Patent Publication Number: US-2023136066-A1

Title: Projection device and projection method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of China application serial no. 202111267687.1, filed on Oct. 29, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND 
     Technical Field 
     The disclosure relates to a display device, and in particular to a projection device and a projection method thereof. 
     Description of Related Art 
     Nowadays, if the resolution of a projector is to be increased, different actuators are often used to swing optical elements to achieve different resolutions. For example, when the resolution of an input video signal is 1080P, different resolutions, such as a resolution of 1440P or 4K, can be achieved through using different actuators. However, once the type of actuator used is determined, the control manner of the actuator is fixed and cannot be adjusted, such that the user cannot choose to project images with different resolutions. 
     The information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the Background section does not mean that one or more problems to be resolved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art. 
     SUMMARY 
     The disclosure provides a projection device and a projection method thereof, which can increase the usage flexibility of the projection device, improve the usage convenience of the projection device, and allow the user to freely choose the resolution of a projection image. 
     A projection device of the disclosure includes a spatial modulator, a first optical actuator, a driving circuit, and a control circuit. The spatial modulator modulates a beam to generate an image beam. The driving circuit is coupled to the first optical actuator, determines a swinging mode of the first optical actuator according to an input video signal, and converts each display frame into multiple sub-display frames corresponding to the swinging mode of the first optical actuator. The control circuit is coupled to the spatial modulator and the driving circuit, controls the spatial modulator to generate the image beam according to the sub-display frames, and outputs a synchronization signal corresponding to each sub-display frame to the driving circuit. The driving circuit drives the first optical actuator to swing according to the synchronization signal and the swinging mode of the first optical actuator to change a optical path of the image beam to generate a projection image corresponding to a resolution of the input video signal. 
     In an embodiment of the disclosure, the projection device further includes a second optical actuator coupled to the driving circuit. The driving circuit further determines a swinging mode of the second optical actuator according to the input video signal. The driving circuit drives the second optical actuator to swing according to the swinging mode of the second optical actuator to change the optical path of the image beam. 
     In an embodiment of the disclosure, the projection device further includes a second optical actuator coupled to the control circuit. The driving circuit further determines a swinging mode of the second optical actuator according to the input video signal. The control circuit drives the second optical actuator to swing according to the swinging mode of the second optical actuator to change the optical path of the image beam. 
     In an embodiment of the disclosure, the control circuit further includes an extended pixel resolution circuit and a spatial modulator control circuit. The extended pixel resolution circuit is coupled to the driving circuit and the second optical actuator. The spatial modulator control circuit is coupled to the driving circuit, the extended pixel resolution circuit, and the spatial modulator, controls the spatial modulator to generate the image beam according to the sub-display frames, and provides synchronization signals corresponding to the sub-display frames to the driving circuit and the extended pixel resolution circuit. The driving circuit and the extended pixel resolution circuit respectively drive the first optical actuator and the second optical actuator to swing according to the synchronization signals to change the optical path of the image beam. 
     In an embodiment of the disclosure, the driving circuit determines the swinging mode of the first optical actuator according to at least one of a resolution and a frequency of the input video signal. 
     In an embodiment of the disclosure, the driving circuit is a field programmable gate array. 
     In an embodiment of the disclosure, the synchronization signal is a vertical synchronization signal. 
     The disclosure also provides a projection method of a projection device. The projection device includes a spatial modulator, an optical actuator, a driving circuit, and a control circuit. The control circuit controls the spatial modulator to generate an image beam. The projection method of the projection device includes the following steps. A swinging mode of the optical actuator is determined according to an input video signal. Each display frame is converted into multiple sub-display frames corresponding to the swinging mode of the optical actuator. The sub-display frames are output to the control circuit, so that the control circuit controls the spatial modulator to generate the image beam according to the sub-display frames. A synchronization signal corresponding to each of the sub-display frames is received from the control circuit. The optical actuator is driven to swing according to the synchronization signal and the swinging mode of the optical actuator to generate a projection image corresponding to a resolution of the input video signal. 
