Color image reading lens system
AssigneeMinolta Co., Ltd.
InventorKeijiro Sakamoto
Life of this patent
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Abstract
An optical system for focusing an original image on an image sensor has an optical element disposed at the image-sensor-side end thereof. The optical element has a positive optical power as a whole, and at least one surface of the optical element has a positive optical power of diffraction.
Claims13
An optical system for focusing an original image on an image sensor, comprising:
- an optical element provided at an image-sensor-side end of the optical system, the optical element having a positive optical power as a whole, wherein at least one surface of the optical element has a positive optical power of diffraction,
- wherein the following condition is fulfilled:
- −5<P×Φ<−1.2
- wherein
- P represents a distance between a last lens surface in the optical system which is closest to the image sensor and an exit pupil, the distance being negative if lying on an object-plane side of the last lens surface and positive if lying on an image-plane side of the last lens surface;
- and
- Φ represents an optical power of the entire optical system.
An optical system for focusing an original image on an image sensor, comprising:
- an optical element provided at an image-sensor-side end of the optical system, the optical element having a positive optical power as a whole, wherein at least one surface of the optical element has a positive optical power of diffraction, wherein the following conditions are fulfilled:
- 0.2<Φd/Φ<1
- 0.3<Φf/Φ<1.2
- wherein
- Φ represents an optical power of the entire optical system;
- Φd represents an optical power of the optical element;
- and
- Φf represents a composite optical power of all optical elements disposed on an original-image side of the optical element.
An optical system for focusing an original image on an image sensor, comprising:
- an optical element provided at an image-sensor-side end of the optical system, the optical element having a positive optical power as a whole, wherein at least one surface of the optical element has a positive optical power of diffraction, wherein the optical element is made of resin and wherein the following condition is fulfilled:
- 0.01<Φs/Φd<0.1
- wherein
- Φs represents an optical power resulting from a light-diffracting action of the optical element;
- and
- Φd represents an optical power of the optical element.
An optical system for focusing an original image on an image sensor, comprising:
- an optical element provided at an image-sensor-side end of the optical system, the optical element having a positive optical power as a whole, wherein at least one surface of the optical element has a positive optical power of diffraction,
- wherein the optical element exhibits a color-separating effect in a direction which is generally perpendicular to longer sides of the image sensor.
An optical system for focusing an original image on an image sensor, comprising:
- a first optical element provided at an image-sensor-side end of the optical system, the first optical element having a positive optical power as a whole, wherein at least one surface of the first optical element has a positive optical power of diffraction;
- and
- a second optical element provided on an original-image side of the first optical element, the second optical element having a positive optical power as a whole, wherein at least one surface of the second optical element has a positive optical power of diffraction.
Dependencies are inferred from the claim text.