JP2009157217A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an image reader small in size in a width direction by reducing space from the rotary shaft of a driving pulley to a sidewall of the housing of the apparatus. <P>SOLUTION: A scanner 10 includes a belt transmission mechanism 100 driving the carriage 36 of an image reading unit 22, and a driving force transmission mechanism 70 transmitting torque of a motor 72 to the belt transmission mechanism 100. The belt transmission mechanism 100 is laid over between a rotating body 102 and a driven pulley 104. The rotating body 102 has a driving pulley 114 at an upper stage, a second gear 112 at a lower stage and a flange 116 at a middle stage. A belt is laid on the driving pulley 114, and an idle gear 98 of the driving force transmission mechanism 70 is meshed with the second gear 112. The flange 116 projects from the outer peripheral surface of the driving pulley 114. The outside diameter of the second gear 112 is set to nearly the same dimension as the outside diameter of the flange 116. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that reads an image of a document by scanning a document with a reading sensor, and in particular, transmits a rotational force of an electric motor to a pulley that supports an annular member such as a belt to which the reading sensor is connected. The present invention relates to a driving force transmission mechanism that moves a reading sensor in a predetermined direction.

  2. Description of the Related Art Conventionally, an image reading apparatus that reads image data of a document by a reading sensor such as a CIS (Contact Image Sensor) or a CCD (Charge Coupled Device) is known. This image reading apparatus has a driving force transmission mechanism (see Patent Document 1 and Patent Document 2) that transmits a driving force to a reading sensor supported so as to be slidable in a predetermined direction.

  As the driving force transmission mechanism, Patent Document 1 and Patent Document 2 describe that an annular belt is bridged between a driving pulley and a driven pulley that are spaced apart from each other, and the rotational force of the motor is transmitted to the driving pulley. What makes the said belt move circumferentially is disclosed. When a rotational force is transmitted from the motor to the drive pulley while the reading sensor is connected to the belt, the reading sensor moves in the belt extending direction along with the circumferential movement of the belt. In the image reading apparatus having such a driving force transmission mechanism, the width size of the casing (the size in the moving direction of the reading sensor) depends on the moving range of the reading sensor, in other words, the arrangement interval of the driving pulley and the driven pulley. Generally determined.

  The driving force transmission mechanism includes a speed change mechanism (see FIGS. 5 and 7 of Patent Document 1 and FIG. 2 of Patent Document 2) including a plurality of gears. This transmission mechanism is provided in the transmission path from the motor to the drive pulley. By this speed change mechanism, the rotation speed of the motor is changed to a rotation speed corresponding to the reading resolution in the image reading apparatus and transmitted to the drive pulley. In general, the image reading apparatus employs the above-described speed change mechanism because a more stable speed can be obtained than when the speed is changed by controlling the rotation speed of a motor.

JP 2000-287038 A JP 2007-187701 A

  However, in any of the driving force transmission mechanisms described in Patent Literature 1 and Patent Literature 2, a gear arranged coaxially with the driving pulley is used as one of the members constituting the speed change mechanism. This gear is larger than the outer diameter of the drive pulley. Therefore, the distance from the rotating shaft of the driving pulley to the side wall of the housing of the image reading device depends on the size of the gear having an outer diameter larger than that of the driving pulley.

  The present invention has been made paying attention to the size of the gear arranged coaxially with the rotation shaft of the drive pulley, and the object thereof is to review the size of the gear so that the rotation shaft of the drive pulley. Another object of the present invention is to provide an image reading apparatus capable of reducing the size in the width direction of the apparatus by reducing the distance from the side wall of the apparatus to the side wall of the apparatus.

(1) The present invention provides an image reading apparatus including an electric motor, a first gear, a speed change mechanism, a second gear, a first pulley, a flange, a second pulley, an annular member, and a reading sensor. It is configured as. The electric motor has an output shaft. The first gear transmits the driving force of the electric motor and is connected to the output shaft. The speed change mechanism changes the rotational speed of the electric motor and is connected to the first gear. The second gear is connected to the transmission mechanism. The first pulley receives the rotational force of the second gear and rotates, and is provided coaxially with the second gear. The flange is provided adjacent to the first pulley. The flange protrudes in a direction perpendicular to the outer peripheral surface of the first pulley. The second pulley is rotatably provided at a position separated from the first pulley by a predetermined distance. The annular member is bridged between the first pulley and the second pulley so as to be capable of circumferential movement between the first pulley and the second pulley. The reading sensor is connected to the annular member and configured to be movable between the first pulley and the second pulley. In the image reading apparatus of the present invention, the outer diameter of the second gear is set to be equal to or smaller than the outer diameter of the flange.

