JP2006303589A - Image reading unit, image reader, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading unit capable of obtaining an excellent image by reducing the effect of optical noise on the image since the image reader prevents stray light not passing through a lens from being reflected in the inside of its photoelectric conversion section and intruding into photoelectric conversion elements, and to provide an image reader and an image forming apparatus. <P>SOLUTION: The image reading unit exposes an original, forms the image of a reflected light from the original to the photoelectric conversion elements 24 arranged in the inside of a CCD 21 via a lens 23 to read the image, and the CCD 21 is provided with a light shield means that prevents the stray light from being reflected in the inside of the CCD 21 and intruding into the photoelectric conversion elements 24. The light shield means includes light shield bodies 25 which are located at a lens 23 remoter from the photoelectric conversion elements 24 on the upper part and the lower part of an optical path from the lens 23 to the photoelectric conversion elements 24. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading unit that is applied to a copying machine, a facsimile, a scanner, and the like and reads an original placed on a contact glass, and an image reading apparatus and an image forming apparatus equipped with the image reading unit.

  As shown in FIG. 9, a conventional image reading unit includes a photoelectric conversion device 54 disposed inside a CCD (Charge Coupled Device) 51, and the incident light side of the CCD 51 is sealed by a cover glass 52. In order to prevent the dust dust from entering the CCD 51, it is known that a good image is obtained.

  In this image reading unit, not only the image forming light passing through the lens 53 but also stray light that does not pass through the lens 53 enters the photoelectric conversion element 54, so that the read image deteriorates as the optical noise, the S / N ratio decreases, Problems such as MTF (Modulation Transfer Function) deterioration and color reproducibility deterioration have occurred.

Therefore, as an image reading unit that solves such a problem, as shown in FIG. 10, stray light that does not pass through the lens 63 directly enters the photoelectric conversion element 64 by covering a part of the cover glass 62 with a mask. What prevents this is known (for example, see Patent Document 1).
Japanese Patent No. 3586701

  However, in the conventional image reading unit, stray light that does not pass through the lens 63 can be prevented from directly entering the photoelectric conversion element 64, but is reflected inside the CCD 61 and enters the photoelectric conversion element 64. Therefore, there is a problem that a good image cannot be obtained.

  In addition, the size of the CCD pixel has been reduced to 10 μm, 7 μm, and 4.7 μm with the progress of technology. Along with this, the amount of light radiated to the CCD has also decreased, so even if the amount of stray light entering the photoelectric conversion element is small, the ratio of noise light to effective image-forming light is increased. In contrast to black and white CCDs, color 3-line CCDs react sensitively to slight changes in noise light and destroy the RGB balance. Etc. will be generated.

  The present invention has been made to solve such a problem. In order to prevent stray light that does not pass through the lens from being reflected inside the CCD and entering the photoelectric conversion element, the influence of optical noise is reduced. It is an object of the present invention to provide an image reading unit, an image reading apparatus, and an image forming apparatus that can obtain a good image.

  The image reading unit of the present invention is an image reading unit that reads an image by exposing a document and forming an image of reflected light from the document on a photoelectric conversion element disposed inside a photoelectric conversion unit via a lens. The photoelectric conversion unit has a light shielding unit that prevents stray light from being reflected inside the photoelectric conversion unit and entering the photoelectric conversion element.

  With this configuration, stray light that does not pass through the lens is prevented from being reflected inside the photoelectric conversion unit and entering the photoelectric conversion element. Therefore, it is possible to reduce the influence of optical noise and obtain a good image.

  In the image reading unit of the present invention, the light shielding unit has a light shielding body on the lens side with respect to the photoelectric conversion element and above and below an optical path from the lens to the photoelectric conversion element. .

  With this configuration, stray light that does not pass through the lens is prevented from being reflected inside the photoelectric conversion unit and entering the photoelectric conversion element. Therefore, it is possible to reduce the influence of optical noise and obtain a good image.

  The image reading unit of the present invention has a configuration in which the light shield is inclined in a direction away from the optical path as it goes from the lens to the photoelectric conversion element.

