JP4472483B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that includes a contact-type image reading sensor having a reading surface and reads an image of a document by conveying the document in close contact with or close to the reading surface.

  This type of image reading apparatus is applied to, for example, an image information processing apparatus such as a printing apparatus, a facsimile machine, a copying apparatus, or an image scanner. As an image reading method, an original fixing apparatus that fixes an original and moves an image reading sensor. On the contrary, there is a document conveyance method in which an image reading sensor is fixed and a document is conveyed by a conveyance mechanism such as a roller.

  As an image reading sensor, there is an image reading sensor using an electrification coupling element (CCD) in addition to the contact type image reading sensor (CIS). Many apparatuses using a type image reading sensor are employed.

  As described above, in the document conveying type image reading apparatus provided with an inexpensive contact type reading sensor, it is necessary to include means for bringing the document into close contact with or close to the reading surface. In general, a white rubber roller 101 such as 9 (Patent Document 1) or a flat back guide plate 209 (Patent Document 2) as shown in FIG. 10 is used.

  In the conventional image reading apparatus shown in FIG. 9, the white roller 101 that can be rotationally driven is brought into contact with the reading surface 106 of the contact image reading sensor 102 at a constant pressure, and is synchronized with the conveyance speed by a driving mechanism (not shown). Then, the white roller 101 is rotated so that the white roller 101 passes the document P on the reading surface 106 while being in close contact with the reading surface 106. In the contact image reading sensor 102, for example, a light emitting element 103, a light receiving element 104, and a self lens 105 are incorporated.

In the conventional image reading apparatus shown in FIG. 10, the flat plate-shaped rear guide plate 209 provided with white is opposed to the lower end reading surface 201a of the contact image reading sensor 201, and the rear guide plate 209 is disposed. The spacer 211 is urged toward the reading surface 201a by the spring 211, and a spacer projection that abuts on the reading surface 201a on the upper surface of the rear guide plate 209 so as to secure a predetermined gap between the rear guide plate 209 and the reading surface 201a. 210 is formed.
Utility Model Registration No. 2527654 JP-A-4-336857

  As shown in FIG. 9, in the method using the white roller 101 as the contact means, in order to maintain the adhesion and transportability of the document P, it is necessary to increase the diameter of the roller 101 to a certain level or more, and for the white roller 101 It is necessary to provide the power transmission mechanism in the apparatus cover or the like, and it is impossible to increase the size of the apparatus. Further, since the cost of the roller 101 itself is high, it is impossible to reduce the price. Further, the white roller 101 is difficult to clean when it becomes dirty, and it is necessary to adjust the contact pressure of the white roller 101 with respect to the reading surface 106 in accordance with the thickness of the original P, which is troublesome to handle.

  As shown in FIG. 10, in the method using the flat plate-like back guide plate 209 as the contact means, the device can be expected to be more compact and less expensive than the roller method. However, it is difficult to process and maintain the flat guide plate 20 with a high degree of flatness, and the gap between the reading surface 201 and the back guide plate 209 is non-uniform when the flatness is distorted due to distortion or deflection. As a result, the depth of field at the time of image reading becomes non-uniform, and the quality of the image may be reduced. Incidentally, if it is intended to maintain the flatness of the back guide plate 209 with high accuracy, for example, the back guide plate 209 may be formed in a block shape to increase rigidity, but in that case, the weight increases, The price goes up.

[Object of invention]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems and to improve the reading accuracy by maintaining a uniform contact (or proximity) state of a document with respect to a reading surface, and to provide a lightweight, small and inexpensive image reading apparatus. is there.

In order to solve the above problem, an invention according to claim 1 of the present application is an image reading apparatus including a contact-type image reading sensor having a reading surface, and a transport mechanism that transports a document in close contact with or close to the reading surface. A document regulating guide rod having a V-shaped cross section is disposed in the vertical direction so that the V-shaped tip portion has a predetermined gap with respect to the reading surface, and the V-shaped tip portion of the document regulating guide rod is disposed on the reading surface. The document regulating guide rod is positioned on the reading line, and the document regulation guide rod is arranged around the axis and in any direction on the upstream side or the downstream side of the shaft via a rotation support shaft having an axis perpendicular to the document conveyance direction. Is also rotatable, and is movable in the vertical direction together with the rotation support shaft.

