Image scanner and image forming apparatus incorporating same

An image scanner includes a stationary original plate on which a stationary original is placed and a moving original plate, over which a moving original is conveyed, aligned with the stationary original plate in a sub-scanning direction and tilted relative to the stationary original plate by a given angle. A reader is movable in the sub-scanning direction between a stationary original reading span disposed opposite the stationary original via the stationary original plate to read an image on the stationary original and a moving original reading position disposed opposite the moving original via the moving original plate to read an image on the moving original. The reader pressingly contacts the stationary original plate and the moving original plate as the reader moves in the sub-scanning direction.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on and claims priority pursuant to 35 U.S.C. §119 to Japanese Patent Application No. 2012-136688, filed on Jun. 18, 2012, in the Japanese Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Example embodiments generally relate to an image scanner and an image forming apparatus, and more particularly, to an image scanner for reading an image on an original and an image forming apparatus incorporating the image scanner.

2. Description of the Related Art

Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile functions, typically form an image on a recording medium according to image data created by an image scanner that scans an image on an original. Such image scanner may be configured to read an image on either a stationary original placed on an exposure glass or a moving original moving over a glass strip.

For example, as shown inFIG. 1, a related-art image scanner2R includes an exposure glass21on which a stationary original is placed stationarily and a glass strip22over which a moving original conveyed from an original tray91moves. A single reader23movable under the exposure glass21and the glass strip22reads an image on the stationary original and an image on the moving original. In order to read the image on the moving original, the reader23moves from a home position below the exposure glass21to a moving original reading position below the glass strip22. As the reader23halts at the moving original reading position, the reader23reads the image on the moving original moving over the glass strip22.

The image scanner2R may be connected to an auto document feeder (ADF)120that loads and feeds a plurality of originals successively. Since rigid originals such as cards are not bent flexibly, a straight conveyance path101extends from the original tray91to an output tray to convey the rigid originals straight without bending them. The straight conveyance path101is provided with a conveyance roller pair97situated upstream from the glass strip22and a conveyance roller pair98situated downstream from the glass strip22in an original conveyance direction, which convey the original over the glass strip22. In order to prohibit the conveyance roller pair97from striking the exposure glass21, the glass strip22constituting the straight conveyance path101is tilted with respect to the exposure glass21.

Since the glass strip22is tilted relative to the exposure glass21, if the reader23moves horizontally from the home position below the exposure glass21to the moving original reading position below the glass strip22, the vertical distance between the reader23and the glass strip22is greater than that between the reader23and the exposure glass21. The difference between those distances may degrade performance of the reader23that reads the image on the stationary original placed on the exposure glass21and the image on the moving original moving over the glass strip22.

Additionally, since the exposure glass21is parallel to the reader23, light emitted from the reader23irradiates the stationary original placed on the exposure glass21vertically. Conversely, the glass strip22tilted relative to the exposure glass21is also tilted relative to the reader23. Accordingly, the optical axis of light emitted from the reader23to the moving original moving over the glass strip22is not perpendicular to the glass strip22, thus degrading performance of the reader23that reads the image on the moving original moving over the glass strip22.

SUMMARY OF THE INVENTION

At least one embodiment may provide an image scanner that includes a stationary original plate on which a stationary original is placed and a moving original plate, over which a moving original is conveyed, aligned with the stationary original plate in a sub-scanning direction and tilted relative to the stationary original plate by a given angle. A reader is movable in the sub-scanning direction between a stationary original reading span disposed opposite the stationary original via the stationary original plate to read an image on the stationary original and a moving original reading position disposed opposite the moving original via the moving original plate to read an image on the moving original. The reader pressingly contacts the stationary original plate and the moving original plate as the reader moves in the sub-scanning direction.

At least one embodiment may provide an image forming apparatus including the image scanner described above.

Additional features and advantages of example embodiments will be more fully apparent from the following detailed description, the accompanying drawings, and the associated claims.

The accompanying drawings are intended to depict example embodiments and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, particularly toFIG. 2, an image forming apparatus1according to an example embodiment is explained.

FIG. 2is an external perspective view of the image forming apparatus1. The image forming apparatus1may be a copier, a facsimile machine, a printer, a multifunction printer (MFP) having at least one of copying, printing, scanning, plotter, and facsimile functions, or the like. For example, the image forming apparatus1forms color and monochrome images on recording media with toner by electrophotography or with ink by inkjet printing.