  With this configuration, even when stray light that does not pass through the lens enters the photoelectric conversion unit, the stray light reflected inside the photoelectric conversion unit reaches the photoelectric conversion element by being finally blocked by the light blocking body. I can't. For this reason, the influence by optical noise can be reduced and a favorable image can be obtained.

  Further, the image reading unit of the present invention has a plurality of light shielding members in which the light shielding body is inclined in a direction away from the optical path as it goes from the lens to the photoelectric conversion element, and the plurality of light shielding members are mutually connected. It has the structure arrange | positioned at intervals.

  With this configuration, even when stray light that does not pass through the lens enters the inside of the photoelectric conversion unit, the stray light reflected inside the photoelectric conversion unit finally reaches the photoelectric conversion element by being blocked by the light blocking member. I can't. For this reason, the influence by optical noise can be reduced and a favorable image can be obtained.

  In the image reading unit of the present invention, the light shield has a bellows shape.

  With this configuration, even when stray light that does not pass through the lens enters the inside of the photoelectric conversion unit, the stray light cannot reach the photoelectric conversion element by being reflected by the surface of the light blocking body. For this reason, the influence by optical noise can be reduced and a favorable image can be obtained.

  In the image reading unit of the present invention, the light shield has a flock-like light shield member, and the light shield member is arranged so that the end of the hair faces the optical path side. .

  With this configuration, even when stray light that does not pass through the lens enters the inside of the photoelectric conversion unit, the stray light cannot reach the photoelectric conversion element by being reflected by the surface of the light shielding member. For this reason, the influence by optical noise can be reduced and a favorable image can be obtained.

  The image reading apparatus of the present invention may be configured to mount the image reading unit.

  The image forming apparatus of the present invention may include the image reading device and an image forming unit that forms an image on a recording medium.

  As described above, the present invention prevents stray light that does not pass through the lens from being reflected inside the photoelectric conversion unit and entering the photoelectric conversion element, thereby reducing the influence of optical noise and obtaining a good image. It is an object of the present invention to provide an image reading unit, an image reading apparatus, and an image forming apparatus that have the effect of being able to be performed.

Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
1 to 5 are schematic configuration diagrams showing an image forming apparatus according to the first embodiment of the present invention. In this embodiment, an example in which the image forming apparatus is applied to a copying machine is shown.

  As shown in FIG. 1, the copying machine 100 includes an image forming unit 200, a paper feeding unit 300, an image reading unit 400, and a document feeding unit 500.

  The image forming unit 200 forms a color-coded image on a plurality of photoconductors based on the color-separated information of the image read by the image reading unit 400, and superimposes the image on a transfer sheet conveyed from the paper supply unit 300. It is designed to make a full color hard copy by transcription.

  The paper feeding unit 300 conveys the transfer paper to the image forming unit 200.

  The image reading unit 400 performs sub-scanning of the first carriage 5 and the second carriage 6 at a predetermined speed, and takes a document image into the CCD 21 by the lens unit 7.

  The document feeder 500 feeds the document directly or directly above the image reading unit 400 either automatically or manually.

  Note that the image reading unit in the present invention includes the image reading unit 400. The image reading apparatus according to the present invention includes an image reading unit 400 and a document feeding unit 500.

  Next, the image reading unit 400 will be described.

  As shown in FIG. 2, the image reading unit 400 includes a first rail and a second rail 8 (not shown) in a main body frame 1 that is a housing of the apparatus, and the first carriage 5 is included in the first rail. However, the second carriage 6 is configured to be slidable on the second rail 8. A wire drive pulley 4 is attached to a drive shaft 2 connected to a drive motor (not shown), and a drive wire 3 is wound around the wire drive pulley 4. Here, two drive wires 3 for the first carriage 5 and for the second carriage 6 are used. In FIG. 2, one of the drive wires 3 for the second carriage 6 is shown as a representative. . Further, the drive wire 3 is configured to pass through a carriage pulley attached to the second carriage 6 and an idler pulley provided near the end of the main body frame 1, but in FIG. Is omitted.

