Display device

Abstract

A display device includes a coherent light source, a display unit, a light diffusion element, and at least one optical element. The coherent light source provides a coherent light beam. The display unit forms a three-dimensional image light beam based on the interference of the coherent light beam, and the three-dimensional image light beam forms an image on an intermediate imaging surface after passing through the display unit. The light diffusion element is disposed on the intermediate imaging surface, wherein the three-dimensional image light beam passes through the light diffusion element to sequentially change the diffusion angle of the three-dimensional image light beam. At least one optical element is located on the transmission path of the three-dimensional image light beam from the light diffusion element for projecting the three-dimensional image light beam passing through the display unit out of the display device to display the three-dimensional image.

Description

Technical Field

[0001] The present invention relates to a display device using a coherent light beam, and particularly to a display device using holography. Background Art

[0002] Three-dimensional (3D) display technology is applied to various image display fields, such as movies, television (TV), and mobile phones. Ultimately, the purpose of 3D display is to enable people to experience 3D effects (as if he or she is in a real environment). Therefore, various technologies, including, for example, the stereophonic scheme and the multi-viewpoint scheme, have been continuously studied. Holography is typically used as a technology for restoring 3D spatial light information into the form of real light. Holography can restore light in space based on interference (i.e., the wave nature of light).

[0003] However, since the coherent light beam used in the display device using holography has high coherence, constructive or destructive interference phenomena are formed in space, and thus speckle-like speckles are generated on the irradiated surface. Such speckles are an irregular noise-like pattern with seemingly irregular bright and dark dots, which causes uneven brightness on the irradiated surface. Therefore, it is easy to cause a decrease in the image quality of the projection device using this light source, and the visual perception of the user becomes worse.

[0004] There is a method for eliminating speckles of a general display device using a coherent light beam, which is to provide a vibrating mirror in front of the coherent light source to equalize the coherent light beam. However, since this method changes the spatial light information of the coherent light beam, it affects the formation of the hologram, so it cannot be applied to the display device using holography. Summary of the Invention

[0005] The present invention provides a display device capable of providing an image with good image quality.

[0006] The display device of the present invention includes a coherent light source, a display unit, a light diffusion element, and at least one optical element. The coherent light source provides a coherent light beam. The display unit forms a three-dimensional image light beam based on the interference of the coherent light beam, and the three-dimensional image light beam forms an image on an intermediate imaging surface after passing through the display unit. The light diffusion element is disposed on the intermediate imaging surface, wherein the three-dimensional image light beam passes through the light diffusion element to sequentially change the diffusion angle of the three-dimensional image light beam. At least one optical element is located on the transmission path of the three-dimensional image light beam from the light diffusion element, and is used to project the three-dimensional image light beam passing through the display unit out of the display device to display the three-dimensional image.

[0007] In an embodiment of the present invention, the above-mentioned light diffusion element has an actuator, which is electrically connected to the light diffusion element and is used to drive the light diffusion element at a driving frequency.

[0008] In an embodiment of the present invention, the above-mentioned actuator is used to drive the light diffusion element to vibrate, and the driving frequency is the vibration frequency of the light diffusion element.

[0009] In an embodiment of the present invention, the above-mentioned actuator is used to drive the light diffusion element to rotate, and the driving frequency is the rotation frequency of the light diffusion element.

[0010] In an embodiment of the present invention, the above-mentioned light diffusion element is a liquid crystal element, and the light diffusion element includes a controller, which controls the arrangement state of the liquid crystal molecules in the liquid crystal element to change with time sequence.

[0011] In an embodiment of the present invention, the above-mentioned controller can control the light diffusion element to form a plurality of diffusion patterns. Each diffusion pattern is respectively formed correspondingly in different time sequences, and the arrangement state of the liquid crystal molecules when the light diffusion element forms one diffusion pattern is different from that when the light diffusion element forms another diffusion pattern.

[0012] In an embodiment of the present invention, the above-mentioned controller can control a diffusion pattern switching frequency of the light diffusion element. The diffusion pattern switching frequency is the frequency at which a plurality of diffusion patterns are formed per unit time, and when the types of the plurality of diffusion patterns are N types, the range of the switching frequency is greater than N times of 60 Hertz.

