Abstract:
An original scanning apparatus comrpises a scanning unit for scanning an original. The scanning unit has a mirror and a light source for illuminating the original. A connecting member is electrically connected to the scanning unit. A guide member supports and guides one end of the scanning unit. The guide member fixes a position of the one end of the scanning unit in a vertical direction. At least a part of a driving element is disposed at the position overlapping with the guide member in the vertical direction, but not overlapping with the mirror of the scanning unit. The connecting member is provided at the side of the guide member.

Description:
This application is a continuation of application Ser. No. 07/459,553 filed Jan. 2, 1990, which is a continuation of application Ser. No. 07/311,280 filed Feb. 16, 1989, both now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an original scanning apparatus used with an electrophotographic copying machine, image reader and the like, and, more particularly, it relates to an original scanning apparatus which scans an original by driving a scanning unit. 
     2. Related Background Art 
     In the past, original scanning apparatuses of this kind, for example, an optical scanning apparatus as shown in FIG. 10 have already been known. This known optical scanning apparatus is intended to be used with an electrophotographic copying machine and the like, and includes a scanning unit 100 having an illumination lamp 102 for illuminating a surface of an original (not shown). The scanning unit 100 is slidably mounted, at its one end, on a guide rail 103 extending in a direction along which original is scanned, and is slidably abutted, at its the other end, against a guide member 104 extending in parallel with the guide rail 103. A mirror 101 incorporated into the scanning unit 100 acts to focus and expose an image recorded on the original onto a photosensitive member (not shown) through a focusing lens (not shown) and a mirror 105 which is moved at a speed of 1/2 of that of the scanning unit 100. 
     A driving means 107 positioned outside of the guide rail 103 operates to shift the scanning unit 100. 
     On the other hand, the scanning unit 100 has a free end portion only a lower end of which is fixed, and a supply cord 106 is connected, at its one end, to the free end portion of the scanning unit. The supply cord 106 extends from the other end thereof fixed to a frame (not shown) of the scanning apparatus toward a returning direction of the scanning unit 100 and is bent in a U-shape near the one end thereof to be connected to the scanning unit 100. Thus, the supply cord 106 can follow the movement of the scanning unit 100 while changing a position of the bent portion 106a thereof. 
     In such conventional scanning apparatus, since the driving means 107 including a driving wire 108, pulleys 109a, 109b and 109c, driving motor (not shown) and the like is arranged outside of the guide rail 103 and since electric parts such as a circuit board (not shown) and the like relating to power supply, as well as the supply cord 106, are arranged outside of the free end portion of the scanning unit, the scanning apparatus itself requires a space, along a lengthwise direction of the mirror 105, for installing the driving means 107, supply cord 106 and the like, thus arising a problem that the scanning apparatus cannot be made compact. 
     Further, in such a conventional scanning apparatus, when the scanning unit 100 reaches its scanning completion position (full scan position), the substantial portion or most part of the supply cord 106 which extends from the bent portion 106a to the above-mentioned other end must be supported by the scanning unit 100. Consequently, if the supply cord 106 has not a certain rigidity, it cannot maintain its proper posture, with the result that the supply cord will flex outwardly or downwardly to contact with the other element or elements of the scanning unit, thus distorting the image to be copied and/or damaging the supply cord 106 itself to threaten the security of the apparatus. 
     In order to eliminate the above-mentioned disadvantage, the supply cord is normally stiffened by applying a coating layer made of resin such as vinyl chloride or polyolefin onto a sheath of the supply cord 106. 
     However, in the supply cord coated by such resin layer, since the hardness of the coating resin layer is increased in response to the change in the circumferential condition (particularly, decrease in temperature), the supply cord 106 cannot be smoothly moved in the scanning operation of the scanning unit 100, with the result that the load derived from the slow-moving supply cord is applied to the scanning unit 100. Accordingly, in the case where the supply cord 106 is attached to the free end portion of the scanning unit 100, there arose a problem that, during the scanning operation, the free end portion of the scanning unit 100 was lifted due to the load from the supply cord 106, thus distorting the copied image considerably. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an original scanning apparatus in which both a driving means for driving a scanning unit and the like and a connecting member such as a supply cord connected to the scanning unit are positioned in the same end of the scanning unit to make the whole scanning apparatus compact. 
     It is another object of the present invention to provide an original scanning apparatus in which the driving means and the connecting member are arranged adjacent to each other, but the interference between the driving means and the connecting member is effectively prevented so as not to disturb the scanning operation. 
     It is a further object of the present invention to provide an original scanning apparatus which can prevent the scanning unit from shaking due to unstable movement of the connecting member to obtain a stable copied image. 
