Scanning actuator and scanning display module

Abstract

The invention discloses a scanning actuator and a scanning display module, the scanning actuator comprises a fast axis actuating part and a slow axis actuating part, the fast axis actuating part and the slow axis actuating part both extend in the front-back direction, and the fast axis actuating part and the slow axis actuating part are arranged in a folded mode; the fast axis actuating part comprises a first actuating part and a first fast axis resonant beam which are arranged on the left side of the slow axis actuating part, and a second actuating part and a second fast axis resonant beam which are arranged on the right side of the slow axis actuating part; the first fast axis resonant beam and the second fast axis resonant beam are both connected with the slow axis actuating part; under the driving of a fast axis driving signal, the first actuating part and the second actuating part drive the first fast axis resonant beam and the second fast axis resonant beam to deform, so that the fast axis actuating part vibrates in the fast axis direction. According to the scheme, the fast axis actuating part and the slow axis actuating part are arranged in a folded mode, and the size of the scanning actuator can be reduced.

Description

Technical Field

[0001] This invention relates to the field of projection display, and more particularly to a scanning actuator and a scanning display module. Background Technology

[0002] The imaging principle of fiber scanning display (FSD) is that an actuator drives an optical fiber to move along a predetermined two-dimensional scanning trajectory, and modulates the light output from the light source 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] A grid-based FSD scanner generally refers to a device that achieves projection display through grid scanning. A grid-based scanning device includes two scanning axes that can vibrate in two directions: a fast axis and a slow axis. To obtain a larger slow axis swing, the slow axis actuator requires a larger piezoelectric ceramic sheet, which increases the size of the scanning device.

[0004] In certain applications, such as wearable devices and in-vehicle projection, it is necessary to minimize the size of the scanning device. Therefore, how to reduce the size of the scanner is an important issue in scanner structural design. Summary of the Invention

[0005] The purpose of this invention is to provide a scanning actuator and a scanning display module for reducing the size of the scanner.

[0006] To achieve the above-mentioned objective, a first aspect of the present invention provides a scanning actuator, including a fast-axis actuation part and a slow-axis actuation part, both extending in a front-rear direction and folded together; the fast-axis actuation part includes a first actuation part and a first fast-axis resonant beam disposed on the left side of the slow-axis actuation part, and a second actuation part and a second fast-axis resonant beam disposed on the right side of the slow-axis actuation part; both the first fast-axis resonant beam and the second fast-axis resonant beam are connected to the slow-axis actuation part; under the drive of a fast-axis drive signal, the first actuation part and the second actuation part cause the first fast-axis resonant beam and the second fast-axis resonant beam to deform, causing the fast-axis actuation part to vibrate in the fast-axis direction.

[0007] Optionally, the nonlinear characteristics of the materials used in the first fast-axis resonant beam and the second fast-axis resonant beam are less than the nonlinear characteristics of the materials used in the first actuation part and the second actuation part.

[0008] Optionally, the first actuating part and the second actuating part are made of piezoelectric material; the first fast-axis resonant beam and the second fast-axis resonant beam are made of steel or copper.

[0009] Optionally, under the drive of the fast axis drive signal, the first fast axis resonant beam and the second fast axis resonant beam are in bending vibration mode.

[0010] Optionally, the resonant frequencies of the first and second fast-axis resonant beams in the bending vibration mode are close to the fast-axis driving frequency.

[0011] Optionally, the slow-axis resonant frequency satisfies the following condition: (F pn +F pn+1 ) / 2≈F d Among them, F pn and F pn+1 These are the slow-axis resonant frequency and the fast-axis resonant frequency, respectively, on the frequency response curves that are closest to the fast-axis drive frequency. d This is the fast axis drive frequency.

[0012] Optionally, the mass of the slow-axis actuator is less than or equal to half the mass of the fast-axis actuator.

[0013] Optionally, the first actuating part and the first fast-axis resonant beam are arranged sequentially from front to back, and the second actuating part and the second fast-axis resonant beam are arranged sequentially from front to back.

[0014] Optionally, both the first actuating part and the second actuating part are sheet-like structures, and the first actuating part and the second actuating part are respectively disposed on the outer surfaces of the first fast-axis resonant beam and the second resonant beam.

[0015] Optionally, the first actuating part and the second actuating part are piezoelectric stacked ceramic blocks.

[0016] Optionally, the first fast-axis resonant beam and the second fast-axis resonant beam are connected to the slow-axis actuation part via a fast-slow axis connector.

[0017] Optionally, the scanning actuator includes a base, and the fixed ends of the first actuating part and the second actuating part are fixedly connected to the base.

[0018] A second aspect of the present invention provides a scanning display module, including an optical fiber and a scanning actuator as described in the first aspect, wherein the optical fiber is fixed on the slow axis actuation part.

