Image scanning unit and image forming apparatus having the same

An image scanning unit an image forming apparatus having the same to scan an image recorded on a document. The image scanning unit includes: a transparent window on which a document to be scanned is laid; an image sensor running straightly under the transparent window for capturing an image recorded on the document, a unit for driving the image sensor; a guide shaft for guiding the straight movement of the image sensor; and an image sensor carrier connected to the driving unit and the guide shaft for straightly moving the image sensor along the guide shaft when the driving unit operates. The image sensor carrier has an image sensor mounting surface on which the image sensor is mounted, and a guide shaft holder integrally formed with the image sensor mounting surface and mounted on the guide shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 2005-19577, filed on Mar. 9, 2005 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the present invention relate to an image forming apparatus, and more particularly, to an image forming apparatus having an image scanning unit for scanning an image recorded on a document.

2. Description of the Related Art

An image forming apparatus is a device for printing an image on a sheet of paper. However, in recent years, more office applications require the use an image forming apparatus having an image scanning function (referred to as combined scanner/printer). The apparatus having the image scanning function (for example, a facsimile or scanner function) captures an image recorded on a document using an image sensor, and converts the image into digital image information to reproduce it on a piece of paper or a display unit.

To perform the scanning function, the image forming apparatus is provided with an image scanning unit.FIG. 1shows one example of a conventional image scanning unit10. Referring toFIG. 1, the image scanning unit10includes a flat transparent window11on which a document (not shown) that is to be scanned is laid, and an image sensor15running linearly under the transparent window11for capturing an image recorded on the document through a scanning process. A guide shaft30is disposed below the image sensor15to guide the linear movement of the image sensor15as indicated by the arrow.

The image sensor15is mounted to an image sensor carrier20made of metal. The guide shaft30is inserted into a guide shaft holder25that can reciprocate along the guide shaft30. The image sensor carrier20is connected to the glide shaft holder25by a bolt27. A spring23is interposed between the image sensor carrier20and the image sensor15so that the image sensor15is biased against the transparent window11. The guide shaft holder25is connected to a belt (not shown) operated by a motor (not shown) in the same direction as a longitudinal direction of the guide shaft30.

When an image reading command is input to the image scanning unit10, the belt is operated by the motor, and thus the guide shaft holder25connected to the belt runs along the guide shaft30. Hence, the image sensor15mounted to the image sensor carrier20runs linearly to scan the image recorded on the document, while in contact with the transparent window11.

However, since the image sensor carrier20and the guide shaft holder25are separately manufactured and assembled, a size, in particular, a height, of the assembly is increased. Therefore, it is difficult to miniaturize the image forming apparatus having the image scanning unit. Also, because of the assembling process of the image scanning unit, the entire assembling time of the image forming apparatus increases, and dimensional tolerances between components accumulate and thereby the accuracy of a completed product is low. In addition, since the image sensor carrier20is made of metal, induced static electricity may result in malfunction or damage of the image sensor15or motor.

SUMMARY OF THE INVENTION

Aspects of the present invention provide an image scanning unit having an image sensor carrier of which an image-sensor mounting portion is integrally formed with a portion for accommodating a guide shaft, and an image forming apparatus having the image scanning unit.

According to an aspect of the present invention, there is provided an image scanning unit comprising: a transparent window on which a document to be scanned is laid; an image sensor running linearly under the transparent window for having an image recorded on the document; a driving unit to drive the image sensor; a guide shaft to guide the linear movement of the image sensor; and an image sensor carrier connected to the driving unit and the guide shaft for linearly moving the image sensor along the guide shaft when the driving unit operates, in which the image sensor carrier has an image sensor mounting surface on which the image sensor is mounted, and a guide shaft holder integrally formed with the image sensor mounting surface and mounted on the guide shaft.

In accordance with an aspect of the present invention, the driving unit includes a belt driven while extending in parallel with the guide shaft, and the image sensor carrier may include a belt fixing portion fixed to the belt.

In accordance with an aspect of the present invention, the image scanning unit further comprises a fixing unit to fix the image sensor to image sensor carrier, the image sensor fixing unit including a positioning boss formed at the image sensor, and a bracket provided to the image sensor carrier for receiving the positioning boss.

In accordance with an aspect of the present invention, the image sensor fixing unit may include a positioning boss formed at the image sensor carrier, and a groove formed at the image sensor for receiving the positioning boss.

In accordance with an aspect of the present invention, the image sensor carrier may be formed of a polymer resin through molding.

In accordance with an aspect of the present invention, the image sensor carrier may further include a tensioning portion for biasing the image sensor against the transparent window.

In accordance with an aspect of the present invention, the guide shaft holder may be provided on an internal surface thereof with a protrusion to reduce a frictional surface with an external surface of the guide shaft.

According to another aspect of the present invention, there is provided an image forming apparatus having an image printing unit for printing an image on a recording medium, and an image scanning unit for scanning the image recorded on a document, the image scanning unit including: a transparent window on which the document to be scanned is laid; an image sensor running linearly under the transparent window to capture the image recorded on the document; a driving unit to drive the image sensor; a guide shaft to guide the linear movement of the image sensor; and an image sensor carrier connected to the driving unit and the guide shaft for moving linearly the image sensor along the guide shaft when the driving unit operates, in which the image sensor carrier has an image sensor mounting surface on which the image sensor is mounted, and a guide shaft holder integrally formed with the image sensor mounting surface and mounted on the guide shaft.

In accordance with an aspect of the present invention, the driving unit may include a belt driven while extending in parallel with the guide shaft, and the image sensor carrier may include a belt fixing portion fixed to the belt.

