JP4117219B2 - Document reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a document reading apparatus that scans and reads a document placed on a document support member, and more particularly, to a document reading apparatus that suppresses positional deviation when reading a document and improves reading quality.
[0002]
[Prior art]
The document reading apparatus includes a moving optical system called a “document reading unit” or a “document reading module” for reading a document placed on a document support member (hereinafter also simply referred to as a module). The module is installed in a plane parallel to the original so as to be movable in a direction perpendicular to the longitudinal direction, and reads the image by scanning the original with the longitudinal direction as the main scanning side and the lateral direction as the sub-scanning side.
[0003]
A conventional module generally includes a drive source, a wire, and a pulley, and is driven in the sub-scanning direction by these. In the wire drive type module, the module moves along the sub-scanning direction when the drive source winds the wire stretched through the pulley.
[0004]
In the original reading apparatus, it is necessary to move the module in the sub-scanning direction while keeping the module parallel to the original in order to read the original faithfully.
[0005]
As a prior art for improving the reading performance, there is a “moving optical system support device, document illumination device, copying device, and document reading device” disclosed in Patent Document 1.
In Patent Document 1, a balance weight for adjusting the center of gravity is arranged on a base plate on which a moving optical system is mounted, and the base plate whose center of gravity is adjusted by the balance weight is brought into contact with the guide rail at three or more points and is slid. A document reading apparatus capable of scanning a document without generating vibration or noise is described.
[0006]
However, in the case of the wire drive method, since the wire must be stretched along a complicated path, it is difficult to adjust the parallelism even if the center of gravity of the optical moving system can be adjusted. Moreover, even if the parallelism is adjusted once, the wire becomes slack over time, so that readjustment is necessary. Therefore, in the invention described in Patent Document 1, it is difficult to stably move the module while maintaining a state parallel to the document.
[0007]
As a document reading apparatus of a drive system other than a wire, an apparatus that moves a module by a rack and a pinion, such as a “contact image reading apparatus” disclosed in Patent Document 2, has been proposed.
In the invention described in Patent Document 2, pinions supported in the vicinity of both ends in the longitudinal direction of the module are respectively installed, and a base having a rack that is shaped to engage with each pinion is provided. One of the pinions is attached to a motor that is a drive source of the module. The torque generated by the motor is linearly moved by the rack and pinion meshing with each other, and the module moves along the base.
[0008]
Also, “a platen for a portable copying machine and a copying apparatus using the same” disclosed in Patent Document 3 discloses a document reading device in which a module runs on a rail attached to glass. However, in the document reading device disclosed in Patent Document 3, torque is converted into thrust by frictional force rather than meshing of gears, and the module moves linearly.
[0009]
[Patent Document 1]
JP-A-9-244156 [Patent Document 2]
Japanese Patent Laid-Open No. 10-93771 [Patent Document 3]
Japanese Patent No. 3232108 [0010]
[Problems to be solved by the invention]
However, in the invention disclosed in Patent Document 2, since each pinion is attached to a separate shaft, torque from the motor is transmitted to only one pinion. In other words, the document reading apparatus disclosed in Patent Document 2 is a one-side drive system in which one of the pinions arranged at both ends of the module is the driving side and the other is the driven side.
[0011]
In the case of the one-side drive method, it becomes difficult to move the module in a direction perpendicular to the main scanning direction as the length of the module in the longitudinal direction becomes longer. That is, when the length of the module in the longitudinal direction is increased, the moment of inertia with the pinion on the drive side as the center and the axis perpendicular to the document is increased, so that the drive side moves in advance. This phenomenon becomes more prominent as the module is moved at a higher speed.
[0012]
In the invention disclosed in Patent Document 2, the pinion is merely arranged on the rack and is not positioned in the main scanning direction. For this reason, the module may be shaken in the main scanning direction, and the quality of the read image may be deteriorated.
[0013]
Furthermore, only one pair of receiving portions that move on the base are arranged near both ends of the module and in the center in the short direction, and the module is not positioned with respect to the base. Will rotate. Therefore, it is difficult to run the module stably.