  When the output shaft of the electric motor is rotated, the rotational force is transmitted to the second gear via the first gear and the speed change mechanism. Accordingly, the first pulley is rotated by receiving the rotational force of the second gear. An annular member made of a belt, a wire, or the like is hung on the first pulley. The flange plays a role of supporting the annular member and preventing the annular member from coming off. When the first pulley is rotated, the annular member moves between the first pulley and the second pulley. Thereby, the reading sensor connected to the annular member moves between the first pulley and the second pulley. Since the reading sensor is connected to the annular member, the reading sensor cannot move to the outside of the first pulley or the outside of the second pulley, and the movement range is within the distance between the first pulley and the second pulley. .

  In the image reading apparatus of the present invention, the outer diameter of the second gear is set to be equal to or less than the outer diameter of the flange. Accordingly, the second gear does not protrude outside the outer peripheral edge of the first pulley or the flange in the moving direction of the reading sensor. Therefore, for example, even if the outer peripheral edge of the flange is brought close to another member (such as a side wall of the housing of the apparatus) that constitutes the image reading apparatus, the second gear does not contact other members such as the side wall. That is, other members such as the side wall can be brought close to the outer peripheral edge of the flange. Specifically, the distance from the shaft of the first pulley to the other member such as the side wall can be approximately the radius of the flange. Thus, it is possible to arrange another member constituting the image reading device in a region where the second gear is conventionally disposed protruding from the outer peripheral edge of the flange. As a result, it is possible to efficiently arrange the members constituting the image reading apparatus in a limited space. For example, when the member close to the outer peripheral edge of the flange is the side wall of the casing, the size in the width direction of the apparatus can be reduced.

  The outer diameter of the flange is an element that is inevitably determined by the outer diameter of the first pulley, the thickness of the annular member, the tension of the annular member, and the like.

(2) The speed change mechanism reduces the rotational speed of the electric motor and transmits it to the second gear.

  When the speed change mechanism reduces the rotational speed of the electric motor, it is a common design means to increase the outer diameter of the second gear that directly transmits the rotational force to the first pulley. Contrary to this conventional means, the present invention makes it possible to reduce the size of the casing in the width direction by making the outer diameter of the second gear the same as or smaller than the outer diameter of the flange.

(3) The flange is a side portion of the second gear adjacent to the first pulley.

  This prevents the annular member from falling off the first pulley and falling off to the second gear. Further, since the second gear also serves as a flange, the number of parts is reduced.

(4) The second gear, the first pulley, and the flange are integrally formed.

  In adopting the speed change mechanism, it is conceivable to reduce the number of parts constituting the speed change mechanism in order to suppress transmission loss such as gear loss. As a technique for this, it is conceivable to integrally form the second gear, the first pulley, and the flange. The present invention is suitable for such a configuration.

(5) The transmission mechanism has a one-stage gear (idle gear) that meshes with the second gear. Here, the one-stage gear means a gear that does not perform gear shifting. That is, it means that only one gear is provided on the shaft.

  Accordingly, the driving force can be smoothly transmitted from the speed change mechanism to the second gear without interfering with the rotation shaft of the second gear. Further, when the speed change mechanism is a speed reduction mechanism, the gear of the one-stage configuration of the speed change mechanism and the second gear are connected, and therefore the height direction of the image reading apparatus of the present invention, that is, the rotation of the gear of the one-stage configuration. It can contribute to the downsizing in the axial direction. Specifically, when the speed change mechanism is a speed reduction mechanism and this speed change mechanism is connected to the second gear by a two-stage gear, the second gear having the smaller diameter and the second gear The gear meshes. At this time, the gear having the larger diameter among the second gear and the two-stage gear is arranged so as to overlap with the rotation axis direction of the second gear. On the other hand, when the speed change mechanism is connected to the second gear by a one-stage gear, the one-stage gear and the second gear are not arranged to overlap each other. Therefore, when the speed change mechanism is a speed reduction mechanism, it is possible to reduce the size of the second gear of the image reading apparatus in the direction of the rotation axis as compared with the case of using a two-stage gear.