[0013] Based on the above, the display device according to the embodiment of the present invention can adjust the overall uniformity of the three-dimensional image light beam through the configuration of the light diffusion element. Therefore, the three-dimensional image light beam formed by the light diffusion element has good uniformity. In this way, the display device can provide a three-dimensional image with uniform brightness, thereby improving the image quality and the visual perception of the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic structural diagram of a display device according to an embodiment of the present invention.

[0015] Figure 2A is a front view of an image provided by an existing display device according to a comparative example.

[0016] Figure 2B is according to Figure 1 The front view of the image provided by the display device of.

[0017] Figure 3 is a schematic structural diagram of a display device according to another embodiment of the present invention.

[0018] Figure 4 It is a schematic structural diagram of a display device according to another embodiment of the present invention. Detailed implementation manners

[0019] Figure 1 It is a schematic structural diagram of a display device according to an embodiment of the present invention. Please refer to Figure 1 , in this embodiment, the display device 100 includes a coherent light source 110, a display unit 120, a light diffusion element 130, and at least one optical element 140. The coherent light source 110 is used to provide a coherent light beam 50. For example, in this embodiment, the coherent light source 110 is a laser light source, and the display unit 120 can be a liquid-crystal-on-silicon panel (LCOS panel), and can be used to modulate the phase of the coherent light beam 50, so that the coherent light beam 50 passing through the display unit 120 can form a three-dimensional image light beam 60 based on the interference between each other. However, the present invention is not limited thereto. In other embodiments, the display unit 120 can also be other beam modulators that can be used to modulate the phase of the coherent light beam 50. As long as the display unit 120 can be used as a spatial light modulator and can have a structure capable of modulating the phase of the coherent light beam 50.

[0020] In addition, as Figure 1 shown, in this embodiment, the display device 100 may further include a lens ML. Specifically, the lens ML can be arranged corresponding to each pixel on the display unit 120, and guide the coherent light beam 50 to a specific position in the display unit 120, so that the coherent light beam 50 can be effectively modulated into a three-dimensional image light beam 60, where the three-dimensional image light beam 60 records the spatial light information required to form a three-dimensional image.

[0021] In this way, the display unit 120 can be used to form a three-dimensional image light beam 60 based on the interference of the coherent light beam 50, and, as Figure 1 shown, the three-dimensional image light beam 60 forms an image on an intermediate imaging surface IS after passing through the display unit 120. More specifically, as Figure 1 shown, in this embodiment, the light diffusion element 130 is also arranged on the intermediate imaging surface IS.

[0022] Furthermore, as Figure 1 shown, in this embodiment, the light diffusion element 130 has an actuator 131, and the actuator 131 is electrically connected to the light diffusion element 130 and is used to drive the light diffusion element 130 at a driving frequency. For example, the actuator 131 is used to drive the light diffusion element 130 to rotate and the driving frequency is the rotation frequency of the light diffusion element 130.

[0023] In this way, the three-dimensional image light beam 60 sequentially changes the diffusion angle of the three-dimensional image light beam 60 through the light diffusion element 130. Moreover, due to the persistence of vision, the brightness of the light spot on the irradiated surface observed by the human eye will be the superposition of the light spots at different time points within a persistence of vision time. Since the light diffusion element 130 can change the light spot distribution of the three-dimensional image light beam 60 over time without affecting the spatial light information it records, the light spot distributions of the three-dimensional image light beam 60 at different time points passing through the light diffusion element 130 are different, but the three-dimensional image light beam 60 can still retain the spatial light information it records. Therefore, the superposition of the light spots at different time points within these persistence of vision times will produce a light spot with relatively uniform brightness, thereby making the three-dimensional image light beam 60 formed through the light diffusion element 130 have better uniformity and still be able to retain the spatial light information it records to successfully display the three-dimensional image.

[0024] Specifically, since the light diffusion element 130 is configured to sequentially change the diffusion angle of the three-dimensional image light beam 60, the size of the light diffusion element 130 is preferably slightly larger than the size of the three-dimensional image light beam 60 imaged on the intermediate imaging surface IS, so that the light diffusion element 130 can adjust the uniformity of the overall three-dimensional image light beam 60. For example, in this embodiment, the size range of the light diffusion element 130 is greater than 1 centimeter.