     Based on the above, the driving circuit of the embodiments of the disclosure may determine the swinging mode of the first optical actuator according to the input video signal, convert each display frame into multiple sub-display frames corresponding to the swinging mode of the first optical actuator, and drive the first optical actuator to swing according to the swinging mode of the optical actuator and the synchronization signals corresponding to the sub-display frames provided by the control circuit to change the optical path of the image beam to generate the projection image corresponding to the resolution of the input video signal. In this way, the swinging mode of the first optical actuator is not limited to the setting of the control circuit and the specification of the spatial modulator, which can increase the usage flexibility of the projection device, improve the usage convenience of the projection device, and allow the user to freely choose the resolution of the projection image. 
     Other objectives, features and advantages of the disclosure will be further understood from the further technological features disclosed by the embodiments of the disclosure wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention. 
     In order for the features and advantages of the disclosure to be more comprehensible, specific embodiments are described in detail below in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG.  1    is a schematic diagram of internal elements of a projection device according to an embodiment of the disclosure. 
         FIG.  2    is a schematic diagram of a relationship between a swinging mode, a sub-display frame, and a pixel displacement according to an embodiment of the disclosure. 
         FIG.  3    is a schematic diagram of a corresponding relationship between a swinging mode and a resolution and a frequency according to an embodiment of the disclosure. 
         FIG.  4 A  is a schematic diagram of a projection device according to another embodiment of the disclosure. 
         FIG.  4 B  is a schematic diagram of a projection device according to another embodiment of the disclosure. 
         FIG.  5    is a schematic diagram of a projection device according to another embodiment of the disclosure. 
         FIG.  6    is a flowchart of a projection method of a projection device according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
     It is to be understood that other embodiment may be utilized and structural changes may be made without departing from the scope of the disclosure. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. 
     In order for the content of the disclosure more comprehensible, the following embodiments are specifically cited as examples on which the disclosure can indeed be implemented. In addition, wherever possible, elements/components with the same reference numerals in the drawings and embodiments represent the same or similar parts. “Coupling” is defined as such that there is transmission of electrical signals between two devices or circuits, which does not necessarily need to be directly transmitted and may also be transmitted by a third device in between. 
       FIG.  1    is a schematic diagram of internal elements of a projection device according to an embodiment of the disclosure. Please refer to  FIG.  1   . The projection device includes a spatial modulator  102 , a first optical actuator  104 , a driving circuit  106 , and a control circuit  108 , wherein the control circuit  108  is coupled to the spatial modulator  102  and the driving circuit  106 , and the driving circuit  106  is coupled to the first optical actuator  104 . 
     The spatial modulator  102  may be used to modulate a beam to generate an image beam L 1 . The spatial modulator  102  may be, for example, a reflective optical modulator such as a liquid crystal on silicon panel (LCoS panel) and a digital micro-mirror device (DMD) or a transmissive optical modulator such as a transparent liquid crystal panel, an electro-optical modulator, a magneto-optical modulator, and an acousto-optical modulator (AOM), but not limited thereto. The image beam L 1  generated by the spatial modulator  102  passes through the first optical actuator  104  to generate a projection image. A sub-display frame mentioned below represents the projection image that is projected onto a screen or a wall in a time sequence. 