(6) The electric motor and the speed change mechanism are disposed within a range from the first pulley to the second pulley.

  As a result, the electric motor, the transmission mechanism, the annular member, the first gear, the second gear, and the reading sensor are arranged between the first pulley and the second pulley in the moving direction of the reading sensor. The annular member, the first gear, the second gear, and the reading sensor can be efficiently arranged between the first pulley and the second pulley. That is, it can contribute to the miniaturization of the entire apparatus.

  According to the image reading apparatus of the present invention, the distance from the shaft of the first pulley to the side wall of the casing of the apparatus can be reduced, and consequently the size of the apparatus in the width direction can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. In addition, the following embodiment is only an example which actualized this invention, and it cannot be overemphasized that embodiment can be changed suitably in the range which does not change the summary of this invention.

[Description of drawings]
FIG. 1 is a perspective view showing an external configuration of a scanner 10 which is an example of an image reading apparatus of the present invention. FIG. 2 is a perspective view of the scanner 10 with the contact glass 20 and the upper frame 26 removed. FIG. 3 is a plan view showing the configuration of the driving force transmission mechanism 70. FIG. 4 is a schematic diagram illustrating a meshing state of each gear of the driving force transmission mechanism 70. FIG. 5 is an enlarged perspective view showing the external configuration of the rotating body 102. FIG. 6 is a cross-sectional view showing a cross-sectional structure of the rotating body 102 in the axial direction. FIG. 7 is a cross-sectional view illustrating a modified example of the rotating body 102.

[Overview of Scanner 10]
The scanner 10 is configured such that a document cover (not shown) is attached to a document table 12 functioning as an FBS (Flatbed Scanner) via a hinge on the back side so as to be opened and closed. For convenience of explanation, the document cover is not shown in FIG. A contact glass 20 is disposed on the upper surface of the document table 12. When the document cover is opened, the contact glass 20 is exposed as the upper surface of the document table 12, and when the document cover is closed, the contact glass 20 is covered.

  An image reading unit 22 (an example of a reading sensor according to the present invention) is provided inside the document table 12. The image reading unit 22 is disposed so as to face the back surface of the contact glass 20. The image reading unit 22 is movably supported within the document table 12. The image reading unit 22 is moved in a state where the document is placed on the upper surface of the contact glass 20, and the document reading surface is imaged through the contact glass 20 in the moving process, whereby the image of the document is used as image data. Read.

[Original platen 12]
The document table 12 has a wide and thin rectangular parallelepiped shape in which the size in the width direction (the direction of the arrow 45) and the depth direction (the direction of the arrow 46) is larger than the height. The document table 12 includes an upper frame 26 (see FIG. 1) and a lower frame 28 (see FIG. 2). As shown in FIG. 2, the upper surface of the lower frame 28 is open. The upper frame 26 has an opening 30 on the upper surface. By fitting the upper frame 26 on the lower frame 28, the casing of the document table 12 is configured.

  The contact glass 20 is sandwiched between the upper end 32 and the periphery of the opening 30 by fitting the upper frame 26 onto the lower frame 28 while being supported by the upper end 32 of the lower frame 28. As a result, the contact glass 20 is fixed to the document table 12 while being exposed from the opening 30. The exposed surface 21 of the contact glass 20 exposed from the opening 30 constitutes a placement surface on which the document is placed. The exposed surface 21 corresponds to the maximum size of a document that can be read by the scanner 10. In the present embodiment, the exposed surface 21 is designed to have a size capable of placing an A3 size document defined by Japanese Industrial Standards (JIS) and International Standards (ISO).

[Image reading unit 22]
As shown in FIG. 2, the image reading unit 22 includes a CIS (Contact Image Sensor) 34 and a carriage 36. The carriage 36 is mounted so that the CIS 34 is brought into close contact with the back surface of the contact glass 20. The CIS 34 is a line image sensor whose main scanning direction is the depth direction 46 of the scanner 10. Specifically, the CIS 34 irradiates light from a light source onto the contact glass 20 on which the document is placed, guides reflected light from the document to a light receiving element (photoelectric conversion element) with a lens, and reflects the light from the light receiving element. This is a so-called contact-type line image sensor that outputs an electrical signal corresponding to the luminance of light.

