Piezoelectric scanning device and scanning display module

Abstract

The invention discloses a piezoelectric scanning device and a scanning display module. The piezoelectric scanning device comprises a piezoelectric actuator; the constant temperature element is arranged on the surface of the piezoelectric actuator, and the constant temperature element is used for conducting temperature compensation on the piezoelectric actuator in the scanning process of the piezoelectric actuator. According to the scheme, temperature compensation is carried out on the piezoelectric actuator in the scanning process of the piezoelectric actuator through the constant-temperature element arranged on the surface of the piezoelectric actuator, so that the influence of environment temperature change on the characteristics of the piezoelectric actuator is eliminated, and the performance stability of the piezoelectric actuator is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of projection display, in particular to a piezoelectric scanning device and a scanning display module. BACKGROUND

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

[0003] In the application of FSD, the actuator is usually composed of multiple piezoelectric devices, and the structure is generally complex, resulting in complex frequency characteristics. When the temperature changes, the characteristics of the piezoelectric actuator change nonlinearly, which will cause changes in the projection image and affect the imaging quality. SUMMARY

[0004] The purpose of the present application is to provide a piezoelectric scanning device and a scanning display module to alleviate the technical problems in the prior art that when the temperature changes, the characteristics of the piezoelectric actuator change nonlinearly, which will cause changes in the projection image and affect the imaging quality.

[0005] In order to achieve the above-mentioned purpose of the application, the first aspect of the embodiment of the present application provides a piezoelectric scanning device, comprising:

[0006] a piezoelectric actuator;

[0007] a constant temperature element arranged on the surface of the piezoelectric actuator, the constant temperature element being used for temperature compensation of the piezoelectric actuator during scanning.

[0008] Optionally, the piezoelectric actuator is in a sheet structure, and the constant temperature element is arranged on the upper surface and / or the lower surface of the piezoelectric actuator.

[0009] Optionally, the constant temperature element is a TEC semiconductor device.

[0010] Optionally, the constant temperature element is a heating element.

[0011] Optionally, the material of the heating element is a positive temperature coefficient (PTC) material.

[0012] Optionally, the PTC material is arranged on the surface of the piezoelectric actuator by coating.

[0013] The second aspect of the embodiment of the present application provides a scanning display module, comprising:

[0014] The shell and the piezoelectric scanning device as described in the first aspect; the piezoelectric actuator is fixed inside the shell through the support structure.

[0015] Optionally, the shell is a vacuum sealed structure.

[0016] Optionally, the outer surface of the shell is provided with a heat insulation layer.

[0017] Optionally, the inner surface of the shell is a mirror surface.

[0018] The one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0019] In the scheme of the embodiments of the present application, the constant temperature element arranged on the surface of the piezoelectric actuator is used to compensate the temperature of the piezoelectric actuator during the scanning process of the piezoelectric actuator, so as to eliminate the influence of the environmental temperature change on the characteristics of the piezoelectric actuator and ensure the performance stability of the piezoelectric actuator. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor under the premise of the drawings:

[0021] Figure 1 The structural schematic diagram of the piezoelectric scanning device provided by the embodiments of the present application is shown in the figure;

[0022] Figure 2 The system block diagram of the scanning display module provided by the embodiments of the present application is shown in the figure;

[0023] Figure 3 The schematic diagram of the driving circuit of the piezoelectric actuator provided by the embodiments of the present application is shown in the figure;

[0024] Figure 4 The structural schematic diagram of the scanning display module provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0026] In the embodiment of the present application, since the actuator part is mainly composed of piezoelectric ceramic PZT, the response characteristic of the scanner will change with the change of environmental conditions such as temperature, and the purpose of the present application is to compensate for the change of the response characteristic of the actuator caused by the change of external conditions such as temperature. In actual application, the piezoelectric actuator can also use other piezoelectric materials, and the present application does not limit this.

[0027] For the scheme of using driving signal compensation, complex calibration and other measures are needed to obtain the characteristics of the actuator changing with temperature, and then the driving signal is compensated. For the scheme of using vibration trajectory detection for compensation, generally, the complexity of such system is high, and it is not friendly to mass production, resulting in high system production cost.

