JP2006191393A - Image reading apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus for reducing the raising degree of temperature, concerning a driving motor which is arranged in a moving means so as to drive a reading optical system, and prolonging a life. <P>SOLUTION: An original (a) passing through a paper passage is irradiated with the light of a lamp 1. The image information is reflected against mirrors 2-5 so as to be inputted to a CCD through a lens 19. The first mirror 2 forms a first carriage 3 together with the lamp 1. The second mirror 4 and the third mirror 5 form a second carriage 6 together with a subordinate pulley 15. The carriages 3, 6 are locked by a driving wire 14. When a white reference board 7 and a book original are read, reading is made by moving the first and second carriages 3, 6. When the first carriage 3 is driven, an electric current larger than the maximum input current value of the driving motor 11 in reading the book original is made to flow. Thus, the white reference board 7 is read in a short period of time and the operation time of the driving motor 11 is shortened by one-time shading. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention uses an image reading apparatus capable of operating in both a mode for reading a document fixed by moving a reading optical system and a mode for reading a document while fixing the reading optical system and conveying the document. The present invention relates to an image forming apparatus.

  As the image reading apparatus as described above, for example, a reading unit using a line sensor is provided, and a fixed original can be read by reading a document image line by line using a line sensor by moving a carriage with a mirror relative to the document. Many scanners equipped with an automatic document feeder that fixes a carriage at a certain reading position, separates and conveys multiple documents one by one, and moves the documents relative to each other on the reading optical axis have been put into practical use. ing.

  In such an image reading apparatus, it is possible to continuously read a document with an automatic document feeder, which is very convenient for reading a large amount of document.

However, since the characteristics of the optical component change due to the influence of temperature rise or the like due to continuous reading or aging deterioration, the value changes with time even if the same document is read. Especially for lamps, the illuminance drop during continuous lighting is large. Therefore, a technique has been proposed in which a white reference plate is read in accordance with the illuminance change rate and the read value is corrected (see, for example, Patent Document 1).
JP 2002-281254 A

  However, as described above, since the judgment is made while monitoring the illuminance reduction rate, a white reference plate for detecting the illuminance fluctuation rate is necessary, which not only increases the cost but also detects that the illuminance reduction has occurred. Therefore, there is a problem that the data immediately before that cannot be corrected.

  In addition, after reading a document, the carriage needs to move to the position of the white reference plate before the next document is read, but if it takes time to move, the number of documents that can be read per unit time Decreases, which decreases productivity.

  Further, the carriage drive motor is stopped during document reading. Although it can be excited with a low current, a high current is required to move the carriage to the white reference plate reading position. Therefore, if it takes a long time to move to the white reference plate reading position, the time during which a high current is passed becomes longer, which causes a problem that the temperature rises and the lifetime of the optical component or the like is reduced.

  However, if the white reference plate is read at a high speed, the number of reading lines (resolution) per unit reading range is reduced, and the number of lines to be read is reduced, so that the reliability of the white level is lowered.

  The present invention has been made in view of the actual situation of the prior art, and an object of the present invention is to reduce the temperature increase degree of the drive motor provided in the moving means for driving the reading optical system and to extend the lifetime. Another object is to improve the reliability of the white level.

  The mounted image reading apparatus according to the first aspect of the present invention includes a reading optical system, a document conveying unit, and a moving unit including a driving motor for driving the reading optical system, and is fixed. An image reading apparatus capable of operating in both a first mode in which a document is read while moving the reading optical system and a second mode in which the reading optical system is fixed and a document being conveyed by the document conveying means is read. In the image reading apparatus including a shading correction unit that reads a white reference plate provided outside the read original region and corrects the characteristic unevenness of the reading optical system, the white reference plate at the time of operation in the second mode. The current value of the drive motor at the time of reading is set to a value equal to or greater than that at the time of document reading during the operation in the first mode.

  According to a second aspect of the present invention, in the image reading apparatus of the first aspect, the reading optical system is driven to the white reference plate reading position when reading the white reference plate during the operation in the second mode. It is characterized by that.

  According to the third aspect of the present invention, in the image reading apparatus according to the first or second aspect, the white reference plate reading speed by the reading optical system at the time of reading the white reference plate during the operation in the second mode is The moving speed to the white reference plate reading position is set to be lower than the moving speed.

  According to the fourth aspect of the present invention, a first mode includes a reading optical system, a document conveying unit, and a moving unit for driving the reading optical system, and reads a fixed document while moving the reading optical system. And an image reading apparatus capable of operating in both modes of the second mode in which the reading optical system is fixed and the original being conveyed by the original conveying means is read, and a white reference plate provided outside the reading original area is provided. In the image reading apparatus including a shading correction unit that reads and corrects the characteristic unevenness of the reading optical system, the driving of the reading optical system at the time of reading the white reference plate during the operation in the second mode is performed by the white reference. It is characterized by the position up to the plate reading position.

