JP2007074445A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader with which productivity is improved. <P>SOLUTION: In the image reader which reads image by arranging a scanner unit 32 to a substantially fixed position, irradiating a document P to be fed with light from a light source 33 and detecting reflected light condensed by a lens 37 by a CCD sensor 38, an aperture 16 provided to a casing 15 is blocked by contact glass 311, a white member 312 for obtaining the reference value of shading compensation is arranged on the contact glass 311, and the contact glass 311 is moved so that the white member 312 is arranged at a reflection position for reflecting the light from the light source 33 with a timing, when the reference value of the shading compensation should be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus, and in particular, irradiates a conveyed document with light from a light source arranged at a fixed position, and detects an original image by detecting reflected light collected by a lens with a sensor. The present invention relates to an image reading apparatus for reading.

  In the image reading apparatus, a document sequentially conveyed by an automatic document feeder (ADF) is irradiated with light from a light source arranged and fixed at substantially the same position in the image reading apparatus casing, and reflected light is reflected. Some of them read images sequentially by detecting. Such a panning type image reading apparatus includes, for example, a contact optical system as disclosed in Patent Document 1, and a reduction optical system that collects reflected light with a lens and detects it with a sensor such as a CCD. There are things.

  In the image reading apparatus as described above, the reflected light is collected in the case of a reduction optical system, in addition to the temporal variation of the light emission amount of the light source, the variation due to the temperature variation, the variation of the sensitivity of the photoelectric conversion unit such as CCD. There are fluctuations in the reading density due to the cosine fourth law of the shining lens, and so-called shading correction is performed in order to prevent deterioration in image quality due to these fluctuations. When performing shading correction, it is common to acquire white reference data by moving the light source to the position where the white reference plate for obtaining the reference value is provided, and to perform correction using the obtained white reference data It is.

JP-A-10-304195

JP 2001-272829 A

  For example, when a xenon lamp is used as the light source, 3 to 4 times of shading (acquisition of white reference data) is performed in the initial one minute in order to correct the light amount deterioration with time. When a hot cathode tube or a cold cathode tube is used as the light source, the number of shadings may be further increased. As described above, when the light source is moved during the shading correction, there is a limit in improving the number of documents that can be read within a predetermined time (for example, 1 minute), that is, productivity.

  The present invention has been made in view of such problems, and an object thereof is to provide an image reading apparatus capable of further improving productivity.

  In order to solve the above problems, an image reading apparatus according to the present invention irradiates light from a light source arranged at a fixed position inside a housing onto a conveyed document and is condensed by a lens. An image reading apparatus for reading a document image by detecting reflected light with a sensor, which closes an opening provided in the casing through which light from the light source passes when reading a document image. A contact glass provided with a white reference region for reflecting a light from the light source to obtain a reference value for shading correction, and a moving means for moving the contact glass while closing the opening And a control means for controlling the timing for obtaining the reference value for shading correction, and the reflected light reflected on the white reference region is detected by the sensor to obtain the reference value for shading correction. The contact glass is arranged at a position where the light from the light source passes through the opening and is irradiated on the document at the timing of reading the document image, and the moving unit includes: The contact glass is moved at the timing of obtaining the reference value for the shading correction so that the white reference region is disposed in a reflection position within the opening and reflecting the light from the light source. .

  In the configuration of the present invention, a white reference region is provided in a part of the contact glass, and the moving means reflects the light from the light source when the white reference region is within the opening at a timing to obtain a reference value for shading correction. The contact glass is moved so as to be arranged at the reflection position. In this case, since the contact glass is transparent, the white reference area can be moved while the document is being read, which contributes to an improvement in productivity.

  It is preferable that the white reference region is provided by fixing a belt-shaped member whose contact glass side is white and whose longitudinal direction coincides with the main scanning direction to the document side surface of the contact glass. This is because the document is often conveyed while being in contact with the surface of the contact glass, and the height of the reflection position of the light from the light source in the white reference region substantially matches the document reading height, which is suitable for acquiring the reference data. .

