JP2006005592A - Image scanner, image reading method, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep resolution in a sub-scanning direction constant while absorbing readout timing deviation on an image sensor side when a color image formed on an arbitrary sheet is read. <P>SOLUTION: The image scanner is equipped with: a linear image sensor 58 in which read sensors for red, green, and blue detection composed by arranging a plurality of photodetecting elements in a horizontal scanning direction are arranged at intervals of a specified distance in the sub-scanning direction orthogonal to the horizontal scanning direction and which reads light information of respective colors at the same vertical-scanning-directional position on a sheet irradiated with light by a light source in time series; an optical system driving section 59 which moves the sensor or a document 30 relatively in the sub-scanning direction; and a control unit 35 which controls inputs and output of the image sensor 58 and optical system driving section 59. The control unit 35 controls the optical system driving section 59 at a sub-scanning speed corresponding to a previously set variable magnification and independently controls the read sensors of the respective colors with readout control signals corresponding to the variable magnification. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is an image reading apparatus suitable for being applied to a tandem type color printer, a color facsimile apparatus, a color copying machine, a complex machine thereof, or the like that reads a document including a color image in a black and white document to form a color image. The present invention relates to an image reading method and an image forming apparatus.

  In recent years, tandem type color printers, color copiers, color facsimile machines, multifunction machines of these, and the like have been increasingly used. In these color image forming apparatuses, yellow (Y), magenta (M), cyan (C), and black (BK) exposure means, developing means, photosensitive drums, and intermediate transfer belts or conveying material transfer belts are used. And a fixing device.

  For example, the Y-color exposure means draws an electrostatic latent image on the photosensitive drum based on arbitrary image information. In the developing device, a color toner image is formed by attaching a Y-color toner to the electrostatic latent image drawn on the photosensitive drum. The photosensitive drum transfers the toner image to the intermediate transfer belt. Similar processing is performed for the other M, C, and BK colors. The color toner image transferred to the intermediate transfer belt is transferred to a sheet and then fixed by a fixing device.

  By the way, according to this type of color image forming apparatus, a color scanner function using a one-dimensional image sensor such as a three-line color CCD sensor is provided. In this image sensor, a line-shaped reading sensor for detecting red (R), green (G) and blue (B) light is configured by arranging a plurality of light receiving element arrays in the main scanning direction. The pixels are divided at different positions in the sub-scanning direction of the document (sheet) that is arranged at a predetermined distance in the sub-scanning direction orthogonal to the light source and irradiated with light from the light source, and the light information of each color is simultaneously obtained. Read.

  According to such an image sensor, the input timing for a plurality of lines is shifted due to the structural reason in the sub-scanning direction of the RGB color reading sensors, that is, the arrangement intervals of the RGB color reading sensors. The shift in the input timing leads to a decrease in the modulation transfer function (also referred to as image resolution; Modulation Transfer Function; hereinafter referred to as MTF) of the scanner and a deterioration in image resolution between the respective colors. This shift in input timing in the sub-scanning direction is corrected by introducing a timing correction function.

  Further, when reading a document, the scaling factor becomes involved in the shift of the input timing. When the variable magnification is set as an integer such as 100% or 50%, it can be dealt with by providing means for correcting the integer line. For example, a FIFO memory for a plurality of lines is prepared for each color, and the input timing is adjusted by delaying the FIFO memory.

  However, the scaling factor may need to be set to a decimal point. For example, when an A3 size original is reduced to A4 size and an image is read, 70.7% is set as the scaling factor. In addition, an arbitrary magnification is designated steplessly as a zoom function. For example, 87.5% or 62.5% is set. In such a case, it is necessary to correct the decimal point line in addition to the integer line. The generation of the decimal point line is because the sub-scanning speed is changed according to the variable magnification, and a timing shift of less than one line occurs.

  Regarding this type of timing deviation correction function of less than one line, Patent Document 1 discloses an image reading apparatus, an image processing system, an image reading method, a medium for providing a control program, and a control program. According to this image reading apparatus, on the premise that a three-line color CCD image sensor is used, an inter-line correction unit and an MTF correction unit are provided, and the inter-line correction is performed by the inter-line correction unit so as to align the RGB colors. The The interline correction unit includes a delay circuit that adjusts the delay for integer lines and a linear interpolation circuit that corrects the delay for decimal lines.

  The delay for the decimal line is linearly interpolated using image data of two lines before and after. The MTF correction unit corrects the MTF difference between the RGB colors generated in the inter-line correction unit to make the resolution uniform. Black character determination processing is performed based on the RGB color image in which the MTF difference is corrected. As described above, when the image reading apparatus is configured to include the interline correction unit and the MTF correction unit, the black character determination accuracy is improved.

FIG. 13 is a diagram showing a delay correction example of the image read data Dr, Dg, Db by the image sensor 58 according to the conventional example.
An image sensor 58 shown in FIG. 13 is a module that constitutes a three-line color CCD image sensor and has a function capable of closely reading a document image at an equal magnification. In FIG. 13, each rectangle represents a read pixel. The three reading sensors Lr, Lg, and Lb for detecting R, G, and B color light are arranged in a line in the main scanning direction on the same semiconductor substrate, and predetermined in the sub-scanning direction orthogonal to the main scanning direction. Are arranged at a distance of.

  The document image is detected simultaneously by three reading sensors Lr, Lg, and Lb divided in the sub-scanning direction. The reading sensor Lr constitutes a line-shaped sensor that reads R-color light, and has a light-receiving element array for detecting R-color light arranged in the main scanning direction. The reading sensor Lg constitutes a line-shaped sensor that reads G color light, and has a light receiving element array for G color light detection arranged in the main scanning direction. The reading sensor Lb constitutes a line-shaped sensor that reads B-color light, and has a light-receiving element array for detecting B-color light arranged in the main scanning direction.

  Further, in the line-shaped reading sensors Lr, Lg, and Lb for detecting RGB color light, the distance between the sensors is, for example, 4 lines apart from the resolution of 600 dpi in the sub-scanning direction. That is, when the zoom ratio is 100%, the distance between the read sensor Lr for detecting the R color light and the read sensor Lg for detecting the G color light is 4 lines apart, and the read sensor for detecting the R color light. The distance between the sensor between Lr and the reading sensor Lb for detecting the B color light is in a state where there is an interval of 8 lines. As a result, the image sensor 58 divides pixels at different positions in the sub-scanning direction of the original 30 irradiated with light from the light source, and reads light information of R color, G color, and B color simultaneously.

In the line-to-line correction unit as found in Patent Document 1, when the magnification ratio is 100%, in FIG. 13, corresponding to the arrangement interval of the reading sensors Lr and Lg between the R color and the G color with reference to the R color. The 4 line FIFO memory absorbs the timing deviation for 4 lines, and the 8 line FIFO memory absorbs the timing deviation for 8 lines corresponding to the arrangement sensor interval of the reading sensors Lr and Lb between the R and B colors. In this example, pixel values R _n , G _n , B _n (n = 1, 2, 3,...) Each indicate a data group for one line main scanning. In the example shown in FIG. 13, the pixel values R ₁ , R ₂ ... For the R color constitute the R color component image read data Dr. The pixel values G ₁ , G ₂ ... For the G color constitute the G color component image read data Dg. The pixel values B ₁ , B ₂ ... For the B color constitute the B color component image read data Db.

  As described above, in the reading process at the same magnification (magnification = 100%), when an image reading signal of RGB 3 channels is obtained at intervals of 4 lines, R color = no delay, G color 4 line delay, B The timing is adjusted via the FIFO, such as color = 8 line delay. When the zoom ratio is 75%, the delay amount between lines is 3 lines, and the delay amount of the FIFO is adjusted such that R color = no delay, G color = 3 line delay, B color = 6 line delay, and so on. It is made like.

