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EP0176334A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Optical low pass filter

Assignee: Sony Corp
•
Filing: 1985-09-23
•
Granted: —
•
Expires: 2005-09-23
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Abstract

Abstract An optical low pass filter (10) used in a video camera having a solid state image sensing device and a color separating filter is disclosed, which includes a first double refraction plate (10A) being arranged to separate an incident light ray to an ordinary light ray (0,) and an extraordinary light ray (e 1 ,) which is displaced from the ordinary light ray (0 1 ) by a distance d in a directon with the angle substantially equal to 8 relative to the horizontal direction (H) of the solid state image sensing device, wherein and a second double refraction plate (10B) being arranged to separate an incident light ray to an ordinary light ray (O 2 ) by a distance d in a direction with the angle substantially equal to -θ relative to the horizontal scanning direction (H) of the solid state image sensing device, whereby the optical low pass filter (10) has the spatial frequency characteristic having a first trap frequency u 1 and a second trap frequency 2u,.

Inventors

  • 👤 Yasuo Nakada
  • 👤 Masuko Amemiya

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-25 20:58
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/46

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 208 words
An optical low pass filter for use in a video camera comprising a solid state image sensing device (Figs. 1A and 3A) and a color separating filter (Figs 1B and 3B), said optical low pass filter characterised by: a first double refraction plate (10A) arranged to separate an incident light ray to an ordinary light ray (9) and an extraordinary light ray (e 1 ) which is displaced from said ordinary light ray (9) by a distance d in a direction with an angle substantially equal to θ relative to the horizontal scanning direction (H) of said solid state image sensing device, wherein cos 2θ=√2 3 (0°<2θ<90°), and a second double refraction plate (10B) arranged to separate an incident light ray to an ordinary light ray (0 2 ) and an extraordinary light ray (e 2 ) which is displaced from said ordinary light ray (0 2 ) by a distance d in a direction with an angle substantially equal to -0 relative to the horizontal scanning direction (H) of said solid state image sensing device (Figs. 1A and 3A), whereby said optical low pass filter (10) has the spatial frequency characteristic having a first trap frequency u 1 and a second trap frequency 2u 1 (Fig. 9A).
Claim 2
Dependent Claim 208 words
An optical low pass filter for use in a video camera comprising a solid state image sensing device (Figs. 1A and 3A) and a color separating filter (Figs 1B and 3B), said optical low pass filter characterised by: a first double refraction plate (10A) arranged to separate an incident light ray to an ordinary light ray (9) and an extraordinary light ray (e 1 ) which is displaced from said ordinary light ray (9) by a distance d in a direction with an angle substantially equal to θ relative to the horizontal scanning direction (H) of said solid state image sensing device, wherein cos 2θ=√2 3 (0°<2θ<90°), and a second double refraction plate (10B) arranged to separate an incident light ray to an ordinary light ray (0 2 ) and an extraordinary light ray (e 2 ) which is displaced from said ordinary light ray (0 2 ) by a distance d in a direction with an angle substantially equal to -0 relative to the horizontal scanning direction (H) of said solid state image sensing device (Figs. 1A and 3A), whereby said optical low pass filter (10) has the spatial frequency characteristic having a first trap frequency u 1 and a second trap frequency 2u 1 (Fig. 9A).
Claim 3
Dependent Claim 25 words
An optical low pass filter (10) according to claim 1, wherein said first and second double refraction plates (10A and 10B) are made of crystal.
Claim 4
Dependent Claim 24 words
An optical low point pass filter (10) according to claim 1, wherein said first and second double refraction plates (10A and 10B) are laminated.
Claim 5
Dependent Claim 60 words
An optical low pass filter according to claim 1, wherein said distance d is selected such that said first trap frequency u 1 is where Px is a horizontal pitch of the image sensing unit of said solid state image sensing device (Fig. 1A), and said color separating filter (Fig. 1B) has a triplet pattern in the horizontal scanning direction.
Claim 6
Dependent Claim 66 words
An optical low pass filter according to claim 1, wherein said distance d is selected such that said first trap frequency u 1 is where Px is a horizontal pitch of the sensing unit of said solid state image sensing unit of said solid state image sensing device (Fig. 3A), and said color separating filter (Fig. 3B) has a doublet pattern in the horizontal scanning direction.
Claim 7
Dependent Claim 51 words
A video image pick up device comprising an image pick up element of the type which performs spatial sampling of an image via a color separating filter, characterised in that the device includes a filter according to any one of the preceding claims to filter light passing to the separating filter.

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