JP3903018B2 - Document feeder, document reader, and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionA mechanism for conveying a sheet document to an image reading position on a transparent flat plateDocument feeder,Document reading apparatus and image forming apparatus provided with the document feeding deviceAbout.
[0002]
[Prior art]
In an image forming apparatus such as a digital copying machine, a printer, or a FAX, an automatic document feeder (ADF: Auto) configured to automatically send a document to a reading position on a platen glass in order to read image information of the document. Document Feeder) is conventionally known. Due to recent rapid digitization and the like, ADF devices are required to have higher accuracy and higher speed image reading performance.
[0003]
2. Description of the Related Art Conventionally, an ADF mode in which an ADF device is installed above a platen glass and the original document is read by the ADF device, and a book mode in which the original is set on the platen glass and the optical system is moved to perform reading. In an ADF apparatus mounted on an image reading apparatus having two reading modes, an original tray is placed over the discharge tray, and the original conveyance path that leads from the original tray to the discharge tray through the reading position is configured by a U-turn path By doing so, the thing which reduced the occupation area and achieved size reduction of an apparatus is known (for example, refer patent document 1, patent document 2, and patent document 3).
[0004]
Some ADF apparatuses of this type are provided with a transparent film member as a member for guiding the surface side of the document. The advantage of this format is
(1) Unlike the case where the member for guiding the outside of the document is composed of a plurality of members, there is no obstacle from the upstream side of the reading position through the reading position to the discharge tray, and it can be smoothly conveyed. In particular, it is possible to reduce a shock when the leading end of the document enters the discharge guide member that leads from the reading position to the discharge tray.
[0005]
(2) Since it is not necessary to provide a configuration for scooping up the document from the reading position to the paper discharge guide member, it is not necessary to provide a reading position in the ADF mode separately from the image reading area in the book mode, and an additional device with an easy configuration can be used. Miniaturization can be achieved.
Etc.
[0006]
FIG. 15 is a configuration diagram showing an example of a conventional ADF apparatus, which is configured by a U-turn path as described above and uses a transparent sheet member as a document surface side guide member. FIG. 16 is an enlarged cross-sectional view of a main part of a conventional ADF device, and FIG. 17 is a cross-sectional view taken along line AA in FIG. Assume that the ADF apparatus described as an example is mounted on an image forming apparatus (not shown).
[0007]
In FIG. 15, 1 is a document tray, and 2 is a width regulating plate for regulating the side of the document. Reference numeral 3 denotes a pickup roller which lowers to the position of the document upper surface 3 'in FIG. Reference numeral 4 denotes a separation roller which always contacts the opposing separation pad 5 and performs frictional separation to convey the originals one by one. Reference numeral 6 denotes a first conveyance roller, and 7 is a conveyance roller.
[0008]
The separated original is formed by the inner guide 10 and the outer guide 18 and travels along a downwardly curved and inclined conveyance path, passes through the pre-reading roller 11 and the reading pressure roller 12 immediately before the reading point Q, and reaches the reading point Q. Be transported. A member that guides the back side of the document near the reading point Q is referred to as a reading guide 13. A guide mylar 14, which is a transparent sheet member, is mounted as a means for guiding the front side of the document, which is located on the opposite side of the reading guide 13.
[0009]
The guide mylar 14 is a transparent plastic film made of, for example, polyester and has a thickness of about 100 μm. A member holding the guide mylar 14 by the boss portion is referred to as a mylar holder 19. One end of the guide mylar 14 is locked by the boss portion 19 a of the mylar holder 19, and the other end rides on the paper discharge guide 20 through the document table glass 62. The reading guide 13 has a plane portion 131 whose surface facing the reading point Q is parallel to the platen glass 62, and an upstream inclination that is curved and inclined in a circular arc shape in series with the plane portion 131 upstream and downstream. It is formed by the portion 132 and the downstream inclined portion 133.