       FIG.  2    is a schematic diagram of a relationship between a swinging mode, a sub-display frame, and a pixel displacement according to an embodiment of the disclosure. The swinging modes include 1P, 2P, 4P, and 8P, but not limited thereto. The 1P mode represents that the optical actuator is not driven, so no displacement is generated. For example, in the 1P mode, when the resolution of a display frame of an input video signal IN 1  is WQXGA+(2716×1528)@120 Hz, since the resolution required by the specification of the spatial modulator  102  is met, the driving circuit  106  or the control circuit  108  does not drive the optical actuator. In the 2P mode, when the resolution of the display frame of the input video signal IN 1  is 4K(3840×1440)@60 Hz, the driving circuit  106  converts the display frame of the input video signal IN 1  into 2 sub-display frames, and sends the sub-display frames to the control circuit  108 , wherein the resolution of each sub-display frame is WQXGA+(2716×1528), and a screen update frequency is 120 Hz. The control circuit  108  may control the spatial modulator  102  to modulate the beam according to the sub-display frame to generate the image beam L 1  with a resolution of WQXGA+(2716×1528) and the screen update frequency of 120 Hz. The control circuit  108  outputs a synchronization signal corresponding to each sub-display frame to the driving circuit  106 , so that the driving circuit  106  drives the first optical actuator  104  to swing according to the synchronization signal, and the first optical actuator  104  projects the 2 sub-display frames to 2 corresponding positions according to the 2P mode for the projection image to have a resolution of 4K(3840×1440)@60 Hz. In another 2P mode, when the resolution of the display frame of the input video signal IN 1  is 4K(3840×1440)@60 Hz, the control circuit  108  converts the display frame of the input video signal IN 1  into 2 sub-display frames, wherein the resolution of each sub-display frame is WQXGA+(2716×1528), and the screen update frequency is 120 Hz. The control circuit  108  may control the spatial modulator  102  to modulate the beam according to the sub-display frame to generate the image beam L 1  with a resolution of WQXGA+(2716×1528) and the screen update frequency of 120 Hz. The control circuit  108  drives a second optical actuator  402  to swing, so that the second optical actuator  402  projects the 2 sub-display frames to 2 corresponding positions according to the 2P mode for the projection image to have a resolution of 4K(3840×1440)@60 Hz. In the 4P mode, when the resolution of the display frame of the input video signal IN 1  is 5.4K(5432×3056)@30 Hz, the driving circuit  106  converts the display frame of the input video signal IN 1  into 4 sub-display frames, and sends the sub-display frames to the control circuit  108 , wherein the resolution of each sub-display frame is WQXGA+(2716×1528), and the screen update frequency is 120 Hz. The control circuit  108  may control the spatial modulator  102  to modulate the beam according to the sub-display frame to generate the image beam L 1  with a resolution of WQXGA+(2716×1528) and the screen update frequency of 120 Hz. The control circuit  108  outputs the synchronization signal corresponding to each sub-display frame to the driving circuit  106 , so that the driving circuit  106  drives the first optical actuator  104  to swing according to the synchronization signal, and the first optical actuator  104  projects the 4 sub-display frames to 4 corresponding positions according to the 4P mode for the projection image to have a resolution of 5.4K(5432×3056)@30 Hz. In the 8P mode, when the resolution of the display frame of the input video signal IN 1  is 8K(7680×4320)@15 Hz, the driving circuit  106  converts the display frame of the input video signal IN 1  into 6 sub-display frames, wherein 4 sub-display frames remain in the driving circuit  106  and 2 sub-display frames are sent to the control circuit  108 , wherein the resolution of the 4 sub-display frames is 4K(3840×1440)@60 Hz, and the resolution of the 2 sub-display frames is WQXGA+(2716×1528)@120 Hz. The control circuit  108  may control the spatial modulator  102  to modulate the beam according to the sub-display frame to generate the image beam L 1  with a resolution of WQXGA+(2716×1528) and the screen update frequency of 120 Hz. The control circuit  108  outputs the synchronization signal corresponding to each sub-display frame to the driving circuit  106 , so that the driving circuit  106  drives the first optical actuator  104  to swing according to the synchronization signal, and the first optical actuator  104  projects the 4 sub-display frames to 4 corresponding positions according to the 4P mode. In addition, the control circuit  108  drives the second optical actuator  402  to swing, so that the second optical actuator  402  projects the 2 sub-display frames to 2 corresponding positions according to the 2P mode. By means of the actuations of the first optical actuator  104  and the second optical actuator  402 , the projection image can have a resolution of 8K(7680×4320)@15 Hz. 
