Patent Application
20120162725
None.
None.
None.
1. Field of the Disclosure
The present disclosure relates generally to scanners, and more particularly, to an optical system for a scanner.
2. Description of the Related Art
Typically, a scanner includes one or more scan heads that are available in two is types of designs for forming scanned images. A first design of the two types of the designs employs an array of thin rod lens to form a line image onto a 1:1 ratio sensor array, which is called a contact image sensor. A second design of the two types of the designs employs folding mirrors to form a reduced image via a lens onto a sensor array, and is often referred to as ‘optical reduction system’. The optical reduction system holds many advantages over the contact image sensor in terms of image quality. However, a scan head of the second design, i.e., a scan head having an optical reduction system therewithin, is usually bulkier than a scan head of the first design, i.e., a scan head having a contact image sensor therewithin. It has been observed that the folding mirrors and lens structure may be laid in many different ways in order to achieve a compact optical reduction system within the scan head.
Traditionally, most document scanners based on the optical reduction system have one scan head that is usually contained within a flatbed chamber. Additionally, an automatic document feeder (ADF) window is used for both simplex scan and duplex scan with a re-circulating paper path in the aforementioned type of document scanners. However, vertical dimension of such scanners needs to be small in order to address the problems associated with bulkiness of the scan head. Further, it is often advantageous to have small vertical as well as horizontal dimensions for scanners that employ two scan heads for duplex scans.
Various optical systems/layouts have been devised to attend to the aforesaid problems. For example, there exists an optical layout that employs 3 mirrors to fold an optical path of light with one mirror being used twice for a scanner. However, such an optical system is disadvantageous in constraining the vertical dimension of the scanner. Further, another optical layout for a scanner exists that employs 4 pieces of mirrors and arranges two pairs of mirrors in a parallel orientation, i.e., horizontally to form multiple reflections. However, such an optical system is also disadvantageous when considering the need of a narrower vertical dimension. Furthermore, yet another optical layout for a scanner is employs 3 pieces of mirrors, and allows a relatively narrower vertical dimension of the scanner, but requires a relatively longer horizontal dimension. Another alternate optical layout for a scanner exists that employs 7 pieces of mirrors to achieve compactness. However, such an optical system employs a large number of mirrors and may be associated with manufacturing complexities. Accordingly, it is desired that an optical system for a scanner is easy-to-manufacture in addition to being compact. For example, when 1 piece of mirror is used for more than one reflection, there may be one less degree of adjustment available for the mirror. Further, width of the mirror also needs to be sufficiently large when an angle of reflection is substantially larger than 45 degrees. Additionally, multiple reflections from a single mirror may be potentially prone to ghosting thereby affecting optical image quality.
Accordingly, there persists a need for an optical system that facilitates in achieving compact dimensions for a scanner, while maintaining high optical image quality.
In view of the foregoing disadvantages inherent in the prior art, the general purpose of the present disclosure is to provide an optical system for a scanner, by including all the advantages of the prior art, and overcoming the drawbacks inherent therein.
The present disclosure provides an optical system for a scanner. The optical system includes at least one light source to illuminate a document to be scanned. The optical system further includes a plurality of mirrors. The plurality of mirrors includes a first mirror positioned in a direction of the document. The first mirror is adapted to receive a light beam from the document illuminated with the at least one light source. Further, the first mirror is adapted to reflect the light beam. The plurality of mirrors includes a second mirror adapted to receive the light beam reflected from the first mirror. Further, the second mirror is adapted to reflect the received light beam across an optical path between the first mirror and the document.
The plurality of mirrors also includes a third mirror positioned in proximity to the document. The third mirror is adapted to receive the light beam reflected from the second mirror. The third mirror is further adapted to reflect the received light beam across the optical path between the first mirror and the document. In addition, the plurality of mirrors includes a fourth mirror positioned adjacent to the second mirror and substantially opposite to is the third mirror for receiving the light beam reflected from the third mirror. The fourth mirror is further adapted to reflect the received light beam across an optical path between the first mirror and the second mirror, and an optical path between the second mirror and the third mirror. Moreover, the optical system includes a fifth mirror positioned adjacent to the second mirror and in a direction of the fourth mirror such that the second mirror is set between the fourth mirror and the fifth mirror. The fifth mirror is adapted to receive the light beam reflected from the fourth mirror. The fifth mirror is further adapted to reflect the received light beam across the optical path between the first mirror and the document.
The optical system also includes an imaging lens unit positioned in a direction of the fifth mirror, and adapted to receive the light beam reflected from the fifth mirror. Furthermore, the optical system includes an image sensor positioned adjacent to the imaging lens unit, and adapted to sense an image formed by the imaging lens unit on the image sensor. The image is formed by focusing the received light beam on the image sensor. Further, the image corresponds to the document.
