阅读说明：本技术 显示装置 (Display device ) 是由 范姜冠旭 林淇文 于 2020-05-18 设计创作，主要内容包括：一种显示装置,包括同调光源、显示单元、光扩散元件以及至少一光学元件。同调光源提供一同调光束。显示单元基于对于同调光束的干涉而形成一三维图像光束,三维图像光束在通过显示单元后成像于一中间成像面上。光扩散元件设置于中间成像面上,其中三维图像光束通过光扩散元件而时序性改变三维图像光束的扩散角度。至少一光学元件位于来自于光扩散元件的三维图像光束的传递路径上,用于将通过显示单元的三维图像光束投影出显示装置,以显示三维图像。(A display device comprises 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 is imaged on an intermediate imaging surface after passing through the display unit. The light diffusion element is arranged on the middle imaging surface, and the three-dimensional image light beams pass through the light diffusion element to change the diffusion angle of the three-dimensional image light beams in time sequence. At least one optical element is positioned on the transmission path of the three-dimensional image light beam from the light diffusion element and used for projecting the three-dimensional image light beam passing through the display unit out of the display device so as to display a three-dimensional image.)

1. A display device, comprising:

a coherent light source providing a coherent light beam;

a display unit for forming a three-dimensional image beam based on interference to the coherent beam, the three-dimensional image beam being imaged on an intermediate imaging surface after passing through the display unit;

a light diffusion element disposed on the intermediate image plane, wherein the three-dimensional image light beam passes through the light diffusion element to change the diffusion angle of the three-dimensional image light beam in time sequence; 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 of claim 1, wherein the light diffusing element has an actuator electrically connected to the light diffusing element and configured to drive the light diffusing element at a driving frequency.

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

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

5. The display device according to claim 1, wherein the light diffusing element is a liquid crystal element, and the light diffusing element includes a controller that controls an arrangement state of liquid crystal molecules in the liquid crystal element to be changed in sequence.

6. The display device according to claim 5, wherein the controller is capable of controlling the light diffusing element to form a plurality of diffusion patterns, the diffusion patterns being respectively formed correspondingly at different timings, and an arrangement state of liquid crystal molecules when the light diffusing element forms one of the diffusion patterns and an arrangement state of liquid crystal molecules when the light diffusing element forms another one of the diffusion patterns are different from each other.

7. The display device according to claim 6, wherein the controller is capable of controlling a diffusion pattern switching frequency of the light diffusing element, the diffusion pattern switching frequency being a frequency at which the plurality of diffusion patterns are formed per unit time, and the switching frequency ranging over N times 60 hz when the plurality of diffusion patterns are N in kind.

Technical Field

The present invention relates to a display device using coherent light beams, and more particularly, to a display device using holography.

Background

Three-dimensional (3D) display technology is applied to various image display fields, such as movies, Televisions (TVs), and mobile phones. Finally, the purpose of 3D display is to enable a person to experience a 3D effect as if he or she were in a real environment, and therefore, research has been conducted on various technologies including, for example, a body calendar sound scheme and a multi-view scheme. Holography (holography) is representatively used as a technique of restoring 3D spatial light information into a form of real light. Holography can recover light in space based on interference (i.e., the waviness of the light).

However, since coherent light beams used in a display device using holography have high coherence, a constructive or destructive interference (interference) phenomenon is formed in a space, and speckle (speckle) is generated on an irradiated surface. This speckle is an irregular noise-like pattern with bright and dark spots that appear irregular, resulting in uneven brightness on the illuminated surface. Therefore, the image quality of the projection device using the light source is easily reduced, and the visual impression of the user is deteriorated.

One prior method for eliminating speckle in a general display device using coherent light beams is to provide a vibrating mirror in front of the coherent light source to homogenize the coherent light beams, but this method cannot be applied to a display device using holography because it changes the spatial light information of the coherent light beams and thus affects the formation of holograms.

Disclosure of Invention

The invention provides a display device capable of providing images with good image quality.

The display device comprises 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 is imaged on an intermediate imaging surface after passing through the display unit. The light diffusion element is arranged on the middle imaging surface, and the three-dimensional image light beams pass through the light diffusion element to change the diffusion angle of the three-dimensional image light beams in time sequence. At least one optical element is positioned on the transmission path of the three-dimensional image light beam from the light diffusion element and used for projecting the three-dimensional image light beam passing through the display unit out of the display device so as to display a three-dimensional image.

In an embodiment of the invention, the light diffusion element has an actuator, and the actuator is electrically connected to the light diffusion element and is configured to drive the light diffusion element at a driving frequency.

In an embodiment of the invention, the actuator is used for driving the light diffusion element to vibrate, and the driving frequency is a vibration frequency of the light diffusion element.

In an embodiment of the invention, the actuator is used for driving the light diffusion element to rotate, and the driving frequency is a rotation frequency of the light diffusion element.

In an embodiment of the invention, the light diffusing element is a liquid crystal element, and the light diffusing element includes a controller that controls an arrangement state of liquid crystal molecules in the liquid crystal element to change with time.