[0010]
The reading guide 13 is mounted so as to be rotatable about a rotation fulcrum 134 and is urged by the spring 21 toward the original platen glass 62. As shown in FIG. 17, abutment projections 135 are provided at both ends of the flat portion 131 in a direction orthogonal to the transport direction, and the abutment projections 135 abut on the document table glass 62 with the guide mylar 14 interposed therebetween. Therefore, the minute interval d with the guide mylar 14 is kept constant. Accordingly, the guide mylar 14 contacts the platen glass 62 near the reading point Q, and the original image is read through the guide mylar 14 and the platen glass 62.
[0011]
The document that has passed the reading point Q is conveyed along a guide mylar 14 mounted on a discharge guide 20 that is inclined upward, and is discharged to a discharge tray 17 by a discharge roller 15 and a discharge pressure roller 16. Is done. That is, this ADF apparatus is configured with a U-turn path in the conveyance path from the document tray 1 through the reading point Q to the discharge tray 17.
[0012]
In the image reading by the ADF device, an optical system of a document reading device (not shown) is fixed immediately below the reading point Q, the document passing through the reading point Q is irradiated by lamp light (white light), and the reflected light is irradiated to a CCD or the like. It is read by a photoelectric conversion element.
[0013]
[Patent Document 1]
Japanese Patent No. 2527431
[Patent Document 2]
JP-A-9-86720
[Patent Document 3]
JP-A-9-86721
[0014]
[Problems to be solved by the invention]
However, in the above-described conventional ADF apparatus in which the document surface side guide member is formed of a transparent sheet member, interference of striped light formed in a single color or several colors as shown in FIG. There is a problem that stripes (Newton rings) occur at irregular positions.
[0015]
The direct cause of the occurrence of the light interference fringes is an air thin film layer formed between the platen glass 62 and the transparent sheet member (guide mylar 14). That is, when the lamp light (white light) of the document reading apparatus is incident when the air layer is sufficiently thin, the reflected light on the surface of the air layer (the boundary between the document table glass 62 and the air layer) and the air layer The light reflected from the back surface (the boundary between the air layer and the guide mylar 14) interferes with light of a specific wavelength, and light interference fringes are generated.
[0016]
If the platen glass 62 is made of a float glass material, its refractive index is about 1.50, and if the guide mylar 14 is made of a polyester sheet, its refractive index is about 1.60. Since the refractive index of air is approximately 1.0, the air layer is surrounded by two members having a high refractive index. Accordingly, in consideration of the fact that reflected light of light incident on a member having a high refractive index from a member having a low refractive index is shifted by a half wavelength, the interference condition by a general thin film is expressed by equations (1) and (2) shown in FIG. expressed.
[0017]
From the equations (1) and (2), it can be seen that the color (wavelength) and the number of colors of the interfering light vary depending on the thickness of the air layer. A condition that ordinary people can observe as interference fringes in a striped pattern is when light having a wavelength of 400 nm to 800 nm, which is visible light, interferes with a single color or several colors.
[0018]
When the thickness of the air layer that satisfies the above conditions is determined in consideration of various refractive indexes and the like, it was found that the thickness of the air layer in which a general person can observe the fringe interference fringes is about 100 nm to 1 μm. As the thickness of the air layer increases, the number of colors (wavelengths) of light that interferes increases. When the air layer has a thickness of about 0.1 mm to 1 mm, a large amount of light interferes. Therefore, the reflected light observed by a general person becomes white light, and no striped interference fringes are observed. Therefore, in the conventional ADF apparatus, an air layer of about 100 nm to 1 μm is formed on the reading point Q, so that it is considered that interference fringes are generated in the read image.
[0019]
In the conventional ADF apparatus, the leading edge of the document is conveyed while pushing down the guide mylar 14 downward until the leading edge of the document passes through the pre-reading roller 11 and reaches the vicinity of the reading point Q. The tendency is more conspicuous as the paper is thicker. At the reading point Q, the guide mylar 14 is pressed against the platen glass 62 and conveyed regardless of the presence or absence of the butting protrusion 135 of the reading guide 13. However, when viewed microscopically, the front end of the document does not push down the guide mylar 14 with a constant pressure in the width direction, but the guide mylar 14 is locally applied to the document according to the skew state or the paper type. It is conceivable that the glass plate 62 is brought into contact with the glass plate 62 or a float of 100 nm to 1 μm is created. Further, when dust or the like adheres to the surface of the guide mylar 14, it may come into contact with the platen glass locally or may float. The gap of 100 nm to 1 μm is a dimension that cannot be managed in terms of dimensions even in the tolerance of parts. From the above, irregular fringe fringes are generated in the image read in the ADF mode.
