IMMY optical design 2

IOptical design of the Immy iC 60 (Source: Immy)

Immy公司已經推出超薄頭戴式顯示器Immy Neo iC 60,最初的應用是在增強現實(AR)領域,後續的產品定位在虛擬現實(VR)應用領域。現在的產品主要基於Immy公司的“自然眼光學”(Natural Eye Optics,簡稱NEO)設計,這與一些頭戴式顯示器上採用的全反射光學設計類似。

作為圖像源,iC 60採用一對索尼0.39” XGA(1024 x 768)OLED微型顯示器,兩個圖像可以100%重疊,從而保證系統的立體3D顯示。Immy在2015年就公開發布過iC 60頭戴式顯示器,但Immy首席執行官Douglas Magyari卻告訴我們該設備的Mark 1版本將在4月13日開放預購,具體出貨時間未做透漏。

最初的市場主要是工業和軍事領域,外加一些重點的戰略性消費應用。關於價格,前5000個產品將以2000美元出售,此後如果元器件供應商的報價下降,將降至1000美元左右。 Douglas Magyari補充到:設備生產是在位於美國密歇根的Immy公司,並非外包。 Mark 2版本的iC 60也將在今年晚些時候問世。兩個版本的關鍵區別之一是Mark 1是通過USB-C與主機連接,而Mark 2是通過CPU / GPU無線連接。此外,Mark 2將有光學的改進並採用一組更強大的傳感器。

Immy與其它頭戴式顯示器廠商不一樣之處在於其光學設計。新設計是基於全反射系統和三項美國專利:美國專利9,268,139,美國專利9,250,444和美國專利9,151,954。 Magyari是專利9,268,139和9,250,444的唯一發明人,而Immy的產品開發副總裁Salvatore Vilardi則是專利9,151,954的聯合發明人。 Immy在日本和墨西哥也獲得了專利。

這種光學設計使用發射顯示器加三塊薄鏡,擁有許多優點,並經常被用於抬頭顯示器(HUD)系統。若不是第一面鏡子朗伯顯示對光的收集,它可以是非常有效的。 Karl Guttag認為,相比在其它頭戴式顯示器採用Birdbath光學設計,這種設計的光學效率是其四倍,其優勢不言而喻。至少有可能具有非常高的分辨率和低失真度。

由於光學元件都很薄且與空氣隔離,具有重量輕的潛在特性。在疊加AR信息的位置沒有物質存在於分光鏡中,因此透視圖像在眼睛分辨率最高的光斑中心凹區不會退化。當微顯示器關閉,透視圖像看起來像通過太陽鏡看到的景象。雖然目前設計的AR視場(FOV)僅60°,但該設計具有達到135°視場的潛力。

這種設計存在一個缺點就是相對笨重。空氣間隔的光學元件需要它們之間存在空氣。相比Immy以往的設計,Immy已經在體積小型化的工作中卓有成效。但是離小型化的目標還有一段路,至少當前的設計還不會有人誤以為是一副太陽鏡。

Magyari談到Immy公司目前的設計實際上已經超越了Mark1和Mark2的設計,正致力於1080p(1920 x 1080)版本。此款將採用基於微型LED技術(MicroLED,也稱為iLED)的顯示屏(像素3µm,大小為0.23”),從而取代索尼XGA OLED微顯示屏(像素7.8µm,大小0.23”)。 iC 60具備60°視場,1024水平像素,每個像素3.5角分,而人眼的極限分辨率為1角分。這比專用的頭戴式顯示設備表現優秀,與基於智能手機顯示屏的頭顯來講就更優秀了,但是這裡談的仍是可見像素。

目前還沒有見到Immy的產品實物。但是Tal Blevins最近在舊金山召開的遊戲開發者大會上看到了,他說:“雖然這只是一個樣品,我嘗試的測試產品很輕,顏色明亮,畫面清晰度,這令我印象深刻。60度視場也明顯優於Hololens和Meta 2,賦予人類更自然的視覺體驗。”

MicroLED版本的設計,將為Immy頭顯帶來巨大的優勢。首先,60度視場內1920像素,每個像素達1.9角分,已經接近人眼的極限分辨率,並很可能將像素變得不可見。
第二點優勢則是MicroLED的亮度是OLED的幾倍。通常情況下,OLED微型顯示器亮度為~500 cd/m2,當公認MicroLED的亮度是10000 cd/m2甚至更高。即使在對於更小的微顯示屏尺寸和更高需求的放大倍率,亮度越高,圖像更明亮。反過來,這也允許了頭顯在高亮度環境下使用,如在陽光直射的室外,仍然可以得到可接受能見度的AR信息。

預計MicroLED顯示器的另一個優勢是比索尼的OLED微型顯示器更高效,功耗更低。當然,如果頭顯需要全亮度時,MicroLED以10000 cd/m2的亮度驅動,它會消耗比OLED在500 cd /m2更多的總功率,所以這種優勢可能並不明顯。
最後,MicroLED顯示器的尺寸更小,相比iC 60 Mark 1或 Mark 2,這允許了一個更加緊湊的光學系統。

Magyari希望在2017年11月或12月得到MicroLED樣品,並拒絕確認供應商。我們猜測Immy和MicroLED顯示屏的研發工作至少需要一年,最樂觀的估計能看到產品也是在2019年第一季度了。

我們順便問了Immy這個公司名稱的由來。 Magyari告訴我:“這是詞語Immersive Imager(身臨其境的成像儀)的簡稱。所有這些頭顯觀眾都是身臨其境的成像儀,所以他們都是Immy的觀眾。”

Immy Inc. has developed the Immy Neo iC 60 see-through HMD, initially for augmented reality (AR) applications but follow-on units will eventually be usable for virtual reality (VR) applications as well. This unit is based on what Immy calls “Natural Eye Optics” (NEO), an all-reflective optical design similar to what is used in some head-up displays. 