In an embodiment of the invention, the controller can control the light diffusing element to form a plurality of diffusion patterns, each diffusion pattern is correspondingly formed at a different timing, and an arrangement state of the liquid crystal molecules when the light diffusing element forms one of the diffusion patterns is different from an arrangement state of the liquid crystal molecules when the light diffusing element forms another diffusion pattern.

In an embodiment of the invention, the controller can control a diffusion pattern switching frequency of the light diffusion element, the diffusion pattern switching frequency is a frequency of forming a plurality of diffusion patterns in a unit time, and when the plurality of diffusion patterns are N types, a range of the switching frequency is greater than N times of 60 hz.

Based on the above, the display device of the embodiment of the present invention can adjust the uniformity of the entirety of the three-dimensional image light beam by the configuration of the light diffusing element. Therefore, the three-dimensional image light beam formed by the light diffusion element has good uniformity, so that the display device can provide a three-dimensional image with uniform brightness, and further improve the image quality and the visual impression of a user.

Drawings

Fig. 1 is a schematic structural diagram of a display device according to an embodiment of the invention.

Fig. 2A is a front view of an image provided by a conventional display device according to a comparative example.

Fig. 2B is a front view of an image provided by the display device according to fig. 1.

Fig. 3 is a schematic structural diagram of a display device according to another embodiment of the invention.

Fig. 4 is a schematic structural diagram of a display device according to yet another embodiment of the invention.

Detailed Description

Fig. 1 is a schematic structural diagram of a display device according to an embodiment of the invention. Referring to fig. 1, in the present embodiment, a display device 100 includes a coherent light source 110, a display unit 120, a light diffusing element 130, and at least one optical element 140. Coherent light source 110 is used to provide a coherent light beam 50. For example, in the embodiment, the coherent light source 110 is a laser light source, and the display unit 120 can be a liquid-crystal-on-silicon (LCOS) panel, which 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 the three-dimensional image light beam 60 based on the interference between the coherent light beam 50 and the laser light beam. However, the invention is not limited thereto, and in other embodiments, the display unit 120 may be other light beam modulators for modulating the phase of the coherent light beam 50. As long as the display unit 120 can function as a spatial light modulator and can have a structure capable of modulating the phase of the coherent light beam 50.

In addition, as shown in fig. 1, in the present embodiment, the display device 100 may further include a lens ML. Specifically, the lens ML may be disposed to correspond 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 the three-dimensional image light beam 60, wherein the three-dimensional image light beam 60 describes spatial light information (spatial light information) required to form a three-dimensional image.

In this manner, the display unit 120 can be used to form the three-dimensional image beam 60 based on the interference with the coherent beam 50, and, as shown in fig. 1, the three-dimensional image beam 60 IS imaged on an intermediate imaging plane IS after passing through the display unit 120. More specifically, as shown in fig. 1, in the present embodiment, the light diffusing element 130 IS also disposed on the intermediate imaging plane IS.

Further, as shown in fig. 1, in the present embodiment, the light diffusing element 130 has an actuator 131, and the actuator 131 is electrically connected to the light diffusing element 130 and is used for driving the light diffusing element 130 at a driving frequency. For example, the actuator 131 is used to drive the light diffusing element 130 to rotate and the driving frequency is the rotating frequency of the light diffusing element 130.

In this manner, the three-dimensional image light beam 60 passes through the light diffusing element 130 to change the diffusion angle of the three-dimensional image light beam 60 in time series. Moreover, due to the effect of persistence of vision, the luminance of the light spot on the illuminated surface observed by the human eye will be the superimposed luminance of the light spots at different time points within a persistence of vision time. Since the light diffusion element 130 can change the spot distribution of the three-dimensional image light beam 60 with time without affecting the spatial light information recorded by the light diffusion element, the spot distributions of the three-dimensional image light beam 60 passing through the light diffusion element 130 at different time points are different, but the three-dimensional image light beam 60 can still maintain the spatial light information recorded by the three-dimensional image light beam 60. Therefore, the overlapped light spots at different time points in the persistence time can generate light spots with uniform brightness, so that the three-dimensional image light beam 60 formed by the light diffusion element 130 has better uniformity, and the recorded space light information can be still maintained, so as to smoothly display the three-dimensional image.

Specifically, since the light diffusing element 130 IS configured to change the diffusion angle of the three-dimensional image beam 60 in a time sequence, the size of the light diffusing element 130 IS preferably slightly larger than the size of the three-dimensional image beam 60 imaged on the intermediate imaging plane IS, so that the light diffusing element 130 can adjust the uniformity of the entire three-dimensional image beam 60. For example, in the present embodiment, the size range of the light diffusing element 130 is greater than 1 cm.

