JP2007295202A - Image reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading device capable of suppressing the rise of a temperature in a light source in the case of an original movement reading mode without increasing a cost accompanied by the increase of the number of components, and suppressing a light amount change accompanied by the rise of the temperature in the light source. <P>SOLUTION: The image reading device includes the original movement reading mode for reading the image of an original while the original is carried so as to pass a reading position at fixed speed in a state that a scanning optical system which has first and second carriages so as to read the image of the original while illuminating the image of the original by the use of the light source mounted to the first carriage is stopped at a prescribed reading position. The light source is mounted to the first carriage in an adhesive state. The first carriage is used as a light source holding function and a radiating function. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus used in an image forming apparatus such as a copying machine, a printer, or a facsimile employing an electrophotographic method, and in particular, a scanning optical system that reads an image of a document is stopped at a predetermined position. The present invention relates to an image reading apparatus having a document movement reading mode in which an image of a document is read by a reading unit while the document is conveyed at a constant speed.

JP 2001-144907 A

  Conventionally, as an image reading apparatus used in an image forming apparatus such as a copying machine, a printer, or a facsimile employing such an electrophotographic system, an image of the original is placed on a platen glass. Is illuminated by a light source, and an image of a document is imaged on a reading element such as a CCD via an imaging lens in a state where the optical path is folded by one full-rate mirror and two half-rate mirrors, and scanning optics. The document image is read by scanning and exposing the document image through the system.

  In the image reading apparatus, the scanning optical system including the light source, the full rate mirror, the half rate mirror, and the like is stopped at a predetermined position in addition to the document fixed reading mode in which the document is placed on the platen glass. In many cases, it is configured to have a document movement reading mode in which an image of the document is read via a scanning optical system while the document is conveyed at a constant speed.

  By the way, in the image reading apparatus configured as described above, when reading the image of the document in the document moving reading mode, the image of the document is passed through the scanning optical system while the scanning optical system is stopped at a predetermined position. Since the light source stopped at a predetermined position illuminates the reading position at all times, the temperature of the light source itself rises, the light amount of the light source decreases, and it becomes non-uniform as well as near the reading position. There was a problem that the temperature of the member increased.

  Therefore, as a technique capable of solving such a problem, for example, a technique disclosed in JP 2001-144907 A has been proposed.

  The document reading apparatus according to Japanese Patent Laid-Open No. 2001-144907 has a first mode in which document data is read by moving the scanning optical system while the document is stationary on the platen on which the document is placed, and the scanning optical system is stationary. A second mode for reading original data by moving the original, and in the second mode, prior to reading the original, the moving original reading position at which the first reference member is provided above the platen is provided. The light source of the scanning optical system is moved to perform shading correction, and then the light source of the scanning optical system is moved to the fixed document reading position, and the shading correction by the second reference member is performed outside the document reading unit in the main scanning direction. An original reading apparatus configured to perform heat radiation, for dissipating heat from the light source in or near the light source of the scanning optical system. It is those, which is configured as.

  However, the conventional technique has the following problems. That is, in the case of the document reading apparatus according to the above Japanese Patent Laid-Open No. 2001-144907, as a specific configuration of the heat radiating means, a metal member is brought into direct contact with the light source of the scanning optical system, or Although it is configured so that air is applied to the light source, it is necessary to newly provide heat dissipation means made of metal members and a fan that forms airflow in order to suppress the temperature rise of the light source, increasing the number of parts There is a problem that it causes an increase in cost.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and the object of the present invention is to avoid an increase in the cost associated with an increase in the number of parts, and in the document movement reading mode. An object of the present invention is to provide an image reading apparatus capable of suppressing a temperature rise of a light source and capable of suppressing a light amount fluctuation accompanying a temperature rise of the light source.

In other words, the invention described in claim 1 includes a scanning optical system including first and second carriages that read an image of an original while illuminating the image of the original with a light source mounted on the first carriage. In an image reading apparatus provided with a document movement reading mode for reading the image of the document while transporting the document so as to pass through the reading position at a constant speed while being stopped at a predetermined reading position.
The image reading apparatus is mounted with the light source in close contact with the first carriage, and the first carriage serves both as a holding function and a heat dissipation function for the light source.

  According to a second aspect of the present invention, the first carriage is configured to come into contact with the reading device housing via a heat conducting member at a reading position in the document movement reading mode. The image reading apparatus according to claim 1.

  Furthermore, the invention described in claim 3 is characterized in that the light source is fixed to the first carriage by bonding through an adhesive having high thermal conductivity. An image reading apparatus.

  According to a fourth aspect of the present invention, in the member for mounting the light source of the first carriage, a heat radiating fin is integrally provided. The image reading apparatus according to the above.

  Furthermore, the invention described in claim 5 is characterized in that the member for mounting the light source of the first carriage also has a function as a reflecting member for reflecting the light of the light source to the document. An image reading apparatus according to claim 1.

