JP2007208672A - Original reading apparatus, image forming apparatus and original reading method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise productivity of original reading even when an original is read while compensating light amount fluctuation of a light source. <P>SOLUTION: A control processing part acquires a white reference value by a first reference white board 96 in instruction of the original reading as a white reference value at an early stage and sets a compensation coefficient to the first original according to the white reference value at an early stage, a predetermined instructed operation mode, fluctuation of the white reference value and history of the compensation coefficient. In addition, the control processing part 100 simultaneously performs reading at a conveyed original reading position 78 of the original to be conveyed and acquisition of the white reference value by a second reference white board 98 in reading and newly sets a compensation coefficient to the original so as to compensate density of the read original according to ratio (change amount) of the white reference value in reading to the white reference value at an early stage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an original reading apparatus, an image forming apparatus, and an original reading method for reading an original by detecting the amount of light by reflection or transmission of the light source with respect to the original.

  2. Description of the Related Art An image reading apparatus that reads an image on a document by irradiating light from a lamp onto the document and reading reflected light from the document with a CCD is known. In this type of image reading device, in order to correct fluctuations in the amount of light received by the CCD due to fluctuations in the amount of light from the lamp, the reference data of the reflected light from the white reference plate and the sample data of the reflected light immediately before reading the document are collected In addition, it is known that the correction coefficient is obtained to cancel out the light amount fluctuation. Further, Patent Document 1 discloses an image reading apparatus capable of obtaining an appropriate correction coefficient for correcting a light amount variation even when the collection position of reflected light from a white reference plate differs depending on a reading mode or the like. To do.

JP 2002-237932 A

  However, in the above conventional example, since the position of the CCD that collects the reflected light from the white reference plate is different from the position of the CCD that collects the reflected light from the document, it takes time to move the CCD immediately before reading the document. There has been a problem that the productivity of document reading cannot be improved.

  SUMMARY An advantage of some aspects of the invention is that it provides a document reading apparatus, an image forming apparatus, and a document reading method capable of improving the productivity of document reading even when the document is read while correcting the light amount fluctuation of the light source. To do.

  In order to achieve the above object, the first feature of the present invention includes a light source, a reference light amount by irradiation of the light source, and a light amount detection means for detecting a light amount of one or more colors by reflection or transmission with respect to the document, Based on the reference light amount detected by the light amount detection means, a correction amount setting means for setting a correction amount for the document density, and the light amount detection means sets the light amount for the document according to the correction amount set by the correction amount setting means. Conversion means for converting the detected result into image data, and control means for controlling the correction amount setting means to newly set a correction amount based on a reference light amount detected by the light amount detection means together with the light amount for the document. A document reading apparatus. That is, since the light amount detection means detects the reference light amount together with the light amount with respect to the document, it is possible to improve the productivity of document reading while correcting the light amount fluctuation of the light source.

  Preferably, the apparatus further includes a document conveying device that conveys a document, and the control unit sets the correction amount based on a reference light amount detected by the light amount detecting unit together with a light amount with respect to the document conveyed by the document conveying unit. The means controls to newly set the correction amount. Accordingly, since the light amount detection unit detects the reference light amount as well as the light amount for the document even for the document conveyed by the document conveying device, it is possible to improve the productivity of document reading while correcting the light amount fluctuation of the light source. .

  Preferably, the apparatus further comprises storage means for storing a correction amount history set by the correction amount setting means, and the control means sets the correction amount setting based on the correction amount history stored by the storage means. The means controls to newly set the correction amount.

  Preferably, the storage unit stores a correction amount history in association with an operation mode for reading a document.

  Preferably, the control unit controls the correction amount setting unit to newly set a correction amount in accordance with an operation mode for reading a document.

  Preferably, the apparatus further includes a change amount determination unit that determines whether or not a change amount of the reference light amount detected by the light amount detection unit is equal to or less than a predetermined threshold, and the reference light amount detected by the light amount detection unit. When the change amount determination unit determines that the change amount is greater than a predetermined threshold, the control unit sets a new correction amount based on the reference light amount detected last by the light amount detection unit. Control to set.

  Preferably, the apparatus further includes a light amount range determining unit that determines whether or not the reference light amount detected by the light amount detecting unit is within a predetermined range, and the reference light amount detected by the light amount detecting unit is within the predetermined range. If the light amount range determination means determines that there is no, the control means controls the correction amount setting means to newly set a correction amount based on the correction amount history stored in the storage means.