[0020]
  SUMMARY OF THE INVENTION In view of the above-described conventional problems, the present invention provides a document feeding device capable of suppressing the occurrence of irregular interference fringes due to a minute air layer formed by a transparent sheet member being in contact with a document table glass locally., Document reading apparatus, and image forming apparatusThe purpose is to provide.
[0021]
[Means for Solving the Problems]
  In order to achieve the above object, in the document feeder of the present invention, a transport unit that transports a sheet document to an image reading position on a transparent flat plate in order to read the sheet document, and a sheet document transported by the transport unit A guide member that guides the back side of the sheet in the vicinity of the image reading position, a transparent sheet member that faces the guide member at a predetermined interval and guides the front side of the sheet original, and the transparent sheet member at the image reading position. And a first gap holding means for holding the gap between the transparent flat plate and a predetermined amount.The first gap holding means is composed of a sheet-like elastic member that lifts the transparent sheet member.It is characterized by that.
  Also,In the document feeding apparatus of the present invention, a conveying unit that conveys a sheet document to an image reading position on a transparent flat plate for reading by the image reading unit, and a back side of the sheet document conveyed by the conveying unit is the image reading position. A guide member that guides in the vicinity, a transparent sheet member that opposes the guide member with a predetermined interval and guides the surface side of the sheet original, and an interval between the transparent sheet member and the transparent flat plate at the image reading position A first interval holding means for holding the gap between the guide member and the transparent sheet member at a predetermined amount, and a first gap holding means for holding the gap between the guide member and the transparent sheet member at a predetermined amount. And the second gap holding means is constituted by a projecting member provided on the guide member, a notch groove is provided in the projecting member, and the transparent sheet member is passed through the notch groove. By, wherein the holding distance between the transparent flat plate and the transparent sheet member in the image reading position, and the distance between the transparent sheet member and the guide member in each predetermined amount.
  According to another aspect of the present invention, there is provided a document reading device or an image forming apparatus including the document feeding device.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
[First Embodiment]
<Image forming apparatus>
FIG. 1 is an overall configuration diagram illustrating an image forming apparatus including a document feeder according to a first embodiment of the present invention.
[0024]
In this image forming apparatus, an image reading section (hereinafter referred to as a scanner section) 90 is placed on an image forming apparatus main body 101, and further, an automatic document feeder (hereinafter referred to as an ADF apparatus) which is a document feeding apparatus of the present invention is further provided thereon. ) 30 is mounted.
[0025]
Reference numeral 113 in FIG. 1 denotes a laser scanner for image writing. After image processing is performed on an image read by the scanner unit 90, laser light is applied to the image forming drum 108 in accordance with a recording signal after the image processing. Irradiation forms a latent image. Further, a toner image based on the latent image is formed by toner supplied from a toner supply device (not shown).
[0026]
A cassette 102 stores recording sheets such as paper or sheet film. A recording sheet is picked up from the cassette 102 by the pickup roller 103 in accordance with the recording signal, and is supplied one by one to the position facing the photosensitive drum 108 by the conveying roller 104 and the separation roller 105, and then the photosensitive member by the transfer device 109. The toner image formed on the drum 108 is transferred onto the recording sheet.
[0027]
Then, the recording sheet on which the toner image is transferred is sent to the fixing device 110 and fixed. When images are formed on both sides of the recording sheet, the recording sheet on which the image has been fixed by the fixing device 110 is discharged to a paper discharge tray 112 by a discharge roller 111 provided on the downstream side of the fixing device 110.
[0028]
<Scanner part>
FIG. 2 is a cross-sectional view showing a main part of the scanner unit 90 shown in FIG.