The band-shaped member may be a film or sheet-shaped member, but is not limited thereto. Basically, it is possible to use the same members as those used for obtaining the reference value for the conventional shading correction.
The moving means moves the white reference area at a timing from when an image of one original is read to when the next original is conveyed to an image reading position when a plurality of originals are conveyed. It can be set as the structure moved to a reflective position.

  The control means controls the timing so as to acquire a plurality of reference values at different positions in the sub-scanning direction in the white reference area as a reference value for shading correction, and the moving means The contact glass can be moved so that the white reference region moves. By setting the peak value of the reference value acquired a plurality of times as the white reference value, it is possible to reduce the influence of noise caused by dust or the like adhering to the contact glass.

  The image reading apparatus according to the present invention has an effect that productivity can be further improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a copying machine equipped with the image reading apparatus according to the present invention will be described as an example.
(1) Configuration of copying machine 100

  Hereinafter, the configuration of the copying machine 100 according to the present embodiment will be described. FIG. 1 is a schematic cross-sectional view showing the overall configuration of the copying machine 100. The copying machine 100 includes an automatic document feeder (hereinafter referred to as “ADF”) 10, a scanner unit 30, an image processing unit 40, a printer unit 50, and a paper feeding unit 70. An operation panel unit 150 as a user interface is disposed on the upper part of the housing of the copying machine 100. The operation panel 150 includes an operation unit 151 provided with a plurality of keys for inputting numbers and the like, a start key for instructing start of copying (starting reading of an original), and a message to the user. A liquid crystal touch panel 152 is provided on which a screen for giving instructions and a screen for a user to input processing contents are displayed (see FIG. 3).

  The ADF 10 automatically transports the document placed on the document tray 11 to the document discharge tray 13 and allows the scanner unit 30 to read the document while the document passes through the transported document reading unit 14. It is of the shooting type. While reading the original conveyed by the ADF 10, the scanner unit 32, the mirror unit 321 and the like of the scanner unit 30 are fixedly arranged at substantially the same original reading position.

  Further, the scanner unit 30 moves the scanner unit 32 and the like in the direction of arrow a to place the image of the document placed on the platen glass 31 and the position of which is fixed by the document pressing surface 12 of the ADF 10 optically. Read on. The scanner unit 30 includes a scanner unit 32, a mirror unit 321, a lens 37, a CCD sensor 38, a scanner motor M2, and the like. The scanner unit 32 includes a light source 33 and a mirror 34 for changing the optical path of light reflected from the original by irradiation of the light source 33 in a direction parallel to the platen glass 31, and is driven by a scanner motor M2 in the direction of arrow a in the figure. The original on the platen glass 31 is scanned by moving to. Reflected light from the document is reflected by the mirror 34 and then guided to the CCD sensor 38 via the mirrors 35 and 36 and the lens 37, where it is converted into an electrical signal to generate an image signal.

  The generated image signal is A / D converted by the image signal processing unit 39 to become a digital signal, which is subjected to image processing such as shading correction and density conversion processing using white reference data, and then page by page. Is stored in the memory unit 41 as original document image data. The document image data stored in the memory unit 41 is subjected to image processing such as image enlargement or reduction in the image processing unit 40 as necessary, and then sent to the print processing unit 42. The print processing unit 42 generates a drive signal for the laser diode (LD) 51. The printer unit 50 forms an image based on the generated drive signal.

  The printer unit 50 forms an image on a recording sheet by a known electrophotographic method. The print processing unit 42 generates a drive signal for the LD 51, drives the LD 51 based on the drive signal, and emits laser light. The laser beam is reflected by the mirror surface on the side of the polygon mirror 52 that rotates at a predetermined angular velocity, and exposure scans the surface of the photosensitive drum 56 that is driven to rotate in the direction of arrow b via the fθ lens 53 and the mirrors 54 and 55. To do.