  The carriage 36 is supported so as to be able to reciprocate below the contact glass 20. A guide shaft 38 is installed on the lower frame 28 in the width direction 46. The carriage 36 is supported by a guide shaft 38 so as to be reciprocally movable. The document table 12 is provided with a driving force transmission mechanism 70 and a belt transmission mechanism 100 described later. The carriage 36 is connected to a belt 106 provided in the belt transmission mechanism 100. When the driving force is transmitted to the carriage 36 through the driving force transmission mechanism 70 and the belt transmission mechanism 100, the carriage 36 is moved so as to slide on the guide shaft 38. As the carriage 36 moves on the guide shaft 38, the CIS 34 is moved in the width direction 45 in parallel with the contact glass 20. In this moving process, the image of the document is read as image data by the CIC 34.

  As shown in FIG. 2, a driving force transmission mechanism 70 and a belt transmission mechanism 100 are provided on the bottom surface 29 of the lower frame 28. The driving force transmission mechanism 70 transmits driving force to the belt transmission mechanism 100. The belt transmission mechanism 100 transmits the driving force transmitted from the driving force transmission mechanism 70 to the carriage 36 to move the carriage 36.

[Driving force transmission mechanism 70]
As shown in FIG. 3, the driving force transmission mechanism 70 includes a motor 72 (an example of an electric motor of the present invention) and a first gear 76 (an example of an eleventh gear of the present invention) coupled to an output shaft of the motor 72. And a speed reduction mechanism 90 (an example of a speed change mechanism of the present invention) coupled to the first gear 76, a speed reduction mechanism 90, and a bracket 78 that supports these members.

  The bracket 78 is made of a plate-like member formed in a substantially rectangular shape. The bracket 78 is fixed to the bottom surface 29 of the lower frame 28 with a fastener such as a screw so that the longitudinal direction thereof is along the width direction 45. As shown in FIG. 2, the bracket 78 is disposed in the vicinity of one side wall 108 in the width direction 45 of the lower frame 28.

  A motor 72 is attached to the bracket 78. The motor 72 is disposed within a range from the rotating body 102 to be described later to the driven pulley 104. The motor body is disposed on the back surface of the bracket 78. A hole 80 is provided in the bracket 78, and the output shaft 74 projects from the back surface of the bracket 78 through the hole 80 to the surface.

  A first gear 76 is connected to the output shaft 74. The first gear 76 is fixed to the output shaft 74. When the output shaft 74 is rotated, the first gear 76 is also rotated with the rotation. As a result, the rotational force (driving force) of the motor 72 is transmitted to the speed reduction mechanism 90 via the first gear 76.

  The speed reduction mechanism 90 reduces the rotational speed of the motor 72, that is, the rotational speed of the output shaft 74. The speed reduction mechanism 90 reduces the rotation speed of the motor 72 to a rotation speed corresponding to the movement speed of the carriage 36 that is moved during image reading. The speed reduction mechanism 90 is disposed within a range from a rotating body 102, which will be described later, to a driven pulley 104. The speed reduction mechanism 90 includes a rotating body 92, a rotating body 95, and an idle gear 98 (corresponding to a one-stage gear of the present invention). The rotating body 92, the rotating body 95, and the idle gear 98 are rotatably supported by a rotating shaft that is erected on the bracket 78. The present invention can also be applied to a configuration provided with a speed increasing mechanism that increases the rotational speed of the motor 72 instead of the speed reducing mechanism 90.

  The rotating body 92 has two types of gears 93 and 94 having different outer diameters and numbers of teeth. The gear 93 and the gear 94 are arranged in two upper and lower stages in the axial direction. Specifically, the rotating body 92 has a small-diameter gear 93 on the upper stage and a large-diameter gear 94 on the lower stage. The gear 94 has a larger diameter and a larger number of teeth than the first gear 76. The first gear 76 is meshed with the lower gear 94. The gear 93 and the gear 94 are joined to each other in the axial direction, and when one of them is rotated, the other is also rotated along with the rotation. The rotating body 92 is obtained, for example, by integrally forming the gear 93 and the gear 94 with synthetic resin or the like.

