Non-scanning type optical reading apparatus having illuminating equalization filter
First Claim
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1. An optical reading apparatus comprising:
- an imaging lens for imaging a two-dimensional pattern as an object to be read and forming a two-dimensional image thereof;
light-receiving means for reading information from the two-dimensional image of the two-dimensional pattern, the two-dimensional image being formed by light travelling from the two-dimensional pattern to the light receiving means; and
damping means for providing attenuation of the light provided to the light-receiving means, the attenuation varying in two dimensions depending on position of the light within the two-dimensional image, wherein said damping means is a bandpass filter for limiting the wavelength of said light reaching said light-receiving means, said bandpass filter being provided between said two-dimensional pattern and said light-receiving means and so set that given the wavelength of said light, a light component incident at an oblique angle to the bandpass filter will have a higher transmittance than a light component incident normal to the bandpass filter.
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Abstract
A non-scanning type optical reading apparatus for reading patterns such as a bar code. The optical reading apparatus comprises an imaging lens for imaging a bar code as a pattern to be read, a CCD line sensor for reading the information of the image of the pattern, and a light damping mirror and/or filter that is provided between the pattern and the CCD line sensor. The central part of the light damping mirror filter is denser than the periphery to achieve a uniform distribution of light on the sensor. According to one embodiment, the filter is a bandpass filter.
52 Citations
9 Claims
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1. An optical reading apparatus comprising:
an imaging lens for imaging a two-dimensional pattern as an object to be read and forming a two-dimensional image thereof; light-receiving means for reading information from the two-dimensional image of the two-dimensional pattern, the two-dimensional image being formed by light travelling from the two-dimensional pattern to the light receiving means; and damping means for providing attenuation of the light provided to the light-receiving means, the attenuation varying in two dimensions depending on position of the light within the two-dimensional image, wherein said damping means is a bandpass filter for limiting the wavelength of said light reaching said light-receiving means, said bandpass filter being provided between said two-dimensional pattern and said light-receiving means and so set that given the wavelength of said light, a light component incident at an oblique angle to the bandpass filter will have a higher transmittance than a light component incident normal to the bandpass filter.
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2. An optical reading apparatus comprising:
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an imaging lens for imaging a pattern as an object to be read and forming an image thereof; light-receiving means for reading information from the image of the pattern, the image being formed by light travelling from the pattern to the light-receiving means; and damping means providing attenuation of the light, the attenuation varying depending on position of the light within the image, the damping means comprising at least two light attenuating devices, each of the at least two light attenuating devices being one of a light-attenuating reflecting mirror and a light-attenuating transmission filter, reflectance of the light-attenuating reflecting mirror varying with position along the surface of the mirror at which the light is reflected, and transmittance of the light-attenuating transmission filter varying with position along the surface of the filter through which the light is transmitted. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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Specification