As shown inFIG. 2, the image forming apparatus1includes an image scanner2located in an upper portion thereof. An auto document feeder (ADF)3is disposed atop the image forming apparatus1, that is, on the image scanner2, such that the ADF3is supported in hinged relationship to the image scanner2.

FIG. 3is an external perspective view of the image scanner2. As shown inFIG. 3, the image scanner2includes a scanner frame5and a scanner cover4mounted thereon, which are formed into a substantially flat box. The scanner cover4is embedded with an exposure glass6and a glass strip7aligned in a longitudinal direction of the scanner cover4parallel to a sub-scanning direction SS. The exposure glass6is made of a transparent material and serves as a stationary original plate where an original bearing an image is placed stationarily. The glass strip7is made of a transparent material and serves as a moving original plate where an original bearing an image passes.

FIG. 4is an exploded perspective view of the image scanner2. Below the scanner cover4and inside the scanner frame5is a first reader10slidably mounted on and guided by a guide rod8extending parallel to the exposure glass6. The first reader10, as it slides over the guide rod8, scans and reads the image on the original. The first reader10accommodates a contact image sensor (CIS) and a light source (e.g., a luminaire) described below.

With reference toFIG. 5, a description is provided of a construction of the first reader10.

FIG. 5is a schematic vertical sectional view of the first reader10. As shown inFIG. 5, the first reader10includes a light-emitting diode (LED)51serving as a light source, a lens52, and a charge-coupled device (CCD)53. The LED51emits light onto an original placed on the exposure glass6through the exposure glass6or an original moving over the glass strip7through the glass strip7. The light reflected by the original passes through the lens52. Thereafter, the light enters the CCD53that converts the light into an electric signal, thus producing image data.

FIG. 6is a vertical sectional view of the ADF3and the image scanner2.FIG. 7is a partially enlarged vertical sectional view of the ADF3and the image scanner2. It is to be noted thatFIGS. 6 and 7schematically illustrate a part of the ADF3situated in proximity to the image reader2.

With reference toFIGS. 6 and 7, a description is provided of an image reading operation of the image scanner2for reading an image on an original conveyed through the ADF3.

Originals P (e.g., sheets and cards) each bearing an image to be read are placed on an original tray31. As a user inputs an instruction to start the image reading operation by using a control panel disposed atop the image forming apparatus1, a lever41pivotable about a shaft of a separation roller38pivots clockwise inFIG. 6, thus moving a pickup roller32rotatably mounted on the lever41downward. Accordingly, the pickup roller32comes into contact with an uppermost original P placed on the original tray31, picking up and feeding the original P toward the separation roller38in an original conveyance direction D1. The separation roller38and a separation pad39movably mounted on the lever41separate the uppermost original P picked up by the pickup roller32from other originals P and feeds the uppermost original P to a conveyance roller pair33disposed downstream from the separation roller38and the separation pad39in the original conveyance direction D1. The conveyance roller pair33conveys the original P onto the glass strip7where the image on the original P is read.

On the other hand, before the original P reaches the glass strip7, the first reader10moves in a moving direction D from a home position where the first reader10is illustrated in the dotted line to a moving original reading position where the first reader10is illustrated in the solid line. Thus, the first reader10below the glass strip7waits for the original P at the moving original reading position. As the original P moves over the glass strip7, the first reader10reads the image on the original P.

As shown inFIG. 7, after the original P passes over the glass strip7, if the original P is a relatively thin, flexible sheet, a conveyance roller pair36disposed downstream from the glass strip7in the original conveyance direction D1 conveys the original P to a reverse conveyance path34curved to convey the original P upward in a direction B to an upper output tray located above the original tray31. Thus, the originals P conveyed from the original tray31successively are stacked on the output tray.

Conversely, if the original P is a relatively thick, rigid sheet, the original P is not conveyed through the curved reverse conveyance path34but is conveyed through a straight conveyance path35.

The straight conveyance path35extends from the glass strip7. Since the conveyance roller pairs33and36are situated upstream and downstream from the glass strip7, respectively, in the original conveyance direction D1, the glass strip7is tilted relative to the exposure glass6by a given angle. The straight conveyance path35extending from the glass strip7is tilted relative to the exposure glass6by an angle substantially identical to the given angle by which the glass strip7is tilted relative to the exposure glass6. The relatively thick, rigid original P is conveyed through the straight conveyance path35in a direction A toward a side output tray mounted on a side of the ADF3. Thus, the originals P conveyed through the straight conveyance path35successively are stacked on the side output tray.