  The rotating body 95 has two types of gears 96 and 97 having different outer diameters and numbers of teeth. The gear 96 and the gear 97 are arranged in two upper and lower stages in the axial direction. Specifically, the rotating body 95 has a large-diameter gear 96 at the upper stage and a small-diameter gear 97 at the lower stage. The gear 96 has a larger diameter and a larger number of teeth than the gear 94 of the rotating body 92. A gear 93 of the rotating body 92 is meshed with the upper gear 96. The gear 96 and the gear 97 are joined to each other in the axial direction, and when one of them is rotated, the other is also rotated along with the rotation. The rotating body 95 is obtained by, for example, integrally forming the gear 96 and the gear 97 with synthetic resin or the like.

  The idle gear 98 is a one-stage gear. The idle gear 98 is engaged with a lower gear 97 of the rotating body 95 (see FIGS. 3 and 4). A rotating body 102 constituting the belt transmission mechanism 100 is pivotally supported on the bracket 78. A second gear 112 (an example of the second gear of the present invention), which will be described later, is provided at the lower stage of the rotating body 102. The idle gear 98 is also meshed with the second gear 112. Since the idle gear 98 is provided, the gear 97 and the second gear 112 can be connected on the same plane, and smooth drive transmission is achieved. Further, since the driving force of the lower gear 97 of the rotary body 95 is transmitted to the second gear 112 by the idle gear 98 that is a one-stage gear, the height direction of the speed reduction mechanism 90, that is, the rotary body. It is possible to contribute to downsizing of the rotating shaft direction of 95 and downsizing of the rotating body 102 in the rotating shaft direction. If the driving force of the lower gear 97 of the rotating body 95 is transmitted to the second gear 112 by a two-stage gear instead of the idle gear 98, the smaller-diameter gear and the second gear among the two-stage gears are transmitted. The two gears 112 are engaged with each other. At this time, the second gear 112 and the two-stage large-diameter gear are arranged so as to overlap each other in the direction of the rotation axis of the second gear 112. On the other hand, in the present embodiment, the reduction mechanism 90 has an idle gear 98 that is a one-stage gear and a second gear 112 engaged with each other. That is, since the idle gear 98 and the second gear are not arranged to overlap each other, it is possible to reduce the size of the rotating body 102 in the direction of the rotation axis as compared with the case where a two-stage gear is used.

  Since the speed reduction mechanism 90 is configured in this way, the rotational force whose rotational speed is reduced by the speed reduction mechanism 90 is transmitted from the motor 72 to the rotating body 102.

[Belt transmission mechanism 100]
As shown in FIG. 2, the belt transmission mechanism 100 includes a rotating body 102, a driven pulley 104 (an example of a second pulley of the present invention), and a belt 106 (an example of an annular member of the present invention). In place of the belt 106, a wire, a chain, or the like may be used.

  The rotating body 102 is pivotally supported by a bracket 78 of the driving force transmission mechanism 70. Specifically, the rotary shaft 110 (an example of the rotary shaft according to the present invention) standing on the bracket 78 is rotatably supported. A washer 118 (see FIG. 5) such as a flat washer and a fixture 120 (see FIG. 5) such as a retaining ring are attached to the top of the rotating shaft 110 in a state where the rotating body 102 is inserted through the rotating shaft 110. The rotating body 102 is provided in the vicinity of one side wall 108 in the width direction 45 of the lower frame 28. Details of the configuration of the rotating body 102 will be described later.

  The driven pulley 104 is provided in the vicinity of the other side wall 109 (the side wall opposite to the side wall 108) in the width direction 45 of the lower frame 28. That is, the driven pulley 104 is disposed at a position separated from the rotating body 102. The separation distance between the driven pulley 104 and the rotating body 102 is determined according to the document size that can be read by the scanner 10, in other words, the moving range of the image reading unit 22. The driven pulley 104 is rotatably supported by a rotation shaft (not shown) standing on the bottom surface 29. The rotating shaft of the driven pulley 104 is biased by an elastic member such as a spring in a direction away from the rotating body 102.

  A belt 106 is stretched between a driven pulley 104 and a driving pulley 114 (described later) of the rotating body 102. A predetermined tension is applied to the belt 106 by urging the rotation shaft of the driven pulley 104 by the elastic member. Thus, the belt 106 is supported by the rotating body 102 and the driven pulley 104 in a stretched state.