In accordance with an aspect of the present invention, the image scanning unit further comprises a fixing unit to fix the image sensor to the image sensor carrier, the image sensor fixing unit including a positioning boss formed at the image sensor, and a bracket provided to the image sensor carrier for receiving the positioning boss.

In accordance with an aspect of the present invention, the image sensor fixing unit includes a positioning boss formed at the image sensor carrier, and a groove formed at the image sensor for receiving the positioning boss.

In accordance with an aspect of the present invention, the image sensor carrier is formed of a polymer resin through molding.

In accordance with an aspect of the present invention, the image sensor carrier further includes a tensioning portion for biasing the image sensor against the transparent window.

In accordance with an aspect of the present invention, the guide shaft holder is provided on an internal surface thereof with a protrusion to reduce a frictional surface with an external surface of the guide shaft.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 2shows of an image forming apparatus according to an embodiment of the present invention.

Referring toFIG. 2, the image forming apparatus is a combined scanner/printer having a function of printing an image on a sheet of paper and a function of scanning the image recorded on the paper, and includes an image printing unit110, a scanning unit120disposed above the image printing unit110, and an operating panel102. The operating panel102is provided with buttons for inputting commands and a display portion103for indicating an operating state, option selections or the like of the apparatus to a user.

The image scanning unit120includes a transparent window121on which a document D to be scanned is laid, an image sensor130running linearly under the transparent window121for taking the image recorded on the document, and a flat cover125covering the transparent window121for shielding light emitted from the image sensor130from dispersing outwardly when capturing the image. The image sensor130may include a contact image sensor (CIS), a charge coupled device (CCD), or the like.

FIGS. 3 and 4show the image scanning unit provided to the image forming apparatus according to aspects of the present invention.

Referring toFIGS. 3 and 4, the image scanning unit120also includes an image sensor carrier160with the image sensor130mounted thereto under the transparent window121(FIG. 2), a driving unit for linearly reciprocating the image sensor carrier160in one direction, and a guide shaft155for guiding the straight movement of the image sensor carrier160.

The guide shaft155is made of a metal rod, and extends in a direction perpendicular to a longitudinal direction of the image sensor130. The driving unit includes a motor140and a belt150driven by the motor140. The belt150extends in parallel with respect to the guide shaft155, and is supported by a driving pulley144and a driven pulley145. The driving pulley144is coaxial with and rotatably connected to a coupling gear143meshed with a motor shaft gear141of the motor140. The belt150is provided on an inner surface thereof with internal gear teeth so as to prevent slippage. The driving pulley144and the driven pulley145are shaped so that they are meshed with the toothed inner surface of the belt150.

The image sensor carrier160includes an image sensor mounting surface161for mounting the image sensor130, a guide shaft holder170slidably mounted to the guide shaft155, and a belt fixing portion180fixed to the belt150. The image sensor carrier160is not made of metal, but is formed of polymer resin through molding.

A fixing unit for fixing the image sensor130is provided on the image sensor mounting surface161and the image sensor130to fix the image sensor130to the image sensor carrier160. Specifically, the image sensor130is formed with first and second positioning bosses132and133for detachably mounting the image sensor130to the image sensor carrier160. The image sensor carrier160is formed with first and second brackets162and163for receiving the positioning bosses132and133. In order to assist positioning of the image sensor130when assembling the image sensor130and the image sensor carrier160, the image sensor carrier160is formed with a positioning boss164, and the image sensor130is formed with a groove134for receiving the positioning boss164.

The image sensor mounting surface161is provided with first and second tensioning portions166and168for biasing the image sensor130against the transparent window121(FIG. 2), which replaces a conventional spring23shown inFIG. 1. The image sensor130moves linearly along the guide shaft155, while spacers136protruded from both ends of the image sensor130are contacting the transparent window.

FIGS. 5 and 6show blown up portions of the image sensor carrier inFIG. 4.

Referring toFIGS. 5 and 6, the belt fixing portion180is formed with a toothed surface181meshed with the internal gear teeth of the belt150to prevent the belt fixing portion180from slipping on the belt150(FIGS. 3 and 4), and belt pressing bosses183for tightly contacting the belt150with the toothed surface181. The belt150is inserted into a slot185formed between the toothed surface181and the belt pressing bosses183.

The guide shaft holder170has an approximately semicircular internal surface172forming a channel matching with the guide shaft155, so that the guide shaft holder170slides on the guide shaft155. The guide shaft holder170is provided on the internal surface thereof with a protrusions formed as planar faces175,176and174so as to reduce a contacting surface with an external surface of the guide shaft155and thereby reduce friction therebetween. The first and second planar faces175and176engage the guide shaft at approximately 180 degree intervals along the diameter of the guide shaft and are substantially parallel to each other

According to aspects of the image scanning unit of the present invention, the image sensor carrier includes the image sensor mounting surface integrally formed with the guide shaft holder mounted on the guide shaft, thereby reducing a height of the image scanning unit. Hence, the image scanning unit and the image forming apparatus having the same can be miniaturized.

Since the number of components is reduced as compared with a conventional assembly, an assembly time of the image scanning unit can be shortened. Also, dimensional tolerances attributable to the number of components do not accumulate, and thereby the assembling accuracy of the image scanning unit compared to the conventional unit can be improved.

Furthermore, according to the embodiments of the present invention, since the image sensor carrier is formed of the polymer resin, it is possible to prevent malfunction of the image sensor or motor due to the static electricity.