As an image source, the iC 60 uses a pair of Sony 0.39” XGA (1024 x 768) OLED microdisplays, one for each eye. There is 100% overlap between the two images so the system can show stereo 3D. Immy has publicly discussed the iC60 HMD since at least 2015 but Douglas Magyari, CEO of Immy, told me the Mark 1 version of the device will be available for pre-order on April 13th, although he would not say when the unit would start shipping. The primary initial market will be industrial and military, plus some focused strategic consumer applications. He said the price of the first 5000 units sold will be $2,000. After that, the price will drop to nearer $1,000, depending on component suppliers. He added the units will actually be made in the US by Immy, a Michigan-based company, and not outsourced.

The Mark 2 version of the iC 60 will be available later in the year. One key difference between the Mark 1 and Mark 2 is the Mark 1 is tethered to its host via a USB-C connection while Mark 2 will be connected wirelessly to the belt-worn CPU/GPU. In addition, Mk. 2 will have improved optics and a more robust set of sensors.

IMMY iC 60 resizeImmy NEO iC 60 see-through HMD (Image: Immy)

Perhaps the thing that sets Immy apart from other HMDs is the optical design. This NEO design is based on an all-reflective system and is subject to three US patents assigned to Immy: US 9,268,139; US 9,250,444; and US 9,151,954. Magyari is named as sole inventor on the ‘139 and ‘444 patents and Salvatore Vilardi, V.P. of Product Development at Immy, is named as his co-inventor on the ‘954 patent. There also have been patents granted in Japan and Mexico.
This optical design, which uses an emissive display plus three thin mirrors, has numerous advantages and has often been used on head up display (HUD) systems. Except for the collection of the light from the lambertian display by the first mirror, it can be very efficient. Karl Guttag tells me it has roughly a 4x optical efficiency advantage over comparable “Birdbath” optical designs used in some other HMDs. It is, potentially at least, very high resolution and low distortion.  

Since the optical elements are all thin and air spaced, it is potentially light weight. As there is nothing special in the beamsplitter at the location of the superimposed AR information, the see-through image is not degraded in the critical foveal region, where eye resolution is the highest. With the microdisplay turned off, the see-through image looks just like it would look through a set of sunglasses. While the current designs have an AR field of view (FOV) of 60°, the design is said to have the potential for a 135° FOV.

There is one big disadvantage of the design, however, it is relatively bulky. The air-spaced optical elements require, well, air between them.  While Immy has done a good job of minimizing this bulk compared to their original designs, it is still a factor and no one would ever mistake this HMD for a pair of ordinary sunglasses.

IMMY US9151954 fig 1 resizeOriginal Immy Optical Layout (Source: US 9,151,954 Figure 1)

Magyari says Immy has already gone beyond the Mark 1 and Mark 2 designs and is working on a 1080p (1920 x 1080) version that replaces the 0.39” Sony XGA OLED microdisplay with 7.8µm pixels with a 0.23” display based on MicroLED technology (which he calls iLED) that will have 3µm pixels. In the iC 60, with 1024 horizontal pixels in a 60° FOV, each pixel subtends 3.5 arc-minutes, compared to the nominal limit of human resolution of 1 arc-minute. This is good, better than most dedicated HMDs and much better than any HMD based on a smartphone display, but the pixels should still be visible.

I haven’t seen an Immy unit so I can’t say for sure. However, Tal Blevins saw one at the recent Game Developers Conference in San Francisco and said, “While just an engineering build at this point, the test unit I tried was very light.  I was impressed by how bright the colors were and the sharpness of the picture.  The 60-degree field of view was also noticeably wider than both the Hololens and Meta 2, and gave a more natural visual feel to the experience.”

The MicroLED version of the design will bring several important things to the Immy HMD. First, the 1920 pixels horizontally spread across a 60° FOV will give 1.9 arc-minutes per pixel, near the limit of human vision and probably close enough to make the pixels effectively invisible. 

Second, the MicroLED display will be orders of magnitude brighter than the OLED unit. Typically, OLED microdisplays are ~500 cd/m² while people are talking 10,000 cd/m² and more for MicroLED display brightnesses. This higher luminance will enable a brighter image, even given the smaller microdisplay size and higher required magnification. This will, in turn, allow the use of the see-through HMD in higher ambient light conditions, e.g. outdoors in direct sunlight, and still get acceptable visibility for the AR information.

Another advantage is the MicroLED display is (expected to be) more efficient than the Sony OLED microdisplay, reducing power consumption. Of course, if the MicroLED is driven at 10,000 cd/m², it is likely to consume more total power than the OLED at 500 cd/m², so this advantage may not be apparent if the HMD is used where the full brightness is needed.

Finally, the MicroLED display is smaller. This should allow a still more compact optical system compared to the current iC 60 Mark 1 or Mark 2.

Magyari said he expected to get working samples of the MicroLED (iLED) display in November or December of 2017. He declined to identify the vendor. I would guess that there will be at least a year of development work both at Immy and at the microdisplay supplier, so I wouldn’t expect product before Q1 2019 at the earliest.

BTW, I asked Magyari where "Immy" came from. He told me, “It's a made-up word to simplify the phrase ‘Immersive Imager’, which is a mouthful. All of these headworn viewers are immersive imagers, so now they're simply Immy's.”  –Matthew Brennesholtz

Source:Immy

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