  A cleaning unit 57, an eraser lamp (not shown), a charging charger 58, and a developing device 59 are provided around the photosensitive drum 56, and detailed description of these operations is omitted. The paper feed unit 70 is provided with two cassettes 71 and 72, and a recording sheet having a required size is stored in either one of the cassettes 71 and 72 in synchronization with the exposure and development operations of the photosensitive drum 56. Paper is fed from. The fed recording sheet is conveyed below the photosensitive drum 56, and the toner image formed on the surface of the photosensitive drum 56 is transferred to the surface of the recording sheet.

  Thereafter, the recording sheet is separated from the surface of the photosensitive drum 56 and conveyed to the fixing unit 63 by the conveying belt 62. In the fixing unit 63, the toner image transferred on the surface of the recording sheet is fixed. The recording sheet after fixing is discharged onto a paper discharge tray 66. Note that the paper conveyance and the driving of the photosensitive drum 56 as described above are controlled by the main motor M1.

  FIG. 2 is a diagram illustrating an example of a hardware configuration in the copying machine 100 according to the present embodiment. As shown in the figure, the operation of each part (including the main motor M1 and the scanner motor M2) such as the ADF 10, the scanner part 30, the printer part 50, the paper feeding part 70, the display on the liquid crystal touch panel 152, and the like are performed by the CPU 201. Be controlled. In addition, input to the operation unit 151 and the liquid crystal touch panel 152 by the user is input to the CPU 201. Various storage devices such as a ROM 210, a RAM 220, and a hard disk 230 are connected to the CPU 201. The control of each unit is realized by the programs stored in the ROM 210 and the programs stored in the hard disk 230 and loaded in the RAM 220 operating on the CPU 201. A nonvolatile rewritable semiconductor memory can also be used as the ROM 210 or the RAM 220.

(2) Configuration of Transported Document Reading Unit 14 The configuration of the transported document reading unit 14 will be described below. The portion shown in FIG. 1 as the transported document reading unit 14 of the present embodiment is configured to capture an image from a document transported from the document tray 11 toward the document discharge tray 13 in the above-described panning image reading mechanism. This is the part to read. FIG. 3 is a perspective view showing a state where the ADF 10 part is opened upward, and FIGS. 4 and 5 illustrate the mirror unit 321 for convenience of explanation, the position of the mirror unit 321 when the scanner unit 32 is fixed below the transported document reading unit 14 is the characteristics of the lens 37 and the like. It is not necessarily arranged at the position shown in the figure.

  As shown in FIG. 3, the lower surface of the ADF 10 (the surface facing the platen glass 31) is a document pressing surface 12 that holds the document placed on the platen glass 31. The document transported from the document tray 11 to the document transport tray 13 passes above the opening 16 provided in the housing 15 for reading the document in the unit 14.

  As shown in FIG. 4, when reading a document image in the transported document reading unit 14, the position of the scanner unit 32 is below the opening 16 provided in the resin casing 15 for reading the document. Light from the light source 33 is applied to the original P which is fixed and conveyed from the original tray 11 toward the original discharge tray 13 by the original conveying roller pair 141 and 142, and reflected light from the original P is emitted from the CCD sensor 38. Detect and read the original image. Although a slight gap is opened between the contact glass 311 and the original P in the drawing, the original P often contacts the surface of the contact glass 311 in practice.

  Although the opening 16 is closed by the contact glass 311, in this embodiment, a white reference area for obtaining shading correction white reference data is fixed on the surface of the contact glass 311 on the original P side. While being provided, the contact glass 311 is configured to be reciprocally movable in the direction of arrow c in FIG. The white reference region has a strip shape whose longitudinal direction coincides with the main scanning direction (direction perpendicular to the drawing), and at least the contact glass 311 side is a resin film or sheet-like member 312 (hereinafter “white member 312”). Can be affixed).