  A tubular lamp 5 a as a light source is disposed on the first carriage 5, and is disposed between the wire drive pulley 4 and the second carriage 6.

  When the first carriage 5 is pulled by the drive wire 3 and moves at a predetermined speed v, the first carriage 5 performs sub-scanning on the document placed on the contact glass plane that forms the image reading area (not shown) immediately above the tubular lamp 5a. It is supposed to be. The reflected light beam from the document is reflected by a first mirror (not shown) in a predetermined direction, that is, toward the second carriage 6. Next, the reflected light flux is folded back by the second mirror 6 a of the second carriage 6 and a third mirror (not shown) and is incident on the lens unit 7. The reflected light beam is focused and formed on a CCD (not shown) placed on the focal plane by a lens included in the lens unit 7. As a result, the CCD performs main scanning on the linear portion on the original along the tubular lamp 5a.

  The second carriage 6 cancels the overlap of the optical path caused by the return of the light flux by the second mirror 6a and the third mirror, so that the second carriage 6 is half the speed of the first carriage 5, that is, the speed of v / 2. It moves in the same direction. Due to this movement speed relationship, even if the first carriage 5 and the second carriage 6 move, the optical path length of the light flux from the document surface to the lens unit 7 does not change.

  Further, since the second carriage 6 has a travel range that is half that of the first carriage 5, almost half of the second rail 8 on the side close to the wire drive pulley 4 is not used for the travel of the second carriage 6. . However, if the unused portion of the second rail 8 is cut off, the parallelism of the second rail 8 is adversely affected, so that the drive shaft 2 of the wire drive pulley 4 is disposed in that portion instead of cutting off that portion. Has been. And about the part in which the drive shaft 2 is arrange | positioned at the 2nd rail 8, the shape of the 2nd rail 8 is changed, and it does not interfere with rotation of the drive shaft 2. FIG.

  The position of the upper end of the drive shaft 2 is arranged so as not to be at least below the rail surface of the second rail 8. Thereby, the wire drive pulley 4 can be brought closer to the document surface side, which can contribute to the downsizing of the image reading apparatus.

  The lens unit 7 is arranged so that the first carriage 5 can travel on the lens unit 7. However, the lens unit 7 is disposed outside the traveling region of the second carriage 6 in the sub-scanning direction so as to receive a reflected light beam from the document.

  Next, the relationship between the drive wire 3 for the second carriage 6 and the pulley will be described.

  As shown in FIGS. 3A and 3B, the drive wire 3 is wound around a wire drive pulley 4 and extends to an idler pulley 11 and an idler pulley 12 whose shafts are fixed to the main body frame 1. There are two systems. The portion 3 a of the drive wire 3 extending to the idler pulley 11 is folded back by the idler pulley 11 to become the portion 3 b, reaches the outer carriage pulley 10 b, and is folded again here to become the portion 3 c, and the end is fixed to the main body frame 1. Is done. The portion 3d of the drive wire 3 extending to the idler pulley 12 is folded back by the idler pulley 12 to become the portion 3e, reaches the inner carriage pulley 10a, and is folded again here to become the portion 3f. 9 is fixed to the apparatus main body.

  Here, since the carriage pulley 10 moves along the second rail 8 together with the second carriage 6 by the rotation of the wire drive pulley 4, the carriage pulley 10 is provided with the carriage pulley 10 in order to ensure constant speed in the movement of the second carriage 6. The directly involved portions 3 b and 3 c are arranged to be parallel to the second rail 8. For the same reason, the portion 3 e and the portion 3 f are also arranged so as to be parallel to the second rail 8. On the other hand, since there is no movement of the positions between the wire drive pulley 4 and the idler pulley 11 and between the wire drive pulley 4 and the idler pulley 12, the portions 3a and 3d are connected to the second rail 8. It is not necessary to arrange them parallel to each other.

  Further, the inner carriage pulley 10a and the outer carriage pulley 10b are concentric and integrally formed as a double groove pulley.