  According to the fifth aspect of the present invention, in the image reading apparatus of the fourth aspect, the white reference plate reading speed by the reading optical system at the time of reading the white reference plate during the operation in the second mode is set as the white reference plate. The moving speed to the plate reading position is lower than the moving speed.

  According to the sixth aspect of the present invention, a first mode includes a reading optical system, a document conveying unit, and a moving unit for driving the reading optical system, and reads a fixed document while moving the reading optical system. And an image reading apparatus capable of operating in both modes of the second mode in which the reading optical system is fixed and the original being conveyed by the original conveying means is read, and a white reference plate provided outside the reading original area is provided. The white reference plate reading speed by the reading optical system at the time of reading the white reference plate during operation in the second mode in an image reading apparatus including a shading correction unit that reads and corrects characteristic unevenness of the reading optical system Is less than the moving speed to the white reference plate reading position.

  According to a seventh aspect of the present invention, in the image reading apparatus of the sixth aspect, the reading optical system is driven to the white reference plate reading position when reading the white reference plate during the operation in the second mode. It is characterized by that.

  An image forming apparatus according to an eighth aspect includes the image reading apparatus according to any one of the first to sixth aspects.

  In the image reading apparatus according to the present invention and the image forming apparatus using the same, the optical system can be moved to the white reference plate reading position at high speed and high acceleration, and the time required for high current can be shortened. The average current value can be suppressed, and the effect of reducing the temperature rise of the motor for driving the optical system and extending the motor life can be obtained.

  In addition, the reading speed of the white reference plate when reading the document by the document conveying means is suppressed to be less than or equal to the moving speed to the reading position of the white plate, the number of reading lines (resolution) per unit reading range is increased, and the movement of the optical system is shortened. In addition, it is possible to obtain the effect of improving the reliability of the white level.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

  FIG. 1 is a diagram showing an image forming apparatus that is an example of an object of the present invention and that includes an image reading apparatus. The image forming apparatus shown in FIG. 1 mainly includes a reading unit 121 that reads a document, an image forming unit 122 that forms an image, a sheet-through type automatic document feeder (hereinafter referred to as ADF) 123, and a document that is sent from the ADF 123. A document stacker 90 for stacking sheets, a sheet feeding unit 129 having sheet feeding cassettes 125 to 128, and a sheet discharge tray 130 for stacking recording sheets. In the image forming unit 122, a plurality of image forming units 132 are arranged in parallel on a belt-like intermediate transfer belt 131. In each image forming unit 132, a photoconductor 133 is arranged around a drum-shaped photoconductor 133. A charging device that charges the surface of the photosensitive member 133, an exposure device that irradiates the surface of the photosensitive member 133 with laser light, a developing device that visualizes the electrostatic latent image formed by exposing the surface of the photosensitive member 133, and a photosensitive member A cleaning device that removes and collects toner remaining on the body 133 is disposed.

  The illustrated example is a color image forming apparatus in which the image forming unit 132 is for yellow (Y), magenta (M), cyan (C), and black (BK), for example. While rotating, toners of yellow (Y) to black (BK) are sequentially developed and transferred to the intermediate transfer belt 131, and the four color toner images developed on the intermediate transfer belt 131 are transferred onto a sheet by a transfer device. However, the present invention is not limited to the image forming apparatus of this example, and can be applied to various types.

FIG. 2 is a cross-sectional view showing the overall layout of the image reading apparatus (reading unit 121 in the example of FIG. 1) according to the present invention.
In the figure, 1 is a lamp, 2 is a first mirror, 3 is a first carriage, 4 is a second mirror, 5 is a third mirror, 6 is a second carriage, 7 is a white reference plate, and 8 is a document scale which is also a glass presser. , 9 is a contact glass for ADF, and 10 is a contact glass. In the figure, 11 is a drive motor for driving the carriages 3 and 6, 12 is a drive transmission belt, 13 is a pulley around which the drive wire is wound, 14 is a drive wire, 15 is a driven pulley of the second carriage, and 16 is a home position side pulley. A driven pulley, 17 is a driven pulley on the CCD side, and 18 is a wire tension spring. In the figure, 19 is a lens, 20 is a CCD, and 21 is a CCD substrate. In addition, a indicates a document that passes through a sheet-passing path using a sheet-through type ADF as illustrated in FIG. 1, and b indicates an optical path.

  In this example, the document a that has passed through the sheet passing path is irradiated with the lamp 1 by a sheet-through type ADF or the like as shown in FIG. 1, and the image information thereof is reflected by the first mirror 2, the second mirror 4, and the third mirror. 5 and the image is input to the CCD through the lens 19. The first mirror 2 forms a first carriage 3 together with the lamp 1, and the second mirror 4 and the third mirror 5 form a second carriage 6 together with a driven pulley 15. The carriages 3 and 6 are respectively locked by the drive wires 14, and when the white reference plate 7 or the book document is read, the first carriage 3 and the second carriage 6 can be read. A load is applied to the drive wire 14 by a wire tension spring 18, and the drive motor 11 operates through a drive transmission belt 12 and a drive (wire) pulley 13.