The original P may bear an image on both front and back sides thereof. To address this circumstance, a second reader37is disposed above the glass strip7. Since the original P is placed on the original tray31facing down, an image on the front side of the original P is read by the lower first reader10and an image on the back side of the original P is read by the upper second reader37. Thus, while the original P is conveyed over the glass strip7once, the image on the back side of the original P is read by the second reader37and the image on the front side of the original P is read by the first reader10.

With reference toFIGS. 6 and 7, a description is provided of an image reading operation of the image scanner2for reading an image on an original P placed on the exposure glass6.

The ADF3is supported in hinged relationship to the image scanner2such that the ADF3is swingable about a shaft mounted on a rear of the image scanner2. The user lifts the ADF3, places the original P on the exposure glass6, and lowers the ADF3to press the original P against the image scanner2. As the user inputs an instruction to start the image reading operation by using the control panel, the first reader10slides over the guide rod8in a moving direction C from the home position where the first reader10is illustrated in the dotted line. Then, the first reader10moves back to the home position. Thus, as the first reader10moves back and forth over a stationary original reading span S where the home position is situated, the first reader10scans and reads the image on the original P stationarily placed on the exposure glass6.

With reference toFIG. 8, a detailed description is now given of a construction of the first reader10according to a first example embodiment.

FIG. 8is an exploded perspective view of the first reader10. The first reader10serves as a reader that reads the image on the original P. The first reader10includes an optical scanner unit11and a bracket12. The optical scanner unit11serves as a scanner assembly, that is, a CIS or an optical scanner unit including the LED51, the lens52, the CCD53, and a mirror, as shown inFIG. 5. The bracket12serves as a support for supporting the optical scanner unit11. Pins13and13A are mounted on both side faces11bof the optical scanner unit11in a longitudinal direction thereof parallel to a main scanning direction MS, respectively, such that the pins13and13A project outward. Arms14and14A are mounted on both lateral ends of the bracket12in a longitudinal direction thereof parallel to the main scanning direction MS, respectively, such that the arms14and14A project toward the optical scanner unit11. Elongate through-holes15and15A are produced through the arms14and14A to engage the pins13and13A, respectively. The elongate through-holes15and15A elongate vertically. A diameter of each of the pins13and13A is slightly smaller than a short diameter of each of the elongate through-holes15and15A in a short direction thereof parallel to a sub-scanning direction SS.

Springs16anchored to the bracket12and the optical scanner unit11are sandwiched between the bracket12and the optical scanner unit11. The springs16serve as biasing members that bias the optical scanner unit11upward. According to this example embodiment, the four springs16are used as biasing members. Alternatively, rubber biasing members may be used instead of the springs16. Additionally, the number of the springs16and the number of the rubber biasing members are not limited to four.

Each of the pins13and13A is situated at a center on each side face11bof the optical scanner unit11in the sub-scanning direction SS and in proximity to an upper face11aof the optical scanner unit11. Alternatively, each of the pins13and13A may be situated at an arbitrary position on each side face11bof the optical scanner unit11as long as the pins13and13A are on an identical axis and so positioned as not to interfere with other components of the image scanner2depicted inFIG. 6.

With reference toFIGS. 8 to 10, a description is provided of movement of the first reader10.

FIG. 9is a partial vertical sectional view of the image scanner2illustrating the first reader10situated at the home position.FIG. 10is a partial vertical sectional view of the image scanner2illustrating the first reader10situated at an intermediate position between the home position and the moving original reading position.FIG. 11is a partial vertical sectional view of the image scanner2illustrating the first reader10situated at the moving original reading position.

As shown inFIG. 9, a lower face of the bracket12is mounted with a leg17having a through-hole engaging the guide rod8. A driver connected to the leg17drives and moves the leg17on the guide rod8in the directions C and D. In a state in which the image scanner2is installed in the image forming apparatus1depicted inFIG. 2, the springs16bias the optical scanner unit11upward against the exposure glass6resiliently as shown inFIG. 9. In order to decrease friction between the optical scanner unit11and the exposure glass6, a plurality of domical bosses18is mounted on the upper face11aof the optical scanner unit11as shown inFIG. 8, that is, an opposed face disposed opposite the exposure glass6and the glass strip7. As shown inFIG. 8, according to this example embodiment, the four bosses18are situated in proximity to four corners on the upper face11aof the optical scanner unit11symmetrically.

