frequencies of the actuator, or can contain the resonance frequency of the optical fiber. In a preferred example, the resonance frequency of the optical fiber and the resonance frequency of a certain actuator are as close as possible, such as Figure 11 in F3 or F4, can be the resonance frequency of the optical fiber. Of course, Figure 11 is only an example. In actual applications, the frequency range [F1, F2] may contain 4 or 5 prominent peaks, and this should not be construed as a limitation to the present application.

[0141] In some other embodiments of the present application, the Lissajous scan form adopted can also be that there is a large frequency ratio between the two scan axes. That is to say, the scan trajectory of such Lissajous is very close to the raster scan trajectory. For example: as Figure 12 shown, shows the Lissajous scan trajectory when the frequency ratio of the two scan axes is: 240 Hz: 18 Hz.

[0142] For these embodiments, they have frequency characteristics similar to the aforementioned raster scan. Specifically, the frequency characteristics corresponding to the Lissajous scan are configured as:

[0143] In the frequency range (0.6*F) x 0, 1.3*F x Within 0), the number of significant peaks on the impedance curve does not exceed 5. Among them, F x 0 represents the drive frequency of the faster scan axis.

[0144] In a better example, the impedance curve shows no obvious resonance peaks in the frequency range (n*F2-200, n*F2+200), where n = 2, 3, 4, 5... Here, F2 is the resonant frequency of the optical fiber.

[0145] In a better example, the driving frequency of the slower scanning axis is Fy, and there is no resonance peak on its impedance curve in the frequency range (0.9*n*Fy, 1.1*n*Fy), where n = 2, 3, 4, 5...

[0146] By configuring the above frequency characteristics for this type of Lissajous scanning, on the one hand, the scanning method will be closer to the raster format, the pixel display sequence will be stronger, the display logic will be simpler, the chip processing will be easier, and hardware resources and overhead will be saved. Especially when the ratio of fast to slow axis frequencies is further increased, the saving of hardware resources is more significant compared to Lissajous displays with similar frequencies. On the other hand, a higher drive frequency for the slower scanning axis results in a higher resonant peak frequency when designing the fiber scanner, which can improve the device's vibration resistance. Furthermore, the drive frequency of the slower scanning axis can be made closer to the resonant peak, reducing the drive voltage, while also resulting in a smaller nonlinear response and a cleaner spectrum, which is beneficial for image display.

[0147] It should be noted that the above content uses the bending vibration mode of the actuator. (Reference) Figure 13 This illustrates an exemplary actuation method utilizing bending vibration modes for a slow-axis actuator or a fast-axis actuator in a piezoelectric ceramic tube configuration, specifically... Figure 13 The image shows an axial cross-section of a portion of the piezoelectric ceramic tube wall. The tube wall substrate 21 is made of piezoelectric ceramic material. Electrodes 22 are arranged on the inner and outer surfaces of the tube wall substrate 21. When an external driving signal is applied to the electrodes 22, the tube wall substrate 21 generates a piezoelectric effect and undergoes bending deformation. By applying a driving signal of a set frequency to the electrodes 22, the tube wall substrate 21 will undergo bending deformation at the set frequency. In practical applications, for the slow axis and the fast axis, the positions of the electrodes and the frequencies of the applied driving signals are different, thereby enabling the slow axis to bend and vibrate in a first direction at a first frequency, and the fast axis to bend and vibrate in a second direction at a second frequency.

[0148] Furthermore, in addition to the typical structure of the fiber optic scanner described above, the fiber optic scanner described in this application also includes other structural forms, see reference. Figure 14This illustrates another fiber optic scanner 200 in an embodiment of this application. While its overall structure also includes an actuator and an optical fiber, the actuator is not... Figure 1a The structure shown has independent fast and slow axes, from Figure 14 As can be seen, the actuator is generally rectangular in shape, with electrodes attached to its four cylindrical surfaces. Figure 14 Only two cylindrical surfaces are shown in the diagram, forming a four-electrode structure. A drive signal of the first frequency is applied to electrode P in the Y-axis direction. y The actuator is actuated in the Y-axis direction; a second frequency drive signal is applied to electrode P in the X-axis direction. x The actuator is mounted on the X-axis to actuate it, and the fixing part 204 is used to connect and fix it to a fixed structure such as a base. For the fiber optic scanner 200, electrodes P are attached to the actuator. y The two sides can be considered as the first actuation part, and electrodes P are attached to the actuator. x The two sides can be considered as the second actuation part. The actuation method of the fiber optic scanner 200 is also piezoelectric actuation, and it can adopt bending vibration mode. For details of the actuation method, please refer to the above. Figure 1b The corresponding content will not be elaborated on here.