  The idler pulleys 11 and 12 and the carriage pulley 10 are attached to the apparatus body with their axes inclined. However, the inclination directions of the idler pulleys 11 and 12 and the carriage pulley 10 are opposite to each other. That is, as shown in FIG. 3B, the idler pulleys 11 and 12 and the carriage pulley 10 are arranged so that the shafts of the idler pulleys 11 and 12 do not contact the shaft of the carriage pulley 10 and are obliquely crossed. Yes. This prevents the portion 3a of the drive wire 3 from slightly moving the winding start position in the axial direction along with the rotation of the wire drive pulley 4, and the portion 3a from coming into contact with the second carriage 6. Can do. Furthermore, it can contribute to the downsizing of the image reading apparatus.

  Next, the positional relationship of each pulley will be described.

  As shown in FIG. 4, the drive belt pulley 14 is fixed to the output shaft 13 a of the drive motor 13 arranged horizontally. The drive belt 15 is stretched between the drive belt pulley 14 and the driven belt pulley 16. The driven belt pulley 16 is coaxially fixed to the drive shaft 2 together with the wire drive pulley 4. As the drive motor 13 rotates in an arbitrary direction, the wire drive pulley 4 rotates in a corresponding direction, and the drive wire 3 moves in a direction orthogonal to the drive shaft 2.

  The drive shaft 2 of the wire drive pulley 4 is arranged horizontally, but the idler pulley 11 is arranged so that the driven belt pulley 16 side is lowered as indicated by an arrow A. On the other hand, the carriage pulley 10 is arranged so that the opposite side of the driven belt pulley 16 is lowered as indicated by an arrow B. Each pulley has its center position in the order of the wire drive pulley 4, idler pulley 11, carriage pulley 10 in the direction from the driven belt pulley 16 toward the wire drive pulley 4 along the direction of the drive shaft 2. It is arranged to be.

  Further, the wire drive pulley 4 is arranged such that the upper end position is above the lower end of the idler pulley 11. As a result, the entire apparatus can be configured to be low, which can contribute to downsizing of the image reading apparatus. Further, the wire drive pulley 4 is arranged such that the upper end position is lower than the upper end of the idler pulley 11. Thereby, the part 3b of the drive wire 3 and the wire drive pulley 4 can be prevented from interfering with each other. These relationships are the same for the wire drive pulley 4 and the idler pulley 12.

  When the drive wire 3 is stretched between the wire drive pulley 4 and the idler pulley 11, the drive wire 3 is substantially tangent to the wire drive pulley 4, and the winding start position of the idler pulley 11 is on the extension thereof. Arranged to exist. Actually, the winding start position of the drive wire 3 around the wire drive pulley 4 slightly moves in the direction of the drive shaft 2. Therefore, here, the winding start position of the idler pulley 11 is a position when the winding start position of the drive wire 3 relative to the wire drive pulley 4 is an average position.

  Further, when the drive wire 3 is stretched between the idler pulley 11 and the carriage pulley 10, the drive wire 3 is disposed so as to be positioned on a tangent line between the idler pulley 11 and the carriage pulley 10. That is, the drive wire 3 coincides with the common outer tangent line of the carriage pulley 10 and the idler pulley 11. Therefore, the winding start position for the carriage pulley 10 and the idler pulley 11 overlaps the same point in FIG. The wire drive pulley 4 and the drive wire 3 in other parts of the carriage pulley 10 are omitted. These relationships are the same for the idler pulley 12 and the carriage pulley 10. Thereby, since there is little overlap of the drive wire 3, the winding operation | work of the drive wire 3 becomes easy. Furthermore, a stable driving force can be transmitted without applying an excessive force to the driving wire 3.

  Next, the internal structure of the CCD 21 will be described.

  As shown in FIG. 5, a photoelectric conversion element 24 for reading a three-line color image with a pitch of 4.7 μm is disposed inside the CCD 21, and image formation that has passed through a lens 23 included in the lens unit 7. Light is photoelectrically converted. The incident light side of the CCD 21 is configured to be sealed with a cover glass 22.