FIG. 9illustrates the first reader10at the home position. While the first reader10reads the image on the original P placed on the exposure glass6stationarily, the driver moves and slides the first reader10along the guide rod8from the home position shown inFIG. 9in the direction C parallel to the sub-scanning direction SS over the stationary original reading span S depicted inFIG. 6and returns to the home position. Conversely, before the first reader10reads the image on the original P conveyed over the glass strip7by the ADF3, the driver moves and slides the first reader10along the guide rod8from the home position shown inFIG. 9in the direction D through the intermediate position shown inFIG. 10to the moving original reading position shown inFIG. 11until the first reader10halts at the moving original reading position. As the first reader10halts at the moving original reading position where the first reader10is below the glass strip7, the first reader10reads the image on the original P, that is, a moving original conveyed over the glass strip7by the conveyance roller pair33depicted inFIG. 6.

As shown inFIG. 9, since the glass strip7is tilted relative to the exposure glass6by a given angle β, the scanner cover4bridged across the exposure glass6and the glass strip7produces a slope19sloping upward from the exposure glass6to the glass strip7. As the first reader10moves from the home position shown inFIG. 9to the moving original reading position shown inFIG. 11below the glass strip7where the first reader10reads the image on the original P moving over the glass strip7, the first reader10is tilted upward along the slope19of the scanner cover4while moving under the slope19through the intermediate position shown inFIG. 10. After the first reader10comes into contact with the glass strip7, the first reader10is tilted downward along the tilted glass strip7while moving under the glass strip7as shown inFIG. 11.

As shown inFIG. 8, the pins13and13A mounted on the optical scanner unit11engage the elongate through-holes15and15A produced through the arms14and14A, respectively. Additionally, the springs16bias the optical scanner unit11upward. Accordingly, the optical scanner unit11moves in a state in which the bosses18mounted on the upper face11athereof contact and slide over an opposed face6aof the exposure glass6, an opposed face19aof the slope19, and an opposed face7aof the glass strip7as shown inFIGS. 9 to 11. As shown inFIG. 9, a lower face of the scanner cover4bridged across the exposure glass6and the glass strip7is attached with the slope19. The slope19facilitates smooth movement of the optical scanner unit11from the stationary original reading span S below the exposure glass6to the moving original reading position below the glass strip7while the first reader10slides over the exposure glass6and the glass strip7as the first reader10moves from the home position shown inFIG. 9through the intermediate position shown inFIG. 10to the moving original reading position shown inFIG. 11. For example, the opposed face19aof the slope19contacted by the bosses18of the optical scanner unit11is contiguous to the opposed face6aof the exposure glass6and the opposed face7aof the glass strip7so that the opposed face6aof the exposure glass6, the opposed face19aof the slope19, and the opposed face7aof the glass strip7are formed into an identical surface.

In order to read the image on the original P precisely, the optical scanner unit11of the first reader10is requested to satisfy three conditions below. A first condition is that the optical scanner unit11is parallel to the opposed face6aof the exposure glass6and the opposed face7aof the glass strip7. A second condition is that the optical scanner unit11is spaced apart from the exposure glass6and the glass strip7with a given interval corresponding to the depth of focus of the optical scanner unit11. A third condition is that the optical axis of light emitted from the optical scanner unit11is perpendicular to the opposed face6aof the exposure glass6and the opposed face7aof the glass strip7.

A detailed description is now given of the first and second conditions.

If the first reader10does not incorporate the springs16and therefore the optical scanner unit11moves horizontally from the home position below the exposure glass6to the moving original reading position below the glass strip7, the vertical distance between the optical scanner unit11and the glass strip7is greater than that between the optical scanner unit11and the exposure glass6. If the optical scanner unit11is an optical reducer producing an increased depth of focus, the difference between those vertical distances may not adversely affect performance of the optical scanner unit11for reading the image on the original P. However, if the optical scanner unit11is a CIS producing a decreased depth of focus, the difference between those vertical distances may degrade performance of the CIS.