  According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the document regulating guide rod is a bent product of sheet metal.

According to a third aspect of the present invention, in the image reading apparatus according to the first or second aspect, the document regulating guide rod is urged toward the reading surface by the urging means.

According to a fourth aspect of the present invention, in the image reading apparatus according to the third aspect, the urging means is urged toward the reading surface by the weight of the original regulating guide rod.

(1) Since the document is guided so as to be in close contact with or close to the reading surface by the V-shaped tip portion of the document regulating guide rod formed in a V-shaped cross section, the document is placed on the reading surface with a low-cost and compact structure. The original can be guided so as to maintain a uniform contact pressure or gap across the entire width, and the reading quality can be maintained high.

(2) If the document regulation guide 竿 is a bent product of sheet metal, the straightness (straightness) in the conveyance width direction of the V-shaped tip of the document regulation guide 竿 is simple and highly accurate by bending. Can be molded.

(3) If the V-shaped tip of the document regulating guide rod is positioned on the reading line of the reading surface, a uniform adhesion or gap is ensured over the entire width of the document when reading the document, and reading is performed. The quality is further improved.

(4) If the document regulation guide 竿 is movable so that the gap between the V-shaped tip of the document regulation guide 竿 and the reading surface can be adjusted, the gap is adjusted to an appropriate gap according to the thickness of the document. The reading accuracy can be maintained regardless of the thickness of the document.

(5) When the document regulating guide rod is urged to the reading surface side by the urging means, the gap can be automatically adjusted with respect to the change in the thickness of the document. Thus, it can be brought into close contact with the reading surface automatically regardless of increase or decrease in thickness.

(6) If the original regulating guide rod is movable in the vertical direction and is urged toward the reading surface by its own weight, it is not necessary to use special urging means, which can contribute to a reduction in price.

(7) If the document restriction guide 竿 can be moved around an axis perpendicular to the document conveyance direction, the document restriction guide 回 動 automatically rotates even if the document is jammed in the document restriction guide た と え ば, for example. Thus, the original can be escaped, thereby preventing the original jam. Even if the document is jammed, it is possible to remove the jammed document by manually rotating the document regulating guide rod.

  1 to 7 show an embodiment of an image reading apparatus to which the present invention is applied. FIG. 1 is a longitudinal sectional view of an image reading apparatus, in which an arrow F direction is a base paper conveyance direction. Hereinafter, an arrow F direction side is a front side (or “conveyance downstream side”), and an arrow R opposite to the arrow F direction. The direction side will be referred to as a rear side (or “transport upstream side”) and will be described below.

[Overall structure of image reading sensor]
In FIG. 1, the image reading apparatus includes an apparatus main body 1 (only a part of which is shown) and an apparatus cover 2 disposed on the upper side of the apparatus main body 1. The apparatus cover 2 has a rotation support shaft 3 at the front end. By being supported so as to be able to rotate in the direction of the arrow A via, it can be opened and closed freely.

  In the upper part of the apparatus main body 1, there are a contact image reading sensor 4, transport driving rollers (transport mechanisms) 5 and 6 disposed before and after the contact image reading sensor 4, and a rear drive roller 6. A paper feed roller 7 disposed on the rear upper side, a lower transport guide plate 10 and the like are provided. The lower transport guide plate 10 is fed from a document insertion port 40 at the rear upper end of the apparatus main body 1. 7 and the vicinity of the rear upper end of the contact-type image reading sensor 4 through the upper part of the contact-type image reading sensor 4 and the upper part of the front-side drive roller 5. .

  The contact-type image reading sensor 4 includes a light-emitting element, a light-receiving element, and a self-focus lens, as well as a general contact-type image reading sensor, and is provided with a reading surface 4a made of a flat transparent glass plate on the upper surface. The depth of field (depth of focus) of the SELFOC lens is, for example, 0.3 mm or less. The paper feed roller 7 and the drive rollers 5 and 6 are linked to a drive source (not shown) such as a motor disposed in the apparatus main body 1 through a gear mechanism or the like, and have the same rotational speed. Each rotates in the direction of arrow B.

  Front and rear driven rollers (transport mechanisms) 15 and 16 that are in pressure contact with the front and rear drive rollers 5 and 6 from above are rotatably supported on the lower portion of the apparatus cover 2 and the lower transport guide. An upper conveyance guide plate 11 is provided opposite to the plate 10 from above at a predetermined interval. A document conveyance path is formed between the upper conveyance guide plate 11 and the lower conveyance guide plate 10. ing.