[0149] In this embodiment of the application, based on the aforementioned fiber optic scanner, a scanning display module is also provided, as shown in the reference. Figure 15 This mainly includes:

[0150] The system includes a processing unit 100, a laser source module 110, a scanner module 120, an optical fiber 130, a source modulation circuit 140, a scanning drive circuit 150, and a beam combining unit 160.

[0151] The processing unit 100 may be a graphics processing unit (GPU), a central processing unit (CPU), or other chips, circuits, or combinations thereof with control and image processing functions, without any specific limitations.

[0152] During operation, the processing unit 100 can control the light source modulation circuit 140 to modulate the laser light source module 110 according to the image data to be displayed. The laser light source module 110 contains multiple monochromatic lasers, each emitting a beam of different colors. Figure 16 As can be seen, the laser array can specifically use red (R), green (G), and blue (B) lasers. The beams emitted by each laser in the laser source module 110 are combined into a single laser beam by the beam combining unit 160 and coupled into the optical fiber 130.

[0153] The processing unit 100 can also control the scanning drive circuit 150 to drive the scanner module 120 to perform scanning, thereby scanning and outputting the image beam transmitted in the optical fiber 130.

[0154] The light beam output by the scanner module 120 acts on a specific pixel location on the medium surface, forming a light spot at that pixel location. During the actual scanning process, the light beam output by the fiber optic cable 130 follows a pre-defined grid pattern, forming a light spot with corresponding image information (such as color, grayscale, or brightness) at each pixel location. Within one frame, the light beam traverses each pixel location at a sufficiently fast speed to complete the scanning of one frame of the image. Due to the "visual persistence" characteristic of human vision, the human eye cannot perceive the movement of the light beam at each pixel location, but instead sees a complete frame of the image.

[0155] Continue to refer to Figure 16 The following is an exemplary specific structure of the scanner module 120, including: an actuator 121, an optical fiber cantilever 122, a mirror assembly 123, a scanner housing 124, and a fixing member 125. The actuator 121 is fixed to the scanner housing 124 by the fixing member 125. The actuator 121 has a channel along its length axis, through which an optical fiber 130 passes, extending to form the optical fiber cantilever 122 at the front end of the actuator 121. During operation, driven by a scan drive signal, the actuator 121's slow axis 121a (also called the first actuation part) moves along the vertical direction (this vertical direction is parallel to the…)… Figure 15 , 16 The Y-axis in the reference coordinate system (in this application, the vertical direction can also be referred to as the first direction) vibrates, and its fast axis 121b (also referred to as the second actuator) vibrates along the horizontal direction (this horizontal direction is parallel to the reference coordinate system). Figure 15 , 16 The X-axis in the reference coordinate system (in this application, this horizontal direction can also be referred to as the second direction) vibrates, driven by the actuator 121. The front end of the fiber optic cantilever 122 performs a two-dimensional sweep according to a preset grid pattern trajectory and emits a light beam. The emitted light beam can then pass through the mirror assembly 123 to achieve scanning imaging. Generally, the structure consisting only of the actuator 121 and the fiber optic cable 130 (including the fiber optic cantilever 122 extending from the front end) can be referred to as a fiber optic scanner (Fiber Scanning Display, FSD).

[0156] The first and second directions mentioned are orthogonal to each other.

[0157] It should be noted that in the embodiments of this application, the descriptions of "rear end" and "front end" are generally determined according to the direction of beam transmission, that is, the direction from front to back is consistent with the direction of beam transmission. The rear end of the actuator refers to the end of the actuator used as a fixed end; the front end of the actuator refers to the other end of the actuator opposite to the rear end. In some embodiments, it can also be called the free end, which is the part of the actuator with the most significant deformation and amplitude. In addition, the light-emitting end of the fiber optic cantilever can also be called the front end of the fiber optic cantilever, or the free end of the fiber optic cantilever. Of course, the definitions and explanations of the concepts of free end, front end, or rear end here also apply to actuators, fiber optic cantilever, or other structures in other embodiments of this application. However, it should be noted that in subsequent embodiments of this application, for some structures that do not have the above-mentioned "front" and "rear" concepts, "fixed end" and "free end" will be used directly. Of course, such descriptions are only for the convenience of those skilled in the art to understand accurately and intuitively, and should not be considered as a limitation of this application.

[0158] The illustrative scanning display module described above is merely an example provided to facilitate understanding of the subsequent solutions in this application. In practical applications, the specific architecture within the scanning display module and the structure of each unit module are not limited to this. Figure 15 and Figure 16 As shown, changes may occur. For example, the light source modulation circuit 140 and the scanning drive circuit 150 may be combined into a processing circuit; the processing unit 100 may be independent of the scanning display module, rather than being a component of the scanning display module; and the actuator 121 in the scanner module 120 may be fixed by a base, rather than... Figure 16 The fasteners 125 are used for fixing, and other variations are not detailed here. In other words, the above examples should not be construed as limiting this application.