  Further, as shown in FIG. 5, the inclined light shield 25 is disposed on the lens 23 side with respect to the photoelectric conversion element 24 and above and below the optical path from the lens 23 to the photoelectric conversion element 24. It has become. Further, the inclined light shield 25 is inclined in a direction away from the optical path as it goes from the lens 23 to the photoelectric conversion element 24.

  With this configuration, even when stray light that does not pass through the lens 23 enters the inside of the CCD 21, the stray light reflected inside the CCD 21 finally reaches the photoelectric conversion element 24 by being blocked by the inclined light shielding body 25. I can't. For this reason, the influence by optical noise can be reduced and a favorable image can be obtained.

  The inclined light shield 25 is positioned based on the positional relationship of the CCD 21, the lens 23, the photoelectric conversion element 24, and the like so that stray light that does not pass through the lens can be prevented from directly entering the photoelectric conversion element 24. Yes.

In this embodiment, the copying machine has been described as an example. For example, a scanner, a facsimile machine, or the like may be formed with the image reading unit 400 and the document feeding unit 500 as basic configurations.
(Second Embodiment)
FIG. 6 is an explanatory diagram of the inside of the CCD according to the second embodiment of the present invention. Further, in the present embodiment, since the shape of the light shield disposed inside the CCD is characterized, this portion will be described in particular, and the same number is assigned to the same configuration as in the first embodiment. The description is omitted.

  As shown in FIG. 6, the blind light-shielding body 26 is disposed on the lens 23 side with respect to the CCD 21 and above and below the optical path from the lens 23 to the CCD 21. Furthermore, the blind light shielding body 26 has a plurality of light shielding members inclined in a direction away from the optical path as it goes from the lens 23 to the photoelectric conversion element 24, and the plurality of light shielding members are arranged at intervals. It is like that.

  With this configuration, even when stray light that does not pass through the lens 23 enters the inside of the CCD 21, the stray light that is reflected inside the CCD 21 is finally blocked by the light blocking member that constitutes the blind light blocking body 26, thereby The conversion element 24 cannot be reached. For this reason, the influence by optical noise can be reduced and a favorable image can be obtained.

The blind light blocking body 26 is positioned based on the positional relationship of the CCD 21, the lens 23, the photoelectric conversion element 24, and the like so that stray light that does not pass through the lens can be prevented from directly entering the photoelectric conversion element 24. Yes.
(Third embodiment)
FIG. 7 is an explanatory diagram of the inside of the CCD according to the third embodiment of the present invention. Further, in this embodiment, since the shape of the light shield disposed inside the CCD is characterized, particularly that portion will be described, and the same components as those in the first embodiment are denoted by the same reference numerals. The description is omitted.

  As shown in FIG. 7, the bellows light-shielding body 27 is disposed on the lens 23 side with respect to the CCD 21 and above and below the optical path from the lens 23 to the CCD 21. Further, the bellows light shielding body 27 has a bellows shape.

  With this configuration, even when stray light that does not pass through the lens 23 enters the inside of the CCD 21, the stray light reflected inside the CCD 21 reaches the photoelectric conversion element 24 by being blocked and reflected by the bellows light blocking body 27. I can't. For this reason, the influence by optical noise can be reduced and a favorable image can be obtained.

The bellows light blocking body 27 is positioned based on the positional relationship of the CCD 21, the lens 23, the photoelectric conversion element 24, and the like so that stray light that does not pass through the lens can be prevented from directly entering the photoelectric conversion element 24. Yes.
(Fourth embodiment)
FIG. 8 is an explanatory diagram of the inside of the CCD in the fourth embodiment of the image forming apparatus according to the present invention. Further, in the present embodiment, since the shape of the light shield disposed inside the CCD is characterized, this portion will be described in particular, and the same number is assigned to the same configuration as in the first embodiment. The description is omitted.