[0014]
Further, the invention disclosed in Patent Document 3 does not disclose a method of paralleling modules or a method of moving on a guide rail while maintaining a posture parallel to the document. Further, since the module is attached at the end of the guide rail, the configuration is not suitable for the built-in type document reading apparatus.
[0015]
As described above, the conventional module cannot be stably moved while maintaining a state parallel to the document.
[0016]
SUMMARY An advantage of some aspects of the invention is that it provides an image reading apparatus including a module that can be stably moved while maintaining a parallel state with respect to a document.
[0017]
[Means for Solving the Problems]
To achieve the above object, according to the present invention, as a first aspect, the reading module scans a document placed on a document support member while moving along a pair of parallel guide rails. In the document reading device, each of the pair of parallel guide rails has a base portion fixed to the document support member and a convex portion protruding horizontally from the base portion having a substantially L-shaped cross-sectional shape. A reading module that is fixed to the document support member so that the portions face each other, a rack is formed vertically below the convex portion, and the length in the longitudinal direction is shorter than the interval between the convex portions of the pair of parallel guide rails includes a shaft gear meshing from both ends by longitudinally therethrough and each rack projecting a pair of parallel guide rails are arranged, a power source for rotationally driving the shaft, set one longitudinal end An elastic member which is, when it was stretched between a pair of parallel guide rails provided on the opposite side of the elastic member, a positioning member in pressure contact with one of the guide rails by the elastic force of the elastic member, a pair A projecting portion that is extendable so as to project from both ends in the longitudinal direction so as to be spanned between the parallel guide rails, and the distance from one end of the projecting portion to the other end is Normally, it is longer than the interval between the projections of the pair of parallel guide rails, and shorter than the interval between the projections of the guide rail when the projection is compressed, and the projection and the gear are paired in parallel. The convex portion of the guide rail is sandwiched and the power source rotates the shaft so that the gear meshed with the rack moves the reading module along a pair of parallel guide rails. There is provided a draft reading apparatus.
[0018]
In order to achieve the above object, according to a second aspect of the present invention, the document is scanned by scanning the document placed on the document support member while the reading module moves along a pair of parallel guide rails. a document reading apparatus for reading, a pair of parallel guide rails, consist of a protrusion that protrudes horizontally from the installed base portion and該土base portion to the housing which is fixed to the document support member, the projecting portions The reading module is fixed to the housing so as to face each other , a rack is formed vertically below the convex portion, and the longitudinal length is shorter than the interval between the convex portions of the pair of parallel guide rails. a shaft gear meshing from both ends through direction with each rack projecting a pair of parallel guide rails are disposed at both ends, a power source for rotationally driving the shaft, provided on one longitudinal end And an elastic member, when it was stretched between a pair of parallel guide rails provided on the opposite side of the elastic member, a positioning member in pressure contact with one of the guide rails by the elastic force of the elastic member, parallel pair of Projecting portions provided so as to protrude from both ends in the longitudinal direction for spanning between the guide rails, and the distance between the gears is variable by moving the gears along the shaft. In a normal state, it is longer than the interval between the projections of the pair of parallel guide rails, and shorter than the interval between the projections of the guide rail when the interval between the gears is narrowed. By sandwiching the convex part of the parallel guide rail and rotating the shaft by the power source, the gear engaged with the rack moves the reading module along the pair of parallel guide rails. It is intended to provide a document reading apparatus characterized by.
[0019]
In the first aspect or the second aspect of the present invention, a smooth surface is formed on the vertical upper side of the convex portions of the pair of parallel guide rails, and the smooth surface and the protrusions may come into contact with each other. preferable. In this case, it is more preferable that the protruding portion is in contact with the smooth surface by rolling contact. In addition, the protruding portion includes a shaft portion erected substantially perpendicular to the end surface of the reading module, and a substantially cylindrical shape. It is more preferable that it is made of a member having a cylindrical outer peripheral surface and rotatable about the shaft portion as a pivot.