[0159] It should also be noted that the above embodiments illustrate the corresponding frequency characteristics using a fiber optic scanner as an example. For other types of scanning devices, such as microelectromechanical systems (MEMS) scanning mirrors, which use two-dimensional galvanometers (also with two scanning axes) to deflect the laser beam (grid scanning trajectory or Lissajous scanning trajectory), the device itself also has strong nonlinearity and coupling effects. The frequency characteristics described in this application are also applicable to such scanning devices.

[0160] Specifically, for MEMS scanning mirrors, the frequency characteristics of their scanning axes can be measured using a vibration tester or modal analyzer, for reference. Figure 18 The figure shows an amplitude-frequency response curve 1803 for a MEMS scanning mirror, in which... Figure 18 The horizontal axis represents frequency, with f1 to f3 indicating different orders of resonant frequencies; the vertical axis characterizes the change in vibration response amplitude (displacement or angle) of the MEMS scanning mirror as frequency changes. The two scanning axes of the MEMS scanning mirror also follow the aforementioned frequency characteristics, which can be found in the previous content, so they will not be elaborated further here.

[0161] The terms "first," "second," "first," or "second" as used in the various embodiments of this disclosure may modify various components regardless of their order and / or importance, but these terms do not limit the corresponding components. The above terms are configured only for the purpose of distinguishing one component from another.

[0162] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A scanning device, characterized in that, When in operation, the scanning device performs grid scanning, and includes at least two scanning axes capable of vibration in a first direction and a second direction. The two scanning axes have different frequency characteristics, and the frequency characteristics of the two scanning axes satisfy the following: Within the set frequency range, the number of significant peaks on the impedance curve, including the frequency response curves of impedance and phase, shall not exceed the set number. The set frequency range is determined based on the driving frequency applied to the scanning axis. The driving frequency includes the frequency in the spectrum of the driving signal applied to the scanning axis where the impedance characteristic amplitude meets the set condition, or the frequency in the spectrum of the scanning trajectory response of the scanning axis where the impedance characteristic amplitude meets the set condition. wherein the number of significant peaks on the impedance curve within the frequency interval [0.6*F x 0, 1.3*F x 0] is not more than 5; F x 0 is the frequency with the largest amplitude in the frequency spectrum of the drive signal applied to the fast-axis actuator, or in the frequency spectrum of the scan trace response; the significant peak is a peak on the impedance curve having a significant linear characteristic, wherein the linear characteristic comprises: the size of the peak, the degree of sharpness, the width.

2. The scanning device as described in claim 1, characterized in that, The drive frequencies applied to the different scan axes are different.

3. The scanning device as described in claim 1, characterized in that, The scanning device includes: a fiber optic scanner and / or a MEMS scanning mirror.

4. A method for setting driving conditions for a scanning device, characterized in that, The method includes at least: At least determine the natural frequency corresponding to the scanning axis in the scanning device; Based on the determined inherent frequency, a drive signal is applied to the scanning axis, and the frequency of the impedance characteristic amplitude pole is determined according to the drive signal. Based on the impedance characteristic amplitude pole frequency and the preset frequency characteristic constraint, the driving frequency range of the driving signal used to drive the scanning axis is determined; the preset frequency range is determined based on the driving frequency applied to the scanning axis, and the driving frequency includes the frequency in the spectrum of the driving signal applied to the scanning axis whose amplitude meets the preset condition, or the frequency in the spectrum of the scanning trajectory response of the scanning axis whose amplitude meets the preset condition. The driving conditions are set by using a defined driving frequency range, impedance characteristic amplitude pole frequency, and frequency characteristic constraint conditions. Among them, in the frequency range [0.6*F] x 0, 1.3*F x Within 0], the number of significant peaks on the impedance curve does not exceed 5; F x 0 is the frequency with the largest amplitude in the spectrum of the drive signal applied to the fast axis actuator, or in the spectrum of the scan trajectory response; the significant peak is a peak with significant linear characteristics on the impedance curve, wherein the linear characteristics include: peak size, sharpness, and width.

5. A scanning display module, characterized in that, It includes at least the scanning device, light source, and control circuitry as described in claim 1; Under the control of the control circuit, the light source outputs image light, which is then output via the scanning device to achieve scanning display.

6. The scanning display module as described in claim 5, characterized in that, The scanning device includes: a fiber optic scanner and / or a MEMS scanning mirror.

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