JP2007293064A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of effectively discharging heat from the vicinity of a document placing member for placing a document without making the image reader large in size, and then, capable of suppressing an increase in temperature near a document passing position. <P>SOLUTION: The image reader has a document moving/reading mode of reading the document image while conveying the document at a fixed speed in a state where a scanning optical system for reading the document image while irradiating the document image with light from the light source is stopped in a prescribed reading position, wherein an air flow forming means for forming an air flow near the reading position when the document moving/reading mode is selected so that external air may flow in near the reading position in the document moving/reading mode is provided, and also, a weight coefficient calculating means for calculating the weight coefficient in reversely diffusing a signal for every sub carrier is provided. <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 state in which reading means for reading an image of a document is stopped at a predetermined position Thus, the present invention relates to an image reading apparatus having a document moving reading mode in which an image of the document is read by a reading unit while the document is conveyed at a constant speed.

Japanese Utility Model Publication No. 3-105585

  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 an original 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. By moving a scanning optical system composed of a full rate mirror and a half rate mirror, an image of an original is read.

  In the image reading apparatus, the scanning optical system including the light source, the full-rate mirror, and the half-rate mirror is stopped at a predetermined reading position in addition to the fixed document reading mode in which the original is placed on the platen glass. In many cases, the apparatus is configured to include a document moving reading mode in which the document is conveyed at a constant speed and the image of the document is read through the stopped scanning optical system.

  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 Japanese Utility Model Laid-Open No. 3-105585 has been proposed.

In the image reading apparatus according to Japanese Utility Model Laid-Open No. 3-1055853, a document image facing the transparent plate of a document conveyed along one surface of a fixed transparent plate is arranged on the other surface side of the transparent plate. In an image reading apparatus that optically reads through the transparent plate by a document reading means,
On one surface side of the transparent plate, a heat radiating means for radiating heat in the vicinity of the transparent plate is provided with an interval from the transparent plate forming a document transport path.

  However, the conventional technique has the following problems. That is, in the case of the image reading apparatus according to Japanese Utility Model Laid-Open No. 3-105853, a document transport path is formed from the transparent plate on one surface side of the transparent plate, that is, on the side on which the document is placed. A heat dissipating means for dissipating heat in the vicinity of the transparent plate is provided at an interval, and an air layer serving as a document transport path is interposed between the heat dissipating means and the transparent plate. It is difficult to obtain a sufficient heat dissipation efficiency, and there is a concern that the temperature inside the document reading unit disposed on the other surface side of the transparent plate may be unintentionally increased.

  In the case of the image reading apparatus according to Japanese Utility Model Laid-Open No. 3-105585, a heat radiating fin is used as a heat radiating means disposed at a distance from the transparent plate to form a document transport path. In order to obtain a sufficient heat radiating effect by the heat radiating fin, the heat radiating fin has a structure having a certain size, and there is a problem that the size of the image reading apparatus is increased.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a document placing member on which a document is placed without causing an increase in the size of the apparatus. An object of the present invention is to provide an image reading apparatus that can effectively radiate and cool the surroundings and can suppress an increase in temperature in the vicinity of the document passage position.

That is, according to the first aspect of the present invention, the original is moved at a constant speed while the scanning optical system for reading the original image is stopped at a predetermined reading position while illuminating the original image with a light source. In an image reading apparatus having a document movement reading mode for reading an image of the document while transporting,
An air flow forming means for forming an air flow in the vicinity of the reading position in the document movement mode so that external air flows in the vicinity of the reading position in the document movement reading mode. An image reading apparatus.

  According to a second aspect of the present invention, the airflow forming unit separates at least a part of the document pressing member adjacent to the reading position in the document movement mode from the document placement unit, thereby The image reading apparatus according to claim 1, wherein an air flow through which external air flows is formed between the document pressing member and the document placement portion.

  Furthermore, the invention described in claim 3 is the image reading apparatus according to claim 2, wherein the document pressing member includes a flow path through which air flows.

  According to a fourth aspect of the present invention, the airflow forming means includes air blowing means for forcibly forming an airflow in the vicinity of the reading position in the document movement reading mode. An image reading apparatus according to claim 1.