[0020]
In any configuration of the first aspect or the second aspect of the present invention, it is preferable that the positioning member and one of the pair of parallel guide rails are in contact with each other by rolling contact.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
A first embodiment in which the present invention is suitably implemented will be described. FIG. 1 shows an appearance of a document reading apparatus according to this embodiment. The document reading apparatus 1 has a structure in which an upper cover 2 and a lower cover 3 are combined from above and below, and an operation unit 4 that is operated by a user when reading a document, and a control panel 5 on which the operation unit 4 is disposed. Have.
[0022]
The upper cover 2 includes a glass 6 for supporting a document, and a pair of guide rails 7 and 8 are disposed below the glass 6. The guide rails 7 and 8 are bonded to each other at a predetermined position of the glass 6 by a jig. A module 9 for reading a document is placed over the guide rails 7 and 8, and the document is scanned as the module 9 reciprocates along the guide rails 7 and 8 by a drive source (not shown). Read.
[0023]
FIG. 2 schematically shows a cross section of the document reading apparatus 1.
The module 9 includes a shaft 12 that is driven by a drive motor 10 and a transmission mechanism 11 that are mounted therein, and gears 13 and 14 that are driven by the shaft 12 are provided at both ends.
As shown in FIG. 3, sliders 18 and 19 that are elastically urged away from the module 9 by elastic force such as a spring are disposed at both ends of the module 9. As shown in FIG. 4, the sliders 18 and 19 are arranged so that they can be pushed in the longitudinal direction of the module 9.
[0024]
A spring material 20 having elasticity in the longitudinal direction of the module 9 is formed or attached to one end of the module 9 in the longitudinal direction, and a sliding material 21 is formed or attached to the other end. ing. Here, when spanning the guide rails 7 and 8, it is assumed that the sliding element 21 is disposed at the end on the guide rail 7 side and the spring 20 is disposed on the end on the guide rail 8 side.
[0025]
FIG. 5 shows an example of the structure of the guide rail 7. Although the guide rail 8 is symmetrical with the guide rail 7, it is not shown because of the same structure. The guide rails 7 and 8 are located in the vicinity of both ends of the module 9 and are arranged in parallel to each other along the driving direction of the module 9. Each of the guide rails 7 and 8 has a cross-sectional shape in which one is approximately L-shaped and the other is approximately inverted L-shaped, and the convex portions are arranged in a state of facing each other.
[0026]
A sliding surface 15 is formed on the upper side (glass 6 side) of the guide rails 7 and 8, a rack 16 is formed on the lower side (lower case 3 side), and a sliding surface 17 is formed on the tip portion. The rack 16 is formed with teeth that mesh with the gears 13 and 14 included in the module 9. In addition, the smooth surface 15 and the smooth surface 17 are so preferable that there are few unevenness | corrugations and surface roughness is small. Further, it is preferable that the sliding surface 15 has a small friction coefficient with the sliders 18 and 19, and the sliding surface 17 has a small friction coefficient with the spring material 20 and the sliding element 21.
Hereinafter, when it is necessary to distinguish the sliding surfaces 15, the racks 16 and the sliding surfaces 17 of the guide rails 7 and 8, each part of the guide rails 7 is given a subscript “a” and the sliding surfaces 15a and the racks 16a. The parts of the guide rail 8 are denoted by a suffix “b” and are denoted as a sliding surface 15b, a rack 16b, and a sliding surface 17b.
[0027]
In a normal state, the distance between the tip of the spring member 20 and the tip of the sliding member 21 is longer than the distance between the sliding surfaces 17a and 17b. However, the spring member 20 is arranged so as to be pushed into the module 9 until the distance between the tip of the spring member 20 and the tip of the sliding member 21 becomes smaller than the distance between the sliding surfaces 17a and 17b.
[0028]
When the module 9 is bridged between the guide rails 7 and 8, the spring material 20 in contact with the sliding surface 17 b is pushed in the longitudinal direction of the module 9. When the spring material 20 is pushed into the module 9, the sliding material 21 is pressed against the sliding surface 17 a by the elastic force of the spring material 20. Thereby, the module 9 is positioned in the main scanning direction.