The above-mentioned and other features and advantages of the present disclosure, and the manner of attaining them, will become more apparent and will be better understood by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings, wherein:
It is to be understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but these are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present disclosure. It is to be understood that the present disclosure is not limited in its application to the details of components set forth in the following description. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology is used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Further, the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.
The present disclosure provides an optical system for a scanner. The optical system of the present disclosure includes an appropriate arrangement of a plurality of mirrors, an imaging lens unit and an image sensor, within the scanner in order to facilitate in achieving compact dimensions for the scanner. The term “dimension” as used herein, may relate to horizontal dimension and/or vertical dimension of the scanner, i.e., length, width and/or height of the scanner. The optical system of the present disclosure is explained in conjunction with
The optical system 100 includes at least one light source, such as a light source 110, to illuminate the document 20 that needs to be scanned. For the purpose of this description, the optical system 100 is depicted to include only one light source 110. However, the optical system 100 may include more than one light source 110 based on a manufacturer's preferences. Further, the light source 110 may be in the form of a lamp such as a fluorescent lamp, a halogen lamp, and other such lamps known in the art for scanning operations. The optical system 100 may also include a reflector (not shown) to reflect a light beam from the light source 110 to efficiently illuminate the document 20.
Further, the optical system 100 includes a plurality of mirrors, and more specifically reflection mirrors. The plurality of mirrors includes a first mirror 120 positioned in a direction, such as a vertical direction ‘A’ of the document 20. The first mirror 120 is adapted to receive a light beam 130 from the document 20 when the document 20 is illuminated with the light source 110. Specifically, the light beam 130 is reflected along an optical path ‘L1’, and strikes at an incident surface ‘S1’ of the first mirror 120. The light beam 130 may correspond to an image of the document 20 to be scanned. Further, the first mirror 120 is adapted to reflect the light beam 130. The plurality of mirrors also includes a second mirror 140 adapted to receive the light beam 130 reflected from the first mirror 120 along an optical path ‘L2’. Specifically, the light beam 130 strikes at an incident surface ‘S2’ of the second mirror 140. Further, the second mirror 140 is adapted to reflect the received light beam 130 across the optical path ‘L1’ between the first mirror 120 and the document 20.
Moreover, the plurality of mirrors includes a third mirror 150 positioned in proximity to the document 20. The third mirror 150 is adapted to receive the light beam 130 reflected from the second mirror 140. Specifically, the light beam 130 is reflected along an optical path ‘L3’ from the second mirror 140 to the third mirror 150. More specifically, the light beam 130 strikes at an incident surface ‘S3’ of the third mirror 150. The third mirror 150 is further adapted to reflect the received light beam 130 across the optical path ‘L1’ between the first mirror 120 and the document 20. Further, the third mirror 150 may be capable of converging the light beam 130 being reflected therefrom. Furthermore, the third mirror 150 is an adjustable mirror, i.e., the position of the third mirror 150 may be adjusted in order to accommodate larger lens magnification error.
In addition, the plurality of mirrors includes a fourth mirror 160 positioned adjacent to the second mirror 140 and substantially opposite to the third mirror 150 for receiving the light beam 130 reflected from the third mirror 150. Specifically, the light beam 130 is reflected along an optical path ‘L4’ from the third mirror 150 to the fourth mirror 160. More specifically, the light beam 130 strikes at an incident surface ‘S4’ of the fourth mirror 160. Further, the light beam 130 may be reflected as a narrow light beam from the third mirror 150 to the fourth mirror 160. Specifically, the light beam 130 striking at/hitting the fourth mirror 160 is substantially narrower, thereby facilitating in saving space for the optical system 100. Accordingly, the scanner 10 that includes the optical system 100 may be manufactured to have reduced vertical and horizontal dimensions.
The fourth mirror 160 is also adapted to reflect the received light beam 130 across the optical path ‘L2’ between the first mirror 120 and the second mirror 140, and the optical path ‘L3’ between the second mirror 140 and the third mirror 150.
Moreover, the optical system 100 includes a fifth mirror 170 positioned adjacent to the second mirror 140 and in a direction, such as a vertical direction ‘B’ of the fourth mirror 160 such that the second mirror 140 is set between the fourth mirror 160 and the fifth mirror 170. The fifth mirror 170 is adapted to receive the light beam 130 reflected from the fourth mirror 160. Specifically, the light beam 130 is reflected along an optical path ‘L5’ from the fourth mirror 160 to the fifth mirror 170. More specifically, the light beam 130 strikes at an incident surface ‘S5’ of the fifth mirror 170. The fifth mirror 170 is further adapted to reflect the received light beam 130 across the optical path ‘L1’ between the first mirror 120 and the document 20.