[0019] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0020] In the embodiment of the present invention, the scanning actuator includes a fast-axis actuating part and a slow-axis actuating part that are folded together. The folded arrangement of the fast-axis actuating part and the slow-axis actuating part can reduce the size of the scanning actuator.

[0021] The fast-axis actuator includes a first actuator and a second actuator, which are respectively disposed on both sides of the slow-axis actuator. The two actuators are connected to the slow-axis actuator through two resonant beams. The high-frequency vibration amplitude is provided by the two resonant beams. The above solution can alleviate the problem of trajectory nonlinearity caused by the coupling of vibrations in the fast and slow axis directions due to the nonlinear characteristics of the piezoelectric ceramic material itself. By avoiding the coupling of vibrations in the fast and slow axis directions, the problem of trajectory nonlinearity is improved and the quality of the scanned image is enhanced. Attached Figure Description

[0022] 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:

[0023] Figure 1 A side view of a scanning actuator provided in an embodiment of the present invention;

[0024] Figure 2 A top view of a scanning actuator provided in an embodiment of the present invention;

[0025] Figure 3 A simulation diagram illustrating the large deformation of the fast-axis resonant beam provided in an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of the impedance curve provided in an embodiment of the present invention;

[0027] Figure 5 A simulation diagram of the bending vibration mode of the slow-axis piezoelectric ceramic sheet in the horizontal direction provided in an embodiment of the present invention;

[0028] Figures 6-8 This is a schematic diagram of the structure of the base provided in an embodiment of the present invention. Detailed Implementation

[0029] 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.

[0030] like Figure 1 and Figure 2As shown, the scanning actuator includes a fast-axis actuation part 10 and a slow-axis actuation part 11, both of which extend in the front-to-back direction and are folded together. The fast-axis actuation part 10 includes a first actuation part 101 and a first fast-axis resonant beam 102 disposed on the left side of the slow-axis actuation part 11, and a second actuation part 103 and a second fast-axis resonant beam 104 disposed on the right side of the slow-axis actuation part 11. The first fast-axis resonant beam 102 and the second fast-axis resonant beam 104 are both connected to the slow-axis actuation part 11. Under the drive of the fast-axis drive signal, the first actuation part 101 and the second actuation part 103 cause the first fast-axis resonant beam 102 and the second fast-axis resonant beam 104 to deform, causing the fast-axis actuation part 10 to vibrate in the fast-axis direction.

[0031] In this embodiment of the invention, the first actuating part 101, the second actuating part 103, and the slow-axis actuating part 11 can all be implemented using piezoelectric ceramics. Driven by the fast-axis drive signal, the first actuating part 101 and the second actuating part 103 extend and retract, causing the first fast-axis resonant beam 102 and the second fast-axis resonant beam 104 to bend and deform, oscillating in the horizontal direction (i.e., the fast-axis direction), thereby causing the slow-axis actuating part 11 to vibrate in the horizontal direction. Figure 3 The figure shown is a simulation diagram of the large deformation of the fast-axis resonant beam provided in an embodiment of the present invention.

[0032] In this embodiment of the invention, since both the first actuating part 101 and the second actuating part 103 can be piezoelectric ceramics, the fast-axis driving part 10 includes piezoelectric ceramics and a fast-axis resonant beam (including a first fast-axis resonant beam 102 and a second fast-axis resonant beam 104). Under the drive of the fast-axis driving signal, the fast-axis resonant beam is in a bending vibration mode. The resonant frequency of the fast-axis resonant beam in the bending vibration mode in the fast-axis direction is close to the fast-axis driving frequency (i.e., the frequency of the fast-axis driving signal), so that the fast-axis resonant beam can provide the high-frequency vibration amplitude required by the scanning actuator. For vibrating devices, vibration modes include extension vibration mode, torsional vibration mode, and bending vibration mode, etc. In this solution, the vibration mode of the fast-axis resonant beam generally refers to the bending vibration mode. In other embodiments, it may also be other types of vibration modes.

[0033] In embodiments of the present invention, such as Figure 1 As shown, the first actuating part 101 and the first fast-axis resonant beam 102 can be arranged in a front-to-back direction, and similarly, the second actuating part 103 and the second fast-axis resonant beam 104 can also be arranged in a front-to-back direction. It should be noted that, in this embodiment of the invention, taking the connection end between the fast-axis resonant beam and the slow-axis actuating part 11 as the rear end, the front-to-back direction is... Figure 2From right to left. In other embodiments, both the first actuating part 101 and the second actuating part 103 are sheet-like structures, respectively disposed on the outer surfaces of the first fast-axis resonant beam 102 and the second fast-axis resonant beam 104. For example, the piezoelectric ceramic sheet included in the first actuating part 101 is attached to the side of the first fast-axis resonant beam 102, and the piezoelectric ceramic sheet included in the second actuating part 103 is attached to the side of the second fast-axis resonant beam 104. In other embodiments, the first actuating part 101 and the second actuating part 103 may also be piezoelectric stacked ceramic blocks, thereby effectively increasing the driving amplitude of the fast-axis actuating part 10 and reducing the driving voltage of the fast-axis driving signal.

