Fiber-optic swing feedback control method and projection display device

Abstract

This invention discloses a fiber optic swing feedback control method and a projection display device. The method is applied to a fiber optic scanner, which includes a piezoelectric actuator for driving the vibration of the fiber optic cable and an optical fiber disposed on the actuator. The method includes: during the operation of the fiber optic scanner, detecting the amplitude of the feedback signal generated on the actuator when the fiber optic cable vibrates; adjusting the driving voltage applied to the actuator so that the driving voltage and the amplitude of the feedback signal satisfy a mapping relationship, thereby maintaining the fiber optic swing at the fiber optic swing calibration value when the mapping relationship is established. This solution avoids the need for additional sensors, thus alleviating the technical problems of increased scanner module size, power consumption, cost, and production assembly complexity caused by adding sensors.

Description

Technical Field

[0001] This invention relates to the field of projection display, and more particularly to a fiber optic swing feedback control method and a projection display device. Background Technology

[0002] The imaging principle of fiber scanning display (FSD) is that a fiber scanner drives an optical fiber to move along a predetermined two-dimensional scanning trajectory, and modulates the light output of the light corresponding to each pixel of the image to be displayed. Then, the light corresponding to each pixel of the image to be displayed is projected onto the projection surface one by one through the optical fiber to form a projected image.

[0003] During projection display, precise control of the scanner's fiber optic scanning trajectory is required. Current technologies typically achieve scanner feedback control by adding external sensors to measure the vibration of the scanner or fiber optic cable. Methods include measuring scanner deformation, measuring scanner vibration information through magnetic or electric fields, or detecting the content of the image projected by the scanner using optical devices. These solutions all require additional sensors, inevitably increasing the size, power consumption, and cost of the scanner module, as well as increasing the complexity of production and assembly. Summary of the Invention

[0004] The purpose of this invention is to provide a fiber optic swing feedback control method and a projection display device to solve the technical problems that existing feedback control schemes all require additional sensors, which increases the size, power consumption, and cost of the scanner module, as well as the complexity of production and assembly.

[0005] To achieve the above-mentioned objective, a first aspect of the present invention provides a fiber optic swing feedback control method applied in a fiber optic scanner. The fiber optic scanner includes a piezoelectric actuator for driving fiber optic vibration and an optical fiber disposed on the actuator. The method includes:

[0006] During the operation of the fiber optic scanner, the amplitude of the feedback signal generated on the actuator when the fiber optic vibration is detected is measured.

[0007] The driving voltage applied to the actuator is adjusted so that the driving voltage and the amplitude of the feedback signal satisfy a mapping relationship, thereby maintaining the fiber swing amplitude at the fiber swing amplitude calibration value when the mapping relationship is established.

[0008] Optionally, the method for establishing the mapping relationship includes:

[0009] Within the operating temperature range of the fiber scanner, the fiber swing amplitude is maintained at the fiber swing amplitude calibration value to establish a mapping relationship between the driving voltage and the amplitude of the feedback signal.

[0010] Optionally, the mapping relationship refers to the calibration function of the feedback signal amplitude with respect to the driving voltage.

[0011] Optionally, adjusting the driving voltage applied to the actuator such that the driving voltage and the amplitude of the feedback signal satisfy a mapping relationship includes:

[0012] Calculate the error between the current amplitude value and the target amplitude value;

[0013] When the error is less than or equal to the threshold, the current driving voltage is taken, and the target amplitude value is updated according to the calculation result of the calibration function;

[0014] Based on the updated target amplitude value, after multiple iterations, the driving voltage and the current amplitude value are made to satisfy the calibration function.

[0015] Optionally, within the operating temperature range of the fiber optic scanner, the driving frequency of the actuator is located on one side of the resonance peak, where the resonance peak refers to the resonance peak formed by the interaction between the fiber optic cable and the actuator.

[0016] Optionally, the calibration function is a monotonically changing curve.

[0017] A second aspect of the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0018] A third aspect of the present invention provides a projection display device, comprising:

[0019] A memory on which computer programs are stored;

[0020] A processor for executing the computer program in the memory to implement the steps of the method as described in the first aspect.