     Other objects of the present invention will be apparent from the following detailed explanation in connection with the embodiments with reference to the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an original scanning apparatus according to a first embodiment of the present invention; 
     FIG. 2 is a plan view of an attachment portion between a rail and a scanning unit of the original scanning apparatus of FIG. 1; 
     FIG. 3 is an elevational view of the attachment portion of FIG. 2; 
     FIG. 4 is a sectional view taken along the line IV--IV of FIG. 3; 
     FIG. 5 is a plan view of the attachment portion of the scanning unit of FIG. 3 in a home position thereof; 
     FIG. 6 is a plan view of an attachment portion between a rail and a scanning unit of an original scanning apparatus according to a second embodiment of the present invention; 
     FIG. 7 is an elevational view of the attachment portion of FIG. 6; 
     FIG. 8 is a perspective view of an alternation of the original scanning apparatus of FIG. 1; 
     FIG. 9 is a schematic constructural view of an electrophotographic copying machine incorporating the original scanning apparatus of the first embodiment therein; and 
     FIG. 10 is a schematic perspective view of a conventional original scanning apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be fully explained in connection with illustrated embodiments thereof. FIG. 1 shows an original scanning apparatus according to a first embodiment of the present invention. In FIG. 1, the original scanning apparatus 1 comprises a scanning unit 2 for scanning an original (not shown) positioned on an original supporting plate (not shown). and a mirror unit 4 which can follow the movement of the scanning unit 2 in parallel with the latter at a speed of 1/2 of that of the scanning unit 2. The scanning unit 2 and mirror unit 4 are guided along a guide rail 6 and a guide member (guide plate) 8 which are arranged in parallel with each other, and are driven by a driving wire 9. 
     Further, the scanning unit 2 includes, an illumination lamp 22 to which a flexible connecting member or supply cord 14 for supplying electric power to the lamp is connected. The scanning unit 2 further includes a reflection hood (not shown) having a slit and extending in a longitudinal direction of the illumination lamp 22, and the original is exposed by slit light reflected from the reflection hood. More particularly, the scanning unit 2 is constituted by integrally assembling the illumination lamp 22 for illuminating the original and a first mirror (not shown) for reflecting the light from the image (on the original) exposed by the slit light toward the mirror unit 4 on a first mirror support 24. 
     The first mirror support 24 is slidably and rotatably mounted, at its one end, on the guide 6 and is provided, at its other free end, with a roller 25 which can roll on a guide surface 8a of the guide plate 8. 
     On the other hand, the mirror unit 4 is arranged in confronting relation with the first mirror (not shown) of the scanning unit 2, and is constituted by integrally assembling a second mirror (not shown) and a third mirror (not shown) on a second mirror support 44. The second mirror acts to reflect the reflected image light from the afore-mentioned first mirror (not shown) downwardly, and the third mirror is arranged in confronting relation with the second mirror and acts to reflect back the reflected image light. Also, the second mirror support 44 is slidably and rotatably mounted, at its one end, on the guide 6 and is provided, at its other free end, with a roller 45 which can roll on a guide surface 8a of the guide plate 8. 
     As mentioned above, each one end of the scanning unit 2 and mirror unit 4 is slidably and rotatably supported on the guide 6 (this supporting fashion will be referred to as &#34;restraining-support&#34; hereinafter), and each other end thereof is supported on the guide plate 8 to slidably roll thereon (this supporting fashion will be referred to as &#34;free-support&#34; hereinafter). 
     The reason why the scanning unit and mirror unit are supported in the above-mentioned fashion is that, if both ends of the scanning unit 2 are restraining-supported, when the scanning unit 2 is inclined in a scanning direction, since the scanning unit is subjected to the load at their restraining-supported ends, it will be difficult for the scanning unit to smoothly move, thus preventing the proper scanning operation. 
     Accordingly, the scanning unit is normally restraining-supported at its one end and is free-supported at the other end, and, it is preferable that the driving means for driving the scanning unit is arranged on a side of the restraining-supported end of the scanning unit, i.e., on a side of the guide rail 6, so that the driving means is not influenced upon the inclination of the scanning unit. The mirror unit 4 is similarly installed. 
     In this way, the driving wire 9 is arranged on a side of the guide rail 6, and is wound around a driving pulley 10 driven reversibly by means of a motor (not shown) and also wound around driven pulleys 11, 12 positioned out of the scanning area of the scanning unit 2 and mirror unit 4. Further, the driving wire 9 is fixed, at its intermediate portion, to the scanning unit 2 by means of a fixing bracket 13 and is wound around a pulley 13a mounted on the mirror unit 4. When the driving pulley 10 is rotated in a clockwise direction shown by an arrow A, the driving wire 9 is pulled in a direction shown by an arrow A&#39; to pull the first mirror support 24 in the scanning direction through the driven pulley 11 and to pull the pulley 13a mounted on the second mirror support 44 so that the second mirror support 44 is shifted at a speed of 1/2 of that of the first mirror support 24. 