  In FIG. 2 showing an enlarged view of the main part of FIG. 1, for example, a tape-shaped bridging sheet is provided in the gap between the front and rear end portions of the upper end reading surface 4 a of the contact image reading sensor 4 and the lower conveyance guide plate 10. In this way, the document P is smoothly transferred between the upper surface of the lower conveyance guide plate 10 and the reading surface 4a.

  A portion 11a corresponding to the reading surface 4a of the contact-type image reading sensor 4 is formed in a stepped shape on the upper conveyance guide plate 11, and the stepped portion 11a has a V-shaped cross section which is a main part of the present invention. The document regulating guide rod 21 is supported in a downward projecting manner, and the V-shaped tip (lower end) 22 of the document regulating guide rod 21 faces the reading surface a of the contact image reading sensor 4 from above. The rear end portion of the stepped portion 11a is formed in a substantially perpendicular step surface, but the front end portion 11b is inclined in a front-lowering manner so as to quickly guide the front end edge of the document P into the conveyance path. .

[Detailed Structure of Document Regulation Guide 規 制]
FIG. 5 is a perspective view of the upper conveyance guide plate 11 and the document regulation guide rod 21, and an opening 28 for arranging the document regulation guide rod is formed in the stepped portion 11 a of the upper conveyance guide plate 11. Bracket portions 24 for supporting the guide rods are formed integrally with the upper conveyance guide plate 11 at both ends of the opening 28 in the conveyance width direction (a direction perpendicular to the conveyance direction F direction). The document regulating guide rod 21 is formed into a V-shaped cross section by bending a sheet metal and has a white surface with a white tape or a white paint, and has a horizontal posture extending in the conveyance width direction and is in the opening 28. Is arranged. At both ends of the document regulating guide rod 21 in the conveyance width direction, support pieces 24 perpendicular to the length direction of the document regulating guide rod 21 are integrally bent, and the both supporting pieces 24 serve as pivot support shafts. Bolts 26 are respectively screwed on the same axis O1, and the document restricting guide rod 21 can be rotated around the bolt axis O1 and vertically moved to both bracket portions 24 via the both bolts 26. It is supported.

  FIG. 6 is an enlarged perspective view of one bracket portion 24, and a long hole 30 that is long in the vertical direction is formed in the bracket portion 24, and a shaft portion (rotating support shaft portion) of the bolt 26 is formed in the long hole 30. However, it is supported so that it can move in the vertical direction and can turn around the bolt axis O1.

  3 is a cross-sectional view taken along the line III-III in FIG. 1, and spacers 32 having a thickness of about 0.1 to 0.2 mm using a tape or the like are attached to both ends of the reading surface 4a in the transport width direction. The V-shaped tip portion 22 of the document regulating guide rod 21 is in contact with the upper surface of the spacer 32 with a constant pressure due to the weight of the document regulating guide rod 21, whereby the reading surface 4 a and the V-shaped tip portion 22 are in contact with each other. A gap C (0.1 to 0.2 mm) narrower than at least the depth of field of 0.3 mm is secured between them.

  4 is an enlarged cross-sectional view taken along the line IV-IV of FIG. 3, and the upward movement amount of the document regulating guide rod 21 is regulated by the upper edge of the long hole 30 of the bracket portion 24, and the axis O1 of the document regulating guide rod 21. The amount of rotational rotation is regulated within a certain range by stoppers 35 arranged at the front upper and rear upper sides of the document regulating guide rod 21.

  4 indicates a reading line on the reading surface 4a, and the reading line E extends in a direction perpendicular to the base paper transport direction so as to cover almost the entire width of the base paper transport width. In this embodiment, the V-shaped tip 22 of the document regulating guide rod 21 is arranged so as to coincide with the reading line E.