[0021] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0022] In this embodiment of the invention, during the operation of the fiber optic scanner, the feedback signal generated by the vibration of the fiber optic cable on the piezoelectric actuator is detected, and the fiber optic scanner is controlled based on the feedback signal. This avoids the need for additional sensors, thereby alleviating the technical problems of increased scanner module size, power consumption, cost, and manufacturing / assembly complexity caused by adding sensors. This solution can achieve scanner feedback control without adding additional sensors, ensuring that the scanner's displayed image remains unchanged when external operating conditions change, while simultaneously reducing the size and weight of the feedback section of the scanner display module, and lowering the power consumption and cost of the scanner display module. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0024] Figure 1A This is a schematic diagram of the structure of a sheet scanner provided in an embodiment of the present invention;

[0025] Figure 1B This is a front view of the sheet scanner provided in an embodiment of the present invention;

[0026] Figure 1C This is a schematic diagram of the back of a sheet scanner provided in an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of a signal processing circuit provided in an embodiment of the present invention;

[0028] Figure 3A A schematic diagram of the amplitude control loop provided in an embodiment of the present invention;

[0029] Figure 3B A schematic diagram of a phase control loop provided in an embodiment of the present invention;

[0030] Figure 4 Impedance curves of scanner electrodes provided for embodiments of the present invention;

[0031] Figure 5 A schematic diagram of the resonance peak formed by the interaction between optical fiber and piezoelectric ceramic provided in an embodiment of the present invention;

[0032] Figure 6 Amplitude control block diagram provided for embodiments of the present invention;

[0033] Figures 7A-7B The target amplitude value A provided in the embodiments of the present invention dst A schematic diagram of the curve;

[0034] Figure 8 This is a schematic diagram of the relationship between the driving voltage and the feedback signal amplitude provided in an embodiment of the present invention;

[0035] Figures 9A-9B A schematic diagram illustrating the iterative process of the target amplitude PID controller provided in an embodiment of the present invention;

[0036] Figure 10 A phase control block diagram provided for an embodiment of the present invention;

[0037] Figure 11 A schematic diagram of the phase temperature correction function provided in an embodiment of the present invention;

[0038] Figure 12 A block diagram illustrating the feedback control principle provided in an embodiment of the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] First, the basic principles of the solutions in the embodiments of the present invention will be explained.

[0041] In this embodiment of the invention, the scanner actuator is mainly composed of piezoelectric ceramics. The scanner utilizes the inverse piezoelectric effect of the piezoelectric ceramics to convert electrical signals into mechanical vibrations. The vibration of the actuator drives the optical fiber fixed on the actuator to vibrate, thereby performing image scanning. Simultaneously, the piezoelectric ceramics exhibit the piezoelectric effect; when deformed by external force, polarization occurs inside the piezoelectric ceramic, causing opposite charges to appear simultaneously on the two opposing surfaces of the piezoelectric ceramic.

[0042] In this embodiment of the invention, the electrical signal generated by the deformation caused by the stress of the optical fiber acting on the piezoelectric ceramic when the optical fiber vibrates is used as a feedback signal to control the vibration of the scanner, thereby ensuring that the vibration amplitude and phase of the optical fiber are stable and do not change with the influence of external factors.

[0043] For a raster scanning scanner, there are two actuators, providing drive along the x-axis (fast axis) and y-axis (slow axis), respectively. Generally, the drive frequency along the y-axis is lower than that along the x-axis. Therefore, the two actuators can also be called the slow-axis actuator and the fast-axis actuator, respectively. The optical fiber sweeps along a raster-like trajectory under the combined effect of the vibrations generated by the two actuators. Therefore, for raster scanning, the two actuators can be considered as the two scanning axes of the fiber optic scanner. Since the fast-axis trajectory is amplified by fiber resonance, it is more susceptible to external influences. Changes in the trajectory can lead to changes in the displayed image and display anomalies, such as changes in fast-axis swing, image ellipticity, image squareness, and odd / even line overlap. Therefore, for raster scanning, feedback control of the fast-axis vibration is necessary.

[0044] For scanners using Lissajous scanning or spiral scanning, both the x-axis and y-axis are amplified by fiber resonance. Therefore, feedback control of the vibration in both directions of the fiber is required.