[0025] Furthermore, as Figure 1 shown, in this embodiment, at least one optical element 140 is located on the transmission path of the three-dimensional image light beam 60 from the light diffusion element 130, and is used to project the three-dimensional image light beam 60 passing through the display unit 120 out of the display device 100 to display the three-dimensional image. For example, in this embodiment, the three-dimensional image light beam 60 passing through the intermediate imaging surface IS can be transmitted to the optical element 140 and projected out of the display device 100 through these optical elements 140 and then imaged again to display the three-dimensional image. The optical element 140 includes optical elements such as a concave mirror CM or a windshield WS. In this way, since the three-dimensional image light beam 60 formed through the light diffusion element 130 has good uniformity, the display device 100 will also be able to provide a display screen with uniform brightness, thereby improving the image quality and the visual perception of the user.

[0026] Figure 2A is a front view of the image provided by an existing display device according to a comparative example. Figure 2B is according to Figure 1 of the display device provided by the image. For displaying Figure 2A of the image of the existing display device and Figure 1is similar to the display device 100, and the differences are as described below. The existing display device does not have the configuration of the light diffusion element 130. Thus, as Figure 2A shown, obvious light spots appear in the image of the existing display device. In contrast, as Figure 2B shown, the image of the display device 100 has uniform and clear brightness, has good image quality, and improves the visual perception of the user.

[0027] It should be noted that in the foregoing embodiment, although the actuator 131 is taken as an example for driving the light diffusion element 130 to rotate, the present invention is not limited thereto. In another embodiment, the actuator 131 can also drive the light diffusion element 130 to vibrate, so that the spot distribution of the three-dimensional image light beam 60 changes with time. Further description will be given below.

[0028] Figure 3 is a schematic structural diagram of a display device according to another embodiment of the present invention. Please refer to Figure 3 , Figure 3 The display device 300 is similar to the Figure 1 display device 100, and the differences are as described below. The actuator 131 is used to drive the light diffusion element 130 to vibrate, and the driving frequency is the vibration frequency of the light diffusion element 130. Thus, the display device 100 can still adjust the uniformity of the overall three-dimensional image light beam 60 through the configuration of the light diffusion element 130, and the display device 300 can also achieve similar effects and advantages as the foregoing display device 100, which will not be elaborated here.

[0029] Furthermore, since the light diffusion element 130 in this embodiment changes the spot distribution of the three-dimensional image light beam 60 with time by vibrating, the moving range of the light diffusion element 130 is smaller compared to the rotating method. Therefore, the volume of the display device 300 can be further reduced.

[0030] Figure 4 is a schematic structural diagram of a display device according to still another embodiment of the present invention. Please refer to Figure 4 , Figure 4 The display device 400 is similar to the Figure 3is similar to the display device 300, and the differences are as described below. In this embodiment, the light diffusion element 430 is a liquid crystal element LC, and the light diffusion element 430 includes a controller 432 that controls the arrangement state of the liquid crystal molecules in the liquid crystal element LC to change over time. For example, when the optical axis directions of the liquid crystal molecules in the liquid crystal element LC are substantially disordered and interlaced with each other, the three-dimensional image light beam 60 passing through the light diffusion element 430 will be scattered by the liquid crystal molecules. In other words, when the controller 432 controls the arrangement state of the liquid crystal molecules in the liquid crystal element LC to be in a disordered state, the light diffusion element 430 can present a foggy state and can be used to change the diffusion angle of the three-dimensional image light beam 60. On the other hand, when the controller 432 controls the optical axis directions of the liquid crystal molecules in the liquid crystal element LC to be substantially consistent, the diffusion angle of the three-dimensional image light beam 60 passing through the light diffusion element 430 will not be changed. In other words, the light diffusion element 430 can present a transparent state at this time.