  As shown in FIG. 8, the flocking shading body 28 is disposed on the lens 23 side with respect to the CCD 21 and above and below the optical path from the lens 23 to the CCD 21. Furthermore, the flocked light shielding body 28 has a plurality of flocked light shielding members, and the plurality of light shielding members are arranged such that the tips of the hairs face the optical path side.

  With this configuration, even when stray light that does not pass through the lens 23 enters the inside of the CCD 21, the stray light reflected inside the CCD 21 is shielded and reflected by the light shielding member that constitutes the bellows light shielding body 27. The conversion element 24 cannot be reached. For this reason, the influence by optical noise can be reduced and a favorable image can be obtained.

  The flocked light shielding body 28 is positioned based on the positional relationship among the CCD 21, the lens 23, the photoelectric conversion element 24, and the like so as to prevent stray light that does not pass through the lens from directly entering the photoelectric conversion element 24. Yes.

  As described above, since the image reading unit according to the present invention prevents stray light that does not pass through the lens from being reflected inside the photoelectric conversion unit and entering the photoelectric conversion element, a good image can be obtained. The image reading unit is applied to a copying machine, a facsimile, a scanner, and the like, and is useful as an image reading unit that reads a document placed on contact glass, and an image reading apparatus and an image forming apparatus equipped with the image reading unit.

1 is a diagram illustrating an image forming apparatus according to a first embodiment of the present invention, and is a schematic configuration diagram of a copier as an image forming apparatus. FIG. 3 is a perspective view illustrating main components of the image reading unit according to the first embodiment of the present invention. (A) It is a side view which shows the relationship between the drive wire and pulley for 2nd carriages concerning the 1st Embodiment of this invention. (B) It is a top view which shows the relationship between the drive wire and pulley for 2nd carriages concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the positional relationship of each pulley which concerns on the 1st Embodiment of this invention. It is explanatory drawing inside CCD which concerns on the 1st Embodiment of this invention. It is explanatory drawing inside the CCD which concerns on the 2nd Embodiment of this invention. It is explanatory drawing inside the CCD which concerns on the 3rd Embodiment of this invention. It is explanatory drawing inside the CCD which concerns on the 4th Embodiment of this invention. It is explanatory drawing inside CCD in the conventional image forming apparatus. It is explanatory drawing inside CCD in the conventional image forming apparatus.

Explanation of symbols

21 CCD (photoelectric converter)
22 Cover glass 23 Lens 24 Photoelectric conversion element 25 Inclined light shield (light shielding means)
26 Blind shading body (shading means)
27 Bellows shading body (shading means)
28 Flocking shade (light shielding means)
100 Copying machine (image forming device)
200 Image forming unit (image forming means)
300 Paper Feeding Unit 400 Image Reading Unit (Image Reading Unit, Image Reading Device)
500 Document feeder (image reading device)

Claims (8)

An image reading unit that exposes an original and forms an image of reflected light from the original through a lens on a photoelectric conversion element disposed in a photoelectric conversion unit, and reads the image,
The image reading unit, wherein the photoelectric conversion unit includes a light shielding unit that prevents stray light from being reflected inside the photoelectric conversion unit and entering the photoelectric conversion element.   The image reading apparatus according to claim 1, wherein the light shielding unit includes a light shielding body on a lens side with respect to the photoelectric conversion element and above and below an optical path from the lens to the photoelectric conversion element. unit.   The image reading unit according to claim 2, wherein the light shield is inclined in a direction away from the optical path as it goes from the lens toward the photoelectric conversion element. The light shielding body includes a plurality of light shielding members that are inclined in a direction away from the optical path from the lens toward the photoelectric conversion element,
The image reading unit according to claim 2, wherein the plurality of light shielding members are arranged at intervals.   The image reading unit according to claim 2, wherein the light shield has a bellows shape. The light shielding body has a flocked light shielding member,
The image reading unit according to claim 2, wherein the light shielding member is disposed such that a front end of the hair faces the optical path side.   An image reading apparatus comprising the image reading unit according to claim 1.   An image forming apparatus comprising the image reading apparatus according to claim 7 and an image forming unit that forms an image on a recording medium.

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