     A more detailed description is as follows. Referring to  FIG.  1   , when the driving circuit  106  receives the input video signal IN 1 , wherein the input video signal IN 1  includes a display frame, the driving circuit  106  may determine the swinging mode of the first optical actuator  104  according to the input video signal IN 1 , for example, determine the swinging mode of the first optical actuator  104  according to at least one of the resolution and the frequency of the input video signal IN 1 , and convert the display frame into multiple sub-display frames corresponding to the swinging mode of the first optical actuator  104 . The driving circuit  106  may be implemented by, for example, a field programmable gate array (FPGA). In addition, the control circuit  108  receives the sub-display frames generated by the driving circuit  106 . According to the sub-display frames generated by the driving circuit  106 , the control circuit  108  may control the spatial modulator  102  to generate the image beam L 1 , and the control circuit  108  outputs the synchronization signal corresponding to each sub-display frame to the driving circuit  106 , wherein the synchronization signal may be, for example, a vertical synchronization signal commonly used in the art, but not limited thereto. The control circuit  108  may be implemented by, for example, a DDP442x chip manufactured by Texas Instruments, but not limited thereto. The driving circuit  106  may drive the first optical actuator  104  to swing according to the synchronization signal and the swinging mode of the first optical actuator  104  to change an optical path of the image beam L 1  to generate the projection image corresponding to the resolution of the input video signal IN 1 . In this way, the swinging mode of the first optical actuator  104  is determined corresponding to the input video signal IN 1  with different specifications, so that the swinging mode of the first optical actuator  104  is not limited to the setting of the control circuit  108  or the specification of the spatial modulator  102  to increase the usage flexibility of the projection device, improve the usage convenience of the projection device, and allow the user to freely choose the resolution of the projection image. 
     Furthermore, the first optical actuator  104  includes a transparent element and a swinging device (not shown). The transparent element is used to allow the image beam L 1  to penetrate, and the transparent element swings in a time sequence by the swinging device to change the optical path of the image beam L 1 . The swinging mode of the first optical actuator  104  may include, for example, a first swinging mode and a second swinging mode. For example, in the first swinging mode, the driving circuit  106  converts the display frame into 2 sub-display frames. The control circuit  108  receives the 2 sub-display frames, generates synchronization signals corresponding to the 2 sub-display frames, and transmits the synchronization signals to the driving circuit  106 . The driving circuit  106  drives the first optical actuator  104  to swing according to the synchronization signals provided by the control circuit  108  to project the 2 sub-display frames to 2 corresponding positions, wherein a distance between the 2 positions is, for example, half of a diagonal distance of a pixel. In addition, for example, in the second swinging mode, the driving circuit  106  converts the display frame into 4 sub-display frames, and the driving circuit  106  drives the first optical actuator  104  to swing according to the synchronization signals provided by the control circuit  108  to project the 4 sub-display frames to 4 corresponding positions, wherein a distance between 2 adjacent positions is, for example, half of a length distance of a pixel. 