FIG. 14 is a diagram illustrating a linear interpolation example of the image read data Dr, Dg, and Db at the time of setting the variable magnification decimal point.
According to the linear interpolation example of the image reading data Dr, Dg, and Db shown in FIG. 14, when the scaling factor is set to a decimal point such that scaling factor = 87.5% (A3 version → B4 version), the interline delay Becomes 3.5 lines. When the zoom ratio is 90%, 3.6 lines are used. This corresponds to a case where the width of 4 lines between the reading sensors Lr, Lg, and Lb adjacent to each other is read in a sub-scanning time of 4 lines × 87.5% = 3.5 lines. Here, with respect to the deviation amount of the 3.5 line interval, the 0.5 line portion is set to 0.5 to 0.5 between the two consecutive lines before and after the linear interpolation process, that is, the average between the two pixels. It is dealt with by finding the value.

  Here, when G color is used as a reference, R color = 0 line + 0.5 line, G color = 4 line, B color = 7 line + 0.5 line delay. Regarding integer lines, G color = 4 lines are absorbed by the 4 line FIFO memory, and B color = 7 lines are absorbed by the 7 line FIFO memory.

  For the 0.5 decimal point line, as seen in the inter-line correction unit of Patent Document 1, interpolation processing is performed by connecting a linear interpolation circuit after the delay circuit. According to this linear interpolation circuit, when the G color is used as a reference with respect to the delay of 0.5 lines, the pixel values of the R color and the B color are averaged, that is, (previous line data + next line data). ) / 2 (0.5: 0.5). The output value obtained by this interpolation processing is used as image read data corresponding to a 0.5 line shift timing.

  Patent Document 2 discloses a scanner and a color image forming apparatus. According to this scanner, on the premise that the reading timing in the sub-scanning direction is shifted by a plurality of lines due to the structure of the 3-line color CCD sensor, the color / monochrome switching switch is provided and the sub-scanning speed in the monochrome image reading operation is provided. The switch is operated so as to switch to N times the sub-scanning speed in the color image reading operation. By configuring the scanner in this way, the time required for the monochrome image reading operation can be shortened.

  Patent Document 3 discloses an image reading apparatus. According to this image reading apparatus, in order to correct the sensor sensitivity variation among the three colors of the three-line color CCD sensor, the accumulation time is controlled independently for the three colors. By configuring the image reading apparatus in this way, it is possible to acquire a high-quality and high-quality image reading output with an improved S / N ratio.

Japanese Unexamined Patent Publication No. 2003-174568 (page 6, FIG. 4) Japanese Unexamined Patent Publication No. 2003-101725 (page 8, FIG. 4) JP-A-6-078107 (page 8, Fig. 4)

  However, the conventional image reading apparatus and the color image forming apparatus to which the image reading apparatus is applied have the following problems.

  i. An image reading apparatus having an image sensor such as a 3-line CCD sensor including Patent Documents 1 and 2 is provided with an interline correction unit, and when a scaling factor is set by a decimal point, an integer line is set by a delay circuit. The decimal point line is corrected by a linear interpolation circuit. For example, when a variable magnification (hereinafter also referred to as a document reading magnification) is set with a decimal point, interpolation calculation processing is performed for the other R and B colors with reference to the G color.

  Accordingly, the black horizontal thin line after image formation does not have the same RGB color level, and the RB color line is blurred in the sub-scanning direction, resulting in color blurring. As described above, since the MTFs of RGB colors vary, there is a possibility that the color image forming apparatus to which the image reading apparatus is applied may lead to a decrease in image forming quality.

  ii. According to Patent Document 1, an MTF correction unit is provided after the interline correction unit, and the MTF deteriorated by the interline correction unit is corrected later by a spatial filter for MTF correction or the like. Therefore, it is necessary to provide an MTF correction unit for aligning the resolution separately from the interline correction unit, which may increase the cost.

  iii. Note that according to the image reading apparatus disclosed in Patent Document 3, the accumulation time is controlled independently by the three-line color CCD sensor, but the pixel density is corrected in order to correct the sensor sensitivity variation between the three colors. Conversion means must be provided, which may increase the circuit scale and increase the cost.

  Therefore, the present invention solves the above-described problem, and when reading a color image formed on an arbitrary sheet, the image sensor side can absorb a reading timing shift and a resolution in the sub-scanning direction. An object of the present invention is to provide an image reading apparatus, an image reading method, and an image forming apparatus capable of maintaining the above constant.

  In order to solve the above-described problems, an image reading apparatus according to the present invention is an apparatus that reads a color image formed on an arbitrary sheet, and includes a light source that irradiates light on the sheet and a plurality of light receiving elements in the main scanning direction. A sub-scan of a sheet in which read sensors for detecting red, green and blue are arranged at a predetermined distance in a sub-scanning direction perpendicular to the main scanning direction and irradiated with light from a light source. A one-dimensional image sensor that reads light information of each color at the same position in the direction in time series, a moving unit that relatively moves the image sensor or the sheet in the sub-scanning direction, and input / output of the image sensor and the moving unit Control means for controlling the moving means at a sub-scanning speed corresponding to a preset document reading magnification, and a reading control signal corresponding to the document reading magnification. It is characterized in that to control the color reading sensor of people independently.

  According to the image reading apparatus according to the present invention, when reading a color image formed on an arbitrary sheet, a reading sensor for detecting red, green, and blue that is configured by arranging a plurality of light receiving elements in the main scanning direction. Are arranged at a predetermined distance in the sub-scanning direction orthogonal to the main scanning direction, and the light information of each color at the same position in the sub-scanning direction of the sheet irradiated with light from the light source is read in time series The original image sensor is used. Based on this assumption, light is emitted from the light source to the sheet. The control unit controls input / output of the image sensor and the moving unit. The control means controls the moving means at a sub-scanning speed corresponding to a preset document reading magnification. Accordingly, the moving unit relatively moves the image sensor or the sheet in the sub scanning direction. The control means independently controls each color reading sensor with a reading control signal corresponding to the original reading magnification.

  Therefore, the light information of each color at the same position in the sub-scanning direction can be read in time series in the order of the reading sensors arranged in the sub-scanning direction. For example, even when the sub-scanning speed changes depending on the original reading magnification at the time of reading the sheet and the scanning timing is shifted according to the reading sensor interval, especially when the reading timing is less than one line reading cycle. This reading timing shift can be absorbed on the image sensor side.

  An image reading method according to the present invention is a method for reading a color image formed on an arbitrary sheet, and is a reading sensor for detecting red, green, and blue colors, in which a plurality of light receiving elements are arranged in the main scanning direction. Using a one-dimensional image sensor that is arranged at a predetermined distance in the sub-scanning direction orthogonal to the main scanning direction, and reads light information of each color at the same position in the sub-scanning direction in time series, When reading a sheet, an original reading magnification is set, and the sheet or image sensor is relatively moved in the sub scanning direction at a sub scanning speed based on the set original reading magnification, and reading control based on the original reading magnification is performed. Each color reading sensor is independently controlled by a signal to irradiate the sheet with light and to read light information returned from the sheet.

  According to the image reading method of the present invention, when reading a color image formed on an arbitrary sheet, the optical information of each color at the same position in the sub-scanning direction is read in the order of the reading sensors arranged in the sub-scanning direction. Can be read in series.

  Accordingly, when the sub-scanning speed is changed depending on the original reading magnification at the time of reading the sheet and the scanning timing is shifted according to the reading sensor interval, the reading timing less than one line accumulation time (one line reading cycle) is generated. Even in this case, this reading timing shift can be absorbed on the image sensor side.

  An image forming apparatus according to the present invention reads a color image formed on an arbitrary sheet to form a color image. The image forming apparatus reads a color image formed on a sheet, and the image reading apparatus reads the color image. An image forming unit configured to form a color image based on the color image information obtained in this way, and the image reading apparatus is configured by arranging a light source for irradiating light on the sheet and a plurality of light receiving elements in the main scanning direction. Read sensors for detecting red, green and blue are arranged at a predetermined distance in the sub-scanning direction orthogonal to the main scanning direction, and each of the same positions in the sub-scanning direction of the sheet irradiated with light from the light source One-dimensional image sensor for reading color light information in time series, moving means for moving the image sensor or sheet relatively in the sub-scanning direction, and controlling input / output of the image sensor and moving means And a control means for controlling the moving means at a sub-scanning speed corresponding to a preset document reading magnification, and for each color reading sensor with a reading control signal corresponding to the document reading magnification. Are controlled independently.