Further, when the module 9 is passed over the guide rails 7 and 8, the sliding surface 15 and the sliders 18 and 19 come into contact with each other, so that the module 9 is supported by the guide rails 7 and 8. At this time, since the sliders 18 and 19 are in pressure contact with the sliding surface 15 due to their own weight, the module 9 is positioned in the vertical direction.
[0029]
Further, under normal conditions, the distance between the tips of the sliders 18 and 19 is longer than the distance between the sliding surfaces 17a and 17b. However, when the sliders 18 and 19 are pushed into the module 9, the distance between the tips becomes shorter than the distance between the sliding surfaces 17 a and 17 b, so that even after the guide rails 7 and 8 are bonded to the glass 6, the module 9 Can be removed.
[0030]
Next, an operation when reading an original will be described.
When the module 9 scans and reads a document placed on the glass 6, the drive motor 10 mounted on the module 9 generates torque and drives the gears 13 and 14 via the speed change mechanism 11 and the shaft 12. .
[0031]
The guide rails 7 and 8 are sandwiched from above and below by gears 13 and 14 meshed with the rack 16 and sliders 18 and 19 in contact with the sliding surface 15. Therefore, when the gears 13 and 14 are driven, the module 9 moves along the guide rails 7 and 8.
[0032]
The gears 13 and 14 are fixed at the same angle by a positioning mechanism provided on the shaft 12 or an adjustment mechanism (not shown) (such as a push screw) and are engaged with the rack 16, so that the glass 6 can be moved even if the module 9 moves. The parallelism between the original placed on the module and the module 9 is maintained.
[0033]
As described above, the module included in the document reading apparatus according to the present embodiment can be moved along the guide rail while maintaining parallelism with the document.
[0034]
[Second Embodiment]
A second embodiment in which the present invention is suitably implemented will be described. FIG. 6 schematically shows a cross section of the document reading apparatus according to the present embodiment.
In the document reading apparatus according to this embodiment, the guide rails 7 and 8 are attached to the lower cover 3. The upper cover 2 is bonded to the lower cover 3 while the glass 6 is bonded thereto.
[0035]
The gears 13 and 14 are slidably attached along the shaft 12. Springs 22 and 23 are arranged between the gears 13 and 14 and the document reading module 9, respectively. The spring 22 elastically moves the gear 13 and the spring 23 elastically moves the gear 14 away from the module 9. Energized.
Members other than these are the same as those in the first embodiment.
[0036]
The distance between the tip of the gear 13 and the tip of the gear 14 is longer than the distance between the sliding surfaces 17a and 17b in a normal state, but when the gears 13 and 14 are pushed into the module 9 side, the distance between the sliding surfaces 17a and 17b. It becomes shorter than the interval.
For this reason, the module 9 can be detached even after the guide rails 7 and 8 are attached to the lower base 3.
[0037]
Similarly to the first embodiment, in this embodiment, the module 9 moves with the guide rails 7 and 8 sandwiched between the gears 13 and 14 and the sliders 18 and 19. Accordingly, even when the module 9 moves, the parallelism between the document placed on the glass 6 and the module 9 is maintained.
As described above, the module included in the document reading apparatus according to the present embodiment can be moved along the guide rail while maintaining parallelism with the document.
[0038]
Each of the above embodiments is an example of a preferred embodiment of the present invention, and the present invention is not limited to these.
For example, although the configuration in which the sliding element is a simple protrusion has been described here, the sliding element 21 may be formed in a disk shape or a ball shape and attached to the module 9 to be rotatable. With such a configuration, when the module 9 moves, the frictional force generated between the sliding element and the guide rail becomes rolling friction, so that the resistance when moving the module 9 is reduced.
As described above, the present invention can be variously modified.
[0039]
【The invention's effect】
As is apparent from the above description, according to the present invention, it is possible to provide a document reading apparatus including a module that can be stably moved while maintaining a state parallel to the document.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an appearance of a document reading apparatus according to a first embodiment in which the present invention is preferably implemented.
FIG. 2 is a diagram illustrating a cross section of the document reading apparatus according to the first embodiment.
FIG. 3 is a diagram showing a slider in a normal state.