  The second feature of the present invention is that a light source, a light amount detection unit that detects a reference light amount by irradiation of the light source, and a light amount of one or more colors by reflection or transmission with respect to the document, and the light amount detection unit include Based on the detected reference light amount, a correction amount setting means for setting the correction amount of the document density, and the light amount detection means detects the light amount with respect to the document according to the correction amount set by the correction amount setting means. Conversion means for converting to data, control means for controlling the correction amount setting means to newly set a correction amount based on a reference light amount detected by the light amount detection means together with the light amount for the document, and the conversion means for conversion The image forming apparatus includes an image forming unit that forms an image according to the image data.

  Preferably, the apparatus further includes a document conveying device that conveys a document, and the control unit sets the correction amount based on a reference light amount detected by the light amount detecting unit together with a light amount with respect to the document conveyed by the document conveying unit. The means controls to newly set the correction amount. Accordingly, since the light amount detection means detects the reference light amount as well as the light amount for the document even for the document conveyed by the document conveying device, the productivity of document reading and image formation is improved while correcting the light amount fluctuation of the light source. be able to.

  The third feature of the present invention is that a document density correction amount is set based on the reference light amount, and the reference light amount is newly acquired while detecting the document density with the set correction amount. In the original reading method, a correction amount for the original density is newly set based on the reference light quantity acquired in step (b).

  According to the present invention, it is possible to improve the productivity of document reading even when the document is read while correcting the light amount fluctuation of the light source.

Next, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, an outline of the image forming apparatus 10 is shown. The image forming apparatus 10 is for color, for example, and includes an image forming unit 12 and a document reading device 14. The image forming unit 12 is of a xerographic type, for example, and has a sheet feeding tray 16 on which sheets are stacked, and forms an image on a sheet supplied from the sheet feeding tray 16 to the sheet conveyance path 20. ing.

  That is, the image forming unit 12 includes a photoreceptor 22, a charger 24 that uniformly charges the photoreceptor 22, and an exposure apparatus that forms a latent image on the photoreceptor 22 uniformly charged by the charger 24. 26, a developing device 28 that visualizes the latent image on the photosensitive member 22 formed by the exposure device 26 with toner, and a primary transfer device 32 that transfers the toner image formed by the developing device 28 to the intermediate transfer belt 30. And a photoreceptor cleaner 34 for cleaning the toner remaining on the photoreceptor 22. The exposure device 26 is of, for example, a laser scanning type, and outputs an image of a document read by a photoelectric conversion element 86 (to be described later) of the document reading device 14 instead of a laser on / off signal. The developing device 28 is of a rotary type, for example, and has Y, M, C, and K four color developing devices 36a, 36b, 36c, and 36d arranged around it, and rotates so as to face the photoreceptor 22 when developing each color. To do. The primary transfer device 32 is composed of, for example, a corotron, and the transfer device 32 transfers four color toner images to the intermediate transfer belt 30. The toner image transferred to the intermediate transfer belt 30 is transferred to a sheet by the secondary transfer device 38, this sheet is sent to the fixing device 40, and the toner image is fixed to the sheet by the fixing device 40. The fixed sheet is discharged to the discharge tray 42. The toner remaining on the intermediate transfer belt 30 is scraped off by the intermediate transfer belt cleaner 44.

  Further, the image forming unit 12 is configured to select a plurality of operation modes for setting monochrome printing or color printing, image magnification, image quality, and the like via a user interface (not shown).

  A resist roll 46 is disposed in the sheet conveyance path 20. The registration roll 46 is controlled so as to temporarily stop the supplied sheet and supply the sheet to the secondary transfer device 38 in synchronization with the timing at which the toner image is formed on the intermediate transfer belt 30.

  The document reader 14 includes an automatic document feeder 48 and an optical system 50 that optically reads the document. The document reader 14 has a function of flowing and reading the document sent by the automatic document feeder 48 and is placed on the platen glass 52. And a function to read the placed document. The document reading device 14 selects a plurality of operation modes for setting a plurality of scan speeds (magnification), black and white reading or color reading, a document conveying method, a plurality of document sizes, and the like via a user interface or sensor (not shown). It has come to be.