  According to the image forming apparatus according to the present invention, the image reading apparatus according to the present invention is applied when a color image formed on an arbitrary sheet is read to form a color image. Therefore, a color image can be formed based on the light information of each color at the same position in the sub-scanning direction read in time series in the order of the reading sensors arranged in the sub-scanning direction. Thereby, even when the variable magnification (reading magnification × sensor line interval) is set to have a value below the decimal point, a high-quality image that is not colored with black thin lines or the like can be formed.

  According to the image reading apparatus and the image reading method according to the present invention, when a color image formed on an arbitrary sheet is read, the image reading apparatus and the image reading method include a control unit that controls input and output of the image sensor and the moving unit. The moving unit is controlled at a sub-scanning speed corresponding to a preset document reading magnification, and each color reading sensor is independently controlled by a reading control signal corresponding to the document reading magnification.

  With this configuration, the light information of each color at the same position in the sub-scanning direction can be read in time series in the order of the reading sensors arranged in the sub-scanning direction. Therefore, even when the original reading magnification is changed and a deviation occurs in the reading timing less than one line accumulation time (one line reading cycle), this reading timing deviation can be absorbed on the image sensor side. As a result, the resolution in the sub-scanning direction can be maintained constant, and the linear interpolation circuit prepared after the delay circuit that corrects the deviation of the integer lines can be omitted.

  According to the image forming apparatus according to the present invention, the image reading apparatus according to the present invention is applied when a color image formed on an arbitrary sheet is read to form a color image.

  With this configuration, it is possible to form a color image based on the light information of each color at the same position in the sub-scanning direction read in time series in the order of the reading sensors arranged in the sub-scanning direction. Therefore, even when the variable magnification (reading magnification × sensor line interval) is set to have a value after the decimal point, it is possible to form a high-quality image that is not colored with black thin lines.

  Hereinafter, an image reading apparatus, an image reading method, and an image forming apparatus according to embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing a configuration example of a color scanner 100 as a first embodiment of the present invention.
In this embodiment, when a color image formed on an arbitrary sheet is read, the image sensor and control means for controlling input / output of the moving means are provided, and the image is moved at a sub-scanning speed corresponding to a preset document reading magnification. In addition to controlling the means, each color reading sensor is independently controlled by a reading control signal corresponding to the original reading magnification, and each color at the same position in the sub-scanning direction is arranged in the order of the reading sensors arranged in the sub-scanning direction. This optical information can be read in time series, and even when the document reading magnification is changed and the reading timing is less than one line reading cycle, this reading timing deviation can be absorbed on the image sensor side. It is what I did.

  A color scanner 100 shown in FIG. 1 is an example of an image reading apparatus, and is an apparatus that reads a color image formed on an arbitrary sheet. In addition to the color scanner 100, the image reading apparatus is suitable for application to a tandem color printer, a color copying machine, a color facsimile apparatus, a complex machine of these, and the like. The color scanner 100 includes a scanner unit 11 and a scanner main body 11a, and constitutes a slit scan scanner. For example, an automatic document feeder (ADF) 40 is attached to the scanner body 11a and operates to automatically feed an arbitrary sheet (hereinafter referred to as a document 30) in the ADF mode. Here, the ADF mode refers to an operation of automatically feeding a document 30 placed on the ADF 40 and automatically reading a document image.

  The ADF 40 includes a document placing portion 41, a roller 42 a, a roller 42 b, a roller 43, a transport roller 44, and a paper discharge tray 46. One or a plurality of originals 30 are placed on the original placing portion 41. A roller 42 a and a roller 42 b are provided on the downstream side of the document placing portion 41. When the automatic paper feeding mode is selected, the document 30 fed out from the document placing portion 41 is U-shaped by the downstream roller 43. It is conveyed so as to rotate. When the ADF mode is selected, the recording surface of the original 30 is placed upward by the original placement portion 41.

  The scanner unit 11 reads the document 30 and acquires image reading information. The scanner unit 11 is provided with a one-dimensional image sensor 58. For example, when the document 30 is reversed in a U shape by the roller 43 in the ADF mode, the surface of the document 30 is read and an image reading signal Sout is output. To be made. A three-line color CCD image pickup device is used for the image sensor 58.

  The image sensor 58 includes three reading sensors for detecting red (R), green (G), and blue (B) light that are configured by arranging a plurality of light receiving element arrays in the main scanning direction. Pixels are divided at the same position in the sub-scanning direction of the document 30 that is arranged at a predetermined distance in the orthogonal sub-scanning direction and irradiated with light, and R, G, and B color light information is sometimes obtained. It is made to read in series.

  The document 30 read by the scanner unit 11 is conveyed by the conveyance roller 44 and discharged to the discharge tray 46. The image sensor 58 outputs an RGB color-based image reading signal Sout obtained by reading the document 30 in the platen mode. Here, the platen mode refers to an operation of automatically reading an original image by scanning an optical drive system on the original 30 placed on the platen glass.

  In addition to the image sensor 58, the scanner unit 11 includes a first platen glass 51, a second platen glass (ADF glass) 52, a light source 53, mirrors 54, 55, and 56, an imaging optical unit 57, and an optical system driving unit 59. have. The light source 53 operates to irradiate the document 30 with light.

  The optical system driving unit 59 constitutes an example of a moving unit and includes a motor 59 '. The motor 59 ′ is attached to the optical system driving unit 59. The optical system drive unit 59 operates so as to relatively move the document 30 or the image sensor 58 in the sub-scanning direction under the rotational force of the motor 59 '. In this example, the optical system driving unit 59 moves the optical system such as the light source 53 and the mirrors 54, 55, and 56 in the sub-scanning direction in the platen mode. The sub-scanning direction is a direction orthogonal to the main scanning direction when the arrangement direction of the plurality of light receiving elements constituting the image sensor 58 is the main scanning direction. In this example, the motor 59 'is controlled so as to vary the reading speed in the sub-scanning direction in accordance with the document reading magnification (hereinafter referred to as variable magnification Z).

  On the other hand, the scanner main body is provided with an operation panel 48 as an example of setting means, and is operated to set the zoom ratio Z when reading the document 30. The operation panel 48 is operated so as to output image read data Dout obtained by reading an arbitrary document 30 to a printer or the like. The operation panel 48 is operated to select the ADF mode or the platen mode.

  A control unit 35 is provided in the scanner body. In this example, the control unit 35 is connected to the output stage of the image sensor 58 described above, and controls the optical system drive unit 59 and the like at a sub-scanning speed corresponding to a preset variable magnification Z. Each color reading sensor is independently controlled by a reading control signal according to the above. For example, the control unit 35 outputs a motor control signal (sub-scanning speed control signal) S1 based on the variable magnification Z set by the operation panel 48 to the optical system driving unit 59 and various reading timings based on the variable magnification Z. The signals SHr, SHg, and SHb are output to the image sensor 58 independently.

  The control unit 35 is provided with a timing controller 34, which outputs read timing signals SHr, SHg, SHb to the above-described image sensor 58, and for each read sensor, a two-phase clock signal φ1A, φ2A, a read clock signal φ2B. The reset signal RS and the clamp signal CP are output, and the reading control of the image sensor 58 is executed.

  Of course, the control unit 35 performs analog signal processing, correction processing, memory access control, and the like on the RGB color image reading signal Sout acquired by the scanner unit 11. For example, an output terminal 9 such as a USB standard is connected to the control unit 35. The output terminal 9 is connected to a printer or the like through a USB standard communication cable, and transmits image read data Dout.