For example, even if the vertical distance between the CIS and the exposure glass6is determined according to the depth of focus of the CIS to improve quality of reading the image on the original P placed on the exposure glass6, since the vertical distance between the CIS and the glass strip7is greater than that between the CIS and the exposure glass6, the CIS may not read the image on the original P moving over the glass strip7precisely with the depth of focus of the CIS that is suitable for the vertical distance between the CIS and the exposure glass6.

A detailed description is now given of the third condition.

Even if the optical axis of light emitted from the optical scanner unit11is configured to be perpendicular to the exposure glass6to improve quality of reading the image on the original P placed on the exposure glass6, the glass strip7tilted relative to the exposure glass6is also tilted relative to the optical scanner unit11. Accordingly, if the optical scanner unit11moves horizontally from the home position below the exposure glass6to the moving original reading position below the glass strip7, the optical axis of light emitted from the optical scanner unit11to the glass strip7is not perpendicular to the glass strip7, thus degrading quality of reading the image on the original P moving over the glass strip7.

The optical scanner unit11is supported by the bracket12such that it is vertically movable as the pins13and13A mounted on the optical scanner unit11move in the elongate through-holes15and15A produced through the arms14and14A mounted on the bracket12, respectively. The springs16constantly press the optical scanner unit11upward so that the bosses18mounted on the upper face11aof the optical scanner unit11constantly contact the opposed face6aof the exposure glass6, the opposed face19aof the slope19, and the opposed face7aof the glass strip7as the optical scanner unit11moves in the sub-scanning direction SS. Accordingly, while the first reader10reads the image on the original P, an optical axis of light emitted from the optical scanner unit11is perpendicular to the exposure glass6and the glass strip7. Additionally, an interval between the optical scanner unit11and the exposure glass6is retained identical to an interval between the optical scanner unit11and the glass strip7. Consequently, the first reader10reads the image on the original P precisely for both moving original reading for reading the original P moving over the glass strip7and stationary original reading for reading the original P placed on the exposure glass6.

With the configuration of the first reader10described above, the single reader, that is, the first reader10, reads the image on the original P precisely even if the glass strip7over which the original P conveyed through the ADF3moves is tilted relative to the exposure glass6on which the original P is placed stationarily by the given angle β.

With reference toFIG. 12, a description is provided of a construction of a first reader10S according to a second example embodiment.

FIG. 12is an exploded perspective view of the first reader10S. The first reader10S differs from the first reader10depicted inFIG. 8in that arms14S and14AS mounted on the bracket12and pins13S and13AS mounted on the optical scanner unit11of the first reader10S are positioned differently from the arms14and14A and the pins13and13A of the first reader10. For example, unlike the arms14and14A mounted on the center of the bracket12in the sub-scanning direction SS shown inFIG. 8, each of the arms14S and14AS is mounted on the bracket12at a position in proximity to a lower edge12aof the bracket12that faces the glass strip7. Similarly, each of the pins13S and13AS is mounted on each side face11bof the optical scanner unit11at a position in proximity to a downstream face11cof the optical scanner unit11that faces the glass strip7.

With reference toFIGS. 13 to 15, a description is provided of movement of the first reader10S.

FIG. 13is a partial vertical sectional view of an image scanner2S illustrating the first reader10S incorporated therein and situated at the home position.FIG. 14is a partial vertical sectional view of the image scanner2S illustrating the first reader10S situated at the intermediate position between the home position shown inFIG. 13and the moving original reading position.FIG. 15is a partial vertical sectional view of the image scanner2S illustrating the first reader10S situated at the moving original reading position.

In order to read the image on the original P conveyed through the ADF3, the first reader10S moves from the home position shown inFIG. 13in the direction D through the intermediate position shown inFIG. 14to the moving original reading position shown inFIG. 15. As the first reader10S halts below the glass strip7at the moving original reading position shown inFIG. 15, the first reader10S reads the image on the original P conveyed by the conveyance roller pair33depicted inFIG. 6and moving over the glass strip7.

Unlike the pins13and13A of the first reader10, serving as pivots of the optical scanner unit11, mounted on the center of the respective side faces11bof the optical scanner unit11in the sub-scanning direction SS as shown inFIG. 8, the pins13S and13AS of the first reader10S situated in proximity to the downstream face11cof the optical scanner unit11as shown inFIG. 12decrease the height of the image scanner2S, downsizing the image scanner2S.

