Optical information reading apparatus having dust-proof plate
First Claim
Patent Images
1. An optical information reading apparatus for reading an image of a reading object comprising:
- a case having a reading opening;
a light receiving device accommodated in the case;
a light emitting device positioned inside the case for irradiating light to the reading object located outside the case through the reading opening of the case;
an image forming optical system positioned in the case for introducing light reflected from the reading object through the reading opening and forming an image of the reading object on the light receiving device;
a lens barrel having an incident-side opening and a transmitting-side opening and holding the image forming optical system therein, the lens barrel being for guiding light reflected from the reading object into the case from the incident-side opening thereof, and sending the reflected light which has passed the image forming optical system to the light receiving device from the transmitting-side opening; and
a dust-proof plate, located nearer to the reading opening than the light emitting device and the lens barrel, for transmitting the light emitted by the light emitting device therethrough and preventing dust from penetrating into the light emitting device and the lens barrel from the reading opening,wherein the incident-side opening of the lens barrel is placed proximately to the dust-proof plate to prevent the light emitted from the light emitting device and reflected from the dust-proof plate from traveling into the lens barrel.
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Abstract
A dust-proof plate transmits light emitted by red light emitting diode unit. When the dust-proof plate reflects a part of the light, the reflected light incident on an image forming optical system becomes an optical noise in reading the image information of a reading object. In order to prevent the optical noise from being generated, an incident-side opening of a lens barrel is positioned proximately to the dust-proof plate. Thus, the light reflected from the dust-proof plate can be prevented from being introduced into the lens barrel.
38 Citations
14 Claims
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1. An optical information reading apparatus for reading an image of a reading object comprising:
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a case having a reading opening; a light receiving device accommodated in the case; a light emitting device positioned inside the case for irradiating light to the reading object located outside the case through the reading opening of the case; an image forming optical system positioned in the case for introducing light reflected from the reading object through the reading opening and forming an image of the reading object on the light receiving device; a lens barrel having an incident-side opening and a transmitting-side opening and holding the image forming optical system therein, the lens barrel being for guiding light reflected from the reading object into the case from the incident-side opening thereof, and sending the reflected light which has passed the image forming optical system to the light receiving device from the transmitting-side opening; and a dust-proof plate, located nearer to the reading opening than the light emitting device and the lens barrel, for transmitting the light emitted by the light emitting device therethrough and preventing dust from penetrating into the light emitting device and the lens barrel from the reading opening, wherein the incident-side opening of the lens barrel is placed proximately to the dust-proof plate to prevent the light emitted from the light emitting device and reflected from the dust-proof plate from traveling into the lens barrel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An optical information reading apparatus for reading an image of a reading object comprising:
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a case having a reading opening; a light receiving device accommodated in the case; a light emitting device positioned inside the case for irradiating light to the reading object located outside the case through the reading opening of the case; an image forming optical system positioned in the case for introducing light reflected from the reading object through the reading opening and forming an image of the reading object on the light receiving device; a dust-proof plate located nearer to the reading opening than the light emitting device for transmitting the light emitted by the light emitting device therethrough, and preventing dust from penetrating into the light emitting device from the reading opening, wherein the light emitting device and the light receiving device are so arranged that the light emitting device is present within a range of a total reflection angleθ
2 (=θ
1) of an acute angleθ
1 made between a maximum visual field of the light receiving device defined by the image forming optical system and the dust-proof plate.
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14. An optical information reading apparatus for reading an image of a reading object comprising:
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a case having a reading opening; a light receiving device accommodated in the case; a light emitting device positioned inside the case for irradiating light to the reading object located outside the case through the reading opening of the case; an image forming optical system positioned in the case for introducing light reflected from the reading object through the reading opening and forming an image of the reading object on the light receiving device; a dust-proof plate located nearer to the reading opening than the light emitting device for transmitting the light emitted by the light emitting device therethrough, and preventing dust from penetrating into the light emitting device from the reading opening; and a cylindrical light interception member interposed between the image forming optical system as well as the light receiving device and the light emitting device and intercepting the light emitted by the light emitting device from a position outside a range of a total reflection angle θ
2 (=θ
1) of an acute angle θ
1 made between a maximum visual field of the light receiving device defined by the image forming optical system and the dust-proof plate by an opening formed at a side of the reading opening so that the light emitted from the position outside the range is prevented from being reflected from the dust-proof plate.
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Specification