  According to the present invention, the temperature increase of the light source in the document moving reading mode can be suppressed without causing an increase in cost due to an increase in the number of parts, and the light quantity fluctuation accompanying the temperature increase of the light source can be suppressed. It is possible to provide an image reading apparatus capable of performing the above.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 is a cross-sectional configuration diagram showing the entire image reading apparatus according to Embodiment 1 of the present invention.

  In FIG. 2, reference numeral 1 denotes a housing of the image reading device. The image reading device housing 1 is a substantially rectangular parallelepiped box body having an inner surface constituted by a metal frame 2 and a large upper end surface. It is formed in a shape. A first platen glass 4 having a large area on which the document 3 is placed is disposed on the upper end surface of the image reading apparatus casing 1, and a first platen glass 4 is disposed above the image reading apparatus casing 1. An automatic document feeder 5 (DADF: duplex auto document feeder) that also serves as a platen cover that presses the document 3 is disposed on the platen glass 4 so as to be openable and closable. Further, on the upper end surface of the image reading apparatus housing 1, the document 3 ′ is conveyed at a constant speed to the left end of the first platen glass 4, and an image of the document 3 ′ is read. A second platen glass 6 having a small width is provided. Further, an abutting member for abutting and positioning one end of the document 3 placed on the first platen glass 4 between the second platen glass 6 and the first platen glass 4. 7 is attached.

  As shown in FIG. 2, the automatic document feeder 5 includes a document transport unit 9 that automatically transports the document 3 at the left end of the platen cover unit 8. The document transport unit 9 feeds the document 3 placed on the document placing tray 10 while being fed by the nudger roll 11 and separated one by one by the retard roll 12 and the feed roll 13. When the document 3 passes through the second platen glass 6 while being transported at a constant speed by a plurality of pairs of transport rollers 15, 16, and 17 disposed along the document transport path 14, As will be described later, it is read by a scanning optical system. The document 3 transported by the transport rollers 15, 16, and 17 is discharged onto a discharge tray 19 provided on the upper surface of the platen cover unit 8 by a discharge roller 18.

  Further, when reading images on both the front and back sides of the document 3, the document 3 on which the image on one side is read is not directly discharged onto the discharge tray 19 by the discharge roll 18, but the rear end of the document 3 is discharged to the discharge roll 18 , The discharge roll 18 is reversed and introduced into the front / back reversing path 20, and the conveying rolls 15, 16, 17 are turned in a state where the front / back of the document 3 is reversed via the front / back reversing path 20. The image on the back surface of the document 3 is read by a scanning optical system as will be described later when passing over the second platen glass 6 while being conveyed at a constant speed.

  Further, as shown in FIG. 2, the document 3 placed on the platen glass 4 while being pressed by the platen cover 8 of the automatic document feeder 5 is placed inside the image reading device housing 1. A first carriage 23 on which an illumination light source 21 including a xenon lamp for illuminating and a full rate mirror 22 for reflecting a reflected light image from the original 3 in the horizontal direction is mounted is disposed. A second carriage 26 to which two half-rate mirrors 24 and 25 that reflect the reflected light image of the reflected original 3 so as to be folded back is provided. The first and second carriages 23 and 26 are slidably attached to the image reading apparatus along the horizontal direction by guide rails (not shown) arranged along the sub-scanning direction. The first and second carriages 23 and 26 are driven in a predetermined direction along the scanning direction by a driving pulley that is rotated by a driving motor (not shown) and a tension wire that is moved by the driving pulley. The second carriage 26 is movable at a predetermined movement speed (1/2) V along the scanning direction. As a result, the first and second carriages 23 and 26 are configured to scan and expose the image of the document 3 placed on the first platen glass 4 without changing the optical path length.

  Further, as shown in FIG. 2, the image reading apparatus illuminates the image of the document 3 with a light source, and stops the scanning optical system that reads the image of the document 3 at a predetermined reading position. A document movement reading mode for reading an image of the document 3 while conveying the document 3 so as to pass through the position at a constant speed is provided. In the original movement reading mode, the first and second carriages 23 and 26 stop at a reading position where the first carriage 23 is located immediately below the second platen glass 6 as shown in FIG. An image of the document 3 moving on the second platen glass 6 at a constant speed is read.

  Further, as shown in FIG. 2, an image forming lens 27 for forming an image of the document 3 scanned and exposed by the first and second carriages 23 and 26 is fixed inside the image reading apparatus housing 1. In addition, the CCD sensor 28 serving as a reading unit that reads an image of the original 3 imaged by the imaging lens 27 is fixed. The image of the original 3 is scanned and exposed on the CCD sensor 28 via the scanning optical system 29, and is read by the CCD sensor 28 at a predetermined dot density (for example, 400 dpi or 600 dpi). .

