Canon Patents

Patent: Quad Pixel autofocus image sensor

Canon News has uncovered a patent application for a quad pixel autofocus image sensor.

Canon News explains Japan Patent Application 2019041178:

This patent application from Canon deals with a quad pixel autofocus sensor.  Right now Canon is using dual pixel autofocus sensors, but if you ever tried to use an EOS R or an EOS M in landscape orientation to focus on a horizontal line you’ll quickly realize that the phase detect sensors just go in one direction, and have little sensitivity in the other 90 degrees offset direction.

This patent application indicates that Canon has split the pixel into 4 pieces, and also offsets the microlenses as you go further out from the center.

The sensor they are describing in this document seems to be a 20.7MP sensor, with 83 million focus detection points!  The pixel size seems to be 4 micrometers, which would make that approximately 22mm on the width (5575×3725) or in other words an APS-C sized sensor.

It’s possible that Canon is looking at decreasing pixel density and moving to quad pixel autofocus in the future. Let’s call it QPAF.

Canon uses 180nm tech for its APS-C sensors that can incorporate copper wiring. This is probably fine for a 20mp image sensor. There would be a loss of efficiency splitting the pixels further, and may lead to Canon dropping the pixel count on APS-C sensors. This would only matter if we actually do see QPAF sensors in the future.

CanonGrunt

EOS 80D
Jan 28, 2012
130
24
Would this have any relevancy to super 35 cinema image sensors? Or is this something completely different. Not sure about such technical things...
 

addola

Sold my soul for a flippy screen
Nov 16, 2015
62
25
This isn't the first Quad-Pixel AF patent. This was posted on CanonRumors here a year ago.

It would be interesting if this is a new sensor technology that we would see in a future camera!
 

juststeve

I'm New Here
Nov 29, 2018
24
33
Yes, quad pixel patents have appeared before. If you multiply the approximately 4 micron pixel size by the 2.56 crop to full frame factor, it comes to just over 50 MP. Sounds something like a 5DS.

This could be a breakthrough but a holdup in a pro R camera, say a Nikon 850-Z7-Sony A7Riii competitor. The amount of information coming off a sensor like this is a torrent. Could it be four times what comes of a dual pixel sensor? How to process it all? How to exploit it to maximum advantage? It could well be worth waiting for. Or not.
 

uri.raz

EOS 80D
Jan 5, 2016
140
95
Could it be four times what comes of a dual pixel sensor?
Not necessarily. X pixels in DPAF translates into 2X value in the raw files. X pixels in QPAF would translate into 4x values in raw file. So for the same resolution you'd get a raw file twice as large, question is whether Canon would make a QPAF sensor with the same resolution.

How to process it all? How to exploit it to maximum advantage?
Apparently it would allow two stops of latitude processing over exposed pixels, and reconstructing 3D info from the sub-pixel phase info. I wouldn't bet on either catching. IIRC, it was noted the former was problematic with DPAF, as the left sub-pixels have a different perspective than the right sub-pixels, which would be worked around with QPAF (average left-top w/ right-bottom and left-bottom w/ right-top), so it might have better success with QPAF.

It could well be worth waiting for. Or not.
I'm gonna keep an open eye for the improved AF performance.
 
  • Like
Reactions: nitram

mb66energy

EOS 6D MK II
Dec 18, 2011
1,268
180
Germany
www.MichaelBockhorst.de
Yes, quad pixel patents have appeared before. If you multiply the approximately 4 micron pixel size by the 2.56 crop to full frame factor, it comes to just over 50 MP. Sounds something like a 5DS.

This could be a breakthrough but a holdup in a pro R camera, say a Nikon 850-Z7-Sony A7Riii competitor. The amount of information coming off a sensor like this is a torrent. Could it be four times what comes of a dual pixel sensor? How to process it all? How to exploit it to maximum advantage? It could well be worth waiting for. Or not.
I am with uri.raz: 2 times the data.

IMO QPAF resolves one problem with DPAF - DPAF can only detect vertical structures. Try focusing on distant venetian blinds and sometimes it struggles. Rotate the camera to portrait mode and AF acquisition is VERY fast. That is an example for the "problem" described in the article

I see QPAF as a solution to that problem: Use a 2nd DIGIC processor and secondary readout lanes orthogonal to the existing ones and you have no speed penalty (just theoretically) for to improve AF for horizontal structures.

With QPAF the whole sensor is a cross type sensor resulting in smaller AF points (no need to include a larger sensor region to find some vertical structures) which might find enough detail just in lower light.

Maybe DPAF and its maybe-successor are much more important for the future of very reliable AF than I thought before: I am not shure if it is possible for other sensor designs of e.g. Sony to implement some QPAF analogon with their phase detect pixels (but maybe they have it just now).

It was a great idea to give imaging pixels both functions: recording image + providing AF information - seems to me that this makes a more homogenous sensor compared to designs with different pixel types!
 