[0034] In this embodiment, the first fast-axis resonant beam 102 and the second fast-axis resonant beam 104 are connected to the slow-axis actuation part 11 via the fast-slow axis connector 13.

[0035] For scanning actuators, to obtain vibration in the fast axis direction, the fast axis actuator needs to be connected to the end or tail of the slow axis actuator. The high-frequency mechanical waves generated by the fast axis actuator will inevitably pass through the slow axis actuator. If the fast axis driving frequency is close to the inherent high-order frequency of the piezoelectric ceramic, the slow axis actuator will resonate. Due to the nonlinear characteristics of the piezoelectric ceramic material itself, the vibrations in the fast and slow axis directions will be coupled, resulting in nonlinear trajectory. This manifests in the scanned image as problems such as forking and asymmetric opening. Forking refers to the vertical lines bending when the image is displayed, and the vertical lines displayed in odd and even rows not coinciding; asymmetric opening refers to the inconsistent degree of closure of the fast axis trajectory at different positions on the slow axis, with some areas being closed straight lines and others being elliptical.

[0036] To alleviate the aforementioned problems, the nonlinear characteristics of the materials used in the first fast-axis resonant beam 102 and the second fast-axis resonant beam 104 are less than those of the materials used in the first actuation part 101 and the second actuation part 103. For example, if the first actuation part 101 and the second actuation part 103 are made of piezoelectric materials, then the nonlinear characteristics of the material used in the fast-axis resonant beam are less than those of the piezoelectric materials. For instance, the fast-axis resonant beam can be made of a metallic material with low nonlinearity, such as steel or copper. Similarly, if the first actuation part 101 and the second actuation part 103 are made of other types of materials, the corresponding nonlinear characteristics of the material used in the fast-axis resonant beam also need to be less than those of the aforementioned types of materials. In other embodiments, the nonlinear characteristics of the materials used in the first fast-axis resonant beam 102 and the second fast-axis resonant beam 104 can also be much less than those of the materials used in the first actuation part 101 and the second actuation part 103. It should be noted that, in the embodiments of the present invention, "much less than" generally means a difference of more than 10 times between the two compared objects.

[0037] In this embodiment of the invention, to achieve a sufficiently large fast-axis drive amplitude, structural resonance is required to amplify the deformation of the piezoelectric ceramic driving the fast axis. To avoid the nonlinear effects of the slow-axis piezoelectric ceramic, the slow-axis piezoelectric ceramic sheet can be implemented using any of the following embodiments or a combination of these embodiments.

[0038] In one possible implementation, the size and mass of the slow-axis piezoelectric ceramic sheet can be reduced, thereby reducing the vibration inertia of the slow-axis actuator 11. For example, the mass of the slow-axis actuator 11 can be less than or equal to half the mass of the fast-axis actuator 10.

[0039] In another possible implementation, the size of the slow-axis piezoelectric ceramic plate can be adjusted so that its resonant frequency is far from the fast-axis driving frequency. The resonant frequency of the slow-axis drive unit and the fast-axis driving frequency satisfy the following condition: (F pn +F pn+1 ) / 2≈F d , of which F d F is the fast axis drive frequency. pn and F pn+1 These are the slow-axis resonant frequency and the fast-axis resonant frequency, respectively, which are closest to the fast-axis drive frequency on the frequency response curve. Next, as... Figure 4 As shown, the impedance curve is used as an example to illustrate the concept.

[0040] In this embodiment of the invention, the impedance curve can be measured using appropriate testing equipment (e.g., an impedance analyzer). In actual operation, a curve within a specific frequency range can be measured by setting frequency boundaries. Generally, at the fast axis drive frequency F... d Within a certain frequency range, the fast-axis actuator 10 and the slow-axis actuator 11 will target this F. d The resulting frequency response is manifested as a peak on the impedance curve. In this embodiment of the invention, F pn and F pn+1 These are the slow-axis resonant frequency and the fast-axis resonant frequency, respectively, which are closest to the fast-axis drive frequency on the frequency response curve.

[0041] like Figure 5 As shown, this is the bending vibration mode of the slow-axis piezoelectric ceramic sheet in the horizontal direction. The resonant frequency of the slow-axis piezoelectric ceramic sheet corresponding to this bending vibration mode is far from the fast-axis driving frequency. Therefore, by adjusting the size, mass, and other parameters of the slow-axis actuator, so that the resonant frequency of the slow-axis actuator is far from the fast-axis driving frequency, it can be achieved that when the fast-axis actuator 10 is driving normally, the slow-axis actuator, that is, the slow-axis piezoelectric ceramic sheet, will not exhibit the bending vibration mode of the slow-axis actuator. Figure 5 The deformation of the bending vibration mode is shown.