  FIG. 2 is a conceptual diagram showing a configuration example of the image sensor 58 for three line colors. An image sensor 58 shown in FIG. 2 is a module that constitutes a CCD linear image sensor and has a function capable of closely reading a document image at an equal magnification. In FIG. 2, each rectangle represents a read pixel. When the image sensor 58 constitutes a 600 linear CCD linear image sensor module for 1 × magnification, assuming that the size of one pixel is a × b, a = 42 μm and b = 42 μm. The three reading sensors Lr, Lg, and Lb for detecting R, G, and B light are, for example, a light receiving element group (photo sensor array) of about 42 μm × 42 μm square in the main scanning direction on the same semiconductor substrate. Thousands are arranged in a line, and are arranged at a predetermined distance in the sub-scanning direction orthogonal to the main scanning direction. In this example, if the arrangement pitch of the light receiving elements in the sub-scanning direction is w (= 4 × b), w is about 168 μm.

  The document image is simultaneously detected by three line-shaped reading sensors Lr, Lg, and Lb divided in the sub-scanning direction. The reading sensor Lr constitutes a line-shaped sensor that reads R-color light, and has a light-receiving element array for detecting R-color light arranged in the main scanning direction. The reading sensor Lg constitutes a line-shaped sensor that reads G color light, and has a light receiving element array for G color light detection arranged in the main scanning direction. The reading sensor Lb constitutes a line-shaped sensor that reads B-color light, and has a light-receiving element array for detecting B-color light arranged in the main scanning direction.

  Further, in the line-shaped reading sensors Lr, Lg, and Lb for detecting RGB color light, the distance between the sensors is 4 lines apart from the resolution of 600 dpi in the sub-scanning direction. That is, when the zoom ratio is 100%, the distance between the read sensor Lr for detecting the R color light and the read sensor Lg for detecting the G color light is 4 lines apart, and the read sensor for detecting the R color light. The distance between the sensor between Lr and the reading sensor Lb for detecting the B color light is in a state where there is an interval of 8 lines.

  FIG. 3 is a block diagram showing an example of the internal configuration of the image sensor 58. The image sensor 58 shown in FIG. 3 includes line-shaped reading sensors Lr, Lg, and Lb for detecting RGB color light. The read sensor Lr for detecting R color light includes m photodiodes PDi (i = 1 to m), a shift gate 81, a shift register 82, a read circuit 83, a reset circuit 84, a sense amplifier 85, and an output terminal 86. The The number of photodiodes PDi is, for example, about m = 7500 pixels.

  The photodiode PDi receives light reflected from the original 30 irradiated with light and performs photoelectric conversion. A shift gate 81 is connected to each photodiode PDi, and the electric charge obtained by photoelectric conversion of each photodiode PDi is read and controlled based on the read timing signal SHr.

  A shift register 82 is connected to the shift gate 81, and the read charge is transferred in the main scanning direction (horizontal direction) based on the two-phase clock signals φ1A, φ2A, etc., and accumulated. A read circuit 83 is connected to the shift register 82 so as to read the accumulated charge based on the read clock signal φ2B.

  A reset circuit 84 is connected to the read circuit 83, and the read sensor Lr is reset by sweeping out the accumulated charge every one line accumulation time (one line reading cycle) based on the reset signal RS.

  A sense amplifier 85 is connected to the reset circuit 84, and a read charge is amplified based on the clamp signal CP during one line reading period, and an analog image reading signal Sr of R color component is output. The R color component analog image reading signal Sr is output to the control unit 35 through the R color output terminal 86.

  Similarly, the read sensor Lg for G color light detection outputs an analog image read signal Sg of a G color component based on a read timing signal SHg supplied independently of the read sensor Lr to an output terminal 86 for G color. To the control unit 35. The read sensor Lb for detecting B color light also receives the B color component analog image read signal Sb through the B color output terminal 86 based on the read timing signal SHb supplied independently of the read sensor Lr. Output to. Note that the G and B color light detection sensors Lg and Lb have the same configuration and functions as the R color light detection sensor Lr, and thus the description thereof is omitted.

  Accordingly, the image sensor 58 can divide pixels and read light information of R, G, and B colors in time series at the same position in the sub-scanning direction of the document 30 irradiated with light from the light source 53. . The image sensor 58 is not limited to a contact image sensor, and may be a three-line color CCD image pickup device including a reduction optical system.

  FIG. 4 is a block diagram illustrating a configuration example of a control system of the color scanner 100. The color scanner 100 shown in FIG. 3 has a control unit 35, and an image sensor 58 and an operation panel 48 are connected to the control unit 35. The control unit 35 includes an MPU (microprocessor) 15, analog signal processing units 31R, 31G, and 31B for RGB colors, correction processing units 32R, 32G, and 32B, and memory access control units 33R, 33G, and 33B. A timing controller 34, an image memory 36, and an optical system drive control unit 37.

  The analog signal processing unit 31R for the R color channel (Rch) has an analog / digital (A / D) converter (not shown). The analog signal processing unit 31R receives the R color component image reading signal Sout (= Sr) from the image sensor 58, performs A / D conversion, and outputs, for example, 10-bit image reading data Dr per pixel. Made.

  Similarly, the analog signal processing unit 31G of the G color channel (Gch) receives the G color component image read signal Sout (= Sg) from the image sensor 58, performs A / D conversion, and performs 10 bit per pixel. The image reading data Dg is output. The analog signal processing unit 31B of the B color channel (Bch) receives the B color component image reading signal Sout (= Sb) from the image sensor 58, performs A / D conversion, and reads 10-bit image reading data Db per pixel. Is output.

  The correction processing unit 32R performs a shading correction process, a timing correction process, a γ correction process, a scaling process, a spatial filter process, and the like. For example, the 10-bit R color channel image read data Dr per pixel from the analog signal processing unit 31R is subjected to a shading correction process, and then replaced with 8-bit image read data Dr through a γ conversion process.

  The correction processing unit 32G also performs a shading correction process, a timing correction process, a γ correction process, a scaling process, a spatial filter process, and the like. For example, 10-bit G color channel image read data Dg per pixel is subjected to a shading correction process from the analog signal processing unit 31G, and then replaced with 8-bit image read data Dg through a γ conversion process.

  The correction processing unit 32B is also configured to perform shading correction processing, timing correction processing, γ correction processing, scaling processing, spatial filter processing, and the like. For example, the 10-bit B color channel image read data Db per pixel is subjected to shading correction processing from the analog signal processing unit 31B, and then γ conversion processing is performed to replace it with 8-bit image read data Db.

  In this example, when the R color component image read signal Sr is used as a reading reference, the G color channel correction processing unit 32G is provided with a delay circuit 61G, and the B color channel correction processing unit 32B has a delay. Each circuit 61B is provided. Each delay circuit 61G, 61B has an integer line portion between the color detection reading sensors Lr, Lg, Lb with respect to optical information obtained by reading by the image sensor 58 from the sheet moved by the optical system driving unit 59. It operates to correct the deviation. For the delay circuits 61G and 61B, a FIFO memory having a delay stage number variable function is used.

  Further, each of the RGB color channel correction processing units 32R, 32G, and 32B is connected to an image processing unit (not shown) such as a γ correction unit, a scaling processing unit, a spatial filter processing unit, and the like. Correction and the like are performed. The Rch memory access control unit 33R is connected to the correction processing unit 32R. The memory access control unit 33R executes writing / reading control (MEM control) of the image reading data Dr. For example, the memory access control unit 33R encodes and compresses the image read data Dr, temporarily stores the compressed image read data Dr in the image memory 36, or decodes and decompresses the image read data Dr, and after decompression The compression / decompression control for outputting the image read data Dr to the printer or the like is executed.

  Further, the Gch memory access control unit 33G is connected to the correction processing unit 32G. The memory access control unit 33G executes MEM control of the image read data Dg in the same manner as described above. For example, the memory access control unit 33G encodes and compresses the image reading data Dg, temporarily stores the compressed image reading data Dg in the image memory 36, or decodes and decompresses the image reading data Dg, and after decompressing The compression / decompression control for outputting the image read data Dg to a printer or the like is executed.