     For example, the maximum resolution supported by the control circuit  108  and the spatial modulator  102  is WQXGA+(2716×1528), and the input video signal IN 1  is a 5.4K@30 Hz video signal (that is, a video signal with a resolution of (5432×3056) and a screen update frequency of 30 Hz). The driving circuit  106  receives the input video signal IN 1 . The driving circuit  106  may determine the swinging mode of the first optical actuator  104  as a mode of shifting pixels of the sub-display frame to 4 different positions according to the resolution and the screen update frequency of the input video signal IN 1 , which is the second swinging mode (the 4 positions (4P) mode as shown in  FIG.  2   ). In detail, the driving circuit  106  may convert the display frame of the video signal IN 1  into 4 sub-display frames, and send the sub-display frames to the control circuit  108 , wherein the resolution of each sub-display frame is WQXGA+(2716×1528), and the screen update frequency is 120 Hz. The control circuit  108  may control the spatial modulator  102  to modulate the beam according to the resolution of the sub-display frame and the image update frequency to generate the image beam L 1  with the resolution of WQXGA+(2716×1528) and the image update frequency of 120 Hz. At the same time, the control circuit  108  outputs the synchronization signal corresponding to each sub-display frame to the driving circuit  106 , so that the driving circuit  106  drives the first optical actuator  104  to swing according to the synchronization signal corresponding to each sub-display frame. For each sub-display frame, the first optical actuator  104  projects the 4 sub-display frames to 4 corresponding positions according to the swinging mode (the 4P mode) determined by the driving circuit  106 . As shown in  FIG.  2   , taking 4 pixel positions representing the movement of the 4 sub-display frames as an example, in the 4P mode, after the image beam L 1  passes through the swinging first optical actuator  104 , the optical path is changed, so that 4 pixels corresponding to the 4 sub-display frames are shifted to 4 different positions 1 to 4, wherein a time point at which the 4 pixels are sequentially projected to the 4 corresponding positions  1  to  4  may be determined by 4 synchronization signals provided by the control circuit  108 . Each synchronization signal may be, for example, the vertical synchronization signal of each sub-display frame, but not limited thereto. In the embodiment, a pixel displacement pitch between adjacent pixels is D/2, that is, the relative displacement pitch between the 4 sub-display frames is D/2, where D is a length between pixels. The 4 sub-display frames after pixel displacement enable the viewer to view with increased number of pixels (increased resolution) and smooth image edges, so that the resolution of the projection image can reach the resolution of the input video signal IN 1  (5432×3056). Similarly, the input video signal IN 1  with a resolution and an image update frequency of 2880P@30 Hz also enables the first optical actuator  104  to swing in the 4P mode, so that the projection device can provide the 2880P@30 Hz projection image. 
     For another example, when the resolution and the image update frequency of the input video signal IN 1  is 4K(3840×1440)@60 Hz, the driving circuit  106  may determine the swinging mode of the optical actuator  104  as a mode of shifting each pixel of the display frame to 2 different positions, that is, the first swinging mode (the 2P mode as shown in  FIG.  2   ) according to the resolution and the image update frequency of the input video signal IN 1 . In detail, the driving circuit  106  may convert the display frame into 2 sub-display frames, and send the sub-display frames to the control circuit  108 , wherein the resolution of each sub-display frame is WQXGA+(2716×1528), and the screen update frequency is 120 Hz. Similarly, the control circuit  108  may control the spatial modulator  102  to modulate the beam according to the sub-display frame to generate the image beam L 1 , and output the synchronization signal corresponding to each sub-display frame to the driving circuit  106 , so that the driving circuit  106  drives the first optical actuator  104  to swing according to the synchronization signal, and the first optical actuator  104  projects the 2 sub-display frames to 2 corresponding positions according to the 2P mode. As shown in  FIG.  2   , in the 2P mode, after the image beam L 1  passes through the swinging first optical actuator  104 , 2 corresponding pixels in the 2 sub-display frames are shifted to 2 different positions  1  and  2 , and the 2 shifted sub-display frames enable the viewer to view the 4K(3840×1440)@60 Hz projection image. It is worth noting that in some embodiments, the control circuit  108  may also convert the display frame into the 2 sub-display frames, and drive the second optical actuator  402  to swing, so that the second optical actuator  402  projects the 2 sub-display frames to the 2 corresponding positions according to the 2P mode. It is not limited that the driving circuit  106  must convert the display frame into the 2 sub-display frames. 
     In addition, when the resolution and the image update frequency of the input video signal IN 1  is WQXGA+(2716×1528)@120 Hz or 1440P@120 Hz, since the specification of the video signal IN 1  is a specification that may be supported by the control circuit  108  and the spatial modulator  102 , the first optical actuator  104  does not need to swing, and the image beam L 1  generated by the spatial modulator  102  may be directly projected, as shown in the 1P mode in  FIG.  2   . 