[0031] Thus, when the controller 432 controls the arrangement state of the liquid crystal molecules in the liquid crystal element LC to change over time, the diffusion angle of the three-dimensional image light beam 60 passing through the light diffusion element 430 will also change over time accordingly. Thus, the display device 400 can still adjust the uniformity of the overall three-dimensional image light beam 60 through the configuration of the light diffusion element 430. Therefore, the display device 400 can also achieve similar effects and advantages as the aforementioned display device 300. Further explanations will be given below.

[0032] More specifically, the controller 432 can further control the arrangement state of the liquid crystal molecules of the light diffusion element 430 to present a specific arrangement state according to the region where it is located. That is to say, the controller 432 can control the light diffusion element 430 to form a plurality of diffusion patterns. And the controller 432 can also control each diffusion pattern to be formed correspondingly at different times, and the arrangement state of the liquid crystal molecules when the light diffusion element 430 forms one diffusion pattern is different from the arrangement state of the liquid crystal molecules when the light diffusion element 430 forms another diffusion pattern.

[0033] More specifically, in this embodiment, the controller 432 can control a diffusion pattern switching frequency of the light diffusion element 430. The diffusion pattern switching frequency is the frequency at which a plurality of diffusion patterns are formed per unit time, and when the number of types of the plurality of diffusion patterns is N, the range of the switching frequency is greater than N times 60 Hz. Thus, the controller 432 can adjust the uniformity of the overall three-dimensional image light beam 60 by controlling the type of the diffusion pattern of the light diffusion element 430 and its diffusion pattern switching frequency, and the display device 400 can also achieve similar effects and advantages as the aforementioned display device 300, which will not be elaborated here.

[0034] In summary, the display device according to the embodiments of the present invention can adjust the overall uniformity of the three-dimensional image light beam through the configuration of the light diffusion element. Therefore, the three-dimensional image light beam formed by the light diffusion element has good uniformity. Thus, the display device can provide a three-dimensional image with uniform brightness, thereby improving the image quality and the visual perception of the user.

[0035] Although the present invention has been disclosed above in the form of embodiments, it is not intended to limit the present invention. Any person skilled in the art within the technical field, without departing from the concept and scope of the present invention, may make some changes and modifications. Therefore, the protection scope of the present invention shall be determined by the scope defined by the claims.

Claims

1. A display device, comprising: A coherent light source that provides a coherent light beam; A display unit that forms a three-dimensional image light beam based on the interference of the coherent light beam, and the three-dimensional image light beam forms an image on an intermediate imaging surface after passing through the display unit; A light diffusion element disposed on the intermediate imaging surface, wherein the three-dimensional image light beam passes through the light diffusion element to sequentially change the diffusion angle of the three-dimensional image light beam; And At least one optical element located on the transmission path of the three-dimensional image light beam from the light diffusion element, for projecting the three-dimensional image light beam passing through the display unit out of the display device to display a three-dimensional image.

2. The display device according to claim 1, wherein the light diffusion element has an actuator, and the actuator is electrically connected to the light diffusion element and is used to drive the light diffusion element at a driving frequency.

3. The display device according to claim 2, wherein the actuator is used to drive the light diffusion element to vibrate, and the driving frequency is the vibration frequency of the light diffusion element.

4. The display device according to claim 2, wherein the actuator is used to drive the light diffusion element to rotate, and the driving frequency is the rotation frequency of the light diffusion element.

5. The display device according to claim 1, wherein the light diffusion element is a liquid crystal element, and the light diffusion element includes a controller that controls the arrangement state of liquid crystal molecules in the liquid crystal element to change over time.

6. The display device according to claim 5, wherein the controller can control the light diffusion element to form a plurality of diffusion patterns, and each of the diffusion patterns is correspondingly formed at different times, and the arrangement state of liquid crystal molecules when the light diffusion element forms one of the diffusion patterns is different from the arrangement state of liquid crystal molecules when the light diffusion element forms another of the diffusion patterns.

7. The display device according to claim 6, wherein the controller can control a diffusion pattern switching frequency of the light diffusion element, the diffusion pattern switching frequency is the frequency at which the plurality of diffusion patterns are formed per unit time, and when the number of types of the plurality of diffusion patterns is N, the range of the switching frequency is greater than N times 60 Hz.

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