  As the white member 312, for example, a white polypropylene sheet can be used, and the same material as conventionally used can be used, and it is not necessary to have a thickness as shown in FIG. 4 (in the present embodiment). 0.3 mm). Note that the white member 312 can be attached using an adhesive, for example, at the end of the white member 312 (the portion that cannot be read when acquiring the white reference data). Further, the white member is used when the transported document reading unit 14 is transported and placed on the platen glass 31 by appropriately adjusting the positional relationship among the platen glass 31, the contact glass 311, and the white member 312. 312 can also be shared.

  As shown in FIG. 5, when acquiring the white reference data, the contact glass 311 is moved so that the white member 312 is disposed in the reflection position where the white member 312 is in the opening 16 and reflects the light from the light source 33. Let As described above, when the document P is conveyed, the reading surface of the document P is often in contact with the contact glass 311, and the white member 312 is attached to the surface of the contact glass 311 on the document P side, thereby The height of the reflection position of the light from the light source 33 substantially coincides with the document reading height, which is suitable for obtaining reference data.

  Although detailed illustration of a configuration for moving (reciprocating) the contact glass 311 in the arrow c direction (sub-scanning direction) is omitted, the contact glass 311 is fixed to a fixing member as disclosed in Patent Document 2, for example. However, a configuration in which the reciprocating motion is configured by a rotating cam or the like and moved is conceivable. The configuration of the moving means is not limited to this, and any configuration that can be appropriately moved in the direction of the arrow c, such as providing a gear groove in the contact glass 311 or the fixing member to transmit the driving force of the motor, may be used.

  FIG. 6 is a timing diagram for explaining the timing of acquiring the white reference data and the movement of the white member 312 at that time. As shown in FIG. 5, when white reference data is acquired at an interval between the reading timing of the document P1 and the reading timing of the document P2, the contact glass 311 is gradually moved at the reading timing of the document P1 (TS in FIG. 5). Represents the moving speed of the contact glass 311.) After the reading of the first original P1, the end of the white member 312 faces from the opening 16.

  Thereafter, the contact glass 311 continues to move, and after the white member 312 reaches the white reference data acquisition position, the white reference data is acquired. The white reference data is acquired a plurality of times (for example, 100 to 200 lines) so that the white reference data is acquired at different positions of the white member 312 while the contact glass 311 is moved at a constant speed (not necessarily constant). )It can be carried out.

  The white reference data acquisition timing can be instructed by, for example, the CPU 201 as the timing at which the image signal processing unit 39 samples the output value of the CCD sensor 38. By setting the peak value of the white reference data acquired a plurality of times as the white reference, it is possible to reduce the influence of noise caused by dust or the like adhering to the contact glass 311.

  The contact glass 311 is moved in the same direction as it is, and after the acquisition of the white reference data is finished, the moving speed of the contact glass 311 is reduced, and after the white member 312 disappears from the opening 16, the contact glass 311 is stopped. Then, the original P2 is read. When the white reference data is acquired again, the white reference data can be acquired in the same manner as described above by moving the contact glass 311 in the reverse direction at the document sheet interval. In the example of FIG. 7, the speed control is performed so that the original P2 is read after the contact glass 311 is stopped. However, after the white member 312 disappears from the opening 16, as shown in FIG. In addition, the original P2 can be read while the contact glass 311 is moved. This is one of the merits of fixing the white member 312 to the transparent contact glass 311 and leads to an increase in the number of readable documents (an increase in productivity).

  Note that when the light source 33 is moved during shading correction as in the prior art, the temperature of the light source 33 may be slightly lowered due to the wind pressure during the movement, and the amount of light may become unstable. When the reference data is acquired, the white reference data can be acquired while maintaining a stable light emission state. That is, it is preferable that the contact glass 311 has a shape that does not cause a temperature change of the light source 33 even if it has a non-flat shape.

