US 12,253,670 B2
Ghost image free head-up display
Daping Chu, Cambridge (GB); and Yuanbo Deng, Cambridge (GB)
Assigned to Cambridge Enterprise Limited, Cambridge (GB)
Appl. No. 17/771,316
Filed by Cambridge Enterprise Limited, Cambridge (GB)
PCT Filed Oct. 23, 2020, PCT No. PCT/GB2020/052700
§ 371(c)(1), (2) Date Apr. 22, 2022,
PCT Pub. No. WO2021/079154, PCT Pub. Date Apr. 29, 2021.
Claims priority of application No. 1915455 (GB), filed on Oct. 24, 2019; and application No. 1915608 (GB), filed on Oct. 28, 2019.
Prior Publication US 2022/0390743 A1, Dec. 8, 2022
Int. Cl. G09G 3/00 (2006.01); G02B 27/01 (2006.01); G02B 30/33 (2020.01)
CPC G02B 27/0101 (2013.01) [G02B 30/33 (2020.01); G09G 3/002 (2013.01); G02B 2027/011 (2013.01); G02B 2027/012 (2013.01); G02B 2027/014 (2013.01); G09G 2320/0257 (2013.01); G09G 2380/10 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An image generation system for providing a ghost image free head-up display, the system comprising:
a display screen having a front surface and a back surface said display screen having a first configuration,
a picture generation unit for projecting an image towards the display screen for reflection towards a first predetermined eye box,
and a field lens with a predetermined aperture size, the field lens being configured to alter a divergent beam from the picture generation unit to a near parallel beam,
wherein the picture generation unit is configured to project light through the field lens such that light incident on the front surface of the display screen is collimated and forms a first virtual image, wherein a portion of the light is transmitted through the display screen and is incident on the back surface of the display screen forming a second virtual image, wherein the first and second virtual images have an offset,
wherein the field lens is configured such:
that the offset between the first and second virtual images incident on the front and back surfaces of the display screen is below a threshold magnitude and the first and second virtual images are substantially overlaid as viewed from the eye box,
the offset between the first and second virtual image is below a threshold angular resolution, and
the aperture size allows for the eye box to be larger than an inter pupil distance,
wherein the picture generation unit and/or field lens are further configured to adjust the offset between the first and second virtual images when one of the configuration of the display screen or predetermined eye box has changed.