     On the other hand, when the scanning unit 2 and mirror unit 4 are returned to their respective home positions, the driving pulley 10 is rotated in a reverse direction (counter-clockwise direction) shown by an arrow B, so that the driving wire 9 is pulled in a direction shown by an arrow B&#39; to retract the second mirror support 44 through the pulley 12 and further to retract the first mirror support 24. In this case, the rollers 25 and 45 arranged on the other ends of the first and second mirror supports 24 and 44 are shifted while rolling on the guide surface 8a of the guide plate 8. 
     In this way, by arranging the portion of the driving wire 9 and the pulley 13a above the units 2, 4 in an overlapped relation at the side of the guide rail 6, a transverse dimension of the original scanning apparatus 1 can be reduced in a direction (i.e., a longitudinal direction of the slit formed in the reflection hood) perpendicular to the scanning direction in a plane parallel to the plane in which the scanning unit 2 is shifted, thus making the apparatus compact, 
     Further, as shown in FIG. 1, a connecting member or supply cord 14 is arranged at the side of the guide rail 6. In the illustrated embodiment, a movable portion comprising a greater part of the connecting member or supply cord 14, which can be changed in its shape (i.e., can be flexed) during the movement of the scanning unit 2, is situated in parallel with the guide rail 6 outside of the scanning unit 2. 
     The connecting member or supply cord 14 is fixed, at its one end, to a lens support 31 (FIG. 3) by a cord holder 14a and is fixed, at its other end, to the first mirror support 24 of the scanning unit 2 by a cord holder 14b (FIG. 2). The connecting member or supply cord 14 extends from the position of the cord holder 14a in a returning direction of the scanning unit 2 along the lens support 31 (FIG. 3) and is bent back upwardly in a U-shaped configuration in the vicinity of the mirror unit 4. Further, the connecting member or supply cord 14 extends from the bent portion 15 in the scanning direction of the scanning unit 2 is fixed to the first mirror support 24 by means of the cord holder 14b. 
     As the scanning unit 2 is shifted from the home position toward the scanning direction, the connecting member or supply cord 14 follows the movement of the scanning unit 2 while changing the position of its bent portion 15. In this way, since a portion of the driving wire 9 is arranged above the scanning unit 2, and the movable portion of the connecting member or supply cord 14 (which can be shifted in response to the movement of the scanning unit 2) is arranged outside of the scanning unit 2, even if the movable portion of the supply cord becomes longer, the connecting member or supply cord 14 would not touch or contact with the driving wire 9 and the like, thus preventing the inconvenience in the scanning operation. 
     Further, since the connecting member or supply cord 14 is arranged in an overlapped condition below the driving wire 9 wound around the driving pulley 10 and driven pulleys 11, 12, there is no need to provide a transverse space for exclusively installing the supply cord 14, thus making the transverse dimension of the original scanning apparatus 1 more compact. 
     As the scanning unit 2 is shifted, the connecting member or supply cord 14 follows the movement of the scanning unit while changing the position of the bent portion 15 thereof. In this case, even if the surrounding temperature decreases to stiffen the resin layer coating the connecting member or supply cord 14 so as to generate the load which tends to lift or float the scanning unit 2, such load from the connecting member or supply cord 14 is resisted or supported by the guide rail 6, thus preventing the floating of the scanning unit 2. Consequently, it is possible to perform the stable scanning operation, thereby obtaining the stable copied image. 
     Further, since the connecting member or supply cord 14 is situated opposite to the guide plate 8 with respect to the guide rail 6, the load from the connecting member or supply cord 14 creates a moment force around the guide rail 6, which moment force acts against the guide surface 8a of the guide plate 8 downwardly through the roller 25, thus further preventing the floating of the scanning unit 2 to perform the more stable scanning operation. 
     FIGS. 2 to 5 show enlarged views of portions of the original scanning apparatus according to the first embodiment of the present invention. In detail, FIGS. 2, 3 and 4 are a plan view, elevational view and sectional view of the attachment portion of the scanning unit at a side of the guide rail, respectively. As shown in these Figures, it, can be understood that the cord holder 14a for the connecting member or supply cord 14 is situated below the fixing bracket 13 for the driving wire 9 and, therefore, the connecting member or supply cord 14 is situated below the driving wire 9. Further, the cord holder 14b is inclined upwardly toward the returning direction of the scanning unit to increase the radius of the bent portion 15. 