  As described above, the document regulation guide rod 21 is a bent product of sheet metal, and its thickness t is, for example, at least 1.2 mm or more in order to maintain a predetermined rigidity. As a material of the cage 21, an aluminum plate, a stainless steel plate, a galvanized steel plate or an iron plate is used. The V-shaped bending angle α of the document regulating guide rod 21 is set to an obtuse angle so that it can be formed by a single bending process. In this embodiment, the bending angle α is bent to α = 120 °, for example. The V-shaped tip 22 is rounded with a radius of 1.2 mm. The V-shaped bending angle α is 110 ° to 130 °, and the radius of the rounded corner of the V-shaped tip 22 is 1.0. About 2.5 mm (plate thickness 1 mm to 2 mm) is most preferable in terms of reading performance and processing.

[Operation of the embodiment]
(1) In FIG. 1, a document P is inserted from a document insertion port 40 at the rear end of the apparatus with the image surface facing down, and is fed forward and downward in the document transport path by a paper feed roller 7, It is sandwiched from above and below by the rollers 6 and 16 on the rear side and is conveyed onto the reading surface 4a via the sheet 20 while being extended in a horizontal plane.

  In FIG. 2, the document P conveyed on the reading surface 4a is guided by the inclined surface of the latter half portion (portion upstream side portion) 21a of the document regulating guide rod 21, and between the V-shaped leading end portion 22 and the reading surface 4a. It is sent.

  When the thickness of the document P is the same as or thinner than the gap C between the reading surface 4a and the V-shaped leading end portion 22, the document P is not directly pressed downward by the V-shaped leading end portion 22. While the upward movement is regulated within the range of the gap C (0.1 to 0.2 mm), the image passes through the reading line E, is read, and is sent to the front rollers 5 and 15. That is, the original P is kept flat by the V-shaped leading end portion 22 extending linearly in the conveyance width direction while being restricted from moving upward within the depth of field of the contact image reading sensor 4. It passes through the line E and is delivered to the transport rollers 5 and 15 on the front side.

  When the thickness of the document P is larger than the gap C between the reading surface 4a and the V-shaped leading end portion 22, the document P is lifted against the weight of the document regulating guide rod 21 and the V-shaped leading end portion 22 and the reading surface. Pass between 4a. That is, the original P passes through the reading line E while being pressed downward by the weight of the original regulating guide rod 21, but the thick original itself has a certain rigidity (stretch strength). The flat state of the original P is maintained by its rigidity, and it smoothly passes through the reading line E while being in close contact with the reading surface 4a, and is transferred to the front conveying rollers 5 and 15.

[Effect of the embodiment]
(1) As described above, the document P is regulated to be in close contact with or close to the reading surface 4a by the V-shaped tip portion (V-shaped bent portion) 22 of the document regulating guide rod 21 formed by bending the sheet metal into a V shape. Therefore, compared to the case of using a flat back guide plate where it is difficult to maintain flatness accuracy as in the past, there is no problem of deflection or distortion on the reading surface, and the V-shaped tip is accurately Thus, the linearity (straightness) in the conveyance width direction of 22 can be secured, and the reading performance can be stabilized.

(2) Further, the document regulating guide rod 21 of the present embodiment has a V-shaped tip 22 bent at an obtuse angle (120 °), so that it is different from a case where the sheet metal is bent at an acute angle. Forming can be easily performed by a single bending process, so that the number of processing steps can be reduced and the guide of the document P to the V-shaped tip 22 can be smoothly performed.

(3) Since the document regulating guide rod 21 is configured to be rotatable around the bolt axis (rotating axis) O1, the document is wrinkled or the document is in an unnatural posture. Even if it cannot enter smoothly between the initial gaps C due to the intrusion, the original regulating guide rod 21 can be rotated to smoothly feed out the original without clogging it.

(4) When the document restricting guide rod 21 can be moved in the vertical direction and is urged toward the reading surface by the weight of the document restricting guide rod 21, the change in the thickness of the document P is automatically performed. The gap can be adjusted. In particular, a thick document P can be automatically brought into close contact with the reading surface 4a regardless of the increase or decrease in thickness, and no special parts are required as a branching means. Contributes to lower prices.

[Other embodiments]
(1) In FIG. 7, a contact-type image reading sensor 4 is arranged on the upper side of the document conveyance path, and a document restriction formed in a V-shaped cross section below the reading surface 4a formed on the lower surface of the image reading sensor 4. This is an example in which the guide rods 21 are arranged in an upward projecting shape. The document regulating guide rod 21 is supported by a bracket portion 24 formed on the lower conveyance guide plate 10 via a bolt 26 so as to be vertically movable and rotatable, and is wound around a shaft portion of the bolt 26. It is urged upward by the wound spring 40 and abuts against the spacer 32 attached to the reading surface 4a. Compared with the embodiment shown in FIGS. 1 to 6, the vertical positional relationship is reversed as described above, and a spring 40 is used instead of its own weight as the biasing means of the document regulating guide rod 21. Except for this, the configuration is the same, and the same parts are denoted by the same reference numerals. The function and effect are the same as in the above embodiment.