[0045] The feedback control method in this embodiment of the invention can keep the vibration amplitude and phase of the optical fiber unchanged in the initial state, thereby ensuring the stability of the image display.

[0046] In this embodiment of the invention, a feedback electrode needs to be set on the scanner in order to detect the feedback signal. The specific shape, size, position, and polarization of the feedback electrode will vary depending on the type and shape of the scanner.

[0047] In one possible implementation, the feedback electrodes can be positioned at the fixed point of the optical fiber, thereby enabling the detected electrical signals to more accurately reflect the operating status of the fiber. Each feedback signal is provided by a pair of symmetrically sized electrodes. Since the signal components generated in each pair of electrodes differ significantly from the interference signals, the interference signals can be greatly weakened and the effective signals obtained through simple addition and subtraction operations.

[0048] In this embodiment of the invention, the configuration of the feedback electrode is described using a sheet scanner as an example.

[0049] like Figures 1A-1C The diagram shows a schematic of the sheet scanner provided in an embodiment of the present invention. The scanner, from left to right, includes a slow-axis drive electrode 101, a fast-axis drive electrode 102, and a feedback electrode 103. The AB electrodes are a pair of feedback electrodes 103. The AB electrodes are located at the fiber optic fixing point. Each AB electrode includes a front electrode and a back electrode, which are respectively disposed on opposite sides of the scanner. The AB electrodes are of the same size, symmetrical about the fiber optic axis, and have the same polarization direction perpendicular to the electrodes. The back electrodes of the AB electrodes are connected as a single unit to form the common feedback electrode 1301.

[0050] When the sheet scanner performs scanning in a grid scanning mode, the target signal F(xf) detected by the feedback electrode 103 of the sheet scanner is the signal generated by the horizontal vibration of the optical fiber in the fast axis direction (hereinafter also referred to as the x direction), and other vibration signals are interference signals.

[0051] The feedback electrode 103 is simultaneously acted upon by the driving electrode and the optical fiber. Therefore, the signal generated by the feedback electrode 103 mainly includes the following types of signals.

[0052] F(xf) is the signal generated by the vibration of the optical fiber in the x-direction, which reacts on the feedback electrode 103.

[0053] F(xcf) is the signal generated by the vibration of the optical fiber in the xc direction (the direction perpendicular to the x direction, i.e., the y direction) and its reaction on the feedback electrode 103.

[0054] F(xd) is the signal generated by the driving electrode vibrating in the x direction and the driving signal coupled to the feedback electrode 103.

[0055] F(xcd) is the signal generated by the driving electrode vibrating in the xc direction and the driving signal coupled to the feedback electrode 103.

[0056] In the AB electrodes, the amplitudes of each signal component are equal, and their phases may be the same or close, or they may be out of phase (i.e., the phase difference is close to 180°). Therefore, by addition and subtraction, interference signals such as F(xcf), F(xd), and F(xcd) can be eliminated or reduced to obtain F(xf).

[0057] The signal components generated by electrodes AB are as follows.

[0058] The signal generated by electrode A is Sa = F(xd) + F(xcd) + F(xcf) + F(xf).

[0059] The signal generated by electrode B is Sb = F(xd) + F(xcd) + F(xcf) - F(xf).

[0060] Then, S = Sa - Sb = 2F(xf).

[0061] In this embodiment of the invention, since the A and B electrodes are the same size and symmetrically positioned, the amplitudes of the signal components generated by the A and B electrodes are the same. For the left and right vibration components of the optical fiber, when the optical fiber swings to the left, the left electrode is subjected to compressive stress and shrinks, while the right electrode is subjected to tensile stress and stretches. Since the polarization directions of the A and B electrodes are the same, the voltage amplitudes generated by the A and B electrodes are the same, but the directions are opposite.

[0062] For the vertical vibration components of the optical fiber, the stress acting on electrodes AB is in the same direction, resulting in voltage signals with the same phase. Components coupled from the driving signal are all in the same direction as the driving signal. Therefore, the target signal F(xf) can be obtained simply by subtracting the signals from electrodes AB.

[0063] In this embodiment of the invention, the reason for ensuring that the polarization directions of electrodes A and B are the same is that if the polarization directions of electrodes A and B are opposite, the signal phase of the horizontal vibration of the optical fiber acting on electrodes A and B will be the same, and the signal phase of the vertical vibration acting on electrodes A and B will be opposite. The signal components of electrodes A and B are as follows.