  According to the present invention, the surroundings of the document placing member on which the document is placed can be effectively radiated and cooled without increasing the size of the apparatus, and the temperature in the vicinity of the document passing position rises. It is possible to provide an image reading apparatus capable of suppressing 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 (ADF) 5 serving as a platen cover for pressing the document 3 is disposed on the platen glass 4 so as to be freely opened and closed. In addition, the upper end surface of the image reading apparatus housing 1 has a width for reading an image of the original 3 while conveying the original 3 at a constant speed to the left end of the first platen glass 4. A narrow second platen glass 6 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 feeder 9 that automatically feeds the document 3 at the left end of the document pressing member 8. The document transport unit 9 feeds the document 3 placed on the document loading tray 10 in a state where the document 3 is fed by the paper feed roll 11 and separated one by one by the nudger roll 12 and the feed roll 13. When the paper 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, 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 scanning unit 23 on which an illumination light source 21 including a xenon lamp that illuminates and a full rate mirror 22 that reflects a reflected light image from the document 3 in the horizontal direction is mounted is disposed. A second scanning unit 26 to which two half-rate mirrors 24 and 25 that reflect the reflected light image of the original 3 reflected by the above-described reflection are attached. As shown in FIG. 1, the first and second scanning units 23 and 26 are slidably attached to the image reading apparatus along the horizontal direction by guide rails 27 arranged along the sub-scanning direction. It has been. In addition, the first and second scanning units 23 and 26 are configured so that the first scanning unit 23 extends in the scanning direction by a driving pulley that is rotationally driven by a driving motor (not shown) and a tension wire that is moved by the driving pulley. The second scanning unit 26 is movable at a predetermined moving speed (1/2) V along the scanning direction. As a result, the first and second scanning units 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 document movement reading mode, the first and second scanning units 23 and 26 stop at the reading position where the first scanning unit 23 is located directly below the second platen glass 6 as shown in FIG. The image of the document 3 moving at a constant speed on the second platen glass 6 is read.

  Further, as shown in FIG. 2, an imaging lens 27 that forms an image of the document 3 that is scanned and exposed by the first and second scanning units 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, 1200 dpi or 2400 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). The image processing / control circuit 31 performs predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color / moving editing, etc. on the image data of the document 3. Image data is output. Further, 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 scanning units 23 and 26. Yes.

  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, while illuminating an image of a document with a light source and stopping the scanning optical system that reads the image of the document at a predetermined reading position, the document is conveyed at a constant speed, In an image reading apparatus having a document movement reading mode for reading an image of the document, in the vicinity of the reading position in the document movement mode so that external air flows in the vicinity of the reading position in the document movement reading mode. The air flow forming means for forming the air flow is provided.

  Further, in this embodiment, the airflow forming unit separates at least a part of the document pressing member adjacent to the reading position in the document movement mode from the document placing portion, thereby An air flow through which external air flows is formed between the document placement portion and the document placement portion.

  That is, the image reading apparatus according to this embodiment includes a document pressing member 8 on the upper portion of the first platen glass 4 as shown in FIGS. The document pressing member 8 is formed by an elastic member 8a such as a sponge for pressing the document 3 on the first platen glass 4, and a white synthetic resin sheet 8b bonded to the lower end surface of the elastic member 8a. Has been. Further, the document pressing member 8 is formed, for example, by a frame body 8c made of synthetic resin or the like around the lower end surface thereof, and by a hinge member on the back side of the automatic document feeder 5 via the frame body 8c. The front side (front side) of the document pressing member 8 is openable and closable.

  Further, as shown in FIG. 4, the image reading apparatus housing 1 includes an eccentric cam 40 and a solenoid 41 that drives the eccentric cam 40 on the front side (front side) of the first platen glass 4. Two sets of the first platen glass 4 are arranged across the width direction. The eccentric cam 40 rotates as shown in FIG. 4 by driving the solenoid 41 at a predetermined timing in the document movement reading mode, and pushes up the front side (front side) of the document pressing member 8. A gap G is formed between the first platen glass 4 and the document pressing member 8, and an air flow is formed so that external air flows. Therefore, in the document movement reading mode, external air flows into the reading position through the gap G formed between the first platen glass 4 and the document pressing member 8, and the reading position in the document movement reading mode. The vicinity of the second platen glass 6 is cooled.

  In place of the solenoid 41, a clutch, a magnet, a motor, or the like can be used. An actuator, a spring, or the like can be used as a substitute for the eccentric cam 40.

  In the above configuration, in the image reading apparatus according to this embodiment, the surroundings of the document placing member on which the document is placed can be effectively radiated without causing an increase in the size of the apparatus as follows. It is possible to cool, and it is possible to suppress an increase in the temperature in the vicinity of the document passage position.