[0029]
An original platen glass 62 for reading a flatly placed original is mounted on the upper surface of the scanner unit 90, and the ADF device 30 is attached to the original table glass 62 so as to be openable and closable, and plays a role of suppressing the original. An image reading carriage 50 is mounted on the scanner unit 90 so as to be movable along the guide shaft 57 in the direction of arrow A in FIG. 2 so that a flatly placed document can be scanned.
[0030]
The drive transmission is transmitted to the image reading carriage 50 from a motor (not shown) through a drive gear 58, drive pulleys 59 and 60, and a drive belt 61. The image reading carriage 50 is provided with a lamp 51 for irradiating a document, reflection mirrors 52, 53 and 54, a lens 55, and a photoelectric conversion element 56. The lamp light is white light, and the document image irradiated by the lamp 51 is guided to the photoelectric conversion element 56 through the lens 55 via the reflection mirrors 52, 53, and 54. When reading a document conveyed by the ADF device 30, reading is performed in a state where the image reading carriage 50 is moved to a predetermined reading point Q and stopped.
[0031]
<ADF device>
The ADF apparatus 30 according to the first embodiment will be described with reference to FIGS. 3, 4, and 5.
[0032]
FIG. 3 is a cross-sectional view showing a main part of the ADF device 30 according to the present embodiment, and FIG. 4 is an enlarged view showing a configuration in the vicinity of the reading point of the ADF device 30 shown in FIG. FIG. 5 is a cross-sectional view taken along the line AA in FIG. 3, 4, and 5, the same members or the same functions as those in FIGS. 15, 16, and 17 are denoted by the same reference numerals, and description thereof is omitted.
[0033]
As shown in FIGS. 4 and 5, the reading point Q of the ADF apparatus 30 according to the present embodiment has spacers 22 at both ends in the document width direction on the document table glass 62, and guide mylars 14 are placed on the spacers 22. The reading guide 13 is urged by the spring 21 so that the abutting protrusion 135 of the reading guide 13 is in contact with the pin. The spacer 22 is used to hold the guide mylar 14 so that an air layer formed between the guide mylar 14 and the original platen glass 62 has an interval that does not generate interference fringes, and has a margin of about 300 μm. It is composed of thickness.
[0034]
The guide mylar 14 is a transparent plastic sheet member such as a polyester sheet, and has a thickness of about 100 μm. One end of the guide mylar 14 is locked by the boss portion 19a of the mylar holder 19, and the other end is mounted on the paper discharge guide 20 through the reading point Q, and is mounted in a state of being curved in the document conveying direction. Therefore, the guide mylar 14 in the vicinity of the reading point Q is seated and stretched straight across the document width direction. Therefore, even if the spacers 22 are provided only at both ends of the mylar holder 19 in the document width direction, the distance from the document table glass 62 can be secured over the entire region in the document width direction. In the present embodiment, the basis weight of the document is assumed to be in the range of 60 g to 110 g, and an interval of 100 μm or more is secured even in the strictest 110 g where the guide mylar 14 is pushed down.
[0035]
FIG. 6 is a perspective view showing a configuration on the scanner unit 90.
[0036]
One of the spacers 22 provided at both ends of the document width direction may be replaced with the document abutting reference 64 in the sub-scanning direction during book mode reading. At the other end, a spacer 22 having the same height is provided at a position corresponding to the reading point in the ADF mode on the platen glass 62. Further, as shown in FIG. 7, the spacer 22 may be mounted on the guide mylar 14 itself.
[0037]
Thus, in the ADF apparatus 30 having the configuration of the present embodiment, the spacer 22 is provided so that the distance between the guide mylar 14 and the document table glass 62 is maintained at about 300 μm. Therefore, it is possible to prevent the occurrence of striped interference fringes in an image read in the ADF mode. Further, the reading guide 13 and the guide mylar 14 are urged by urging the reading guide 13 toward the scanner unit 90 so that the abutting projection 135 provided on the reading guide 13 contacts the spacer 22 with the guide mylar 14 interposed therebetween. , And the distance between the guide mylar 14 and the document table glass 62 can be set to a predetermined amount.