With reference toFIGS. 16 to 19, a detailed description is now given of a configuration of the first reader10S that downsizes the image scanner2S.

FIG. 16is a partial vertical sectional view of the image scanner2illustrating the first reader10situated at the home position.FIG. 17is a partial vertical sectional view of the image scanner2illustrating the first reader10situated at the moving original reading position.FIG. 18is a partial vertical sectional view of the image scanner2S illustrating the first reader10S situated at the home position.FIG. 19is a partial vertical sectional view of the image scanner2S illustrating the first reader10S situated at the moving original reading position.

As shown inFIGS. 16 and 17, the pin13serving as a pivot of the optical scanner unit11is mounted on the center of one side face11bof the optical scanner unit11at a position interposed between the springs16in the sub-scanning direction SS. Similarly, the pin13A serving as a pivot of the optical scanner unit11is mounted on the center of another side face11bof the optical scanner unit11at a position interposed between the springs16in the sub-scanning direction SS. Accordingly, when the first reader10is at the home position shown inFIG. 16, the length of the respective springs16is defined as a minimum length L plus α.

A detailed description is now given of the length of the respective springs16.

As the first reader10moves from the home position shown inFIG. 16in the direction D to the moving original reading position under the glass strip7shown inFIG. 17, the optical scanner unit11pivots about the pins13and13A counterclockwise, compressing the left, downstream spring16and expanding the right, upstream spring16. The minimum length L of the respective springs16is specific and preset individually.

With reference toFIGS. 20A,20B, and20C, a detailed description is now given of the minimum length L of the springs16.

FIG. 20Ais a diagram illustrating the spring16applied with no force. As shown inFIG. 20A, the spring16has a length L1 when the spring16is applied with no force.FIG. 20Bis a diagram illustrating the spring16applied with a force. An available range AR defines a range in which a stress not greater than an allowable torsional stress is applied to the spring16as the spring16is compressed. If the length of the compressed spring16is in the available range AR, the spring16causes a proper resilience.

An available lower limit L2 defines a length below which the compressed spring16is applied with a stress greater than the allowable torsional stress and at the worst the spring16is broken.FIG. 20Cis a diagram illustrating the spring16applied with a substantial force. A solid length L3 defines a length of the spring16compressed to the limit. If the spring16is compressed to have the solid length L3, the spring16no longer has resiliency and therefore does not achieve its function. Accordingly, the minimum length L of the spring16defines a minimum length above which the spring16causes a proper resilience, that is, the available lower limit L2 or the solid length L3.

For example, when the first reader10halts at the moving original reading position below the glass strip7as shown inFIG. 17, the left, downstream spring16compressed by the optical scanner unit11should have a length greater than the minimum length L. It is because if the compressed left, downstream spring16has a length smaller than the minimum length L, that is, the solid length L3, a resilience of the left, downstream spring16is smaller than a resilience of the right, upstream spring16and therefore the left, downstream spring16does not press the optical scanner unit11against the glass strip7precisely. Accordingly, the optical axis of light emitted from the optical scanner unit11is oblique to the glass strip7, not perpendicular to the glass strip7, resulting in faulty reading of the image on the original P by the optical scanner unit11. Further, if the minimum length L is the available lower limit L2, at the worst, the spring16may be broken and therefore replacement of the first reader10may be needed.

To address this problem, when the first reader10is at the home position shown inFIG. 16, the length of the spring16is the minimum length L plus α. In contrast, as shown inFIGS. 18 and 19, the pin13S serving as a pivot of the optical scanner unit11is mounted on one side face11bof the optical scanner unit11at the position in proximity to the downstream face11cof the optical scanner unit11. Similarly, the pin13AS serving as a pivot of the optical scanner unit11is mounted on another side face11bof the optical scanner unit11at the position in proximity to the downstream face11cof the optical scanner unit11. The left, downstream spring16and the right, upstream spring16are situated upstream from the pins13S and13AS in the direction D in which the first reader10S moves from the home position to the moving original reading position. Accordingly, when the first reader105is at the home position shown inFIG. 18, the length of the respective springs16is the minimum length L.

A detailed description is now given of the length of the respective springs16equivalent to the minimum length L.