[Rotating body 102]
As shown in FIGS. 5 and 6, the rotating body 102 includes a second gear 112, a drive pulley 114, and a flange 116 (an example of the flange of the present invention). The belt 106 is hung on the driving pulley 114. The idle gear 98 of the driving force transmission mechanism 70 is engaged with the second gear 112. The flange 116 plays a role of preventing the belt 106 from falling off or shifting. In the present embodiment, the rotating body 102 is obtained by integrally forming the second gear 112, the drive pulley 114, and the flange 116 with synthetic resin or the like.

  A plurality of teeth are formed on the outer peripheral surface of the drive pulley 114. The teeth engage with a plurality of tooth valleys provided on the inner side of the belt 106 to prevent the belt 106 from shifting or slipping in the outer peripheral direction of the drive pulley 114.

  When a driving force (rotational force) is transmitted from the idle gear 98 to the second gear 112, the rotating body 102 is rotated by receiving the driving force. In other words, the drive pulley 114 rotates in response to the rotational force of the second gear 112. In the rotating body 102, the second gear 112 and the drive pulley 114 are disposed on the same axis. Therefore, when the rotating body 102 is rotated, the second gear 112 and the driving pulley 114 are rotated at the same rotational speed in the same direction.

  The rotating body 102 has a second gear 112 disposed at the lower stage and a drive pulley 114 disposed at the upper stage. The flange 116 is provided between the second gear 112 and the drive pulley 114. In other words, the flange 116 is provided adjacent to the drive pulley 114. Specifically, the flange 116 protrudes from the lower end of the drive pulley 114, that is, in a direction perpendicular to the outer peripheral surface of the drive pulley 114, that is, in a direction perpendicular to the rotation shaft 110 of the rotating body 102.

The outer diameter D ₁ (or the protrusion amount L ₁ ) of the flange 116 is inevitably determined by the outer diameter D _{2 of} the drive pulley 114, the thickness T of the belt 106 hung on the drive pulley 114, and the like. In the present embodiment, the outer diameter of the circle passing through the top of the teeth formed on the outer peripheral surface of the drive pulley 114 is the outer diameter D ₂ of the drive pulley 114. Outer diameter D ₁ of the flange 116, for example, is designed to a size that satisfies the equation (1) below. In the formula (1), α is an element determined in consideration of the safety factor against the slackness of the belt 106. Specifically, it depends on the tension of the belt 106, the secular change of the belt 106 used, and the like. It is determined.

D ₁ = D ₂ + 2T + α (1)

  If the flange 116 is dimensionally designed in this manner, the belt 106 hung on the drive pulley 114 can be effectively prevented from falling off or shifting.

The second gear 112 has a plurality of teeth that can mesh with the idle gear 98 of the driving force transmission mechanism 70. Outer diameter D ₃ of the second gear 112 is set to the same dimension as the outer diameter D ₁ of the said flange. Here, in the present embodiment, the outer diameter of the circle passing through the top of the teeth formed in the second gear 112 is the outer diameter D ₃ of the second gear 112.

  In the scanner 10 of the present embodiment, since the driving force transmission mechanism 70 and the belt transmission mechanism 100 described above are provided, when the output shaft 74 of the motor 72 is rotated, the rotational force is reduced to the first gear 76 and the deceleration. It is transmitted to the second gear 112 via the mechanism 90. As a result, the driving pulley 114 rotates together with the rotating body 102. When the driving pulley 114 rotates, the belt 106 moves between the driving pulley 114 and the driven pulley 104 in a circumferential manner. As a result, the image reading unit 22 connected to the belt 106 reciprocates between the drive pulley 114 and the driven pulley 104.

  Further, the outer diameter of the second gear 112 is set to the same dimension as the outer diameter of the flange 116. Therefore, even if the outer peripheral edge of the flange 116 is brought close to the side wall 108 of the lower frame 28, the second gear 112 does not contact the side wall 108. That is, the side wall 108 can be brought as close to the flange 116 as possible. As a result, the distance from the rotating shaft 110 to the side wall 108 of the rotating body 102 can be reduced to approximately the radius of the flange 116. As a result, the size of the scanner 10 in the width direction 45 can be reduced.

In the above embodiment, although the outer diameter _{D 3} of the second gear 112 to the same dimension as the outer diameter _{D 1} of the flange 116, the outer diameter _{D 1} of the outer diameter _{D 3} is at least flange 116 of the second gear 112 The following is sufficient. Be a second gear 112 which is dimensioned in such an outer diameter D _3, the distance from the axis of rotation 110 of the rotary member 102 to the side wall 108 can be shortened than conventional, the size in the width direction 45 of the scanner 10 Can be reduced.

