US-12619067-B2 - Display device

US12619067B2US 12619067 B2US12619067 B2US 12619067B2US-12619067-B2

Abstract

The present disclosure provides a technology for dealing with coarseness and minuteness of an interval of scanning lines that occur in a case where the Foveated rendering technology is applied. The present disclosure provides a display device including: a laser light source unit that emits laser light used for video formation by scanning; and a laser light source drive unit, in which the laser light source unit can emit two or more pieces of laser light having different beam sizes, or can emit two or more pieces of laser light and can switch the number of pieces of emitted laser light, and the laser light source drive unit changes the laser light emitted from the laser light source unit according to an interval of scanning lines where two or more non-resonant axial direction scanning speeds are used in a drawing region of one frame of a video.

Inventors

Yusuke Ogawa

Assignees

Sony Group Corporation

Dates

Publication Date: 20260505
Application Date: 20211227
Priority Date: 20210129

Claims (14)

1 . A display device, comprising: a laser light source unit that emits laser light used for video formation by scanning; and a laser light source drive unit that drives the laser light source unit, wherein the laser light source unit is configured to draw at least first and second regions of an image frame by: emitting a scanning line using a first beam size for use in the first region of the image frame and using a second beam size for use in the second region of the image frame, wherein the first beam size is larger than the second beam size; or emitting a scanning line using a first number of pieces of laser light in the first region of the image frame and using a second number of pieces of laser light in the second region of the image frame, wherein the first number of pieces of laser light is greater than the second number of pieces of laser light, wherein a first interval of scanning lines and a first scanning speed in a non-resonant axial direction is applied in the first region of the image frame, wherein a second interval of scanning lines and a second scanning speed is applied in the non-resonant axial direction is applied in the second region of the image frame, wherein the first interval of scanning lines is greater than the second interval of scanning lines, wherein a first non-resonant axial direction scanning speed is used in drawing the first region of the image frame, wherein a second non-resonant axial direction scanning speed is used in drawing the second region of the image frame, and wherein the image frame is a frame of a video.
2 . The display device according to claim 1 , wherein the laser light source unit includes an optical waveguide element, wherein the first number of pieces of laser light is two or more, and wherein the two or more pieces of laser light are emitted from the optical waveguide element.
3 . The display device according to claim 2 , wherein the optical waveguide element has two or more emission points having different sizes, wherein the first number of pieces of laser light is two or more, and wherein the two or more pieces of laser light are emitted from each of the two or more emission points.
4 . The display device according to claim 3 , wherein the two or more emission points are provided in the optical waveguide element so as to be aligned in a same direction as the non-resonant axial direction in the scanning.
5 . The display device according to claim 3 , wherein the two or more emission points are provided in the optical waveguide element so as to be aligned in a same direction as a resonant axial direction in the scanning.
6 . The display device according to claim 2 , wherein the optical waveguide element includes two or more emission points of a same size.
7 . The display device according to claim 1 , wherein the laser light source unit includes two or more laser light sources, and the laser light source drive unit changes the beam size of the laser light emitted from the laser light source unit by controlling driving of the two or more laser light sources.
8 . The display device according to claim 1 , wherein the laser light source unit is configured to be able to emit two or more pieces of laser light having different beam sizes.
9 . The display device according to claim 1 , wherein the laser light source unit is configured to be able to emit two or more pieces of laser light and to be able to switch the number of pieces of laser light to be emitted.
10 . The display device according to claim 1 , wherein the laser light source drive unit stops emission of the laser light by the laser light source unit while the scanning speed in the non-resonant axial direction changes.
11 . The display device according to claim 10 , wherein the laser light source unit includes an optical waveguide element having two or more emission points having different sizes, and the two or more emission points of the optical waveguide element are spaced apart such that an angle of view of the laser light in the non-resonant axial direction immediately before a stop period of emission of the laser light matches an angle of view of the laser light in the non-resonant axial direction immediately after the stop period of emission of the laser light.
12 . The display device according to claim 1 , wherein the display device is configured to condense the laser light scanned by a scanning mirror near a pupil to reach a retina.