  The CCD sensor 28 is attached to a CCD printed circuit board 30 and is configured to be driven by a drive circuit (not shown) provided on the CCD printed circuit board 30. The image of the document 3 read by the CCD sensor 28 is sent to the image processing / control circuit 31 as image data of three colors, for example, red (R), green (G), and blue (B) (8 bits each). In the image processing / control circuit 31, predetermined image processing such as shading correction, position shift correction, lightness / color space conversion, gamma correction, and frame erasing is performed on the image data of the document 3, and the image data is converted into image data. Is output. The image processing / control circuit 31 can read an image of the document 3 at a predetermined magnification by controlling a driving motor (not shown) that drives the first and second carriages 23 and 26. .

  The image data subjected to the image processing by the image processing / control circuit 31 as described above is an image of four colors of yellow (Y), magenta (M), cyan (C), and black (K) (each 8 bits). The data is converted into data and output to an image output device such as a copying machine or a printer (not shown). Of course, the image data subjected to the image processing by the image processing / control circuit 31 as described above may be output to a personal computer or the like (not shown) and desired processing may be performed by the personal computer.

  By the way, in this embodiment, the scanning optical system including the first and second carriages that reads the image of the original while illuminating the image of the original with a light source mounted on the first carriage is set at a predetermined reading position. In the image reading apparatus having a document movement reading mode for reading the image of the document while transporting the document so as to pass through the reading position at a constant speed in a state where the first carriage is stopped. The light source is mounted in close contact, and the first carriage is configured to serve both as the light source holding function and the heat dissipation function.

  In this embodiment, the light source is fixed to the first carriage by bonding via an adhesive having high thermal conductivity.

  Furthermore, in this embodiment, the member for mounting the light source of the first carriage is configured to be integrally provided with a heat radiation fin.

  That is, in the image reading apparatus according to this embodiment, as shown in FIGS. 1 and 3, an illumination light source 21 including a xenon lamp or the like is mounted on the first carriage 23. It is fixed to a holding member 32 provided on one carriage 23 by adhesion via an adhesive 33 having high thermal conductivity. The holding member 32 is manufactured by, for example, aluminum die-casting, and the holding member 32 has a radius of curvature slightly larger than the radius of curvature of the illumination light source 21 in order to fix the illumination light source 21 by bonding. The arc-shaped part 34 is provided integrally. As shown in FIG. 1, the arc-shaped portion 34 of the holding member 32 is provided over substantially the entire length of the long illumination light source 21, and is configured to hold the illumination light source 21 over substantially the entire length. For example, the illumination light source 21 is bonded to the arc-shaped portion 34 of the holding member 32 via a silicon-based adhesive 33. As this adhesive 33, it is desirable to use an adhesive 33 having a high thermal conductivity in order to efficiently transmit the heat of the illumination light source 21 to the holding member 32.

  Further, the lower end portion of the holding member 32 is provided with a mounting portion 35 formed in a flat plate shape, and a plurality of (three in the illustrated example) heat radiation fins 36 are provided at the distal end portion of the mounting portion 35. Is erected. The holding member 32 is attached to the first carriage 23 by screws or the like via the attachment portion 35.

  Further, the illumination light source 21 is usually mounted on the first carriage 23 via holders provided at both ends in the longitudinal direction. In the present embodiment, the illumination light source 21 is attached to the first carriage 23. Since the holder 37 is directly bonded and attached to the holding member 32 provided above, the holder 37 can be omitted, and the number of components can be reduced also in this respect.

  In FIG. 3, reference numeral 38 denotes a reflecting member that reflects light from the illumination light source 21 to the document 3.

  With the above configuration, in the image reading apparatus according to the first embodiment, the temperature rise of the light source in the document moving reading mode is suppressed without causing an increase in cost due to an increase in the number of parts as follows. Therefore, it is possible to suppress fluctuations in the amount of light accompanying the temperature rise of the light source.

  That is, in the image reading apparatus according to the first embodiment, as shown in FIG. 2, the first and second carriages 23 and 26 move to the left end portion of the image reading apparatus housing 1 in the document moving reading mode. Then, the first carriage 23 moves to a reading position located below the second platen glass 6 and stops.

  In this state, the image reading apparatus conveys the document 3 at a constant speed by the automatic document conveyance unit 9 of the automatic document conveyance device 5 as shown in FIG. It passes through the platen glass 6. At that time, the first carriage 23 turns on the illumination light source 21 to illuminate the image of the document 3 that moves on the second platen glass 6 at a constant speed, and displays the reflected light image from the document 3. The original 3 is reflected by the full-rate mirror 22 of the first carriage 23 and the two half-rate mirrors 24 and 25 of the second carriage 26, and scanned and exposed on the CCD sensor 28 via the imaging lens 27. Are read by the CCD sensor 28.