  FIG. 3 is an enlarged view (A) and a carriage speed fluctuation graph (B) for explaining the first operation of this embodiment. When the first carriage 3 is driven, a current larger than the maximum input current value of the drive motor 11 at the time of reading a book document is supplied. As a result, the white reference plate 7 can be read in a short time, and the operation time of the drive motor 11 in one shading can be shortened.

  FIG. 4 is an enlarged view (A) for explaining the second operation of the present embodiment and a carriage speed fluctuation graph (B). When the first carriage 3 is driven, the carriage movement distance is set to the shortest distance (only the minimum required data amount of the white reference plate 7 is moved). Accordingly, since the white reference plate 7 is read in a short time, the operation time of the drive motor 11 in one shading can be shortened.

  FIG. 5 is an enlarged view (A) for explaining the third operation of the present embodiment and a carriage speed fluctuation graph (B). When the first carriage 3 is driven, the carriage moving speed is set to a low speed only when the white reference plate 7 is read, and the moving speed is set to the maximum. Thereby, the operation time of the drive motor 11 in one shading can be shortened, and the number of reading lines of the white reference plate 7 can be increased.

1 is a diagram illustrating an image forming apparatus that is an example of an implementation target of the present invention and includes an image reading apparatus. Sectional drawing which shows the whole layout of the image reader which concerns on this invention Enlarged view (A) for explaining the first operation of the present embodiment and a carriage speed fluctuation graph (B) Enlarged view (A) for explaining the second operation of the present embodiment and carriage speed fluctuation graph (B) Enlarged view (A) for explaining the third operation of the present embodiment and carriage speed fluctuation graph (B)

Explanation of symbols

1: Lamp 2: First mirror 3: First carriage 4: Second mirror 5: Third mirror 6: Second carriage 7: White reference plate 8: Document scale 9: Contact glass for ADF 10: Contact glass 11: Drive motor 12: Drive transmission belt 13: Pulley 14: Drive wire 15: Driven pulley 16: Driven pulley 17: Driven pulley 18: Wire tension spring 19: Lens 20: CCD
21: CCD substrate 121: reading unit 122: image forming unit 123: automatic document feeder (ADF)
90: Document stacker 125 to 128: Paper feed cassette 129: Paper feed unit 130: Paper discharge tray 131: Intermediate transfer belt 132: Image forming unit 133: Photoconductor a: Document passing through a paper passing path by ADF b: Optical path

Claims (8)

A first mode for reading a fixed document while moving the reading optical system, and a reading optical system, comprising: a reading optical system; a document conveying unit; and a moving unit including a driving motor for driving the reading optical system. An image reading apparatus capable of operating in both modes of a second mode for reading a document being conveyed by the document conveying means while fixing the system, and reading the white reference plate provided outside the reading document area In the image reading apparatus provided with the shading correction means for correcting the characteristic unevenness of the optical system,
An image reading apparatus characterized in that a current value of the drive motor at the time of reading the white reference plate at the time of operation in the second mode is set to a value greater than that at the time of document reading at the time of operation in the first mode. 2. The image reading apparatus according to claim 1, wherein the reading optical system is driven to the white reference plate reading position when reading the white reference plate during the operation in the second mode. . 3. The image reading apparatus according to claim 1, wherein the white reference plate reading speed by the reading optical system at the time of reading the white reference plate during the operation in the second mode is a moving speed to the white reference plate reading position. An image reading apparatus characterized by the following. A first optical mode for reading a fixed document while moving the reading optical system; and the reading optical system, and a reading optical system, a document conveying unit, and a moving unit for driving the reading optical system. An image reading apparatus capable of operating in both modes of a second mode for reading a document being conveyed by the document conveying means, and reading a white reference plate provided outside the read document region to cause characteristic unevenness of the reading optical system In the image reading apparatus provided with the shading correction means for correcting
The image reading apparatus according to claim 1, wherein the reading optical system is driven to the white reference plate reading position when reading the white reference plate during the operation in the second mode. 5. The image reading apparatus according to claim 4, wherein the white reference plate reading speed by the reading optical system at the time of reading the white reference plate during the operation in the second mode is equal to or less than a moving speed to the white reference plate reading position. An image reading apparatus characterized by that. A first optical mode for reading a fixed document while moving the reading optical system; and the reading optical system, and a reading optical system, a document conveying unit, and a moving unit for driving the reading optical system. An image reading apparatus capable of operating in both modes of a second mode for reading a document being conveyed by the document conveying means, and reading a white reference plate provided outside the read document region to cause characteristic unevenness of the reading optical system In the image reading apparatus provided with the shading correction means for correcting
An image reading apparatus characterized in that the white reference plate reading speed by the reading optical system at the time of reading the white reference plate during the operation in the second mode is equal to or lower than the moving speed to the white reference plate reading position. . The image reading apparatus according to claim 6, wherein the reading optical system is driven to the white reference plate reading position when reading the white reference plate during the operation in the second mode. . An image forming apparatus comprising the image reading apparatus according to claim 1.