[0064] Sa=F(xd)+F(xcd)+F(xcf)+F(xf)

[0065] Sb=F(xd)+F(xcd)-F(xcf)+F(xf)

[0066] At this point, Sa + Sb = F(xd) + F(xcd) + 2F(xf)

[0067] Sa-Sb=2F(xcf)

[0068] It is evident that when the polarization directions of electrodes A and B are opposite, a pure F(xf) signal cannot be obtained through addition or subtraction.

[0069] The above signal analysis shows that when collecting feedback signals, since the back electrodes of the AB electrodes are connected as a common feedback electrode, the front electrodes of the AB electrodes are directly led out, which is the differential signal of the AB electrodes S = Sa - Sb = 2F(xf).

[0070] Then, the differential signal is processed by a signal processing circuit to extract amplitude and phase information. For example... Figure 2 As shown, the acquisition circuit includes a preamplifier, a multiplier, and a low-pass filter. The signal is amplified by the preamplifier, multiplied by a reference signal of the same frequency, and the DC voltage output after passing through the low-pass filter represents the phase of the signal. The DC voltage output after passing through the preamplifier and low-pass filter represents the amplitude of the signal. The two DC voltages are sampled by an analog-to-digital converter (ADC) and then sent to the controller for calculation.

[0071] In other embodiments, the number and shape of the feedback electrodes may vary depending on the type of scanner. For example, two or more pairs of feedback electrodes can be provided on the scanner. The arrangement of the feedback electrodes can be determined according to the scanner type, and the shape of the feedback electrodes can be square, circular, planar, curved, etc. Similarly, for multiple pairs of feedback electrodes, the difference between the effective signal and the interference signal generated by the multiple pairs of feedback electrodes can be used to weaken the interference signal and obtain the effective signal through calculation.

[0072] After the feedback signal is acquired, feedback control can be performed based on the acquired feedback signal. In this embodiment of the invention, the amplitude feedback control method and the phase feedback control method are described respectively, taking the grid scanning method as an example.

[0073] In this embodiment of the invention, the piezoelectric ceramic response characteristics of the scanner are stable when the temperature is stable. When the optical fiber is affected by conditions such as air pressure, contaminants, and root constraint, the vibration response characteristics of the optical fiber will change. At this time, the voltage signal generated by the optical fiber's reaction on the feedback electrode will change accordingly. For example... Figure 3A and Figure 3B As shown, Figure 3AThis is a schematic diagram of the amplitude control loop provided in an embodiment of the present invention. During the operation of the scanner, the current amplitude value A of the signal generated on the feedback electrode is detected. x Compare the current amplitude value A x and target amplitude value A dst . Figure 3B This is a schematic diagram of the phase control loop provided in an embodiment of the present invention. Similarly, during the operation of the scanner, the current phase value P of the signal generated on the feedback electrode is detected. x Compare the current phase value P x and target phase value P dst Then, a PID controller is used to control the amplitude and phase of the optical fiber respectively.

[0074] Next, we will explain the temperature compensation for fiber amplitude adjustment, phase adjustment, and correction signal in the xc direction.

[0075] Fiber optic amplitude adjustment temperature compensation

[0076] Since the scanner actuator is mainly composed of piezoelectric ceramics, which are temperature-sensitive devices, their response characteristics change when the ambient temperature changes. For example... Figure 4 As shown, Figure 4 This is the impedance curve of a certain electrode of the scanner provided in an embodiment of the present invention (in this specification, different colors are used in the figures for easy distinction). The impedance curve can be measured using a piezoelectric ceramic impedance analyzer.

[0077] from Figure 4 It can be seen that both the impedance and phase curves of the piezoelectric ceramic shift with temperature. When the driving frequency applied to the piezoelectric ceramic remains constant, the response amplitude and phase of the piezoelectric ceramic change. Similarly, since both the scanner driving electrode and the scanner feedback electrode are piezoelectric ceramics, temperature changes will lead to the following results.

[0078] (1) When the drive signal remains unchanged, the amplitude and phase of the scanner vibration will change when the ambient temperature changes, resulting in abnormal image display.