     It is worth noting that the swinging mode of the first optical actuator  104  is not limited to the above embodiments. In other embodiments, the driving circuit  106  may convert the display frame into more sub-display frames (for example, 8 sub-display frames, but not limited thereto) according to the input video signal IN 1 , and drive the first optical actuator  104  to swing according to the synchronization signals provided by the control circuit  108  and the swinging mode of the first optical actuator  104  to project the sub-display frames to corresponding positions (for example, project the 8 sub-display frames to 8 corresponding positions) to generate the projection image corresponding to the resolution of the input video signal IN 1 . The first optical actuator  104  may generate multiple swinging modes in a multi-axis manner. 
     It can be seen from the above embodiments that the driving circuit  106  determines the swinging mode of the first optical actuator  104  according to the input video signal IN 1 , and drives the first optical actuator  104  to swing according to the swinging mode of the first optical actuator  104  and the synchronization signal corresponding to the sub-display frame provided by the control circuit  108  to generate the projection image corresponding to the resolution of the input video signal IN 1 , and the swinging mode of the first optical actuator  104  is not limited to the setting of the control circuit  108  and the specification of the spatial modulator  102 , thereby increasing the usage flexibility of the projection device, improving the usage convenience of the projection device, and allowing the user to freely choose the resolution of the projection image. For example,  FIG.  3    is a schematic diagram of a corresponding relationship between a swinging mode and a resolution and a frequency according to an embodiment of the disclosure. As shown in  FIG.  3   , for example, in a case where the maximum video signal specification supported by the control circuit  108  and the spatial modulator  102  is a resolution of 1080p(1920×1080), the driving circuit  106  controls the first optical actuator  104  to swing, so that the projection image projected by the projection device has a resolution of 2560×1440 and the screen update frequency of 120 Hz (in the 2P mode) or a resolution of 3840×2160 and a screen update frequency of 60 Hz (in the 4P mode). For another example, when the maximum video signal specification supported by the control circuit  108  and the spatial modulator  102  is a resolution of 3840×2160, the driving circuit  106  controls the first optical actuator  104  to swing, so that the projection image projected by the projection device has a resolution of 5120×2880 and the screen update frequency of 60 Hz (in the 2P mode) or a resolution of 7680×4320 and the screen update frequency of 30 Hz (in the 4P mode). 
       FIG.  4 A  is a schematic diagram of a projection device according to another embodiment of the disclosure. In the embodiment, the projection device may further include the second optical actuator  402 , which is coupled to the driving circuit  106 . The swinging mode of the second optical actuator  402  may be determined by the driving circuit  106  according to the input video signal IN 1 . The control circuit  108  may drive the second optical actuator  402  to swing according to the swinging mode of the second optical actuator  402  determined by the driving circuit  106 . The driving circuit  106  generates multiple sub-display frames. The control circuit  108  receives the sub-display frames generated by the driving circuit  106 . According to the sub-display frames generated by the driving circuit  106 , the control circuit  108  may control the spatial modulator  102  to generate the image beam L 1 , and the control circuit  108  outputs the synchronization signal corresponding to each sub-display frame to the driving circuit  106 . The driving circuit  106  may respectively drive the first optical actuator  104  to swing according to the synchronization signal, the swinging mode of the first optical actuator  104 , and the swinging mode of the second optical actuator  402  to change the optical path of the image beam L 1 , and drive the second optical actuator  402  to swing to change the optical path of the image beam L 1  to generate the projection image corresponding to the resolution of the input video signal IN 1 . It is worth mentioning that the image beam L 1  emitted from the spatial modulator  102  sequentially passes through the second optical actuator  402  and the first optical actuator  104 , so that the image beam L 1  may form the projection image corresponding to the resolution of the input video signal IN 1 . 