  Furthermore, a Bch memory access control unit 33B is connected to the correction processing unit 32B. Similarly, the memory access control unit 33B executes MEM control of the image read data Db. For example, the memory access control unit 33B encodes and compresses the image read data Db, temporarily stores the compressed image read data Db in the image memory 36, or decodes and decompresses the image read data Db, and after decompression The compression / decompression control for outputting the image read data Db to the printer or the like is executed. For the image memory 36, a DRAM or a hard disk is used.

  A system bus 29 is connected to the correction processing units 32R, 32G, and 32B and the memory access control units 33R, 33G, and 33B. An MPU (Micro Processor Unit) 15, an image memory 36, an optical system drive control unit 37, and an operation panel 48 are connected to the system bus 29. The system bus 29 includes a data bus for transferring data and a control bus for transmitting various control signals.

  In this example, the optical system drive control unit 37 is connected to a motor 59 ′ of the optical system drive unit 59. The optical system drive control unit 37 is controlled by the MPU 15 to control the motor 59 '. For example, the optical system drive control unit 37 outputs a motor control signal S1 corresponding to the variable magnification Z to the motor 59 'so as to vary the reading speed in the sub-scanning direction. The motor 59 'rotates at a rotational speed based on the motor control signal S1 (motor control).

  The MPU 15 controls input / output of the correction processing units 32R, 32G, and 32B based on the scaling factor Z set by the operation panel 48. The operation panel 48 includes the operation unit 14 and the display unit 18. The operation unit 14 is operated so as to select the ADF mode or the platen mode in addition to being operated to set the zoom ratio Z when reading the document 30. The display unit 18 displays, for example, a percentage with respect to the scaling factor Z. In addition to integer settings such as 100%, 90%, and 80%, decimal points such as 87.5% and 72.8% can be set.

  For example, the MPU 15 calculates a delay amount for correcting a shift of a decimal line between the color reading sensors Lr, Lg, and Lb based on the variable magnification Z. A timing controller 34 is connected to the MPU 15 to generate the read timing signals SHg and SHb based on the delay amount output from the MPU 15.

  In this example, when the sensor interval in the sub-scanning direction of the reading sensors Lr, Lg, and Lb is N lines, the one-line accumulation time of each reading sensor Lr, Lg, and Lb is T, and the document distance is t, In the equal magnification reading process in which Z = 100%, the document 30 or the optical system drive unit 59 is sub-scanned at a document distance t = NT corresponding to this sensor interval N line.

  In addition, when performing variable magnification reading processing at an arbitrary variable magnification Z (Z ≠ 100%), the width of the sensor interval N line is sub-scanned at a time of ZNT proportional to the variable magnification Z. At this time, with respect to the time corresponding to the fractional line of ZN, the delay timing is taken into consideration between the reading sensors Lr, Lg, and Lb, and the reading timings SHr, SHg, and SHb are shifted to correct the remaining integer lines of ZN to the correction processing unit 32G. The delay circuit 61 </ b> G and the delay circuit 61 </ b> B of the correction processing unit 32 </ b> B perform correction.

  For example, when the variable magnification Z = 90% is set, the MPU 15 calculates a sensor interval of 4 lines × 90%, and acquires an interline delay amount = 3.6 lines. Here, when the read sensor Lr for R color is used as a reference, the interval between the read sensor Lr for R color and the read sensor Lg for G color is 3.6 lines, and the read sensor Lr for R color and the B color are read. The interval between the reading sensors Lb for use is 7.2 lines.

  In this case, the integer line between the sensors Lr and Lg is 3 lines, the decimal line is 0.6 lines, the integer line between the sensors Lr and Lb is 7 lines, and the decimal line is 0.2 lines. Here, since the sensor Lr is used as a reference, there is no FIFO memory delay for the R color component image read data Dr, that is, the correction processing unit 32R is not provided with a delay circuit. Of course, when changing the reference, a delay circuit is provided in the correction processing unit 32R.

  On the premise of this, the MPU 15 controls the timing controller 34 to output a reading timing signal SHg considering a delay time of Gt = 0.6T to the G color reading sensor Lg. The reading timing is set so that the accumulation time is common in order to prevent the MTF deterioration, and the timing is relatively shifted. For example, the reading timing signals SHg and SHb may be shifted to either before or after the reading timing signal SHr. Further, the delay stage number of the FIFO memory = 3 lines is set for the delay circuit 61G of the correction processing unit 32G.

  Similarly, the MPU 15 controls the timing controller 34 to output a read timing signal SHb that takes into account a delay time of Bt = 0.2T to the B color read sensor Lb. Further, the number of delay stages of the FIFO memory = 7 lines is set for the delay circuit 61B of the correction processing unit 32B.

  FIG. 5 is a block diagram illustrating an internal configuration example of the timing controller 34. The timing controller 34 shown in FIG. 5 includes a clock oscillator 71, a timing signal generator 72, and a timing correction unit 73.

  The clock oscillator 71 has a crystal oscillator or the like (not shown) and oscillates a reference clock signal CLK having a predetermined frequency. A timing signal generator 72 is connected to the clock oscillator 71. In the timing signal generator 72, a signal generation command D1 based on the variable magnification Z is input from the MPU 15, and the reference clock signal CLK is subjected to signal processing such as frequency division, multiplication, waveform shaping, and the like, and the read timing signal SHr for the read sensor Lr. Then, the two-phase clock signals φ1A, φ2A, the read clock signal φ2B, the reset signal RS, and the clamp signal CP for the read sensors Lr, Lg, and Lb are generated.

  A timing correction unit 73 is connected to the timing signal generator 72. The timing correction unit 73 includes a delay circuit (DELY) 74 for the reading sensor Lg and a delay circuit (DELY) 75 for the reading sensor Lb. The delay circuit 74 receives the first decimal line adjustment data D4 based on the variable magnification Z, delays the reading timing signal SHr based on the decimal line adjustment data D4, and reads the delayed reading timing signal SHr as a reading sensor Lg. Is output as a read timing signal SHg. In the above example, the delay time Gt = 0.6T is set by the decimal line adjustment data D4, and the reading timing signal SHg considering this Gt = 0.6T is output to the reading sensor Lg for G color.

  Similarly, the delay circuit 75 receives the second decimal line adjustment data D5 based on the scaling factor Z, delays the read timing signal SHr based on the decimal line adjustment data D5, and reads the delayed read timing signal SHr. Is output as a read timing signal SHb for the read sensor Lb. In the above-described example, the delay time Bt = 0.2T is set by the decimal line adjustment data D5, and the reading timing signal SHb considering this Bt = 0.2T is output to the reading sensor Lb for B color.

  6A and 6B are time charts showing an example of a delay relationship between the reading sensor Lr and the sensor Lg during document reading. In FIG. 6A, T is one line accumulation time in each sensor Lr, Lg, etc.

  In this example, when the variable magnification Z = 90% is set, the read timing signal SHr shown in FIG. 6A is supplied from the timing controller 34 to the read sensor Lr shown in FIG. The Lr two-phase clock signals φ1A and φ2A, the read clock signal φ2B, the reset signal RS, and the clamp signal CP are output from the timing controller 34 to the read sensor Lr based on the read timing signal SHr.

  In contrast, a read timing signal SHg delayed by a delay time Gt = 0.6T from the read timing signal SHr shown in FIG. 6A is supplied from the timing controller 34 to the read sensor Lg shown in FIG. The Lg two-phase clock signals φ1A and φ2A, the read clock signal φ2B, the reset signal RS, and the clamp signal CP are output from the timing controller 34 to the read sensor Lg based on the read timing signal SHg.

7A and 7B are time charts showing an example of the relationship between the reading sensor Lr and the reading sensor Lb during document reading.
In this example, when the variable magnification Z = 90% is set, the read timing signal SHb delayed by the delay time Bt = 0.2T from the read timing signal SHr shown in FIG. 7A is shown from the timing controller 34 in FIG. Is supplied to the reading sensor Lb. The Lb two-phase clock signals φ1A and φ2A, the read clock signal φ2B, the reset signal RS, and the clamp signal CP are output from the timing controller 34 to the read sensor Lb with reference to the read timing signal SHb. As a result, the drive timing of each of the reading sensors Lr, Lg, and Lb can be shifted and controlled independently for each color within one line accumulation time.