     In this way, the connecting member or supply cord 14 is not subjected to an excessive load, and the portions of the connecting member or supply cord 14 do not interfere with each other. Thus, the scanning operation is not disturbed by the movement of the connecting member or supply cord 14 at all, thereby obtaining the stable copied image. 
     Further, FIG. 5 shows an elevational view of the scanning unit, similar to FIG. 3, but in the home position. A position sensor 17 is provided for detecting the home position of the scanning unit 2, which position sensor 17 is turned ON or OFF by means of a flag 18 protruded from the side of the first mirror support 24. As shown in FIG. 3, the flag 18 is arranged slightly higher than the cord holder 14b mounted on the first mirror support 24 so that, when the units 2 and 4 are shifted from their home positions toward the scanning direction, the flag 18 disengages from the position sensor (not seen in FIG. 3) and presses the swelled portion near the bent portion 15 of the supply cord 14 from above. 
     In this way, since the flag 18 also acts to restrain the swelling of the bent portion 15 of the connecting member or supply cord 14, even if any restraining element for the supply cord is not provided, the interference between the connecting member or supply cord 14 and the driving wire positioned above the supply cord can be effectively prevented, and the height of the original scanning apparatus can be reduced, thus making the apparatus compact. 
     On the other hand, the cord holder 14a mounted on the lens support 31 is so arranged that, as shown in FIG. 5, during the returning operation, as the scanning unit 2 and mirror unit 4 approach the respective home positions, the radius of curvature of the bent portion 15 of the connecting member or supply cord 14 is decreased to separate the connecting member or supply cord 14 from the flag 18. With this arrangement, since the radius of curvature of the bent portion 15 of the connecting member or supply cord 14 is smallest, the interference between the connecting member or supply cord 14 and the position sensor 17 can be prevented in the home position. Consequently, the connecting member or supply cord 14 does not have influence upon the position sensor 17, whereby the position sensor 17 can positively detect the home position. 
     FIGS. 6 and 7 show a second embodiment of the present invention, wherein a restraining member is provided on the side of the mirror unit shown in FIGS. 2 and 3, for restraining the movement of the connecting member (supply cord). More particularly, as shown in FIGS. 6 and 7, the connecting member or supply cord 14 is arranged between a side surface 44a of the mirror unit 4 and a restraining member 19 attached thereto. 
     In this way, by arranging the connecting member or supply cord 14 between the side surface 44a of the mirror unit 4 and the restraining member 19, during the scanning operation, since the bent portion 15 of the connecting member or supply cord 14 is shifted at a speed of about 1/2 of that of the scanning unit 2, like to the mirror unit 4, the positional relation, between the bent portion 15 of the connecting member or supply cord 14 and the mirror unit 4 remains unchanged during the scanning operation, thus preventing lateral deviation of the supply cord 14. 
     FIG. 8 shows an alternation of the original scanning apparatus of FIG. 1, wherein the connecting member or supply cord 14 is arranged on a side of the guide plate 8. In the original scanning apparatus shown in FIG. 8, since the connecting member or supply cord 14 is situated on the side of the guide plate 8 which is not restrained from above, there may arise a problem that, in the lower temperature condition, the scanning unit 2 is lifted due to the hardening of the coating resin layer of the supply cord 14. 
     FIG. 9 shows an example of an electrophotographic copying machine incorporating the original scanning apparatus according to the first embodiment of the present invention therein. In the illustrated electrophotographic copying machine, the light from the image on the original 0 slit-exposed by the illumination lamp 22 is reflected by the first mirror 23 of the scanning unit 2 and the second and third mirrors 42, 43 of the mirror unit 4, and is focused on a photosensitive member 3 through a focusing lens 20. A latent image formed on the photosensitive member 3 is visualized by a developing device 32 and is transferred onto a recording medium (not shown) fed through rollers 33 by means of a transferring and charging device 34, and then is fixed by a fixing device 35 to obtain the copied image. 
     In this way, in the electrophotographic copying machine, since the original scanning apparatus incorporated therein can always perform the stable scanning operation and is compacted, the electrophotographic copying machine itself can also perform a stable copying operation and is also made compact. 
     In the illustrated embodiments, while the connecting member was explained as the connecting member or supply cord connected to the illumination lamp, but the connecting member is not limited to the supply cord alone; for example, a connecting cord connected to a read-out element such as a dimmer sensor, temperature fuse, CCD and the like assembled into the scanning unit may be used as the connecting member.