     Furthermore, the display frame of the input video signal IN 1  is converted by the driving circuit  106  into 4 first sub-display frames and 2 second sub-display frames. The control circuit  108  receives the 4 first sub-display frames and the 2 second sub-display frames from the driving circuit  106 . The control circuit  108  forms synchronization signals to be provided to the driving circuit  106  according to the 4 first sub-display frames and the 2 second sub-display frames. The driving circuit  106  may drive the first optical actuator  104  to swing according to the synchronization signal corresponding to each first sub-display frame provided by the control circuit  108 . At the same time, the driving circuit  106  may drive the second optical actuator  402  to swing according to the synchronization signal corresponding to each second sub-display frame provided by the control circuit  108 . When the input video signal IN 1  is 8K(7680×4320)@15 Hz, the driving circuit  106  drives the first optical actuator  104  to swing (in the 4P mode) according to the synchronization signals corresponding to the first sub-display frames provided by the control circuit  108 . At the same time, The driving circuit  106  drives the second optical actuator  402  to swing (in the 2P mode) according to the synchronization signals corresponding to the second sub-display frames provided by the control circuit  108 . In this way, the first optical actuator  104  and the second optical actuator  402  swing in coordination with each other. The optical path of the image beam L 1  is changed by the first optical actuator  104  and the second optical actuator  402 , and 8 sub-display frames are projected to 8 corresponding positions. As shown in  FIG.  2   , taking 8 pixels corresponding to the 8 sub-display frames as an example, in the 8P mode, after the image beam L 1  sequentially passes through the swinging second optical actuator  402  and first optical actuator  104 , the optical path is sequentially changed, so that positions of the pixels are shifted to 8 different positions  1  to  8 , wherein a time sequence of sequentially projecting the 8 pixels to the 8 corresponding positions  1  to  8  may be determined by the synchronization signals provided by the control circuit  108 . Each synchronization signal may be, for example, the vertical synchronization signal of each sub-display frame, but not limited thereto. 
       FIG.  4 B  is a schematic diagram of a projection device according to another embodiment of the disclosure. In the embodiment, the second optical actuator  402  of the projection device is coupled to the control circuit  108 . The swinging mode of the second optical actuator  402  may be determined by the driving circuit  106  according to the input video signal IN 1 . The control circuit  108  may drive the second optical actuator  402  to swing according to the swinging mode of the second optical actuator  402  determined by the driving circuit  106 . 
     Furthermore, the display frame of the input video signal IN 1  is converted into 4 first sub-display frames by the driving circuit  106  and converted into 2 second sub-display frames by the control circuit  108 . The driving circuit  106  provides the 4 first sub-display frames to the control circuit  108 . The driving circuit  106  may drive the first optical actuator  104  to swing according to the synchronization signal corresponding to each first sub-display frame provided by the control circuit  108 . The control circuit  108  may drive the second optical actuator  402  to swing according to each second sub-display frame to project the 6 sub-display frames (the 4 first sub-display frames and the 2 second sub-display frames) to 8 corresponding positions. Taking the 8P mode of the embodiment in  FIG.  2    as an example, when the input video signal IN 1  is 8K@15 Hz, the driving circuit  106  may convert the display frame into the 4 first sub-display frames, wherein the resolution of each first sub-display frame is 4K, and the screen update frequency is 60 HZ. The control circuit  108  converts the display frame into the 2 second sub-display frames (wherein the resolution of each second sub-display frame is WQXGA+(2716×1528), and the screen update frequency is 120 HZ), and transmits the synchronization signal corresponding to each first sub-display frame to the driving circuit  106 , so that the driving circuit  106  drives the first optical actuator  104  to swing (in the 4P mode) according to the synchronization signals provided by the control circuit  108 . In addition, the control circuit  108  also controls the second optical actuator  402  to swing (in the 2P mode) according to the synchronization signals (such as the vertical synchronization signals) of the second sub-display frames. In this way, the first optical actuator  104  and the second optical actuator  402  swing in coordination with each other. The optical path of the image beam L 1  is changed by the first optical actuator  104  and the second optical actuator  402 , and the image beam L 1  is projected to the 8 corresponding positions. As shown in  FIG.  2   , taking 8 pixels corresponding to 8 sub-display frames as an example, in the 8P mode, the image beam L 1  sequentially passes through the swinging second optical actuator  402  and first optical actuator  104 , and the optical path is sequentially changed, so that positions of the pixels are shifted to 8 different positions  1  to  8 , wherein a time sequence of sequentially projecting the 8 pixels to the 8 corresponding positions  1  to  8  may be determined by the synchronization signals provided by the control circuit  108 . Each synchronization signal may be, for example, the vertical synchronization signal of each sub-display frame, but not limited thereto. 
