[Patent] Another Canon Patent For Improved Phase-Detection Autofocus (next mirrorless sensor?)

Conventional approach (left) and patented approach (right)

Egami (machine translated) spotted another patent filed by Canon and related to methods that aim to improve the performance and accuracy of the phase-detection AF. This is the second patent in a few days – the first one can be seen here. Such an AF method is featured on the Rebel T4i/650D and on Canon’s recently announced mirrorless camera, the EOS M. Note that such an AF method is particularly useful on a mirrorless camera, given that such cameras, since they are missing the mirror, can not focus in the “traditional way”.

As far as I can tell, the patent details methods to increase AF performance by eliminating problems caused by the angle of incidence of the light: “[…] reduce the diffraction limit by a high refractive index layer“. Another discussed issue is the reduction of the pixel size (higher resolution??). I am more and more confident that both patents are related to an upcoming sensor which, I guess, will be at the heart of the more pro-oriented mirrorless camera most of us are expecting to be announced in September at Photokina.

  • Patent Publication No. 2012-151367
    • 2012.8.9 Release Date
    • 2011.1.20 filing date
  • The diameter of the spot light focusing of the micro lens
    • Determined by the numerical aperture and λ the wavelength of the incident light
    • By the wave nature of light, not smaller than the diffraction limit
    • When the pixel size below the diffraction limit, pupil division is impossible
    • ⊿ = 1.22 * (λ / n * sinθ) diffraction limit
    • ※ This angle θ is half the chance of lens optical system was synthesized in the micro-lenses and layers
  • Related art
    • There is a light flux can not reach into the openings of the light-shielding layer of the phase difference AF pixel for the image plane, the light-receiving efficiency is reduced
    • Although the distance can be shortened and the photoelectric conversion unit if microlens back-illuminated (BSI), if the pixel consists of a low refractive index layer in the layer lens +, for total internal reflection occurs, can not be expected to increase the angle
  • Canon’s patented
    • To reduce the diffraction limit by a high refractive index layer
    • Structure of the pixel
      • Within a layer lens, and light shielding layer formed between the microlens
      • The high refractive index layer, filled between the lens and the light-shielding layer in the layer
      • The low refractive index layer, a light shielding layer filled between the microlens and
      • Optical system consisting of micro-lens and lens in the layer, connecting the focal point in the PD
      • A case
        • Λ = 540nm wavelength of the incident light
        • 1.6 refractive index of the microlens
        • 1.45 refractive index of the low refractive index layer
        • Layer of high refractive index lens and in the layer refractive index n = 2.3 (silica Sio 2 of the prior art is n = 1.46)
[via egami]

[Patent] New Canon Phase-Detection AF Method With Higher Accuracy And Smaller Pixel Size (for the next mirrorless camera?)

Egami (machine translated) found a Canon patent for an improved phase-detection AF. Higher accuracy is obtained by better propagation of light. The patent text also suggests, the method should improve accuracy when light is falling in with a low-angle incident. I found another thing very interesting: the patent refers to smaller pixel size, i.e. you can pack more pixel on the sensor. So, given that a phase-detection AF is particularly useful on a mirrorless camera, could that indicate that Canon is working on a higher resolutions sensor (with an improved AF) for its more pro-oriented mirrorless camera that we expect to be announced later this year?

  • Patent Publication No. 2012-151215
    • 2012.8.9 Release Date
    • 2011.1.18 filing date
  • Existing techniques
    • JP 2002-314062
    • Conventional techniques beam separation is insufficient, Ranging Accuracy is poor
      • Scattering effects due to wiring
      • The smaller the angle of incidence, it is difficult to detect
      • Smaller pixel size, the value of F becomes larger microlenses (dark), they spread the light next to almost the same in the size of the image pixel size and pixel diffraction
  • And waveguide
    • The waveguide, depending on the angle of incidence of the light flux, there is a characteristic (waveguide mode) is different states of light propagation in the waveguide
  • Canon ‘s patented
    • Consisting of waveguide waveguide and vice
      • Guiding light of two different incident direction: waveguide
      • Vice waveguide: one for each waveguide comprises a waveguide two sub-
    • Can be detected by the photoelectric conversion unit specific, the incident light at a particular angle
    • Impact of wiring
      • The incident light to propagate the core portion of the waveguide, reducing the impact of wiring
    • Low-angle incident light, by using the corresponding waveguide mode depends on the incident direction
    • Small pixel size, support by limiting the distribution of the emitted light
      • Achieved by suppressing the spatial width confinement in the waveguide propagation of light sub-

 

[Rumor] New 35mm f/1.4L II Soon To Be Announced?

The rumor comes from CR. Not a new rumor, and a plausible one. It’s said that three prototypes of the next iteration of the 35mm f/1.4L are already out in the wild, given to selected photographers for testing purposes. The new 35mm should then be announced after Canon has started mass production and shipping of the 24-70mm f/2.8 II USM. Finally, the 35mm f/1.4L II USM should be announced in 2012 and be available for the masses in 2013. Last month I reported about a patent that most probably refers to the new 35mm, check it to know more about the optical properties of this lens.