The optical system 100 also includes an imaging lens unit 180 positioned in a direction, such as a horizontal direction ‘C’ of the fifth mirror 170, and adapted to receive the light beam 130 reflected from the fifth mirror 170. Specifically, the light beam 130 is reflected along an optical path ‘L6’ from the fifth mirror 170 to the imaging lens unit 180, and more particularly, to an incident surface ‘S6’ of the imaging lens unit 180. The imaging lens unit 180 may include one or more lens.
Furthermore, the optical system 100 includes an image sensor 190 positioned adjacent to the imaging lens unit 180, and adapted to sense an image formed by the imaging lens unit 180 on the image sensor 190. The image is formed by focusing the received light beam 130 on the image sensor 190. Further, the image corresponds to the document 20. The image sensor 190 may be in the form of a charge-coupled device array and may serve as a reading means. The optical system 100 may also include a filter (not shown) adjacent to the imaging lens unit 180 in order to facilitate the imaging lens unit 180 to focus the light beam 130 onto the image sensor 190 through the filter.
As depicted in
Further, the first mirror 120, the second mirror 140, the fourth mirror 160 and the fifth mirror 170 may be mounted within a first bracket (not shown) configured within the housing 12 of the scanner 10. Furthermore, the third mirror 150 may be mounted within a second bracket (not shown) configured opposite to the first bracket within the housing 12 of the scanner 10. Additionally, without departing from the scope of the present disclosure, one or more mirrors, such as the third mirror 150, of the plurality of mirrors may be slightly curved to focus the reflected light beam 130 onto a respective smaller surface of a consecutive mirror, such as the fourth mirror 160.
As depicted in
For the purpose of this description, only one light beam has been depicted. However, it should be understood that more than one light beams may be reflected in the above described sequence, i.e., from the document 20 to the first mirror 120, then from the first mirror 120 to the second mirror 140, then from the second mirror 140 to the third mirror 150, then from the third mirror 150 to the fourth mirror 160, then from the fourth mirror 160 to the fifth mirror 170, and finally from the fifth mirror 170 to the imaging lens unit 180.
In use, a document, such as the document 20, to be scanned is placed over the is scanning window 14. When power is provided to the scanner 10 for a scanning operation, the light source 110 illuminates the document 20. Subsequently, the light beam 130 strikes at the incident surface ‘S1’ of the first mirror 120 along the optical path ‘L1’. Thereafter, the light beam 130 is reflected from the first mirror 120 onto the incident surface ‘S2’ of the second mirror 140 along the optical path ‘L2’. The light beam 130 is then reflected from the second mirror 140 onto the incident surface ‘S3’ of the third mirror 150 along the optical path ‘L3’. Subsequently, the light beam 130 is reflected from the third mirror 150 onto the incident surface ‘S4’ of the fourth mirror 160 along the optical path ‘L4’. Thereafter, the light beam 130 is reflected from the fourth mirror 160 onto the incident surface ‘S5’ of the fifth mirror 170 along the optical path ‘L5’. The light beam 130 is then reflected from the fifth mirror 170 onto the incident surface ‘S6’ of the imaging lens unit 180 that focuses the light beam 130 for forming the image onto the image sensor 190.
The optical system 200 is similar to the optical system 100 of
The first mirror 220 is positioned optically farthest from the document 40 and in proximity to the imaging lens unit 280. Further, the first mirror 220, the second mirror 240, the fourth mirror 260 and the fifth mirror 270 are mounted within a first bracket 34 configured within the housing 32 of the CCDM 30 of the scanner. Furthermore, the third mirror 250 is mounted within a second bracket 36 configured opposite to the first bracket 34 within the housing 32 of the CCDM 30. Additionally, the third mirror 250 is an adjustable mirror, i.e., the position of the third mirror 250 may be adjusted in order to accommodate larger lens magnification error.
As depicted in
The aforementioned arrangement of the first mirror 220 that is positioned further away from a plane of the document 40 makes dust inevitably less visible on the first mirror 220, as the light beams 230 and 232 may be more defocused when striking at the incident surface ‘S7’ of the first mirror 220. Further and as depicted in
Further, the light beams 230 and 232 striking at/hitting the fourth mirror 260 are substantially narrower, thereby facilitating in saving space for the optical system 200. Accordingly, the scanner utilizing the CCDM 30 that includes the optical system 200 may be manufactured to have reduced vertical and horizontal dimensions as opposed to conventional scanners.
Based on the foregoing, the present disclosure provides an optical system (such as the optical systems 100 and 200) that facilitates in achieving compact dimensions for a scanner employing the optical system, while maintaining high optical image quality. In other words, a compact scanner having a reduced length and a reduced width as opposed to a conventional scanner may be obtained by employing the optical system of the present disclosure. Further, arrangement of the plurality of mirrors, the imaging lens unit and the image sensor with respect to a document to be scanned, as described in conjunction with
The foregoing description of several embodiments of the present disclosure has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the disclosure be defined by the claims appended hereto.