       FIG.  5    is a schematic diagram of a projection device according to another embodiment of the disclosure. In the embodiment, the control circuit  108  may include a spatial modulator control circuit  502  and an extended pixel resolution circuit  504 , wherein the spatial modulator control circuit  502  is coupled to the spatial modulator  102 , the extended pixel resolution circuit  504 , and the driving circuit  106 , and the extended pixel resolution circuit  504  is coupled to the driving circuit  106  and the second optical actuator  402 . The extended pixel resolution circuit  504  is used to convert the display frame into each second sub-display frame. The spatial modulator control circuit  502  may control the spatial modulator  102  to generate the image beam L 1 . The driving circuit  106  and the extended pixel resolution circuit  504  respectively drive the first optical actuator  104  and the second optical actuator  402  to swing to change the optical path of the image beam L 1 , so that the projection device provides the projection image corresponding to the resolution of the input video signal IN 1 . 
       FIG.  6    is a flowchart of a projection method of a projection device according to an embodiment of the disclosure. The projection device includes a spatial modulator, an optical actuator, a driving circuit, and a control circuit. The control circuit is used to control the spatial modulator to generate an image beam. It can be seen from the above embodiments that the projection method of the projection device may include the following steps. First, the driving circuit determines a swinging mode of the optical actuator according to an input video signal (Step S 602 ), for example, determines the swinging mode of the optical actuator according to at least one of a resolution and a frequency of the input video signal. Next, a display frame is converted into multiple sub-display frames corresponding to the swinging mode of the optical actuator (Step S 604 ). For example, the swinging mode of the optical actuator may include a first swinging mode and a second swinging mode. In the first swinging mode, the optical actuator is driven to swing according to synchronization signals corresponding to the sub-display frames, and the sub-display frames are projected to corresponding positions. In the second swinging mode, the optical actuator is driven to swing according to the synchronization signals corresponding to the sub-display frames to project the sub-display frames to the corresponding positions. The sub-display frames are output to the control circuit, so that the control circuit controls the spatial modulator to generate the image beam according to the sub-display frames (Step S 606 ). Then, the driving circuit receives the synchronization signal corresponding to each sub-display frame from the control circuit (Step S 608 ), wherein the synchronization signal may be, for example, a vertical synchronization signal. Finally, the optical actuator is driven to swing according to the synchronization signals and the swinging mode of the optical actuator to generate a projection image corresponding to the resolution of the input video signal (Step S 610 ). 
     In summary, the driving circuit of the embodiments of the disclosure may determine the swinging mode of the first optical actuator according to the input video signal, convert each display frame into multiple sub-display frames corresponding to the swinging mode of the first optical actuator, and drive the first optical actuator to swing according to the swinging mode of the optical actuator and the synchronization signals corresponding to the sub-display frames provided by the control circuit to change the optical path of the image beam to generate the projection image corresponding to the resolution of the input video signal. In this way, the swinging mode of the first optical actuator is not limited to the setting of the control circuit and the specification of the spatial modulator, which can increase the usage flexibility of the projection device, improve the usage convenience of the projection device, and allow the user to freely choose the resolution of the projection image. 
     The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the disclosure” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. Moreover, these claims may refer to use “first”, “second”, etc. following with noun or element. Such terms should be understood as a nomenclature and should not be construed as giving the limitation on the number of the elements modified by such nomenclature unless specific number has been given. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the disclosure as defined by the following claims. Moreover, no element and component in the disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.