The actual 35mm f/1.4L USM has a price tag around $1,344 (click on the shop name to learn more): Amazon, B&H Photo, Digitalrev, eBay, Adorama, KEH Camera, Canon USA

[Patent] Canon Patent For Improved Phase Detection Auto Focus

Phase Detection AF

Egami (machine translated) found a patent by Canon regarding an improved Phase Detection Auto Focus. Such a “hybrid” autofocusing system has been featured on the Rebel T4i/650D and the recently announced EOS M. The patented technology aims at improving speed and accuracy. Is this the AF system that Canon will implement on its next, more pro-oriented mirrorless camera, expected to be announced later this year?

  • Patent Publication No. 2010-60771
    • 2010.3.18 Release Date
    • 2008.9.3 filing date
  • Existing techniques
    • Patent Publication No. H11-281878
    • Different lengths of baseline using the AF sensor
      • F2.8 sensor: high focusing accuracy
      • Can detect a wide range of defocus amount (the amount of deviation of focus): F5.6 sensor
      • After roughly at F5.6 sensor is focused, making focus F2.8 sensor with high accuracy
    • Drawback
      • Depending on the timing F2.8 sensor is not used, focusing accuracy is not good
  • Canon’s patent
    • Different lengths of baseline using the AF sensor
      • Because of the defocus amount detection range is limited, must search as duplicate detection range
      • By using the F5.6 sensor, within a limit not exceeding the amount of defocus, it is possible to focus lens is driven at high speed
    • If the Live View
      • The image plane using phase difference AF
      • Focus lens is driven at high speed
        • Using the central pixel: When low-intensity
        • Using the neighboring pixels: When high-intensity

Imaging surface phase detection AF

[via Egami]

[Patent] Canon 135mm f/2.8 and a 180mm f/3.5 Using An Apodization Filter

135mm f/2.8

180mm f/3.5

Japanese site Egami (machine translated) spotted another patent filed by Canon. This time it is about a 135mm f/2.8 and a 180mm f/3.5 lens. The news are an apodization filter that should help provide a more pleasant bokeh.

  • Patent Publication No. 2012-128151
    • 2012.7.5 Release Date
    • 2010.12.15 filing date
  • Example 1
    • 137.2mm – f = 135.0 focal length
    • Fno 2.83 -. 3.90
    • 9.1 deg half each painting.
    • Image height 21.60mm
    • 186.7mm – 150.0 full-length lens
    • BF 47.4 – 80.7mm
    • Lens Construction 10 elements in 7 groups sheet
    • 1 UD glass sheet
    • 0.25 times the maximum magnification ratio
  • Example 6
    • 179.1mm – f = 180.0 focal length
    • Fno 3.50 -. 4.00
    • 6.9 deg half each painting.
    • Image height 21.60mm
    • 218.0mm – 199.8 full-length lens
    • BF 70.0 – 89.8mm
    • Lens Construction 11 elements in 7 groups sheet
    • 1 UD glass sheet
    • 0.11 times the maximum magnification ratio
  • (Bokeh) out of focus look of the important
  • Apodization filter
    • The periphery of the filter transmittance is reduced
    • Added to the luminous flux intensity distribution
    • Bokeh is beautiful and the outline of the
  • Apodization element variable
    • If the liquid of same refractive index as the shape of the interface, no variation occurs in aberration
    • To be the same refractive power of the two liquids, the Abbe number is difficult
  • Canon‘s patented
    • Variable element shape
      • Voltage is applied, changing the shape of the interface
      • Obtain the effect of apodization
      • Varying refractive power, the Abbe number
    • To reduce the time variable aberrations of shape
      • By a twist of the material performed, to optimize the absorption coefficient, to suppress the generation of aberration to moderate the curvature of the interface
      • To reverse the two materials (such as liquid), the amount of chromatic aberration, do the negation
      • Suppress the two materials (such as liquid), refractive index, the difference between the Abbe number
    • The entire feeding (with floating)

 

[Patent] Canon Files Patent For 600mm f/5.6 and 800mm f/5.6

600mm f/5.6 DO

800mm f/5.6 DO

Egami (machine translated) found a patent filed by Canon for a 600mm and a 800mm f/5.6 lens using diffractive optical elements.

  • Patent Publication No. 2012-123152
    • 2012.6.28 Release Date
    • 2010.12.8 filing date
  • Example 1
    • Focal length f = 584.99mm
    • Fno. 5.80
    • Half angle of 2.12 deg.
    • Image height 21.64mm
    • Length 360.03mm
    • BF 94.84mm
    • 17 pieces in 10 groups Lens Construction
    • 3 UD glass sheet
    • One fluorite
    • A surface diffraction plane
  • Example 3
    • Focal length f = 779.00mm
    • Fno. 5.80
    • Half angle of 1.59 deg.
    • Image height 21.64mm
    • Length 462.02mm
    • BF 120.29mm
    • 17 pieces in 10 groups Lens Construction
    • 2 UD glass sheet
    • Two fluorite
    • A surface diffraction plane
  • Low dispersion material with anomalous partial dispersion
    • To be effective in the correction of chromatic aberration
    • Specific gravity is large (heavy)
      • 3.18 fluorite
      • FK01 3.63
      • The specific gravity of small anomalous partial dispersion glass material
        • FK5 2.46
        • BK7 2.52
    • Surface may be damaged easily
    • FK01 is fragile due to temperature changes and large diameter
  • Diffractive optical element (DOE)
    • To be effective in the correction of chromatic aberration
    • Is generated by unwanted light flare and ghosting
  • Canon’s patented
    • Become positive from negative to DOE
    • DOE to place the position is hard to unwanted light incident