  At this time, since the illumination light source 21 mounted on the first carriage 23 is always lit in the document movement reading mode, the temperature of the illumination light source 21 rises.

  By the way, in the first embodiment, the illumination light source 21 is fixed to the arc-shaped portion 34 of the holding member 32 provided in the first carriage 23 by bonding via the adhesive 33 having high thermal conductivity. The heat of the illumination light source 21 is transmitted to the first carriage 23 via the arcuate portion 34 of the holding member 32 and is released to the outside via the heat radiation fin provided on the holding member 32.

  Therefore, in the first embodiment, as shown in FIG. 4, the temperatures of the first carriage 23 and the illumination light source 21 do not increase unintentionally, and the temperature of the illumination light source 21 increases in the document movement reading mode. Accordingly, it is possible to avoid the adverse effects caused by the decrease in the light amount (illuminance) of the light source, the variation in the light amount, and the temperature of the member such as the second platen glass 6 disposed in the vicinity of the reading position. ing. 4A and 4B, solid lines indicate the characteristics of an image reading apparatus that does not have a conventional heat dissipation function, and broken lines indicate characteristics of an image reading apparatus that has a heat dissipation function of the present invention.

  Further, in the first embodiment, it is only necessary to provide the holding member 32 on the first carriage 23, and it is not necessary to provide a heat radiating member such as a heat radiating member or a fan as a separate member, and the cost increases due to an increase in the number of parts. Is not invited.

Embodiment 2
FIG. 5 shows a second embodiment of the present invention. The same parts as those of the first embodiment are denoted by the same reference numerals. In the second embodiment, the first carriage is At the reading position in the document moving reading mode, the reading device housing is configured to be in contact with the reading position through the heat conducting member.

  That is, in the second embodiment, as shown in FIG. 5, the heat conducting member 40 made of a synthetic resin or the like whose thermal conductivity is increased by filling the tip surface 23a of the first carriage 23 with a metal or a filler. The first carriage 23 is configured to come into contact with the frame 2 of the image reading apparatus housing 1 via the heat conducting member 40 at the reading position in the document moving reading mode. .

  In the second embodiment, even when the heat radiation fin 36 of the first carriage 23 cannot sufficiently radiate heat, as shown in FIG. 5, the first carriage 23 is heated at the reading position in the document movement reading mode. Since it is configured to come into contact with the frame 2 of the image reading apparatus casing 1 via the conductive member 40, the heat of the first carriage 23 is transmitted to the frame 2 of the image reading apparatus casing 1 via the heat conductive member 40. It is possible to more effectively prevent the temperature of the first carriage 23 and the illumination light source 21 from rising unintentionally.

  The heat conducting member 40 is not limited to being provided on the first carriage 23 side, but may be provided on the frame 2 side of the image reading apparatus housing 1.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

  Further, the arc-shaped portion 34 of the holding member 32 may be configured to have a function of an auxiliary reflector that reflects the light of the illumination light source 21 toward the document 3 by appropriately setting the curvature and direction thereof. .

FIG. 1 is a plan view showing the main part of an image reading apparatus according to Embodiment 1 of the present invention. FIG. 2 is a sectional configuration diagram showing the image reading apparatus according to Embodiment 1 of the present invention. FIG. 3 is a plan view showing the principal part of a modification of the image reading apparatus according to Embodiment 1 of the present invention. FIG. 4 is a graph showing the operation of the image reading apparatus according to Embodiment 1 of the present invention. FIG. 5 is a plan view showing the main part of an image reading apparatus according to Embodiment 2 of the present invention.

Explanation of symbols

  1: Image reading device housing, 2: Metal frame, 3, 3 ′: Document, 4: First platen glass, 6: Second platen glass, 21: Illumination light source, 23: First carriage, 26: Second carriage, 32: holding member, 33: adhesive.

Claims (5)

While the scanning optical system including the first and second carriages for reading the original image is stopped at a predetermined reading position while illuminating the original image with a light source mounted on the first carriage, In an image reading apparatus having a document moving reading mode for reading an image of the document while conveying the document so as to pass through a reading position at a constant speed,
An image reading apparatus, wherein the light source is mounted in close contact with the first carriage, and the light source holding function and the heat radiation function are combined by the first carriage. 2. The image reading apparatus according to claim 1, wherein the first carriage is configured to contact a reading device housing via a heat conductive member at a reading position in the document movement reading mode. The image reading apparatus according to claim 1, wherein the light source is fixed to the first carriage by bonding through an adhesive having high thermal conductivity. 4. The image reading apparatus according to claim 1, wherein a member for mounting the light source of the first carriage is integrally provided with a heat radiation fin. 5. The image according to claim 1, wherein a member for mounting the light source of the first carriage also has a function as a reflecting member that reflects light of the light source to a document. Reader.

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