[0038]
[Second Embodiment]
FIG. 8 is an enlarged view showing the configuration near the reading point of the document feeder according to the second embodiment of the present invention, and FIG. 9 is a perspective view showing the configuration of the butting protrusion in FIG. In addition, the same member or the same function as FIG.15 and FIG.16 is shown with the same code | symbol, and the description is abbreviate | omitted.
[0039]
In the ADF apparatus 31 according to the second embodiment, the reading guide 13 is provided with an abutting projection 135 that directly contacts the document table glass 62, and the guide mylar 14 is held away from the document table glass 62 by the abutting projection 135. For this purpose, a notch groove 135a is provided. The position of the notch groove 135a is provided so as to ensure an interval of about 300 μm between the document table glass 62 and the guide mylar 14.
[0040]
The guide mylar 14 is mounted through the notch grooves 135a of the butting protrusions 135 provided at both ends in the document width direction. The guide mylar 14 is supported at two points in the document width direction. However, as described in the first embodiment, the guide mylar 14 is mounted in a curved state, so that it is seated and covers the entire document width. Thus, a distance from the document table glass 62 is secured. Therefore, as in the first embodiment, the guide mylar 14 is arranged at a position away from the original platen glass 62 to a position where no interference fringes are observed, so that the occurrence of interference fringes in the read image can be suppressed.
[0041]
Further, in order to ensure the holding force of the guide mylar 14 in the notch groove 135a, it is effective to provide a guide part 135b in accordance with the notch groove 135a as shown in FIG.
[0042]
Furthermore, as an application of the second embodiment, a configuration as shown in FIG. 11 is also conceivable. That is, the abutting projection 135 of the reading guide 13 is formed in a tapered shape, and a fitting hole is provided in the guide mylar 14, and the guide mylar 14 is lightly caulked and fixed to the abutting projection 135. The fixing position is the same as the configuration using the notch groove 135a. Thereby, the space | interval of the guide mylar 14 and the original plate glass 62 is ensured. 135c in the drawing is a stop member for preventing the guide mylar 14 from dropping, and is made of an elastic member such as rubber, and is fitted and fixed to the butting protrusion 135.
[0043]
In the ADF device 31 of the second embodiment, the abutting projection 135 of the reading guide 13 is brought into contact with the document table glass 62, and a means for holding the guide mylar 14 is provided on the abutting projection 135 itself so that the guide mylar 14 and the document table are provided. A distance from the glass 62 is secured. Therefore, it is possible to prevent the occurrence of striped interference fringes in the image read in the ADF mode.
[0044]
[Third Embodiment]
FIG. 12 is an enlarged view showing a configuration near the reading point of the document feeder according to the third embodiment of the present invention. The same members or the same functions as those in FIGS. Is omitted.
[0045]
In the ADF device 32 of the third embodiment, an auxiliary mylar 23 is provided so as to lift the guide mylar 14 from the back side of the sheet passing surface on the upstream side of the reading point Q. One end of the auxiliary mylar 23 is fixed to the mylar holder 19 with a double-sided tape or the like, and the other end is a free end to lift the guide mylar 14 toward the reading guide 13. The auxiliary mylar 23 can use any plastic film having an elastic property, and is made of, for example, a polyester sheet. The auxiliary mylar 23 has a thickness of about 200 μm and is provided over the document width.
[0046]
The reason why an elastic member is used as the auxiliary mylar 23 is that, for example, a shock occurs when a thick paper document passes through the point of action, and a conveyance failure such as leading edge registration or skew does not occur. On the downstream side of the reading point Q, an abutting protrusion 135 of the reading guide 13 that is disposed on the reading point Q in the first and second embodiments is provided. The abutting protrusion 135 is in contact with the document table glass 62 with the guide mylar 14 interposed therebetween.
[0047]
As described above, the guide mylar 14 is lifted on the upstream side of the reading point Q and brought into contact with the original platen glass 62 on the downstream side, thereby providing the interval H1 between the guide mylar 14 on the reading point Q and the original platen glass 62. . The interval H1 is a gap of about 300 μm as in the first and second embodiments, and an interval of 100 to 200 μm is secured even when cardboard is passed.