(2) In the embodiment shown in FIGS. 1 to 6, the V-shaped tip 22 is positioned on the reading line E. However, the V-shaped tip 22 is a range that does not affect shading. If the document can be regulated or pressed within the depth of field and can be read stably, the V-shaped tip 22 is shifted forward or backward with respect to the reading line E. Is also possible. In that case, since the method of shifting the V-shaped tip portion 22 to the rear side, that is, the upstream side of the conveyance (in the direction of the arrow R) with respect to the reading line E is regulated immediately before the conveyance to the reading line, The document can be sent to the reading line E in a state where the document is sufficiently pressed or regulated by the front end portion 22, and the reading is stabilized.

(3) The bending angle α of the document regulating guide rod 21 having a V-shaped cross section can be 90 ° or an acute angle.

(4) FIG. 8 shows a modification of the document regulating guide rod 21 having a V-shaped cross section. The latter half portion 21a of the document regulating guide rod 21 is formed longer than the front half portion. And the reading stability of the original P between the reading surface 4a is improved.

(5) The radius of the V-shaped tip 22 can be increased or decreased depending on the sensor sensitivity to the extent that shading is not affected.

(6) The document regulation guide rod 21 is preferably manufactured by bending a sheet metal in consideration of light weight, ease of processing, and maintaining high-precision straightness of the V-shaped tip 22. In the invention, it is also possible to use a surface processed from a thin angle material or the like.

(7) In the embodiment shown in FIGS. 1 to 6, the bolt 26 is used as the rotation shaft of the document regulating guide rod 21, but a simple pin is press-fitted and fixed to the support piece as the rotation shaft. You can also

1 is a longitudinal sectional view of an image reading apparatus to which the present invention is applied. It is an enlarged view of the principal part of FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 1. FIG. 4 is an enlarged sectional view taken along the line IV-IV in FIG. 3. FIG. 6 is a perspective view of an upper conveyance guide plate and a document regulation guide rod. FIG. 5 is an enlarged perspective view of a supporting portion of a document regulation guide rod. It is sectional drawing similar to FIG. 4 which shows another embodiment of this invention. FIG. 5 is a cross-sectional view similar to FIG. 4 showing a modification of the document regulation guide rod. It is a longitudinal cross-sectional view of a prior art example. It is a longitudinal cross-sectional view of another conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Apparatus cover 4 Contact-type image reading sensor 4a Reading surface 5, 6 Drive roller (conveyance mechanism)
10, 11 Transport guide plate 15, 16 Driven roller (transport mechanism)
21 Document restriction guide rod 22 V-shaped tip portion 23 Support piece 24 Bracket portion 26 Bolt (rotating support shaft)
32 Spacer E Reading line

Claims (4)

An image reading apparatus comprising a contact image reading sensor (4) having a reading surface (4a) and a transport mechanism for transporting a document in close contact with or close to the reading surface (4a).
A document regulating guide rod (21) having a V-shaped cross section is disposed so as to face the vertical direction so that the V-shaped tip (22) has a predetermined gap with respect to the reading surface (4a).
The V-shaped tip (22) of the document regulating guide rod (21) is positioned on the reading line (E) of the reading surface (4a),
The document regulating guide rod (21) is disposed on either the upstream side or the downstream side of the conveyance around the axis (O1) via a rotation support shaft having an axis (O1) perpendicular to the document conveyance direction. It can also rotate in the direction,
An image reading apparatus, wherein the image reading apparatus is movable in the vertical direction together with the rotation support shaft.   The image reading apparatus according to claim 1, wherein the document regulation guide rod is a bent product of sheet metal. 3. The image reading apparatus according to claim 1 , wherein the document restriction guide rod is urged toward the reading surface by an urging unit. 4. The image reading apparatus according to claim 3 , wherein the urging unit is urged toward the reading surface by the weight of the document regulating guide rod .

Images