TMHKR

EOS 700D
Sep 1, 2018
19
10
29
Wouldn't QPAF also decrease light sensitivity of the sensor, since you split the pixels even further?
It always baffled me how DPAF sensor actually performed better in this regard than sensors with "whole" pixels.
 

uri.raz

EOS 80D
Jan 5, 2016
140
95
Wouldn't QPAF also decrease light sensitivity of the sensor, since you split the pixels even further?
AFAIK, the pixels don't cover 100% of the sensor area, and the microlenses concentrate the light into the active area. Thus, as long as the four sub pixels have the same total area as the pixel whence they were split, everything should be fine.
 
  • Like
Reactions: nitram

Sharlin

EOS 6D MK II
Dec 26, 2015
1,034
531
Turku, Finland
Wouldn't QPAF also decrease light sensitivity of the sensor, since you split the pixels even further?
It always baffled me how DPAF sensor actually performed better in this regard than sensors with "whole" pixels.
Why would it? As long as the total light-sensitive area stays the same, nothing changes. 2*n/2 equals n.
 

Mt Spokane Photography

I post too Much on Here!!
Mar 25, 2011
15,475
712
Not necessarily. X pixels in DPAF translates into 2X value in the raw files. X pixels in QPAF would translate into 4x values in raw file. So for the same resolution you'd get a raw file twice as large, question is whether Canon would make a QPAF sensor with the same resolution.
Not correct. The outputs from the dual pixel are combined into one pixel before saving to the card as a CR2 / CR3 so files are no larger. Try it with any dual pixel camera. It will be the same for Quad pixel cameras.

The 5D MK IV and the EOS R have a option to output separate values using Dual Pixel RAW, and that doubles the file size, but few use that. I'm not certain why Canon bothered to put it in the EOS R, perhaps there are future plans to make better use of it.
 
  • Like
Reactions: uri.raz and nitram

djack41

EOS 80D
Jul 12, 2014
164
109
Interesting but Canon has boxes filled with patents. This is as likely to come to market as Canon's years-old patents for stacked sensors or back light illumination. Hard to imagine Canon making the investment to build such a sensor when the CEO is predicting market doom. Hope I'm wrong!
 

Kit.

EOS 6D MK II
Apr 25, 2011
1,258
681
Hard to imagine Canon making the investment to build such a sensor when the CEO is predicting market doom. Hope I'm wrong!
"Market doom" is for traditional photo cameras, not for video sensors.
 

Graphic.Artifacts

EOS 7D MK II
Aug 1, 2017
426
244
DPAF and ultimately QPAF are great core technology and I’d expect that the processing will eventually catch up to what seems like a lot of data to crunch between frames. Right now, I think they’ll need to stick to getting DPAF processing up to speed before doubling the data flow. Sounds like very promising future tech though. So far I haven’t seen where anyone else has a better core AF model.
 

SecureGSM

2 x 5D IV
Feb 26, 2017
1,239
263
Not correct. The outputs from the dual pixel are combined into one pixel before saving to the card as a CR2 / CR3 so files are no larger. Try it with any dual pixel camera. It will be the same for Quad pixel cameras.

The 5D MK IV and the EOS R have a option to output separate values using Dual Pixel RAW, and that doubles the file size, but few use that. I'm not certain why Canon bothered to put it in the EOS R, perhaps there are future plans to make better use of it.
there is an extra stop of DR that lives in the second sub frame of the DPRAW file. I do use it when multiple exposure are not an option - e.g. slow / fast moving subject.
 

crazyrunner33

EOS RP
Nov 4, 2011
262
80
Yes, quad pixel patents have appeared before. If you multiply the approximately 4 micron pixel size by the 2.56 crop to full frame factor, it comes to just over 50 MP. Sounds something like a 5DS.

This could be a breakthrough but a holdup in a pro R camera, say a Nikon 850-Z7-Sony A7Riii competitor. The amount of information coming off a sensor like this is a torrent. Could it be four times what comes of a dual pixel sensor? How to process it all? How to exploit it to maximum advantage? It could well be worth waiting for. Or not.
The way you're describing it is assuming they'll use quad bayering for the sensor like Sony Semicondocutor is using on the newer products. The A7S III rumors shows a quad bayer sensor, the GH5 S is also using a variation of a quad bayer sensor. Below is an idea of how the concept works on small sensors that are already in the field.

 

CJudge

EOS M50
Mar 22, 2019
25
24
Ireland
www.colin-judge.com
there is an extra stop of DR that lives in the second sub frame of the DPRAW file. I do use it when multiple exposure are not an option - e.g. slow / fast moving subject.
For real? That's awesome! Do you need to use Canon's DPP to process? And would this also benefit max usable ISO in low light, or is it just for low ISO DR?
 

tiggy@mac.com

Pentax K-1000
Jan 20, 2014
490
168
Thetford, VT
www.ForestMetrix.com
For real? That's awesome! Do you need to use Canon's DPP to process? And would this also benefit max usable ISO in low light, or is it just for low ISO DR?
Yeah. I think people underestimate the DPP factor on the lack of uptake for Dual Pixel features. That is precisely and only what has kept me from exploiting the focus-after-exposure feature. Even though its effects are slight, I'd still go out of my way to get the extra millimeter of sharpness if I could do it in Lightroom or, really, anything else. That software is truly dreadful.
 
  • Like
Reactions: CJudge