[0048]
A distance H1 between the guide mylar 14 on the reading point Q and the original platen glass 62 can be derived from simultaneous equations shown in FIG.
[0049]
The expression (3) shown in FIG. 13 is an expression for obtaining the interval H1 by a ratio from the lifting height H2 of the auxiliary mylar 23. Since the amount of deflection δ differs depending on the load received during document conveyance, the relationship between the amount of deflection δ and the fixed end of the auxiliary mylar 23 is expressed by equation (4). Equation (5) is a deflection equation when cantilevered.
[0050]
From the above relationship, the distance H1 may be determined to be 200 to 300 μm. In the present embodiment, the abutting protrusion 135 is shifted about 8 mm downstream from the reading point Q, the tip of the auxiliary mylar 23 is positioned about 7 mm from the reading point Q, and the guide mylar 14 is lifted by about 600 μm. The distance between the guide mylar 14 and the platen glass 62 is set to 200 μm or more.
[0051]
In the ADF apparatus 32 configured as described above, the guide mylar 14 is lifted by the auxiliary mylar 23 from the back side of the sheet passing surface upstream of the reading point Q, and the reading guide 13 is in contact with the document table glass 62 with the guide mylar 14 interposed therebetween. By disposing the abutting protrusion 135 on the downstream side of the reading point Q, the interval between the guide mylar 14 and the document table glass 62 at the reading point Q is secured. Therefore, it is possible to prevent the occurrence of striped interference fringes in the image read in the ADF mode.
[0052]
[Fourth Embodiment]
FIG. 14 is an enlarged view showing a configuration in the vicinity of the reading point of the document feeder according to the fourth embodiment of the present invention. The same members or the same functions as those in FIGS. 15 and 16 are denoted by the same reference numerals, and the description thereof is omitted.
[0053]
In the ADF device 32 of the fourth embodiment, in the third embodiment, the positional relationship between the auxiliary mylar 23 and the butting protrusion 135 is reversed. That is, the auxiliary mylar 23 is provided so as to lift the guide mylar 14 from the back side of the sheet passing surface on the downstream side of the reading point Q. One end of the auxiliary mylar 23 is fixed to the paper discharge guide 20 via a spacer 20a for height adjustment, and the other end is a free end to lift the guide mylar 14 toward the reading guide 13 side.
[0054]
As in the third embodiment, the auxiliary mylar 23 is made of a polyester sheet, for example, and has a thickness of about 200 μm and is provided over the width of the document. On the upstream side of the reading point Q, an abutting protrusion 135 of the reading guide 13 that is disposed on the reading point Q in the first and second embodiments is provided. The abutting protrusion 135 is in contact with the document table glass 62 with the guide mylar 14 interposed therebetween.
[0055]
As described above, the distance H1 between the guide mylar 14 on the reading point Q and the document table glass 62 is provided by contacting the document table glass 62 on the upstream side of the reading point Q and lifting the guide mylar 14 on the downstream side. ing. The interval H1 is a gap of about 300 μm as in the first, second, and third embodiments, and an interval of 100 to 200 μm is ensured even when a cardboard is passed. As in the third embodiment, the various dimensional relationships are the relationships of equations (3) to (5) shown in FIG.
[0056]
In the ADF apparatus 33 configured as described above, the guide mylar 14 is lifted by the auxiliary mylar 23 from the back side of the sheet passing surface downstream of the reading point Q, and the reading guide 13 is in contact with the document table glass 62 with the guide mylar 14 interposed therebetween. By disposing the abutting protrusion 135 on the upstream side of the reading point Q, a distance between the guide mylar 14 and the original table glass 62 at the reading point Q is secured. Therefore, it is possible to prevent the occurrence of striped interference fringes in the image read in the ADF mode.
[0069]
【The invention's effect】
  As explained above,ClearlyShakeToruThe generation of irregular interference fringes due to the minute air layer formed by the bright sheet member locally contacting the transparent flat plate can be suppressed. Thereby, in an image forming apparatus using the document feeder of the present invention,While transporting the documentA high-quality image can be formed without forming a fringe pattern on the read image.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram illustrating an image forming apparatus including a document feeder according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a main part of the scanner unit 90 shown in FIG.
