Method and apparatus for optically reading information from object based on control of optical path length
An optical information reading apparatus for reading information codes such as a bar code and a two-dimensional code includes, an image-forming lens fixed at a given point and imaging a reflection light from the information code, an optical sensor locating at a position relative to that of the image-forming lens and receiving an image formed by the image-forming lens, a light path bending unit bending the reflection light between the image-forming lens and the optical sensor a plurality of times, a shifter shifting the light path bending unit, a distance measurement unit measuring the distance from the information code to the reading apparatus and a controller controlling the shifter based on the measurement result of the distance measurement unit. The light path length between the image-forming lens and the optical sensor is changed by shifting the light path bending unit using the shifter.
1. An apparatus for optically reading information from an object, the apparatus comprising:
image-forming means fixed at a first position in the apparatus and imaging a reflection light from the obiect;
an optical sensor fixed at a second position relative to the first position in the apparatus and receiving an image formed by the image-forming means;
light path bending means bending the reflection light between the image-forming means and the optical sensor a plurality of times; and
shifting means shifting the light path bending means in response to information of a distance between the object and the apparatus so that a light path length between the image-forming means and the optical sensor is changed,
wherein the light path bending means includes an optical member having at least two reflection surfaces which bend a light path of the reflection light so that an input light path direction to the reflection surface and an output light path direction from the reflection surface are in parallel and opposite to each other.
2. An apparatus as claimed in claim 1 , wherein the light path bending means includes the optical member having at least a set of reflection surfaces which bend the light path two times by 90 degrees.
3. An apparatus as claimed in claim 2 , wherein a direction of the light path bended by the reflection surface includes a direction which is in parallel with and perpendicular to an optical axis of the image-forming means.
4. An apparatus as claimed in claim 3 , wherein the reflection surface is composed of a surface of one member selected from a group of optical members consisting of a reflection mirror or a prism.
5. An apparatus as claimed in claim 2 , wherein the reflection surface is composed of a surface of one member selected from a group of optical members consisting of a reflection mirror and a prism.
6. An apparatus as claimed in claim 1 , wherein a direction of the light path bended by the reflection surfaces includes a direction which is in parallel with and perpendicular to an optical axis of the image-forming means.
7. An apparatus as claimed in claim 6 , wherein the reflection surface is composed of a surface of one member selected from a group of optical members consisting of a reflection mirror or a prism.
8. An apparatus as claimed in claim 1 , wherein the reflection surface is composed of a surface of one member selected from a group of optical members consisting of a reflection mirror and a prism.
9. An apparatus as claimed in claim 1 , further comprising distance measurement means for measuring the distance between the object and the apparatus and control means for controlling the shifting means in response to information of the distance measured by the distance measurement means.
10. An apparatus for optically reading information from an object, the apparatus comprising:
image-forming means fixed at a first position in the apparatus and imaging a reflection light from the object;
an optical sensor fixed at a second position relative to the first position in the apparatus and receiving an image formed by the image-forming means;
light path bending means bending the reflection light between the image-forming means and the optical sensor a plurality of times; and
shifting means shifting the light path bending means in response to information of a distance between the object and the apparatus so that a light path length between the image-forming means and the optical sensor is changed,
wherein the light path bending means includes an optical member having two reflection surfaces which bend the light path so that an incident light and a reflection light to and from the reflection surfaces cross to each other and the shifting means which shifts the two reflection surfaces along optical axes of the image-forming means and the optical sensor, respectively.
11. An apparatus as claimed in claim 10 , wherein the reflection surfaces are provided by two members bonded as a single unit and the two members are to be displaced together by the shifting means.
12. An apparatus as claimed in claim 11 , wherein the light path bended by the two reflection surfaces forms an isosceles triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light and the reflection light to and from the reflection surfaces.
13. An apparatus as claimed in claim 12 , wherein two optical axes of the image-forming means and the optical sensor are configured to cross at right angles and the light path bended by the two reflection surfaces forms an isosceles right triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light and the reflection light to and from the reflection surfaces.
14. An apparatus as claimed in claim 11 , wherein two optical axes of the image-forming means and the optical sensor are configured to cross at right angles and the light path bended by the two reflection surfaces forms an isosceles right triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light and the reflection light to and from the reflection surfaces.
15. An apparatus as claimed in claim 10 , wherein each reflection surface are provided by two members shifted in each direction at the same time and the same distance by using a single driver.
16. An apparatus as claimed in claim 15 , wherein the light path bended by the two reflection surfaces forms an isosceles triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light and the reflection light to and from the reflection surfaces.
17. An apparatus as claimed in claim 16 , wherein two optical axes of the image-forming means and the optical sensor are configured to cross at right angles and the light path bended by the two reflection surfaces forms an isosceles right triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light and the reflection light to and from the reflection surfaces.
18. An apparatus as claimed in claim 15 , wherein two optical axes of the image-forming means and the optical sensor are configured to cross at right angles and the light path bended by the two reflection surfaces forms an isosceles right triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light and the reflection light to and from the reflection surfaces.
19. An apparatus as claimed in claim 10 , wherein the light path bended by the two reflection surfaces forms an isosceles triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light to the reflection surface and the reflection light from the reflection surface.
20. An apparatus as claimed in claim 19 , wherein two optical axes of the image-forming means and the optical sensor are configured to cross at right angles and the light path bended by the two reflection surfaces forms an isosceles right triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light and the reflection light to and from the reflection surfaces.
21. An apparatus as claimed in claim 10 , wherein two optical axes of the image-forming means and the optical sensor are configured to cross at right angles and the light path bended by the two reflection surfaces forms an isosceles right triangle with two reflection points on each reflection surface and one cross point formed by both of the incident light to the reflection surface and the reflection light from the reflection surface.
22. An apparatus as claimed in claim 10 , further comprising distance measurement means for measuring the distance between the object and the apparatus and control means for controlling the shifting means in response to information of the distance measured by the distance measurement means.