2 and 3, the details of the document reading device 14 are shown.
The automatic document feeder 48 includes a document table 54 on which a large number of documents are placed, a document conveyance path 56 that conveys the document, and a discharge table 58 from which the document after the image is read is discharged. The document conveyance path 56 includes a main conveyance unit 60 and a reversing unit 62. The main conveyance unit 60 is formed in a U-shape, and is provided with a pickup roll 64, a feed roll 66, a pre-registration roll 68, a registration roll 70, an out roll 72, and a discharge roll 74 that constitute a conveyance device. The pickup roll 64 descends when the document is fed and picks up the document placed on the document table 54. The feed roll 66 feeds the original sent from the pickup roll 64 and supplies only the uppermost original. The pre-registration roll 68 temporarily stops the document sent from the feed roll 66 to form a loop and correct skew feeding. The registration roll 70 temporarily stops the document sent from the pre-registration roll 68 and takes a reading timing. When discharging the document, the discharge roll 74 is rotated forward and discharged to the discharge table 58 via the out roll 72 and the discharge roll 74.

  The reversing unit 62 has one end connected to the main conveyance unit 60 between the out roll 72 and the discharge roll 74, and the other end connected to the main conveyance unit 60 with a pre-registration roll 68. A reversing gate 76 is provided near one end of the reversing unit 62. When the document is reversed, the discharging roll 74 is reversed when the trailing end of the document reaches the vicinity of the discharging roll 74, and the reversing gate 76 is positioned below. The document is guided to the reversing unit 62 by being positioned at. The inversion gate 76 may be opened by the pressing force of the document and may be closed by its own weight, or an actuator for opening and closing the inversion gate 76 may be provided.

  The transport document reading position 78 is provided between the registration roll 70 and the out roll 72 so that the optical system 50 reads the document sent by the automatic document transport device 48 at the transport document reading position 78.

  The optical system 50 includes a full rate carriage 80, a half rate carriage 82, a lens 84, and a photoelectric conversion element 86. The full-rate carriage 80 includes a light source 88 and a first mirror 90, and moves the entire stroke in the document reading device 14 in the scanning direction with the document sub-scanning direction (from left to right in FIG. 2) as the scanning direction. Have been to.

  The light source 88 is a lamp such as halogen or xenon extending in the main scanning direction of the document, and has a predetermined scan width. The half-rate carriage 82 includes a second mirror 92 and a third mirror 94, and is configured to move within the document reader 14 by a half stroke in the sub-scanning direction.

  The lens 84 emits light emitted from the light source 88 to a document placed on the platen glass 52 provided above the moving range of the full-rate carriage 80 and the half-rate carriage 82 or a document passing through the transported document reading position 78. Is reflected through the first mirror 90, the second mirror 92, and the third mirror 94 to form an image.

  The photoelectric conversion element 86 receives the reflected light at the image formation position of the reflected light by the lens 84, and for example, analog signals corresponding to the respective RGB amounts of light by a photodiode provided with RGB filters (primary color filters). For example, it is a 3-line color CCD that outputs an electrical signal to a control processing unit 100 described later.

  A first reference white plate 96 that reflects the light emitted from the light source 88 is provided between the transported document reading position 78 and the platen glass 52. The first reference white plate 96 has a reflective surface that reflects light as a reference white color. For example, when the image forming apparatus 10 is turned on, the light source 88 irradiates the first reference white plate 96. The photoelectric conversion element 86 can receive reflected light (initial reference light amount light) through the first mirror 90, the second mirror 92, the third mirror 94 and the lens 84.

  In addition, second reference white plates 98 that reflect light emitted from the light source 88 are provided at both ends of the transported document reading position 78 (upper and lower ends of the transported document reading position 78 in FIG. 3). The second reference white plate 98 has a reflecting surface that reflects light as a reference white. For example, when the document reading device 14 reads and reads a document, the light source 88 is in contact with the second reference white plate 98. The photoelectric conversion element 86 can receive reflected light (reference light amount light at the time of reading) irradiated through the first mirror 90, the second mirror 92, the third mirror 94, and the lens 84.

When the document reader 14 reads a document placed on the platen glass 52, the light source 88 emits light toward the document, and the full rate carriage 80 and the half rate carriage 82 move in the scanning direction. The photoelectric conversion element 86 sequentially receives reflected light corresponding to the entire surface of the document.
When the document reading device 14 reads and scans the document, the photoelectric conversion element 86 converts the reflected light from the conveyed document and the reflected light from the second reference white plate 98 at the transported document reading position 78. Receives light at the same time.