FIG. 8 is a diagram illustrating a correction example of the delay between lines in the correction processing units 32R, 32G, and 32B when the zoom ratio Z is 90%. In this example, when the variable magnification Z = 90% is set and the image reading data Db arrives at the delay circuit 61B of the correction processing unit 32B from the image sensor 58 shown in FIG. 8, the image reading data Dg is delayed by 4 lines from this. Reaches the delay circuit 61G of the correction processing unit 32G. The image read data Db is composed of pixel values B ₁ , B ₂ , B ₃ . The image read data Dg is composed of pixel values G ₁ , G ₂ , G ₃ .

Further, the image reading data Dr is input to the correction processing unit 32R with a delay of three lines. The image reading data Dr is composed of pixel values R ₁ , R ₂ , R ₃ . The number of integer lines between the sensors Lr-Lg is three. In this example, since the number of FIFO memory delay stages = 3 lines is set from the MPU 15 to the delay circuit 61G, the delay time of the integer 3 lines between the sensors Lr-Lg of the image read data Dg is set in the delay circuit 61G. Absorbed.

  Further, the number of integer lines between the sensors Lr and Lb is seven. In this example, since the number of FIFO memory delay stages = 7 lines is set from the MPU 15 to the delay circuit 61B, the delay time for the integer 7 lines between the sensors Lr-Lb of the image read data Db is set in the delay circuit 61B. Absorbed. The image read data Dr is output as it is. These Dr, Dg, and Db constitute image read data Dout.

Next, an image reading method according to the present invention will be described. FIG. 9 is a flowchart illustrating an example of image reading in the color scanner 100.
In this embodiment, it is assumed that a color image is read from an arbitrary document 30 according to the setting of the zoom ratio Z. In the color scanner 100, a one-dimensional image sensor 58 is used in which the RGB scanning sensors Lr, Lg, and Lb have a distance of 4 lines in the sub-scanning direction. In this example, when the R color reading sensor Lr is used as a reference, and the scaling factor Z ≠ 100% is set, the fractional line delay is absorbed on the image sensor side, and the integer number of line delays are absorbed. As for an example, correction is performed by the delay circuit 61G of the G color correction processing unit 32G and the delay circuit 61B of the B color correction processing unit 32B, respectively. Under these image reading conditions, the MPU 15 waits for setting of the document 30 in step A1 of the flowchart shown in FIG.

[Platen mode]
For example, the user opens the ADF 40 on the platen glass upward, places the document 30 with the image forming surface down on the platen glass, and then operates the ADF 40 downward to cover the platen cover 50. As a result, the document 30 placed on the platen glass is covered with the platen cover 50 with the image forming surface facing downward. The document 30 on the platen glass is recognized by the MPU 15 by a sheet detection signal indicating that “the document has been set on the platen glass” by a known sheet detection technique.

  Next, in step A2, the MPU 15 inputs and sets the variable magnification Z. The variable magnification Z is set by the user using the operation panel 48. The scaling factor Z can be input as an integer and a decimal point. The default value of the scaling factor Z is 100%. For example, 90% or the like is set as the scaling factor Z.

  The MPU 15 calculates a sensor interval of 4 lines × 90%, and acquires an interline delay amount = 3.6 lines. In this example, since the read sensor Lr for R color is used as a reference, the distance between the read sensor Lr for R color and the read sensor Lg for G color is 3.6 lines, and the read sensor Lr for R color The interval between the read sensors Lb for B color is 7.2 lines.

  The MPU 15 that has obtained the calculation result outputs to the timing controller 34 a signal creation command D1 that creates a read timing signal SHg in consideration of a delay time of Gt = 0.6T for the G color read sensor Lg. . In this example, the MPU 15 outputs several line adjustment data D4 for setting the delay time Gt = 0.6T to the delay circuit 74. Further, the delay stage number of the FIFO memory = 3 lines is set for the delay circuit 61G of the correction processing unit 32G.

  Similarly, the MPU 15 outputs to the timing controller 34 a signal creation command D1 that creates a read timing signal SHb in consideration of a delay time of Bt = 0.2T for the B color read sensor Lb. The MPU 15 outputs the decimal line adjustment data D5 for setting the delay time Bt = 0.2T to the delay circuit 75. Further, the number of delay stages of the FIFO memory = 7 lines is set for the delay circuit 61B of the correction processing unit 32B.

  Then, in step A3, the MPU 15 branches the control based on the ADF mode or the platen mode. In this example, since the platen mode is set, the process proceeds to step A4, and the control is branched by pressing the start or stop button. When the start button is pressed, the process proceeds to step A5, and the optical system drive control unit 37 drives the optical system relative to the document 30 using the paper detection signal and the start-on signal generated by pressing the start button as a trigger. The unit 59 starts to move in the sub-scanning direction.

  In step A6, the image sensor 58 reads the document 30. At this time, the image sensor 58 reads light information of R color, G color, and B color in time series at the same position in the sub-scanning direction of the document 30 irradiated with light from the light source 53. For example, in the timing controller 34 shown in FIG. 5, the reference clock signal CLK having a predetermined frequency oscillated by the clock oscillator 71 is output to the timing signal generator 72. The timing signal generator 72 receives a signal creation command D1 based on the scaling factor Z from the MPU 15 and a reference clock signal CLK from the clock oscillator 71, and divides or multiplies the reference clock signal CLK based on the signal creation command D1, Perform signal processing such as waveform shaping.

  As a result of the execution of this signal processing, the timing signal generator 72 generates the read timing signal SHr for the read sensor Lr, the two-phase clock signals φ1A, φ2A, the read clock signal φ2B for each of the read sensors Lr, Lg, Lb, A reset signal RS and a clamp signal CP are generated.

  In the timing correction unit 73 connected to the timing signal generator 72, the delay circuit (DELY) 74 for the reading sensor Lg inputs the decimal line adjustment data D4 based on the variable magnification Z, and the decimal line adjustment data D4 is input to the decimal line adjustment data D4. Based on this, the read timing signal SHr is delayed, and the delayed read timing signal SHr is output as the read timing signal SHg for the read sensor Lg. A delay circuit (DELY) 75 for the read sensor Lb receives decimal line adjustment data D5 based on the variable magnification Z, delays the read timing signal SHr based on the decimal line adjustment data D5, and reads the delayed read timing signal SHr. Is output as a read timing signal SHb for the read sensor Lb.

  The read sensor Lr shown in FIG. 3 is supplied with the read timing signal SHr shown in FIG. 6A from the timing controller 34. The Lr two-phase clock signals φ1A and φ2A, the read clock signal φ2B, the reset signal RS, and the clamp signal CP are output from the timing controller 34 to the read sensor Lr based on the read timing signal SHr.

  As shown in FIG. 6A, the read timing signal SHg delayed by the delay time Gt = 0.6T from the read timing signal SHr is supplied from the timing controller 34 to the read sensor Lg shown in FIG. The Lg two-phase clock signals φ1A and φ2A, the read clock signal φ2B, the reset signal RS, and the clamp signal CP are output from the timing controller 34 to the read sensor Lg based on the read timing signal SHg.

  Further, a read timing signal SHb delayed by a delay time Bt = 0.2T from the read timing signal SHr shown in FIG. 7A is supplied from the timing controller 34 to the read sensor Lb shown in FIG. The Lb two-phase clock signals φ1A and φ2A, the read clock signal φ2B, the reset signal RS, and the clamp signal CP are output from the timing controller 34 to the read sensor Lb with reference to the read timing signal SHb. As a result, the drive control of each reading sensor Lr, Lg, Lb is shifted and controlled independently for each color within one line accumulation time.