  That is, in the image reading apparatus according to the first embodiment, as shown in FIG. 2, the first and second scanning units 23 and 26 move to the left end portion of the image reading apparatus housing 1 in the document movement reading mode. Then, the first scanning unit 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 scanning unit 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 reflects the reflected light image from the document 3. Is reflected by the full-rate mirror 22 of the first scanning unit 23 and the two half-rate mirrors 24 and 25 of the second scanning unit 26, and is scanned and exposed on the CCD sensor 28 via the imaging lens 27. The image of the document 3 is read by the CCD sensor 28.

  At this time, since the illumination light source 21 mounted on the first scanning unit 23 is always lit in the document movement reading mode, the temperature of the illumination light source 21 rises, and the temperature of the illumination light source 21 is increased by the heat of the illumination light source 21. One scanning unit 23 itself is heated, and the temperature of the first scanning unit 23 also rises.

  By the way, in the image reading apparatus according to this embodiment, as shown in FIG. 1, when the document moving reading mode is designated by a user interface (not shown) or the like, the solenoid 41 is driven, as shown in FIG. The eccentric cam 40 is rotated, and the front side (front side) of the document pressing member 8 is pushed up by the eccentric cam 40 to form a gap G between the first platen glass 4 and the document pressing member 8. It has become.

  Therefore, in the image reading apparatus, as shown in FIG. 1, in the document movement reading mode, external air from the surroundings passes through a gap G formed between the first platen glass 4 and the document pressing member 8. An air flow is formed so that the air flows into the reading position. Therefore, in the document movement reading mode, external air flows into the reading position through the gap G formed between the first platen glass 4 and the document pressing member 8, and the reading position in the document movement reading mode. The vicinity of the second platen glass 6 is effectively cooled. Therefore, it is possible to prevent the temperature of the member disposed near the reading position of the image reading apparatus and the illumination light source 21 of the first scanning unit 23 from unintentionally rising.

  For this reason, in the first embodiment, the temperatures of the first scanning unit 23 and the illumination light source 21 do not increase unintentionally. It is possible to avoid adverse effects associated with a decrease in the amount of light, variation in the amount of light, and an increase in the temperature of a member such as the second platen glass 6 disposed in the vicinity of the reading position.

  Further, in the first embodiment, it is only necessary to provide the eccentric cam 40 that pushes up the front side (front side) of the document pressing member 8 and the solenoid 41, so that the size of the apparatus is not increased.

  In the illustrated embodiment, the case where the eccentric cams 40 respectively disposed on both sides of the document pressing member 8 are driven by the solenoids 41 provided corresponding to the eccentric cams 40 has been described. As shown, the eccentric cams 40 respectively disposed on both sides of the document pressing member 8 are driven by a single solenoid 41 via a link mechanism 42, whereby the number of parts can be reduced and the size of the apparatus can be reduced. And cost reduction.

Embodiment 2
8 and 9 show the second embodiment of the present invention. The same parts as those in the first embodiment will be described with the same reference numerals. In the second embodiment, the document presser will be described. Rather than pushing up only the front side (front side) of the member 8, the first platen glass 4 and the document pressing member 8 are moved upward by pushing up the entire document pressing member 8, that is, the four corners of the document pressing member 8. The gap G is formed on the entire surface between the two.

  That is, in the second embodiment, as shown in FIGS. 8 and 9, eccentric cams 40 and solenoids 41 are respectively arranged at the four corners of the document pressing member 8, and by driving each solenoid 41, As shown in FIGS. 10 and 11, the entire document pressing member 8 is moved upward by the eccentric cams 40 provided at the four corners of the document pressing member 8, so that the first platen glass 4 and the document pressing member 8 are moved. The gap G is formed on the entire surface between the two.

  In the second embodiment, since the gap G is formed on the entire surface between the first platen glass 4 and the document pressing member 8, the first platen glass 4 and the document pressing member 8 The outside air flows into the reading position through the gap G formed on the entire surface during the period, and the vicinity of the second platen glass 6 that is the reading position in the document moving reading mode is further effectively cooled. can do. Therefore, it is possible to more reliably prevent the temperature of the member disposed in the vicinity of the reading position of the image reading apparatus and the illumination light source 21 of the first scanning unit 23 from being unintentionally increased.

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

Embodiment 3
FIG. 12 shows Embodiment 3 of the present invention. The same reference numerals are given to the same parts as those in Embodiment 1, and in this Embodiment 3, the airflow forming means is In the vicinity of the reading position in the document moving reading mode, an air blowing means for forcibly forming an air flow is provided.