The control processing unit 100 includes a CPU and a memory (not shown), controls each part of the document reading device 14, and converts the initial reference light amount light, the reference light amount light at the time of reading, and the reflected light from the document into a photoelectric conversion element 86. Each of the RGB electrical signals converted by the image data is received, predetermined processing is performed to generate image data in which the image density of each color is corrected, and the image data is output to the image forming unit 12.
For example, the control processing unit 100 uses the electrical signal corresponding to the reference light amount light at the initial time and the reading as the white reference value at each timing, and the ratio (change) of the white reference value at the time of reading to the initial white reference value every time the document is read. A correction coefficient is calculated so as to correct the electric signal corresponding to the reflected light from the original in accordance with the light amount fluctuation of the light source 88, and the electric signal corresponding to the reflected light from the original is calculated using the calculated correction coefficient. Image data is generated from
In addition, the control processing unit 100 stores the white reference value at the initial time and at the time of reading and the correction coefficient at the time of reading as a history.

FIG. 4 is a graph showing the variation of the white reference value accepted by the control processing unit 100 in the different operation modes (A) to (D) of the document reading apparatus 14.
As shown in FIG. 4, in the different operation modes (A) to (D) set for the document reading device 14, the white reference value varies with respect to the reference light quantity acquisition count (time).
Note that the control processing unit 100 stores, as a history, the variation of the white reference value (initial and read white reference values) for each operation mode together with the respective correction coefficients at the time of reading.

Next, an operation example of the document reading device 14 will be described.
FIG. 5 is a flowchart showing an operation example (S10) in which the document reading device 14 scans and reads the document after the user instructs the document reading device 14 to read the document in the predetermined operation mode.
As shown in FIG. 5, in step 100 (S100), the control processing unit 100 moves the full-rate carriage 80 to the first reference white so that the first mirror 90 receives the reflected light from the first reference white plate 96. It is moved below the plate 96.

  In step 102 (S102), the control processing unit 100 acquires, as an initial white reference value, a white reference value obtained by the first reference white plate 96 at the time of document reading instruction.

  In step 104 (S104), the control processing unit 100 moves the full-rate carriage 80 to the transported original so that the first mirror 90 receives the light passing through the transported original reading position 78 and the reflected light from the second reference white plate 98. The reading position 78 is moved below.

  In step 106 (S106), the control processing unit 100 selects a white reference value variation and a correction coefficient history corresponding to a predetermined operation mode according to a user instruction or the like.

  In step 108 (S108), the control processing unit 100 sets a correction coefficient for the first document according to the initial white reference value, the designated predetermined operation mode, the fluctuation of the white reference value, and the correction coefficient history. To do.

  In step 110 (S110), the control processing unit 100 reads the document at the transported document reading position 78 via the full-rate carriage 80, the half-rate carriage 82, the photoelectric conversion element 86, and the like, and the second reference white at the time of reading. The white reference value is simultaneously acquired by the plate 98.

  In step 112 (S112), the control processing unit 100 calculates the ratio (change amount) of the white reference value at the time of reading to the initial white reference value.

  In step 114 (S114), the control processing unit 100 determines whether or not the ratio (change amount) of the white reference value is equal to or less than a predetermined threshold value indicating an allowable range, and if the change amount is equal to or less than the threshold value. The process proceeds to S118, and if the change amount exceeds the threshold, the process proceeds to S116.

  In step 116 (S116), the control processing unit 100 newly sets a correction coefficient for the original so as to correct the density of the read original according to the ratio of the white reference value.

  In step 118 (S118), the control processing unit 100 determines whether or not the document reading is completed. If the reading is not completed, the process proceeds to S110. If the reading is completed, the control processing unit 100 proceeds to S120. Proceed to the process.

  In step 120 (S120), the control processing unit 100 updates the correction coefficient setting history.

As described above, the document reading device 14 acquires the white reference value while reading the document, and newly sets the correction coefficient of the document density with respect to the document according to the ratio (change amount) of the white reference value. Even when reading, the document can be efficiently read according to the document conveyance speed by the automatic document conveyance device 48.
The document reader 14 may be configured to arbitrarily set the timing for newly setting a correction coefficient for the document.
Further, the document reading device 14 may set a correction coefficient for the document using a correction coefficient setting history when the white reference value at the time of reading indicates a value outside the normal range, for example.