[0079] (2) When the fiber vibration remains constant, the amplitude and phase of the signal response of the feedback electrode will also change when the ambient temperature changes.

[0080] Therefore, in this embodiment of the invention, it is necessary to correct and compensate the feedback electrode signal. For example... Figure 5 As shown, Figure 5The resonance peaks within the green range are formed by the interaction between the optical fiber and the piezoelectric ceramic. Their frequencies are close to the natural frequency of the optical fiber. When the optical fiber is driven near this resonance peak, it is in a resonant state, amplifying the vibration of the piezoelectric ceramic. Therefore, in this embodiment of the invention, a frequency near this resonance peak needs to be selected as the fast-axis driving frequency.

[0081] In this embodiment of the invention, a driving frequency needs to be selected on one side of the resonance peak, such as... Figure 5 As shown in the two green areas, the driving frequency falls on the same side of this resonant peak throughout the entire operating temperature range of the scanner. Thus, the fast-axis response of the scanner exhibits a monotonic trend with temperature variation throughout the entire operating temperature range. Therefore, the calibration function A can be obtained by establishing a mapping relationship between the fast-axis driving voltage and the feedback signal amplitude under the condition of fixed fiber optic swing. dst =F axdst (V dx ), where A dst For the amplitude of the feedback signal, V dx This is the fast axis drive voltage.

[0082] After obtaining the calibration function, during the feedback control of the fiber optic swing, the fast axis drive voltage is adjusted to make the feedback signal amplitude A... dst With fast axis drive voltage V dx Satisfy A dst =F axdst (V dx This allows the actual swing amplitude of the optical fiber to be kept constant at the amplitude when the mapping relationship was established.

[0083] like Figure 6 As shown, Figure 6 The amplitude control block diagram provided in this embodiment of the invention adds correction control for the amplitude target value based on the amplitude control loop, including the following steps.

[0084] Once the amplitude control loop error is less than the threshold, the current fast axis drive voltage is taken, and the calibration function F is applied. axdst (V dx The calculation results are used to update the target amplitude value A. dst After multiple iterations, the amplitude value A x With driving voltage D x Ultimately, it will satisfy the function F. axdst (V dx This process controls the actual swing of the fast axis of the optical fiber to match the swing at the calibration time. The iterative process will be explained later in this manual.

[0085] Next, the amplitude control method in this embodiment of the invention will be described using actual measurement data from the scanner sample. The actual measurement data shows that the scanner that meets the design requirements yields the function F. axdst (V dx The curve exhibits a monotonically changing pattern.

[0086] The measurement data of scanner sample 1 is shown in Table 1, with the target amplitude value A. dst The curve is as follows Figure 7A As shown.

[0087] 10.7772 1.631361 788.764343 11.9472 1.582785 800.141907 12.9672 1.512326 799.124084 14.3672 1.469944 797.535339 15.3672 1.416226 800.588806 16.4672 1.355213 799.519043 17.4672 1.306732 799.721985

[0088] Table 1

[0089] The measurement data of scanner sample 2 is shown in Table 2, with the target amplitude value A. dst The curve is as follows Figure 7B As shown.

[0090] 22.3 0.945195 894.410095 23.9 0.926732 894.282104 25.4 0.911274 894.405029 26.5 0.887624 894.361084 27.4 0.858671 895.392639 28.4 0.835152 895.75885 29 0.810312 895.218567

[0091] Table 2

[0092] In this embodiment of the invention, as shown in Table 3, the graph represents the measured values ​​of the scanner sample. The data in Table 3 shows that the driving voltage is positively correlated with the fiber swing and the feedback signal amplitude. At a fixed temperature, the curve showing the relationship between the driving voltage and the feedback signal amplitude is an upward-sloping curve, as shown below. Figure 8 As shown.

[0093]

[0094] Table 3

[0095] Next, we will illustrate the iterative process with an example.

[0096] like Figure 9A As shown, Figure 9A The iterative process of the target amplitude PID controller provided in this embodiment of the invention when the P parameter is set to 1, wherein the P parameter refers to the proportional parameter.