As the first reader10S moves from the home position shown inFIG. 18in the direction D to the moving original reading position below the glass strip7shown inFIG. 19, the optical scanner unit11pivots about the pins13S and13AS counterclockwise, expanding the left, downstream spring16and the right, upstream spring16situated upstream from the pins13S and13AS in the direction D. When the first reader10S is at the moving original reading position below the glass strip7, the left, downstream spring16and the right, upstream spring16are not compressed further than at the home position. Accordingly, unlike the compressed springs16of the first reader10at the moving original reading position shown inFIG. 17, the springs16of the first reader10S at the moving original reading position shown inFIG. 19need not satisfy the minimum length L. Consequently, when the first reader10S is at the home position shown inFIG. 18, the springs16have the minimum length L.

As shown inFIGS. 16 and 18, the length of the springs16changes the height of the image scanners2and2S. For example, with the image scanner2shown inFIG. 16, the length L plus α of the springs16at the home position of the first reader10changes a height G of the image scanner2. With the image scanner2S shown inFIG. 18, the length L of the springs16at the home position of the first reader10S changes a height H of the image scanner2S.

As shown inFIGS. 18 and 19, the image scanner2S incorporates the pins13S and13AS situated in proximity to the downstream face11cof the optical scanner unit11. Accordingly, the springs16are configured to have the minimum length L when the first reader10S is at the home position shown inFIG. 18. Consequently, the height H of the image scanner2S is reduced by a length a compared to the height G of the image scanner2incorporating the pins13and13A situated at the center of the side faces11bof the optical scanner unit11in the sub-scanning direction SS, respectively, as shown inFIG. 16, resulting in downsizing of the image scanner2S.

With reference toFIG. 21, a description is provided of an angle of the slope19.

FIG. 21is a partial vertical sectional view of the image scanner2S illustrating the first reader10S coming into contact with a boundary between the glass strip7and the slope19. As the first reader10S moves from the moving original reading position below the glass strip7in the direction C to return to the home position below the exposure glass6, the leading bosses18, that is, the right bosses18inFIG. 21, come into contact with the slope19. Accordingly, the optical scanner unit11is applied with a force that rotates the optical scanner unit11about the pins13S and13AS. To address this circumstance, the opposed face19aof the slope19is angled at a given angle to produce a moment M that rotates the optical scanner unit11about the pins13S and13AS clockwise inFIG. 21, thus facilitating movement of the first reader10S to the home position below the exposure glass6.

Conversely, if the opposed face19aof the slope19is angled at an angle to produce a moment opposite the moment M, that rotates the optical scanner unit11about the pins13S and13AS counterclockwise inFIG. 21, as the first reader10S moves to the home position below the exposure glass6, the bosses18may be caught in a compartment E depicted inFIG. 15created by the glass strip7and the slope19, producing a resistance that obstructs movement of the first reader10S to the home position below the exposure glass6.

With reference toFIGS. 9 and 13, a description is provided of advantages of the image scanners2and2S.

The respective image scanners2and2S include a transparent, stationary original plate (e.g., the exposure glass6) on which a stationary original P is placed; a transparent, moving original plate (e.g., the glass strip7) over which a moving original P is conveyed; and a reader (e.g., the first readers10and10S) movably disposed opposite the stationary original P and the moving original P via the stationary original plate and the moving original plate, respectively, to read an image on either the stationary original P or the moving original P. The opposed face7aof the moving original plate disposed opposite the reader is tilted relative to the opposed face6aof the stationary original plate disposed opposite the reader by the given angle β. The reader contacts and moves along the opposed face6aof the stationary original plate and the opposed face7aof the moving original plate.

That is, even if the respective image scanners2and2S are connected to the straight conveyance path35depicted inFIG. 6that receives the moving original P from the respective image scanners2and2S, the reader moves along the opposed face6aof the stationary original plate and the opposed face7aof the tilted moving original plate. Accordingly, the reader is disposed opposite the stationary original P and the moving original P with a constant given interval therebetween. Further, light emitted from the reader irradiates the stationary original P and the moving original P perpendicularly. Thus, the single reader reads the image on the stationary original P and the moving original P precisely.

The present invention has been described above with reference to specific example embodiments. Note that the present invention is not limited to the details of the embodiments described above, but various modifications and enhancements are possible without departing from the spirit and scope of the invention. It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein. For example, elements and/or features of different illustrative example embodiments may be combined with each other and/or substituted for each other within the scope of the present invention.