1 is a side view illustrating an outline of an image forming apparatus according to an embodiment of the present invention. 1 is a side view showing details of a document reading apparatus according to an embodiment of the present invention. FIG. 3 is a plan view of an inner upper surface of the document reading device as viewed from below. 6 is a graph showing changes in white reference values accepted by the control processing unit in different operation modes (A) to (D) of the document reading apparatus. FIG. 10 is a flowchart showing an operation example (S10) in which the document reading device flows and reads the document after the user instructs the document reading device to read the document in a predetermined operation mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming part 14 Document reading apparatus 48 Automatic document conveying apparatus 50 Optical system 78 Conveyance original reading position 80 Full rate carriage 82 Half rate carriage 84 Lens 86 Photoelectric conversion element 88 Light source 90 First mirror 92 Second mirror 94 First 3 mirrors 96 first reference white plate 98 second reference white plate 100 control processing unit

Claims (10)

  Based on the light source, the reference light amount by irradiation of the light source, and the light amount detection means for detecting one or more light amounts by reflection or transmission with respect to the document, the correction amount of the document density is determined based on the reference light amount detected by the light amount detection means. A correction amount setting means to be set, a conversion means for converting the result of detection of the light amount by the light amount detection means into image data according to the correction amount set by the correction amount setting means, and the light amount detection means And a control unit that controls the correction amount setting unit to newly set a correction amount based on a reference light amount detected together with the light amount with respect to the document reading apparatus.   The apparatus further includes a document conveying device that conveys the document, and the control unit newly sets the correction amount setting unit based on a reference light amount detected by the light amount detecting unit and a light amount with respect to the document conveyed by the document conveying unit. The document reading apparatus according to claim 1, wherein control is performed so as to set a correction amount.   A storage unit that stores a history of correction amounts set by the correction amount setting unit; and the control unit sets a new correction amount based on the correction amount history stored by the storage unit. The document reading apparatus according to claim 1, wherein the document reading device is controlled so as to set the value.   The document reading apparatus according to claim 3, wherein the storage unit stores a correction amount history in association with an operation mode for reading a document.   5. The document reading apparatus according to claim 4, wherein the control unit controls the correction amount setting unit to newly set a correction amount in accordance with an operation mode for reading the document.   It further includes a change amount determination unit that determines whether or not a change amount of the reference light amount detected by the light amount detection unit is equal to or less than a predetermined threshold value, and the change amount of the reference light amount detected by the light amount detection unit is a predetermined threshold value If the change amount determination means determines that the value is larger than the reference value, the control means controls the correction amount setting means to newly set a correction amount based on the last reference light amount detected by the light amount detection means. The document reading apparatus according to claim 3.   A light amount range determining unit that determines whether or not the reference light amount detected by the light amount detecting unit is within a predetermined range, and the light amount range determining unit if the reference light amount detected by the light amount detecting unit is not within the predetermined range; 7. The control unit according to claim 3, wherein, when the unit determines, the control unit controls the correction amount setting unit to newly set a correction amount based on a correction amount history stored in the storage unit. Document reader.   Based on the light source, the reference light amount by irradiation of the light source, and the light amount detection means for detecting one or more light amounts by reflection or transmission with respect to the document, the correction amount of the document density is determined based on the reference light amount detected by the light amount detection means. A correction amount setting means to be set, a conversion means for converting the result of detection of the light amount by the light amount detection means into image data according to the correction amount set by the correction amount setting means, and the light amount detection means A control unit that controls the correction amount setting unit to newly set a correction amount based on a reference light amount detected together with a light amount with respect to the image, and an image forming unit that forms an image according to the image data converted by the conversion unit, An image forming apparatus.   The apparatus further includes a document conveying device that conveys the document, and the control unit newly sets the correction amount setting unit based on a reference light amount detected by the light amount detecting unit and a light amount with respect to the document conveyed by the document conveying unit. The image forming apparatus according to claim 8, wherein the image forming apparatus is controlled to set a correction amount.   Set the document density correction amount based on the reference light amount, detect the document density with the set correction amount, acquire a new reference light amount, and based on the newly acquired reference light amount, the document density correction amount Original reading method to set a new.

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