FIG. 4 is a diagram showing the slider in a compressed state.
FIG. 5 is a view showing a structure of a guide rail.
FIG. 6 is a diagram showing a cross section of an original reading apparatus according to a second embodiment in which the present invention is preferably implemented.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Document reader 2 Upper cover 3 Lower cover 4 Operation part 5 Control panel 6 Glass 7, 8 Guide rail 9 Module 10 Drive motor 11 Transmission mechanism 12 Shaft 13, 14 Gear 15, 17 Sliding surface 16 Rack 18, 19 Slider 20 Spring Material 21 Slippers 22, 23 Spring

Claims (6)

A document reading device that reads a document by scanning a document placed on a document support member while a reading module moves along a pair of parallel guide rails ,
In each of the pair of parallel guide rails, a base portion fixed to the document support member and a convex portion protruding horizontally from the base portion have a substantially L-shaped cross-sectional shape, and the convex portions face each other. is secured to the document support member to the rack is formed vertically downward side of the convex portion,
The reading module having a length in the longitudinal direction shorter than the interval between the convex portions of the pair of parallel guide rails is provided with a gear that penetrates in the longitudinal direction and projects from both ends and meshes with each rack of the pair of parallel guide rails. A shaft, a power source for rotationally driving the shaft, an elastic member provided at one end in the longitudinal direction, and spanned between the pair of parallel guide rails provided on the opposite side of the elastic member In this case, the elastic member is provided so that it can extend and contract so as to protrude from both ends in the longitudinal direction so as to span between the positioning member that presses against one guide rail by the elastic force of the elastic member and the pair of parallel guide rails. With protrusions ,
The distance from one tip of the projection to the other tip is normally longer than the interval between the projections of the pair of parallel guide rails, and the projection of the guide rail when the projection is compressed. It is shorter than the distance between each other,
The protrusions and the gears sandwich the convex portions of the pair of parallel guide rails, and the power source rotates the shaft so that the gear meshed with the rack causes the reading module to move the pair of parallel guides. An original reading apparatus which is moved along a rail. A document reading device that reads a document by scanning a document placed on a document support member while a reading module moves along a pair of parallel guide rails ,
The pair of parallel guide rails includes a base part installed in a housing fixed to the document support member and a convex part protruding horizontally from the base part, and the convex parts are opposed to each other. is fixed to the housing, the rack is formed vertically downward side of the convex portion,
The reading module having a length in the longitudinal direction shorter than the interval between the protrusions of the pair of parallel guide rails, has a gear that penetrates in the longitudinal direction and protrudes from both ends and meshes with each rack of the pair of parallel guide rails. Hang between the pair of parallel guide rails provided on the opposite side of the elastic member, the shaft disposed in the section , the power source for rotationally driving the shaft, the elastic member provided at one end in the longitudinal direction when passed, the positioning member presses against the one guide rail by the elastic force of the elastic member, provided so as to protrude from the longitudinal ends to pass over between the pair of parallel guide rails With protrusions ,
The gap between the gears is variable by moving the gear along the shaft, and is normally longer than the gap between the protrusions of the pair of parallel guide rails, and the gap between the gears is narrowed. In the state where it is shorter than the interval between the convex portions of the guide rail,
The protrusions and the gears sandwich the convex portions of the pair of parallel guide rails, and the power source rotates the shaft so that the gear meshed with the rack causes the reading module to move the pair of parallel guides. An original reading apparatus which is moved along a rail.   3. The document reading apparatus according to claim 1, wherein a smooth surface is formed vertically above the convex portions of the pair of parallel guide rails, and the smooth surface and the protrusion are in contact with each other.   The document reading apparatus according to claim 3, wherein the protrusion is in contact with the smooth surface by rolling contact.   The protrusion includes a shaft portion erected substantially perpendicular to an end surface of the reading module, and a member having a substantially cylindrical outer peripheral surface and rotatable about the shaft portion as a pivot. The document reading device according to claim 4.   6. The image reading apparatus according to claim 1, wherein the positioning member is in contact with one of the pair of parallel guide rails by rolling contact.

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