[0028] For the scheme in the embodiment of the present application, as shown in Figure 1 , it is a structural schematic diagram of a piezoelectric scanning device, which includes a piezoelectric actuator 11 and a constant temperature element 12; the constant temperature element 12 is arranged on the surface of the piezoelectric actuator 11, and the constant temperature element 12 is used to compensate for the piezoelectric actuator 11 during the scanning process of the piezoelectric actuator 11.

[0029] In the above scheme, the constant temperature element 12 maintains the stability of the working temperature of the piezoelectric actuator 11, thereby eliminating the influence of environmental temperature change on the characteristics of the piezoelectric actuator 11 and ensuring the performance stability of the piezoelectric actuator 11.

[0030] In the embodiment of the present application, the constant temperature element 12 can use TEC semiconductor devices to realize refrigeration and heating at the same time. In order to simplify the structure and reduce the volume, PTC (Positive Temperature Coefficient) and other materials can also be selected to realize the heating function, so as to maintain the working temperature of the FSD higher than the highest rated working environmental temperature of the product, that is, T fsd = T max +dT, wherein T fsd is the internal temperature of the device, T max is the highest rated working environmental temperature of the device, and the value of dT can be selected according to actual needs, and T fsd is maintained to be higher than the working environmental temperature, which can eliminate the influence of environmental temperature change on the characteristics of the piezoelectric actuator 11, thereby ensuring the performance stability of the piezoelectric actuator 11.

[0031] In the embodiment of the present application, the constant temperature element 12 can be arranged in different ways according to different structures of the piezoelectric scanning device. For example, if the piezoelectric actuator 11 is in a sheet structure, the constant temperature element 12 can be arranged on the upper surface or the lower surface of the piezoelectric actuator 11, or arranged on both the upper surface and the lower surface. If the piezoelectric actuator 11 is in a tube structure, the constant temperature element 12 can be arranged on the outer surface of the tube structure or the inner surface of the tube structure, or arranged on both the inner surface and the outer surface of the tube structure, and the present application does not limit this.

[0032] In the embodiment of the present application, the piezoelectric actuator 11 can be temperature-compensated in the following control mode.

[0033] The temperature characteristics of the piezoelectric actuator 11 are used to extract the electrical signals (voltage signals / current signals) at the two ends of the piezoelectric actuator 11 after temperature drift as feedback signals, and the constant temperature element 12 is adjusted based on the feedback signals, thereby temperature-compensating the piezoelectric actuator 11.

[0034] When extracting the electrical signals in the driving circuit 13 of the piezoelectric actuator 11, the voltage signals or the current signals of the piezoelectric ceramic can be extracted as feedback signals according to different piezoelectric ceramic driving modes.

[0035] For example, as shown in FIG. 2, the scanning display module includes the driving circuit 13 and the temperature compensation controller 14, and as shown in FIG. 3, when the LC driving mode is used, the free end voltage waveform of the piezoelectric actuator 11 can be used as the feedback signal. The FB end voltage signal can be used as the feedback signal. Since the amplitude and the phase of the FB end voltage signal will change after the piezoelectric ceramic generates temperature drift, both the amplitude and the phase of the voltage signal can be used as the feedback signal. Further, since the amplitude detection circuit is simpler in structure than the phase detection circuit, the amplitude signal can be selected as the feedback error signal. Figure 2 Figure 3 Of course, the current of the piezoelectric ceramic can also be used as the feedback signal, and similarly, the amplitude of the current signal can be selected as the feedback error signal. In the specific implementation process, the current signal can be collected by connecting a sampling resistor in series at the ground end of the piezoelectric ceramic.

[0036]

[0037] ​​In the embodiment of the present application, when temperature compensation is performed, a PID controller can be used as a temperature compensation controller. After the FSD actuator image is initialized correctly, the feedback signal value is extracted and recorded as the signal initial value S0, which is used as the preset value of the PID controller. During the operation of the FSD actuator, the feedback signal St is collected in real time. The error input value of the PID controller is set as Error=St-S0. In the specific implementation process, better control effect can be obtained by adjusting the PID parameters, and the preset condition corresponding to the difference Error can be set near 0, so as to realize real-time and precise temperature compensation.