[0042] In embodiments of the present invention, such as Figures 6-8As shown, the scanning actuator includes a base 12, with the fixed ends of the first actuating part 101 and the second actuating part 103 fixedly connected to the front end of the base 12. The free ends of the first actuating part 101 and the second actuating part 103 are respectively connected to corresponding fast-axis cantilever beams, and the fast-axis cantilever beams are connected to the fixed end of the slow-axis actuating part 11. The base 12 includes... Figure 7 The main body 121 shown and Figure 8 The top cover 122 is shown. The rear end of the main body 121 has a hole for optical fiber to pass through.

[0043] Based on the same inventive concept, this embodiment of the invention also provides a scanning display module, including an optical fiber and the scanning actuator in the above embodiment. Regarding the setting of the optical fiber, the optical fiber can be fixed at the end face of the slow axis actuator, so that the slow axis actuator and the fast axis actuator together drive the optical fiber to swing in space.

[0044] The scanning display module in this invention can be applied to various scenarios, including but not limited to AR (Augmented Reality) devices, laser TVs, laser projectors, vehicle-mounted projectors, etc. In these application scenarios, one scanning display module can be used for projection display, or multiple scanning display modules can be used in concert to display or splice multiple images. This invention does not limit this.

[0045] 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.

[0046] 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.

[0047] 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 scanning actuator, characterized in that, The device includes a fast-axis actuation unit and a slow-axis actuation unit, both extending in the front-to-back direction and folded together. The fast-axis actuation unit includes a first actuation unit and a first fast-axis resonant beam located to the left of the slow-axis actuation unit, and a second actuation unit and a second fast-axis resonant beam located to the right of the slow-axis actuation unit. Both the first and second fast-axis resonant beams are connected to the slow-axis actuation unit. Under the drive of a fast-axis drive signal, the first and second actuation units cause the first and second fast-axis resonant beams to deform, causing the fast-axis actuation unit to vibrate in the fast-axis direction.

2. The scanning actuator as claimed in claim 1, characterized in that, The nonlinear characteristics of the materials used in the first fast-axis resonant beam and the second fast-axis resonant beam are less than those of the materials used in the first actuation part and the second actuation part.

3. The scanning actuator as described in claim 2, characterized in that, The first actuation part and the second actuation part are made of piezoelectric material; the first fast-axis resonant beam and the second fast-axis resonant beam are made of steel or copper.

4. The scanning actuator as claimed in claim 1, characterized in that, Under the drive of the fast axis drive signal, the first fast axis resonant beam and the second fast axis resonant beam are in bending vibration mode.

5. The scanning actuator as claimed in claim 4, characterized in that, The resonant frequencies of the first and second fast-axis resonant beams in the bending vibration mode are close to the fast-axis driving frequency.

6. The scanning actuator as claimed in claim 1 or 4, characterized in that, The slow-axis resonant frequency satisfies the following condition: (F pn +F pn+1 ) / 2≈F d Among them, F pn and F pn+1 These are the slow-axis resonant frequency and the fast-axis resonant frequency, respectively, on the frequency response curves that are closest to the fast-axis drive frequency. d This is the fast axis drive frequency.

7. The scanning actuator as claimed in claim 1, characterized in that, The mass of the slow-axis actuator is less than or equal to half the mass of the fast-axis actuator.

8. The scanning actuator as claimed in claim 1, characterized in that, The first actuation unit and the first fast-axis resonant beam are arranged sequentially from front to back, and the second actuation unit and the second fast-axis resonant beam are arranged sequentially from front to back.

9. The scanning actuator as claimed in claim 1, characterized in that, Both the first actuating part and the second actuating part are sheet-like structures, and the first actuating part and the second actuating part are respectively disposed on the outer surfaces of the first fast-axis resonant beam and the second resonant beam.

10. The scanning actuator as claimed in claim 1, characterized in that, The first actuation part and the second actuation part are piezoelectric stacked ceramic blocks.

11. The scanning actuator as claimed in claim 1, characterized in that, The first fast-axis resonant beam and the second fast-axis resonant beam are connected to the slow-axis actuation part through a fast-slow axis connector.

12. The scanning actuator as claimed in claim 1, characterized in that, The scanning actuator includes a base, and the fixed ends of the first actuating part and the second actuating part are fixedly connected to the base.

13. A scanning display module, characterized in that, It includes an optical fiber and a scanning actuator as described in any one of claims 1-12, wherein the optical fiber is fixed to the slow-axis actuation part.

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