13 . The display device according to claim 1 , wherein the display device is configured to cause the laser light scanned by a scanning mirror to reach a projection surface without through a projection optical system or through the projection optical system.
14 . The display device according to claim 1 , wherein the first non-resonant axial direction scanning speed is greater than the second non-resonant axial direction scanning speed.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a national stage application under 35 U.S.C. 371 and claims the benefit of PCT Application No. PCT/JP2021/048554, having an international filing date of 27 Dec. 2021, which designated the United States, which PCT application claimed the benefit of Japanese Patent Application No. 2021-013186, filed 29 Jan. 2021, the entire disclosures of each of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a display device. More specifically, the present disclosure relates to a display device that presents a video by laser light scanning. BACKGROUND ART In recent years, attention has been focused on technology of superimposing an image on a scene of an outside world. The technology is also called augmented reality (AR) technology, and AR glasses can be cited as a product using the technology. Examples of AR glasses include devices using displays and devices using laser beam scan (also referred to as LBS). For AR glasses using the LBS, a Foveated rendering technology may be used. This technology slows down the scanning speed of the MEMS only in a portion that a user is gazing at (in particular, only in a fovea part), which relaxes the required MEMS specification. Regarding a device using this technology, for example, Patent Document 1 below discloses “A scanning display system including: a laser light source including two or more offset lasers; a scanning mirror system configured to scan light from the laser light source in a first direction at a higher frequency, and in a second direction at a lower frequency to form an image; and a controller configured to control the scanning mirror system to scan the laser light in an interlaced pattern to form the image, and to adjust one or more of a scanning speed in the second direction and a phase offset between a first frame and a second frame of the interlaced image.” (Claim 1). CITATION LIST Patent Document Patent Document 1: Japanese Translation of PCT Application No. 2020-510870 SUMMARY OF THE INVENTION Problems to be Solved by the Invention In the field related to AR glasses, it is required to achieve both wide angle of view and high resolution. The AR glasses using the display described above can achieve a wide angle of view but have a low resolution (PPD). On the other hand, since the AR glasses using the LBS are of the Scan method, the number of scanning lines in one frame increases when the angle of view is widened. In order to cope with an increase in the number of scanning lines, a scanning mirror having higher performance, in particular, a scanning mirror having a higher resonance frequency of scanning is required. Furthermore, when the number of scanning lines increases, the amount of video data to be transferred increases accordingly, and thus there are disadvantages such as an increase in power consumption and delay. The Foveated rendering technology may be utilized to mitigate the performance of the scanning mirrors required. In this technology, for example, the number of scanning lines is increased and high resolution is maintained by slowing the speed of the scanning mirror only at a portion (particularly, a region including the fovea) at which the AR eyewear wearer is gazing, and the number of scanning lines is decreased and low resolution is achieved by increasing the speed of the scanning mirror at other portions. Therefore, in a case where this technology is applied, a rapid change in the scanning speed occurs in one frame. Furthermore, in this technology, a region where the scanning lines drawn by the scanning mirror are coarse and a region where the scanning lines drawn by the scanning mirror are minute are generated in one frame. In a case where the Foveated rendering technology is applied, as described above, coarseness and minuteness occurs in the scanning lines. The coarseness and minuteness of the scanning lines may cause image quality degradation of the video. Therefore, it is required to adjust the beam to be scanned to an optimum size according to the scanning speed of the scanning mirror. Furthermore, in a case where the Foveated rendering technology is applied, the scanning speed of the scanning mirror, particularly, the scanning speed in the non-resonant axial direction rapidly changes. When the scanning speed changes, the operation of the scanning mirror may become unstable, and for example, vibration unnecessary for the scanning mirror may occur. The unnecessary vibration causes deterioration in image quality, and may cause distortion in a video, for example. Furthermore, in a case where the Foveated rendering technology is applied, it is conceivable to switch the beam size of the laser light. However, it is difficult to seamlessly switch the beam size. A main object of the present disclosure is to provide a technology for dealing with coarseness and minuteness of scanning lines that occur in a case where the Foveated rendering technology