  As described above, the image 30 is irradiated with light and the optical information returned from the document 30 is read by the image sensor 58. The sensor Lr outputs an analog image reading signal Sr to the analog signal processing unit 31R, the sensor Lg outputs the image reading signal Sg to the analog signal processing unit 31G of the control unit 35, and the sensor Lb outputs the image reading signal Sb to the analog signal. The data is output to the processing unit 31B. The image reading signals Sr, Sg, and Sb constitute an RGB color image reading signal Sout. The RGB color image reading signal Sout obtained by reading the document 30 is output in units of one page of the document 30.

  In the control unit 35, the image reading signal Sout input from the image sensor 58 is A / D converted by the analog signal processing units 31R, 31G, and 31B of the RGB color channels. In this example, the image reading data Dr output from the analog signal processing unit 31R for the R color channel, the image reading data Dg output from the analog signal processing unit 31G for the G color channel, and the analog signal processing unit 31B for the B color channel. With respect to the output image read data Db, the line delay between the read sensors Lr-Lg and the sensors Lr-Lb is corrected by an integer.

  For example, when the image reading data Db arrives from the image sensor 58 shown in FIG. 8 to the delay circuit 61B of the correction processing unit 32B, the image reading data Dg reaches the delay circuit 61G of the correction processing unit 32G with a delay of 4 lines. Further, the image reading data Dr is input to the correction processing unit 32R with a delay of three lines.

  In this example, since the number of FIFO memory delay stages = 3 lines is set from the MPU 15 to the delay circuit 61G, the delay time of the integer 3 lines between the sensors Lr-Lg of the image read data Dg is set in the delay circuit 61G. Absorbed. Since the number of FIFO memory delay stages = 7 lines is set in the delay circuit 61B, the delay time for the integer 7 lines between the sensors Lr-Lb of the image read data Db is absorbed by the delay circuit 61B.

Thereby, image read data Db composed of pixel values B ₁ , B ₂ , B ₃ ..., Image read data Dg composed of pixel values G ₁ , G ₂ , G _3. Image reading data Dr composed of ₁ , R ₂ , R ₃ ... Can be obtained, and image reading data Dout composed of these data Dr, Dg, Db and without interline delay can be obtained. .

  The image read data Dr, Dg, Db (= Din, Dout) of the above-mentioned RGB color 3 channels is stored in the image memory 36. The image reading data Din is stored in units of one page, and an end of flag (EOF) is added to the image reading data Din of the page. When the scanner 100 is used by connecting a printer or the like, the image reading data Dout to which an end of flag or the like is added for each page is output to the printer or the like. Thereafter, the process proceeds to step A11.

[ADF mode]
When the user sets the document 30 on the ADF 40 in step A1, a sheet detection signal indicating that “the document is set on the ADF 40” is output to the MPU 15 by a known sheet detection technique. In step A2, the MPU 15 inputs and sets the variable magnification Z from the user in the same manner as in the platen mode. Thereafter, the process proceeds to step A3, and the MPU 15 branches the control based on the ADF mode or the platen mode. In this example, since the ADF mode is set, the process proceeds to step A7, and the control is further branched by pressing the start or stop button.

  In this example, when the start button is pressed, the process proceeds to step A8 where the original 30 is fed by the roller 43. At this time, the optical system drive control unit 37 starts feeding the document 30 in the sub-scanning direction relative to the optical system including the image sensor 58 using a paper detection signal and a start-on signal when the start button is pressed as a trigger. To do. Thereafter, the process proceeds to step A9 to execute an image reading process.

  In this example, when the document 30 reverses the roller 43 in a U shape, the image sensor 58 reads the surface of the document 30. At this time, the image sensor 58 reads light information of R color, G color, and B color in time series at the same position in the sub-scanning direction of the document 30 irradiated with light from the light source 53. The reading sensor Lr reads the accumulated charge based on the reading timing signal SHr shown in FIG. 6A, the reading sensor Lg reads the accumulated charge based on the reading timing signal SHg, and the reading sensor Lb is based on the reading timing signal SHb. Then, the accumulated charge is read out. An image reading signal Sout composed of these accumulated charges is output from the image sensor 58 to the control unit 35.

  Similarly to the platen mode, the control unit 35 receives the image reading signal Sout from the image sensor 58, and the image reading signal Sout is A / D converted by the analog signal processing units 31R, 31G, and 31B of the RGB color channels. To do. Even in the ADF mode, the inter-line delay is corrected for the RGB color three-channel image read data Dr, Dg, and Db output from the RGB color channel analog signal processing units 31R, 31G, and 31B. The image read data Dr, Dg, Db (= Din, Dout) are stored in the image memory 36 in the same manner as in the platen mode. Alternatively, the image reading data Dout is output to a printer or the like with an end-of-flag or the like added to each page.

  Thereafter, the process proceeds to step A10, and the MPU 15 determines whether or not the document 30 is the last page based on the detection of the paper detection signal. If the original 30 is not the last page, that is, if the original 30 remains on the original placement portion 41, the paper detection signal indicates “paper present”, so the process returns to step A9 to perform the above-described image reading process. It is made to repeat. If the document 30 is the last page, the process proceeds to step A11 after completing the image reading process.

  If the stop button is pressed in steps A4 and A7 described above, the process proceeds to step A11, and the MPU 15 makes an end determination regarding the image reading process. For example, the power-off information is detected and the image reading process is terminated. If the power-off information is not detected, the process returns to step A1 to wait for the document set. Thereafter, the above-described processing is repeated.

  As described above, according to the color scanner and the image reading method as the first embodiment of the present invention, when the color image formed on an arbitrary document 30 is read, the control unit 35 changes the preset value. The optical system drive unit 59 is controlled at a sub-scanning speed corresponding to the magnification Z, and reading timing signals SHr, SHg, SHb corresponding to the variable magnification Z are output to independently read the color reading sensors Lr, Lg, Lb. It is made to control.

  Accordingly, the light information of each color can be read in time series at the same position in the sub-scanning direction in the order of reading sensors arranged in the sub-scanning direction. That is, even if the sub-scanning speed is changed based on the variable magnification Z, the same position is shifted between the reading sensors Lr, Lg, and Lb with respect to the document 30, and the reading sensors Lr, Lg, and Lb Since the original image is read, the resolution in the sub-scanning direction can be kept constant even when the zoom ratio Z changes.

  In addition, even when the sub-scanning speed changes due to the magnification Z at the time of reading the document and the scanning timing is shifted according to the reading sensor interval, even when the reading timing is less than one line reading cycle. The reading timing shift can be absorbed on the image sensor side.

  That is, since the driving timings of the reading sensors Lr, Lg, and Lb for the respective colors can be shifted in accordance with the change in the sub-scanning speed based on the variable magnification Z, the subsequent stage of the delay circuit that absorbs the line delay by an integer as in the conventional method. The linear interpolation circuit that performs the linear interpolation processing between the data for two lines, which has been prepared in (1), can be omitted. As a result, deterioration of the image resolution (MTF) in the sub-scanning direction can be completely prevented, and color blurring of black horizontal fine lines due to different linear interpolation coefficients for each color does not occur in principle.

FIG. 10 is a conceptual diagram showing a configuration example of a color copying machine 200 as a second embodiment according to the present invention.
In this embodiment, the color copying machine 200 having the color scanner function shown in FIGS. 1 to 9 is configured, and a color image is read from an arbitrary document 30 based on the setting of the variable magnification Z and the ADF mode or the platen mode. A color image corresponding to the zoom ratio Z is formed.

  A color copying machine 200 shown in FIG. 10 is an example of an image forming apparatus, reads a color image formed on an arbitrary document 30, acquires image information, and superimposes colors on the image forming body based on the image information. A device for forming a color image. The color copying machine 200 includes a copying machine main body 201 and a color scanner 100. The scanner 100 is an example of an image reading apparatus and incorporates the functions described in the first embodiment, and reads a color image formed on the document 30.

  An ADF (automatic document feeder) 40 and a scanner unit (image reading / scanning / exposure device) 11 are arranged on the upper part of the copying machine main body 201. The document 30 placed on the document placement unit 41 of the ADF 40 is transported by a transport unit, and an image on one or both sides of the document 30 is scanned and exposed by the optical system of the scanner unit 11, and incident light reflecting image reading is imaged. It is read by the sensor 58.