  In the above-described embodiment, the flange 116 (see FIG. 6) is provided between the second gear 112 of the rotating body 102 and the drive pulley 114. For example, as shown in FIG. And the side surface portion 122 of the second gear 112 adjacent to the drive pulley 114 may have the function of the flange 116. That is, the second gear 112 also serves as the flange 116. As a result, the height of the rotating body 102 can be reduced, and the number of parts can be reduced.

  In the above-described embodiment, the driving force of the lower gear 97 of the rotating body 95 is transmitted to the second gear 112 by the idle gear 98 that is a one-stage gear. Thereby, it is possible to contribute to the downsizing of the speed reduction mechanism 90, that is, the downsizing of the rotating body 95 in the rotating shaft direction and the downsizing of the rotating body 102 in the rotating shaft direction. If the driving force of the lower gear 97 of the rotating body 95 is transmitted to the second gear 112 by a two-stage gear instead of the idle gear 98, the smaller-diameter gear and the second gear among the two-stage gears are transmitted. The two gears 112 are engaged with each other. At this time, the second gear 112 and the two-stage large-diameter gear are arranged so as to overlap each other in the direction of the rotation axis of the second gear 112. On the other hand, in the present embodiment, the speed reduction mechanism 90 is configured such that the idle gear 98 that is a one-stage gear and the second gear 112 are meshed with each other. In other words, since the idle gear 98 and the second gear are not overlapped with each other, it is possible to reduce the size of the rotating body 102 in the direction of the rotation axis as compared to the case where a two-stage gear is used.

FIG. 1 is a perspective view showing an external configuration of the scanner 10. FIG. 2 is a perspective view of the scanner 10 with the contact glass 20 and the upper frame 26 removed. FIG. 3 is a plan view showing the configuration of the driving force transmission mechanism 70. FIG. 4 is a schematic diagram illustrating a meshing state of each gear of the driving force transmission mechanism 70. FIG. 5 is an enlarged perspective view showing the external configuration of the rotating body 102. FIG. 6 is a cross-sectional view showing a cross-sectional structure of the rotating body 102 in the axial direction. FIG. 7 is a cross-sectional view illustrating a modified example of the rotating body 102.

Explanation of symbols

10 ... Scanner 22 ... Image reading unit 34 ... CIS
36 ... Carriage 70 ... Driving force transmission mechanism 72 ... Motor 76 ... First gear 78 ... Bracket 90 ... Deceleration mechanism 92 ... Rotating body 95 ... Rotating body 98 ..Idle gear 100... Belt transmission mechanism 102... Rotating body 104 .. driven pulley 106... Belt 108 and 109 .. side wall 110. ..Drive pulley 116 ... flange 122 ... side surface

Claims (6)

An electric motor having an output shaft;
A first gear connected to the output shaft and transmitting the driving force of the electric motor;
A speed change mechanism coupled to the first gear and configured to change a rotation speed of the electric motor;
A second gear coupled to the speed change mechanism;
A first pulley which is provided coaxially with the second gear and rotates by receiving the rotational force of the second gear;
A flange provided adjacent to the first pulley and projecting in a direction perpendicular to the outer peripheral surface of the first pulley;
A second pulley spaced from the first pulley;
An annular member that is bridged between the first pulley and the second pulley and is capable of circumferential movement between the first pulley and the second pulley;
A reading sensor connected to the annular member and configured to be movable between the first pulley and the second pulley;
The image reading apparatus, wherein an outer diameter of the second gear is set to be equal to or less than an outer diameter of the flange.   The image reading apparatus according to claim 1, wherein the speed change mechanism reduces the rotation speed of the electric motor and transmits the reduced speed to the second gear.   The image reading apparatus according to claim 1, wherein the flange is a side surface portion of the second gear adjacent to the first pulley.   The image reading apparatus according to claim 1, wherein the second gear, the first pulley, and the flange are integrally formed.   5. The image reading apparatus according to claim 1, wherein the speed change mechanism has a one-stage gear that meshes with the second gear. 6.   The image reading apparatus according to claim 1, wherein the electric motor and the speed change mechanism are disposed within a range from the first pulley to the second pulley.

Images