Further, as shown in fig. 1, in the present embodiment, at least one optical element 140 is located on the transmission path of the three-dimensional image light beam 60 from the light diffusing element 130, and is used for projecting the three-dimensional image light beam 60 passing through the display unit 120 out of the display device 100 to display a three-dimensional image. For example, in the present embodiment, the three-dimensional image beam 60 passing through the intermediate image plane IS can be transmitted to the optical elements 140, and projected out of the display device 100 through the optical elements 140 to be imaged again, so as to display a three-dimensional image. The optical element 140 includes an optical element such as a concave mirror CM or a windshield WS. Thus, the three-dimensional image beam 60 formed by the light diffusing element 130 has good uniformity, so that the display device 100 can provide a display screen with uniform brightness, thereby improving the image quality and the visual impression of the user.

Fig. 2A is a front view of an image provided by a conventional display device according to a comparative example. Fig. 2B is a front view of an image provided by the display device according to fig. 1. The conventional display device for displaying the image of fig. 2A is similar to the display device 100 of fig. 1, but the conventional display device does not have the arrangement of the light diffusing element 130, as described below. As shown in fig. 2A, the image of the conventional display device has obvious flare, whereas as shown in fig. 2B, the image of the display device 100 has uniform and clear brightness, good image quality and improved visual impression for the user.

It should be noted that, in the foregoing embodiment, the actuator 131 is used for driving the light diffusing element 130 to rotate, but the invention is not limited thereto. In another embodiment, the actuator 131 can also drive the light diffusing element 130 to vibrate, so that the light spot distribution of the three-dimensional image light beam 60 changes with time. As will be further described below.

Fig. 3 is a schematic structural diagram of a display device according to another embodiment of the invention. Referring to FIG. 3, the display device 300 of FIG. 3 is similar to the display device 100 of FIG. 1, and the differences are as follows. 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 entire three-dimensional image beam 60 by the configuration of the light diffusing element 130, and the display device 300 can achieve similar effects and advantages to those of the display device 100, which will not be described herein again.

Further, since the light diffusion element 130 of the present embodiment changes the light spot distribution of the three-dimensional image beam 60 with time by means of vibration, the moving range of the light diffusion element 130 is smaller than that by means of rotation. Accordingly, the volume of the display device 300 may be further reduced.

Fig. 4 is a schematic structural diagram of a display device according to yet another embodiment of the invention. Referring to FIG. 4, the display device 400 of FIG. 4 is similar to the display device 300 of FIG. 3, and the differences are as follows. In the present embodiment, the light diffusing element 430 is a liquid crystal element LC, and the light diffusing element 430 includes a controller 432, and the controller 432 controls the arrangement state of the liquid crystal molecules in the liquid crystal element LC to be changed in sequence. For example, when the directions of the optical axes of the liquid crystal molecules in the liquid crystal cell LC are substantially disordered and staggered, the three-dimensional image beam 60 passing through the light diffusing element 430 is scattered by the liquid crystal molecules. In other words, when the controller 432 controls the alignment state of the liquid crystal molecules in the liquid crystal element LC to be a disordered state, the light diffusing element 430 can assume a foggy state and can be used to change the diffusion angle of the three-dimensional image 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 uniform, the diffusion angle of the three-dimensional image light beam 60 passing through the light diffusion element 430 is not changed. In other words, the light diffusing element 430 may be in a transparent state.

As such, when the controller 432 controls the alignment state of the liquid crystal molecules in the liquid crystal element LC to change with timing, the diffusion angle of the three-dimensional image light beam 60 passing through the light diffusion element 430 also changes with timing accordingly. Thus, the display device 400 can still adjust the uniformity of the entire three-dimensional image beam 60 by the configuration of the light diffusing element 430. Therefore, the display device 400 can achieve similar effects and advantages as the display device 300. As will be further described below.

More specifically, the controller 432 may also control the alignment state of the liquid crystal molecules of the light diffusing element 430 to assume a specific alignment state depending on the region in which it is located. That is, the controller 432 can control the light diffusing element 430 to form a plurality of diffusion patterns. Also, the controller 432 may control the diffusion patterns to be correspondingly formed at different timings, respectively, and the arrangement state of the liquid crystal molecules when one of the diffusion patterns is formed by the light diffusion element 430 and the arrangement state of the liquid crystal molecules when the other diffusion pattern is formed by the light diffusion element 430 may be different from each other.

More specifically, in the present embodiment, the controller 432 is capable of controlling a diffusion pattern switching frequency of the light diffusing element 430, the diffusion pattern switching frequency being a frequency of forming a plurality of diffusion patterns per unit time, and when the plurality of diffusion patterns are N types, a range of the switching frequency is greater than N times of 60 hz. Thus, the controller 432 can adjust the uniformity of the entire three-dimensional image beam 60 by controlling the diffusion pattern type of the light diffusing element 430 and the switching frequency of the diffusion pattern thereof, and the display device 400 can achieve the effects and advantages similar to those of the display device 300, which will not be described herein again.

In summary, the display device according to the embodiment of the invention can adjust the overall uniformity of the three-dimensional image light beam by the configuration of the light diffusing element. Therefore, the three-dimensional image light beam formed by the light diffusion element has good uniformity, so that the display device can provide a three-dimensional image with uniform brightness, and further improve the image quality and the visual impression of a user.

Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.