[0038] In the above scheme, by using the built-in temperature adjustment mechanism, the piezoelectric ceramic itself electric signal is used as the controller error input, so that the accurate control of the temperature of the PZT actuator can be realized without increasing the external sensor and complex circuit, the performance stability of the piezoelectric actuator 11 in a wide temperature range is ensured, and the reliability and real-time performance of the piezoelectric actuator 11 are significantly improved. In addition, the simplified design in the embodiment of the present application can also reduce the cost, improve the overall efficiency of the system and the flexibility of application.

[0039] In the embodiment of the present application, the constant temperature element 12 can be a heating element or a refrigeration element. For the heating element, a positive temperature coefficient PTC material can be used, and in the specific implementation process, in combination with the PTC driving voltage limiting, the overheating and spontaneous combustion after out of control can be effectively prevented. In order to ensure the heat transfer efficiency and response speed, the heating element can select a high molecular PTC material as a coating layer and be directly coated on the surface of the actuator.

[0040] In the embodiment of the present application, as shown in Figure 4 The shell 10 can adopt a packaging and heat insulation structure, the piezoelectric actuator 11 is fixed in the shell 10 through a low thermal conductivity support structure 15, the shell 10 is sealed through a vacuum 18, and the inner wall 16 of the shell can be processed as a mirror surface. The piezoelectric actuator 11 is provided with a constant temperature element 12, which can be a PTC heating layer or other refrigeration element. The outer layer of the shell 10 is provided with a heat insulation layer 17, which can be wrapped with a material with low thermal conductivity as the heat insulation layer 17 in the specific implementation process.

[0041] In the embodiment of the present application, the scanning display device is packaged by vacuum, the inner wall 16 is reflected, and the shell 10 is provided with heat insulation material, so that the internal and external thermal resistance of the device can be increased, the sensitivity of the device to the external environment temperature can be reduced, the external heat dissipation power and the heating power consumption of the device can be reduced.

[0042] In this embodiment of the invention, additional limiting protection measures can be added to prevent the device from overheating in the event of a runaway. For example, measures such as limiting the maximum power and maximum temperature of the heating element can be adopted. When using PTC as the heating material, the risk of overheating in the event of a runaway can be effectively avoided. Furthermore, when the internal temperature of the device is set higher than the maximum rated operating ambient temperature, the dual measures of the PTC heating material characteristics ensure that there is no risk of overheating and spontaneous combustion in the event of a runaway. In other embodiments, the heating material can also be used in conjunction with a temperature sensor for temperature control.

[0043] Based on the same inventive concept, this invention also provides a scanning display module. Various specific methods of the scanning display module have been described in detail in the above embodiments related to piezoelectric scanning devices, and will not be elaborated here.

[0044] 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.

[0045] 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.

[0046] 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 piezoelectric scanning device, characterized by, The piezoelectric actuator is in a sheet structure, and the thermoelectric element is arranged on the upper surface and / or the lower surface of the piezoelectric actuator. The thermoelectric element is a TEC semiconductor device. The thermoelectric element is a heating element.

2. The piezoelectric scanning device of claim 1, wherein, The material of the heating element is a positive temperature coefficient (PTC) material.

3. The piezoelectric scanning device of claim 1, wherein, The PTC material is arranged on the surface of the piezoelectric actuator by coating.

4. The piezoelectric scanning device of claim 1, wherein, The piezoelectric scanning device comprises:

5. The piezoelectric scanning device of claim 4, wherein, A housing and the piezoelectric scanning device according to any one of claims 1-6; 6. The piezoelectric scanning device of claim 5, wherein, The piezoelectric actuator is fixed in the housing by a support structure.

7. A scanning display module, characterized by The housing is a vacuum-sealed structure. The outer surface of the housing is provided with a heat insulation layer. The inner surface of the housing is a mirror surface.

8. The scanning display module of claim 7, wherein the scanning display module is configured to be mounted on a headgear. ​ 9. The scanning display module of claim 7, wherein the scanning display module is configured to be mounted on a headgear. ​ 10. The scanning display module of claim 7, wherein the scanning display module is configured to be mounted on a headgear. ​

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