[0097] Curve 1 shows the change in feedback signal amplitude as a function of drive voltage at a certain temperature. Curve 2 shows the functional relationship between the calibrated fast-axis drive voltage and feedback signal amplitude at different temperatures with a fixed fiber swing. axdst (V dx The curves are plotted. The intersection of curve 1 and curve 2 represents the fast axis drive voltage and feedback signal amplitude when the fiber swing reaches the calibrated value at the current temperature.

[0098] Assuming that at time t1, the amplitude control loop adjustment error is less than the threshold, the fast axis drive voltage D xWith feedback signal amplitude A x The corresponding point falls at point 1. The target value of the feedback signal amplitude is calculated based on the fast-axis drive voltage corresponding to point 1, and the calculated target value of the feedback signal amplitude is updated to the amplitude target A of the amplitude control loop. dst .

[0099] Then, wait for the amplitude control loop to adjust the fast axis drive voltage so that the feedback signal amplitude A x Equal to the updated magnitude target A dst Then, the point corresponding to the current fast axis drive voltage and the amplitude of the feedback signal falls at point 2.

[0100] Repeat the above process so that the point after the amplitude control loop is adjusted to the correct position will gradually approach the intersection of curve 1 and curve 2, thereby allowing the fiber optic swing to reach the calibrated value.

[0101] In this embodiment of the invention, by modifying the parameters of the target amplitude PID controller, the iteration process can be made smoother and the number of iterations can be reduced.

[0102] For example, if the P parameter is set to P<1, I=0, and D=0, the adjustment process will be optimized to... Figure 9B As shown, P, I, and D are the proportional, integral, and differential parameters, respectively.

[0103] Phase adjustment temperature compensation

[0104] like Figure 10 The diagram shown is a phase control block diagram provided in an embodiment of the present invention. Similar to the amplitude compensation principle, at different temperatures, with a fixed fiber swing amplitude, a function P is used to calibrate the phase value of the feedback signal and the amplitude of the feedback signal when the image's odd and even rows coincide. x =F pxdst (A x ), that is, the phase temperature correction function, such as Figure 11 The diagram shown is a schematic of the phase temperature correction function provided in an embodiment of the present invention.

[0105] For raster scanning, odd-row images refer to the scanning trajectory within the first half of a fast-axis scanning cycle; even-row images refer to the scanning trajectory within the second half of a fast-axis scanning cycle. During drive signal phase adjustment, maintaining the response phase of the fiber scanning trajectory at the response phase calibration value established when the above functional relationship was established ensures that the odd and even-row images remain aligned. Therefore, using the above function, the target phase value P is corrected in real-time based on the feedback signal amplitude. dst Then, the phase of the drive signal is adjusted through the phase control loop so that the phase of the feedback signal P is adjusted. x equals P dst This allows the odd and even rows of the image to remain overlapping.

[0106] In this embodiment of the invention, as shown in Table 4, the actual measured data of the scanner sample are presented.

[0107] 1.631361 788.764343 0.031168 1.582785 800.141907 -0.084231 1.512326 799.124084 -0.148407 1.469944 797.535339 -0.275246 1.416226 800.588806 -0.412165 1.355213 799.519043 -0.478997 1.306732 799.721985 -0.556608

[0108] As can be seen, the solution of this invention corrects the target value of the phase feedback controller by calibrating the relationship between the amplitude and phase of the feedback signal when the odd and even rows coincide under the same swing at different temperatures, thereby eliminating the influence of temperature changes on the phase response of piezoelectric ceramics and achieving phase control.

[0109] xc direction correction signal temperature compensation

[0110] like Figure 12 As shown in the previous embodiment, the xc direction refers to the direction perpendicular to the x direction. The amplitude control loop and the phase control loop can adjust the amplitude and phase of the driving voltage and the driving phase at the same time, so as to ensure that the scanning trajectory does not open and to ensure the squareness of the image, that is, the vibration trajectory of the optical fiber in the x-axis direction is closed and does not draw circles, and the vibration direction is horizontal (the vibration component of the optical fiber in the xc direction is 0).

[0111] To simplify scanner feedback control, this embodiment of the invention does not require a separate feedback electrode designed for temperature compensation of the xc direction correction signal, nor does it require separate signal acquisition for xc direction feedback control. Instead, the xc drive signal is corrected based on the adjustment of the amplitude control loop and phase control loop in the x direction.