(Modification)
Although the embodiment of the present invention has been described above, the content of the present invention is not limited to the specific examples described in the embodiment, and for example, the following modifications may be implemented. it can.

  (1) In the above-described embodiment, the white member 312 is attached to the contact glass 311 substantially at the center in the sub-scanning direction. However, as shown in FIG. 8, the white member 312 is attached to the end of the contact glass 311. The reference glass 311 may be reciprocated once in the direction of the arrow c at intervals of the original paper, and white reference data may be acquired during the reciprocation. With this configuration, the width of the contact glass 311 in the sub-scanning direction can be shortened, and the apparatus width can be reduced.

  (2) In the above embodiment, the case where the present invention is applied to a copying machine has been described. However, the present invention can also be applied to an image reading apparatus having no print function.

  The present invention can be applied to, for example, an image reading apparatus.

1 is a schematic cross-sectional view showing an overall configuration of a copying machine 100. FIG. 2 is a diagram illustrating an example of a hardware configuration in the copying machine 100. FIG. It is a perspective view in the state where the ADF10 portion was opened upward. FIG. 3 is a diagram schematically illustrating a configuration of a transported document reading unit 14 (a state during document reading). FIG. 6 is a diagram schematically illustrating a configuration of a transported document reading unit 14 (state when white reference data is acquired). It is a timing diagram for explaining the timing of obtaining white reference data and the movement of the white member 312 at that time. FIG. 10 is a timing chart when reading the document P2 while moving the contact glass 311. It is a figure which shows typically the structure of the conveyance original reading part 14 in the modification of this invention.

Explanation of symbols

10 ADF (automatic document feeder)
DESCRIPTION OF SYMBOLS 11 Document tray 13 Document discharge tray 141, 142 Document transport roller pair 15 Housing 16 Opening portion 30 Scanner unit 31 Platen glass 311 Contact glass 312 White member 32 Scanner unit 33 Light source 37 Lens 38 CCD sensor 40 Control unit 41 Memory unit 42 Print processing unit 50 Printer unit 70 Paper feed unit 100 Copier 201 CPU

Claims (6)

An image reading apparatus for reading a document image by irradiating a conveyed document with light from a light source arranged at a fixed position inside a housing and detecting reflected light collected by a lens with a sensor. ,
In order to obtain a reference value for shading correction by blocking light from the light source, which is provided in the housing, through which light from the light source passes during document image reading. Contact glass provided with a white reference area,
Moving means for moving the contact glass while closing the opening;
Control means for controlling timing for obtaining a reference value for shading correction;
Reference value acquisition means for detecting reflected light reflected on the white reference region by the sensor and acquiring a reference value for shading correction,
The contact glass is
At the timing of reading the document image, the light from the light source is disposed at a position where the light passes through the opening and is irradiated on the document.
The moving means is
The contact glass is moved so that the white reference region is arranged at a reflection position in the opening and reflecting the light from the light source at a timing of obtaining the shading correction reference value. Reader. The white reference region is provided on a side surface of the original of the contact glass by adhering a band-shaped member whose contact glass side is white and whose longitudinal direction coincides with the main scanning direction. The image reading apparatus described. The image reading apparatus according to claim 2, wherein the belt-like member is a film or a sheet-like member. The moving means is
When a plurality of originals are conveyed, the white reference area is moved to the reflection position at a timing after the image of one original is read and the next original is conveyed to the image reading position. The image reading apparatus according to claim 1, wherein: The control means includes
As a reference value for shading correction, the timing is controlled so as to acquire a plurality of reference values at different positions in the sub-scanning direction in the white reference region,
The moving means is
The image reading apparatus according to claim 1, wherein the contact glass is moved so that the white reference region is moved at the timing. The moving means is
The image reading apparatus according to claim 1, wherein the contact glass is also moved while the document is conveyed facing the opening.

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