1. Field of the Invention
The present invention relates to a barcode scanner and more particularly, to a light source and lens arrangement for barcode scanner, which enables the lens to pick up the image of the barcode in uniform brightness.
2. Description of the Related Art
In the multimedia era, needs for optical input devices are expected to increase in terms of both quality and quantity. For automation in commercial as well as in industry, barcode has been intensively used to mark and classify products, tools, and equipments. A barcode scanner is an electronic device for scanning a barcode and generating a digital representation of the scanned barcode for reading.
Therefore, it is desirable to provide a light source and lens arrangement for barcode scanner that produces a bright image of uniform brightness of the scanned object.
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a light source and lens arrangement for barcode scanner, which enables light rays to enter the lens uniformly so that the lens can map the image of the barcode in uniform brightness onto an image plane for processing into a strong and clear signal for accurate reading. To achieve and other objects of the present invention, the light source and lens arrangement is used in a barcode scanner, comprising a lens, and two light sources arranged at two opposite lateral sides of the lens and adapted to emit light onto a barcode for enabling the lens to pick up the image of the barcode and to map the image onto an image plane. The light sources each comprise a light-emitting element, and a mirror disposed at one side relative to the light-emitting element. The mirror has a reflecting surface adapted to reflect light from the light-emitting element toward a predetermined direction. The reflecting surface has an anisocurvature for reflecting light onto the barcode in such a manner that the intensity of light projected onto the center area of the barcode is comparatively weaker than the intensity of light projected onto the two opposite lateral sides of the barcode, so that the image of the barcode mapped onto the image plane has a uniform brightness, and the barcode scanner can obtain a strong and clear signal for accurate reading of the content of the barcode during the posterior processing process.
Referring to
The lens 1 is adapted to pick up the image of the object in front of the barcode scanner and to map the image onto an image plane 11.
The light sources 2 are provided at two sides relative to the lens 1, each comprising a light-emitting element 21 and a mirror 22. The mirror 22 is disposed near one side of the respective light-emitting element 21, having a reflecting surface 221 of anisocurvature design facing the light-emitting element 21.
The condenser elements 3 are disposed at two sides relative to the lens 1 and spaced from the light-emitting elements 21 of the light sources 2 at one side opposite to the mirrors 22 of the light sources 2.
When using the barcode scanner, the light-emitting elements 21 of the light sources 2 are driven to emit light onto the reflecting surface 221 of the mirror 22 of each of the light sources 2, and the reflecting surface 221 of the mirror 22 of each of the light sources 2 reflects light from the light-emitting elements 21 onto a barcode 4 through the condenser elements 3. Because the reflecting surface 221 of the mirror 22 of each of the light sources 2 is a curved surface having an anisocurvature design, the intensity of light projected onto the center area of the barcode 4 is comparatively weaker than the intensity of light projected onto the two opposite lateral sides of the barcode 4. When the lens 11 picking up the image of the barcode 4, a comparatively greater amount of light from the center area of the barcode 4 passes through the relatively broader middle area of the lens 11, and a comparatively smaller amount of light passes from the two opposite lateral sides of the barcode 4 through the two relatively narrower lateral areas of the lens 11. Therefore, when the image of the barcode 4 is mapped onto the image plane 11, the mapped image has a uniform brightness, and the barcode scanner can obtain a strong and clear signal for accurate reading of the content of the barcode during the posterior processing process.
Further, the condenser elements 3 condense reflected light from the reflecting surface 221 of the mirror 22 of each of the light sources 2 into linear light rays to fit the elevation of the barcode 4, enabling light rays to be effectively gathered in the barcode 4 so that the lens 1 can pick up a bright image of the barcode 4.
Further, the light-emitting element 21 of each light source 2 can be a LED (light emitting diode) or laser LED.
As indicated above, the invention has the following features.
1. The mirror of each light source has a reflecting surface of anisocurvature design for reflecting light onto the barcode in such a manner that the intensity of light projected onto the center area of the barcode is comparatively weaker than the intensity of light projected onto the two opposite lateral sides of the barcode, so that the image of the barcode mapped onto the image plane has a uniform brightness, and the barcode scanner can obtain a strong and clear signal for accurate reading of the content of the barcode during the posterior processing process.
2. The invention uses the anisocurvature design of the reflecting surface of the mirror of each of the light sources to distribute the light rays from the light-emitting elements of the light sources, enabling light to enter the lens when the lens is picking up the image of the barcode, and therefore the barcode scanner can obtain the image of the barcode in uniform brightness for processing into a strong and clear signal for accurate reading.
A prototype of light source and lens arrangement for barcode scanner has been constructed with the features of
Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention.