Ricoh AF Patent


jules

Link Posted 27/05/2015 - 17:23
http://egami.blog.so-net.ne.jp/2015-05-13

In Japanese, so, one for your barmy Translator of choice!

Here's my go...

Ricoh patent to achieve a wide ranging scope and dark AF [optical technology in general]

It is a pending patent of the AF sensor to realize the AF of at a wide ranging scope and dark Ricoh. It is increasingly expected to be likely future Pentax digital SLR.
Ricoh Pentax

Explanation and self-interpretation of the patent literature

Patent Publication No. 2015-87404
Published 2015.5.7
Filing date 2013.10.28
First mirror
Leading to OVF by reflecting part of incident light flux
Leading to the second mirror passes through the part of the incident light beam
Second mirror
Concave mirror
Quarter wave plate for changing the polarization state is provided
Changes the polarization state of the incident light beam is reflected and guided to the first mirror
Focus detection
The light beam reflected by the second mirror is incident from the rear to the first mirror, it is reflected by the first mirror and guided to the AF sensor

AF can not use only the center

Ranging range of SLR are concentrated in the center. This street that was introduced earlier in this Blog, is to depend on the sub-mirror of magnitude. The sub-mirror, the light beam transmitted through the reflex mirror (quick return mirror) derived from "Lev" SLR, it is the reflection plate for reflecting the AF sensor. This sub-mirror is positioned at an angle, it has to reflect the light beam incident on the sub-mirror toward the AF sensor. The Will be extended distance measurement range A larger sub-mirror, but remain for now without the space, you will need to redo the SLR design flange back, including from zero.

Ranging scope of the APS-C SLR is said often and wider than the full-size SLR, but it is not the correct words. APS-C SLR is not to those without scaling down the full size SLR, only the imaging device became smaller. Concomitantly to I OVF and reflex mirror, etc. also can be miniaturized. Since the mount or flange back is the same as the full-size single-lens reflex, since there is no need to reduce the sub-mirror has a space with a relatively surplus, I ranging range of APS-C SLR is the only broad relatively.
Patent of Ricoh

Ricoh's patent application is, the sub-mirror is waste, seems to have disposed substantially perpendicular to the optical axis of the concave mirror, which corresponds to the sub-mirror. This I was able to widen the distance measurement range if not the whole area in.

It seems that the quarter-wave plate provided as another device. When varying the reflectance characteristics of the P-polarized light and S-polarized light, seems to one of the light amount is increased, also increases the amount of light of the combined light beam is incident on the AF sensor. It seems AF performance is improved in this dark place.
Pentax full-size SLR

Ricoh is planning a full-size SLR Pentax brand. Patent filing date is the previous one and a half years old, but since the distance measurement range the size of the imaging element is relatively narrow, it seems to be considered as a countermeasure. I do not know whether the patent application is incorporated into the product, full-size SLR Pentax is not just a camera image pickup device is large in size, it is likely to be a twist.
Cheers Jules...

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Last Edited by jules on 27/05/2015 - 17:26

lennythelion

Link Posted 27/05/2015 - 19:49
Can anyone translate, to plain understandable English?

Assume this is the new patent for the ff AF system?

McGregNi

Link Posted 27/05/2015 - 22:47
I think its clear enough that the dark Ricoh's sub-mirror is a waste, and the ranging scope of a full sized slr is obviously not the right words.
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mera

Link Posted 31/05/2015 - 15:42
I had a look at the picture in the original link and think I understand what is being proposed.

In a traditional autofocus system, the light enters, and some passes through the primary mirror, is reflected of the secondary mirror and down into the autofocus assembly. I believe the secondary mirror is quite small which probably impacts autofocus coverage area. Example.

It looks like, in the patent, the light that hits the secondary mirror is reflected straight back in the direction it came in. It then is reflected a second time off the back of the primary mirror and down into the autofocus sensor. So it now bounces of the primary mirror twice. The secondary mirror also has a lensing arrangement (curved mirror?) that probably focuses a wider coverage area onto the current small autofocus sensor. They also talk about a half-wave filter, I believe the light passing through the primary mirror is polarised. so I assume this filter adjusts the polarisation so more gets reflected when the light is bounced again off the primary mirror.

Looks quite clever - I wonder if it is effective and we will see it in the FF camera?
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