Image sensing module, imaging lens and code reading method
AssigneeSharp Kabushiki Kaisha
InventorsNorimichi Shigemitsu, Kazuya Kitamura, Hiroyuki Hanato
Life of this patent
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Abstract
In order to produce, for example, an image sensing module which has a resolving power enough to meet required specifications for both photographing a close object and photograph a far object, and which has a simple structure, an image sensing module includes: an imaging lens having an increased depth of field and a decreased curvature of field; and a sensor provided between (i) a location of a best image surface of the imaging lens with respect to white light from a sunflower and (ii) a location of a best image surface of the imaging lens with respect to white light from a tree.
Claims8
An image sensing module, comprising:
- an imaging lens having an increased depth of field and a decreased curvature of field;
- and
- an image sensing element provided between (i) a location of a best image surface of the imaging lens which best image surface is obtained when the imaging lens receives white light from a first object which is closer to the image sensing element than a predetermined location is and (ii) a location of a best image surface of the imaging lens which best image surface is obtained when the imaging lens receives white light from a second object which is farther from the image sensing element than the predetei mined location is.
An imaging lens, having an increased depth of field and a decreased curvature of field,
- said imaging lens forming an image of an object between (i) a location of a best image surface which is obtained when the imaging lens receives white light from the object which is closer to an image forming location than a predetermined location is and (ii) a location of a best image surface which is obtained when the imaging lens receives white light from the object which is farther from the image forming location than the predetermined location is.
A code reading method for reading, with use of an image sensing module, a two-dimensional matrix code on a basis of information on pixels which is obtained from a green monochromatic radiation,
- the image sensing module comprising:
- an imaging lens having an increased depth of field and a decreased curvature of field;
- and
- an image sensing element provided between (i) a location of a best image surface of the imaging lens which best image surface is obtained when the imaging lens receives white light from a first object which is closer to the imaging lens than a predetermined location is and (ii) a location of a best image surface of the imaging lens which best image surface is obtained when the imaging lens receives white light from a second object which is farther from the imaging lens than the predetermined location is, the image sensing element being capable of supplying only information on pixels which is obtained from the green monochromatic radiation,
- said code reading method, comprising the steps of:
- finding, on a basis of a pitch of the pixels which is obtained when the green monochromatic radiation is received, first and second values of respective critical resolving performances of the imaging lens and the image sensing element so as to set, as a value of a critical resolving performance of the image sensing module, the first value or the second value, whichever is lower;
- finding a magnification at which an image is formed by the imaging lens, on a basis of (i) a distance between the imaging lens and the first object, (ii) an angle of view of the image sensing module, and (iii) an image circle diameter of the image sensing element;
- and
- finding a size of a two-dimensional matrix code which the image sensing module can read, on a basis of (i) the value of the critical resolving capability of the image sensing module and (ii) the magnification.
Dependencies are inferred from the claim text.