[0112] Within the scanner's operating temperature range, after the amplitude and phase are adjusted to their proper positions, adjust the correction voltage amplitude and phase, and record the ratio n of the current correction voltage amplitude to the drive voltage amplitude. During the amplitude control loop adjustment process, the correction voltage D is always set. xc =n*D x Correcting voltage phase P xc =P xc0 +dP x +F xc (A x ), where P xc0 To correct the initial value of the voltage phase, dP x F is the difference between the current driving phase and the initial driving phase of the x-axis. xc (A x A is the phase correction function. x The amplitude value of the feedback signal is used. The correction phase correction function is similar to the amplitude temperature correction and the phase temperature correction function. It fits the correction phase compensation values ​​calibrated at different temperatures into a curve.

[0113] Next, the calibration method for the corrected phase correction function will be explained.

[0114] Under normal operating conditions of the phase loop control loop and amplitude control loop, set D xc =n*D x P xc =P xc0 +dP x +dP xc , where dP xc At a certain temperature, after the phase control loop and amplitude control loop have been adjusted, dP is modified. xc The value of dP is determined so that the image has no opening and the image is rectangular. Then, the corresponding dP values ​​at different temperatures are recorded. xc and A x The value of is obtained by fitting the function F. xc (A x ).

[0115] As can be seen, the solution in this embodiment of the invention can correct the correction axis drive signal without designing a separate feedback electrode or acquiring signals for feedback control of the xc direction. By calibrating the ratio n of the correction voltage amplitude to the driving voltage amplitude when the odd and even rows coincide under different temperatures, the same swing amplitude, and the correction function of the correction phase, the image abnormality caused by the xc direction response change due to temperature drift (temperature change) can be eliminated, thereby ensuring stable image display.

[0116] In another exemplary embodiment, a computer-readable storage medium including program instructions is also provided, which, when executed by a processor, implement the steps of the fiber optic swing feedback control method described above. For example, the computer-readable storage medium may be a memory, and the program instructions may be executed by a processor of a projection display device to complete the fiber optic swing feedback control method described above.

[0117] In another exemplary embodiment, a computer program product is also provided, the computer program product comprising a computer program executable by a programmable device, the computer program having a code portion for performing the above-described fiber optic swing feedback control method when executed by the programmable device.

[0118] In this embodiment of the invention, the projection display device can be a head-mounted AR (Augmented Reality) device, a head-mounted VR (Virtual Reality) device, a projection TV, a projector, etc., and its applications are very wide.

[0119] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0120] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0121] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A fiber swing feedback control method applied to a fiber scanner, the fiber scanner including a piezoelectric actuator for driving a fiber to vibrate and a fiber disposed on the actuator, characterized by, The method includes: During the operation of the fiber optic scanner, the amplitude of the feedback signal generated on the actuator when the fiber optic vibration is detected is measured. Calculate the error between the current amplitude value and the target amplitude value; When the error is less than or equal to the threshold, the current driving voltage is taken, and the target amplitude value is updated according to the calculation result of the calibration function of the feedback signal amplitude with respect to the driving voltage. Based on the updated target amplitude value, after multiple iterations, the driving voltage applied to the actuator and the current amplitude value satisfy a mapping relationship, thereby maintaining the fiber swing at the fiber swing calibration value when the mapping relationship was established; wherein, the mapping relationship refers to the calibration function.

2. The method of claim 1, wherein, The methods for establishing the mapping relationship include: Within the operating temperature range of the fiber scanner, the fiber swing amplitude is maintained at the fiber swing amplitude calibration value, thereby establishing a mapping relationship between the driving voltage and the amplitude of the feedback signal.

3. The method of claim 2, wherein, Within the operating temperature range of the fiber optic scanner, the driving frequency of the actuator is located on one side of the resonance peak, which refers to the resonance peak formed by the interaction between the fiber optic cable and the actuator.

4. The method of claim 3, wherein, The calibration function is a monotonically changing curve.

5. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, When executed by a processor, the program implements the steps of the method described in any one of claims 1-4.

6. A projection display device, characterized by comprising: include: A memory on which computer programs are stored; A processor for executing the computer program in the memory to implement the steps of the method according to any one of claims 1-4.

Images