  That is, in the third embodiment, as shown in FIG. 12, a blower fan 50 as an air flow forming unit is disposed at the left end of the document pressing member 8, and the duct 51 is provided by the blower fan 50. The air sent through the air passes through a plurality of air ventilation grooves 52 formed inside the document pressing member 8, and external cold air is moved to a reading position near the second platen glass 6 in the document movement reading mode. It is configured to be sent. The cross-sectional shape of the ventilation groove 52 may be a V-shaped cross section as shown in FIG. 13 or a circular cross-section as shown in FIG.

  For this reason, in the third embodiment, the reading position in the vicinity of the second platen glass 6 can be forcibly cooled in the document movement reading mode, and members disposed near the reading position of the image reading apparatus can be used. In addition, the temperature of the illumination light source 21 of the first scanning unit 23 can be more reliably prevented from unintentionally increasing.

  In the third embodiment, the blower fan 50 is not limited to the case where the blower fan 50 is disposed at the right end portion of the document pressing member 8, and the blower fan 50 is disposed at the left end of the document conveying portion 9 as shown in FIG. It may be arranged in the section and blown to the vicinity of the reading position of the image reading apparatus by the blower fan 50.

  Even in this case, as shown in FIG. 15, by providing a plurality of air ventilation grooves 52 having a V-shaped cross section inside the document pressing member 8, the document is passed through the plurality of air flow paths. In the moving reading mode, the air can be exhausted to the outside by being warmed at the reading position of the image reading apparatus, and the reading position in the vicinity of the second platen glass 6 can be forcibly cooled.

  Note that the first platen glass 4 and the first platen glass 4 can be combined with the first or second embodiment and the third embodiment by moving at least a part of the document pressing member 8 upward during blowing by the blower fan 50. Even if the gap G is formed with the document pressing member 8, the reading position in the vicinity of the second platen glass 6 can be more effectively cooled.

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

FIG. 1 is a cross-sectional configuration diagram showing a 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 cross-sectional configuration diagram showing the main part of the image reading apparatus according to Embodiment 1 of the present invention. FIG. 4 is a cross-sectional configuration diagram showing the main part of the image reading apparatus according to Embodiment 1 of the present invention. FIG. 5 is a main part explanatory view showing the operation of the image reading apparatus according to Embodiment 1 of the present invention. FIG. 6 is a main part explanatory view showing the operation of the image reading apparatus according to Embodiment 1 of the present invention. FIG. 7 is a main part configuration diagram showing a modification of the image reading apparatus according to Embodiment 1 of the present invention. FIG. 8 is a side configuration diagram showing a main part of an image reading apparatus according to Embodiment 2 of the present invention. FIG. 9 is an explanatory view showing the operation of the image reading apparatus according to Embodiment 2 of the present invention. FIG. 10 is an explanatory view showing the operation of the image reading apparatus according to Embodiment 2 of the present invention. FIG. 11 is an explanatory view showing the operation of the image reading apparatus according to Embodiment 2 of the present invention. 12 is a block diagram showing an image reading apparatus according to Embodiment 3 of the present invention. FIG. 13 is a cross-sectional configuration diagram showing a ventilation groove. FIG. 14 is a cross-sectional configuration diagram showing a ventilation groove. FIG. 15 is a block diagram showing a modification of the image reading apparatus according to Embodiment 3 of the present invention. FIG. 16 is a cross-sectional configuration diagram showing a ventilation groove.

  1: image reading device housing, 3: document, 4: first platen glass, 8: document pressing member, 23, 26: first and second scanning units, 40: eccentric cam, 41: solenoid.

Claims (4)

Document movement for reading an image of the original while illuminating the image of the original with a light source and transporting the original at a constant speed while a scanning optical system for reading the image of the original is stopped at a predetermined reading position In an image reading apparatus having a reading mode,
An air flow forming means for forming an air flow in the vicinity of the reading position in the document movement mode so that external air flows in the vicinity of the reading position in the document movement reading mode. Image reading device. The airflow forming unit separates at least a part of the document pressing member adjacent to the reading position in the document movement mode from the document placing unit, thereby allowing the airflow forming unit to be interposed between the document holding member and the document placing unit. The image reading apparatus according to claim 1, wherein an air flow through which external air flows is formed. The image reading apparatus according to claim 2, wherein the document pressing member includes a flow path through which air flows. The image according to any one of claims 1 to 3, wherein the airflow forming unit includes a blowing unit that forcibly forms an airflow in the vicinity of a reading position in the document movement reading mode. Reader.

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