FIG. 3 is a cross-sectional view showing a main part of the ADF device 30 according to the first embodiment.
4 is an enlarged view for explaining a configuration in the vicinity of a reading point of the ADF device 30 shown in FIG. 3. FIG.
5 is a cross-sectional view taken along line AA in FIG.
6 is a perspective view showing a configuration on a scanner unit 90. FIG.
FIG. 7 is a perspective view illustrating the configuration of a guide mylar used in an application example of the first embodiment.
FIG. 8 is an enlarged view showing a configuration in the vicinity of a reading point of a document feeder according to a second embodiment of the invention.
9 is a perspective view showing a configuration of an abutment protrusion in FIG. 8. FIG.
FIG. 10 is a perspective view showing a schematic configuration of an abutting protrusion of a reading guide used in an application example of the second embodiment.
FIG. 11 is a perspective view showing a schematic configuration of an abutting protrusion of a reading guide used in another application example of the second embodiment.
FIG. 12 is an enlarged view showing a configuration near a reading point of a document feeder according to a third embodiment of the present invention.
13 is a diagram showing an equation for obtaining a distance between the guide mylar 14 on the reading point Q and the document table glass 62. FIG.
FIG. 14 is an enlarged view showing a configuration in the vicinity of a reading point of a document feeder according to a fourth embodiment of the invention.
FIG. 15 is a configuration diagram illustrating an example of a conventional ADF apparatus.
FIG. 16 is an enlarged cross-sectional view of a main part of a conventional ADF device.
17 is a cross-sectional view taken along line AA in FIG.
FIG. 18 is a diagram illustrating a state in which striped interference fringes are generated.
FIG. 19 is a diagram illustrating an equation for obtaining an interference condition by a thin film.
[Explanation of symbols]
1 Document feed tray
3 Pickup roller
13 Reading guide
14 Guide Myra
17 Discharge tray
22 Spacer
30 ADF equipment
62 Platen glass
63, 64 Document abutment criteria
90 Scanner unit
101 Image forming apparatus main body
135 Butting protrusion
135a Notch groove
135b Guide part
Q reading point

Claims (5)

Conveying means for conveying a sheet document to an image reading position on a transparent flat plate for reading by the image reading means;
A guide member for guiding the back side of the sheet document conveyed by the conveying means in the vicinity of the image reading position;
A transparent sheet member facing the guide member at a predetermined interval and guiding the surface side of the sheet document;
First interval holding means for holding a predetermined amount of an interval between the transparent sheet member and the transparent flat plate at the image reading position ;
The document feeder according to claim 1, wherein the first interval holding means is composed of a sheet-like elastic member for lifting the transparent sheet member .   2. The document feeder according to claim 1, further comprising a second gap holding unit for holding a gap between the guide member and the transparent sheet member at a predetermined amount.   3. The document feeding apparatus according to claim 2, further comprising an urging unit that urges the guide member so that the second interval holding unit abuts on the transparent sheet member. Conveying means for conveying a sheet document to an image reading position on a transparent flat plate for reading by the image reading means;
A guide member for guiding the back side of the sheet document conveyed by the conveying means in the vicinity of the image reading position;
A transparent sheet member facing the guide member at a predetermined interval and guiding the surface side of the sheet document;
First interval holding means for holding a predetermined amount of an interval between the transparent sheet member and the transparent flat plate at the image reading position;
A second gap holding means for holding the gap between the guide member and the transparent sheet member at a predetermined amount;
The first gap holding means and the second gap holding means are constituted by a protruding member provided in the guide member, a notched groove is provided in the protruding member, and the transparent sheet member is passed through the notched groove. Thus, the distance between the transparent sheet member and the transparent flat plate at the image reading position and the distance between the guide member and the transparent sheet member are each maintained at a predetermined amount. Document reading apparatus, or the image forming apparatus characterized by comprising a document feeder according to claims 1 to 4.

Images