  As described with reference to FIGS. 2 and 3, the image sensor 58 includes three reading sensors Lr, Lg for detecting R, G, and B color light configured by arranging a plurality of light receiving element arrays in the main scanning direction. , Lb are arranged at a predetermined distance in the sub-scanning direction, and the pixels are divided at the same position in the sub-scanning direction of the document 30 irradiated with light from the light source 53, thereby R, G, and B colors. The optical information is read in time series.

  In addition to the image sensor 58, the scanner unit 11 includes a first platen glass 51, a second platen glass 52, a light source 53, mirrors 54, 55, and 56, an imaging optical unit 57, and an optical system driving unit 59. ing. The optical system drive unit 59 operates so as to relatively move the document 30 or the image sensor 58 in the sub-scanning direction. In this example, the optical system drive unit 59 is provided with a motor 59 ', and moves the optical system such as the light source 53, the mirrors 54, 55, and 56 in the sub-scanning direction. In this example, the optical system driving unit 59 is controlled by a motor so as to vary the reading speed in the sub-scanning direction according to the variable magnification Z.

  The analog image reading signal Sin photoelectrically converted by the image sensor 58 is subjected to analog processing, A / D conversion, shading correction, image compression processing, processing, and the like in an image processing unit (not shown) to become digital image data Din. . The image reading data Din is converted into image data Dy, Dm, Dc, Dk for Y, M, C, BK colors, and then image writing units (exposure means) 3Y, 3M, Sent to 3C, 3K.

  The ADF 40 described above is provided with automatic double-sided document conveying means. The ADF 40 continuously reads the contents of a large number of documents 30 fed from the document placing section 41 at once, and accumulates the document contents in a storage means (electronic RDH function). This electronic RDH function is conveniently used when copying the contents of a large number of documents by the copying function or when transmitting a large number of documents 30 by the facsimile function.

  The copying machine main body 201 is called a tandem type color image forming apparatus. The copying machine main body 201 is provided with an image forming means 60. The image forming unit 60 forms a color image based on the image data Dy, Dm, Dc, Dk obtained by reading with the scanner 100. The image forming means 60 includes a plurality of sets of image forming units (image forming systems) 10Y, 10M, 10C, and 10K each having an image forming body for each color, an endless intermediate transfer belt (image transfer system) 6, and A sheet feeding / conveying unit including a sheet re-feeding mechanism (ADU mechanism) and a fixing device 17 for fixing the toner image are provided.

  The image forming unit 10Y that forms a yellow (Y) image includes a photosensitive drum 1Y as an image forming body that forms a Y-color toner image, and a Y-color charging disposed around the photosensitive drum 1Y. Means 2Y, exposure means 3Y, developing device 4Y, and image forming body cleaning means 8Y. An image forming unit 10M for forming a magenta (M) color image includes a photosensitive drum 1M as an image forming body for forming an M color toner image, an M color charging unit 2M, an exposure unit 3M, and a developing device 4M. And an image forming member cleaning means 8M.

  An image forming unit 10C for forming a cyan (C) color image includes a photosensitive drum 1C as an image forming body for forming a C toner image, a charging unit 2C for C color, an exposure unit 3C, and a developing device 4C. And an image forming member cleaning means 8C. An image forming unit 10K that forms a black (BK) color image includes a photosensitive drum 1K as an image forming body that forms a BK color toner image, a charging unit 2K for BK color, an exposure unit 3K, and a developing device 4K. And an image forming member cleaning means 8K.

  The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit. Development by the developing devices 4Y, 4M, 4C, and 4K is performed by reversal development in which a development bias in which an AC voltage is superimposed on a DC voltage having the same polarity (negative polarity in this embodiment) as the polarity of the toner to be used is applied. . The intermediate transfer belt 6 is wound around a plurality of rollers and is rotatably supported. Each of the Y, M, C, and BK colors formed on each of the photosensitive drums 1Y, 1M, 1C, and 1K. A toner image is transferred.

  Here, an outline of the image forming process will be described below. Each color image formed by the image forming units 10 </ b> Y, 10 </ b> M, 10 </ b> C, and 10 </ b> K is subjected to primary transfer bias (not shown) having a polarity (positive polarity in this embodiment) opposite to the toner to be used. Rollers 7Y, 7M, 7C, and 7K sequentially transfer onto the rotating intermediate transfer belt 6 to form a color image (color image: color toner image) that is synthesized by superimposing colors (primary transfer). .

  Further, below the image forming unit 60, sheet feeding cassettes 20A, 20B, and 20C constituting a sheet feeding unit are provided. The paper P stored in the paper feed cassette 20A or the like is fed by a feed roller 21 and a paper feed roller 22A provided in the cassette 20A or the like, passes through the transport rollers 22B, 22C, 22D, the registration roller 23, and the like, and then 2 The sheet is conveyed to the next transfer roller 7A, and the color image is collectively transferred from the intermediate transfer belt 6 to the sheet P on one surface (front surface) on the sheet P (secondary transfer).

  The paper P on which the color image has been transferred is fixed by the fixing device 17, is sandwiched between the paper discharge rollers 24, and is placed on a paper discharge tray 25 outside the apparatus. The transfer residual toner remaining on the peripheral surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K after the transfer is cleaned by the image forming body cleaning means 8Y, 8M, 8C, and 8K, and enters the next image forming cycle.

  At the time of double-sided image formation, the paper P formed on one side (front surface) and discharged from the fixing device 17 is branched from the document 30 discharge path by the branching unit 26, and each of the lower sides constituting the paper feeding and conveying unit. , The front and back are reversed by a reversing conveyance path 27B which is a refeeding mechanism (ADU mechanism), passes through the refeeding conveyance section 27C, and merges at the sheet feeding roller 22D.

  The reversely conveyed sheet P is conveyed again to the secondary transfer roller 7A through the registration roller 23, and a color image (color toner image) is collectively transferred onto the other side (back side) of the sheet P. On the other hand, after the color image is transferred to the paper P by the secondary transfer roller 7A, the residual toner is removed by the intermediate transfer belt cleaning means 8A from the intermediate transfer belt 6 that has separated the curvature of the paper P.

The time of forming these images, 52.3~63.9kg / m ² (1000 sheets) as the paper P about thin and 64.0~81.4kg / m ² (1000 sheets) of approximately plain paper, 83 .0~130.0kg / m ² (1000 sheets) about cardboard and 150.0kg / m ² (1000 sheets) about super thick paper is used. The thickness of the paper P (paper thickness) is about 0.05 to 0.15 mm.

  FIG. 11 is a block diagram illustrating a configuration example of a control system of the color copying machine 200. A color copying machine 200 shown in FIG. 11 includes a scanner unit 11, a control unit 35 ', a communication unit 19, a paper feeding unit 20, an operation panel 48, and an image forming unit 60.

  The scanner unit 11 includes the image sensor 58 and the optical system driving unit 59 described with reference to FIG. The control unit 35 ′ includes the MPU 15, RGB color analog signal processing units 31R, 31G, and 31B, correction processing units 32R, 32G, and 32B, memory access control units 33R, 33G, and 33B, a timing controller 34, an image memory 36, and an optical unit. In addition to the system drive control unit 37, a color conversion processing unit 38 and timing control units 39Y, 39M, 39C, and 39K are included. In addition, since the thing of the same name and code | symbol demonstrated in the 1st Example has the same function, the description is abbreviate | omitted.

  In this example, the operation panel 48 includes the operation unit 14 formed from a touch panel and the display unit 18 formed from a liquid crystal display element (LCD). The operation unit 14 is operated so as to set a zoom ratio Z when reading the document 30, and input image forming conditions such as setting of image density, selection of paper size, setting of the number of copying machines, and the like. Operated. The display unit 18 reduces the size of the document image based on the image reading data Dout acquired by the scanner unit 11 and displays a preview, or displays selection items related to image forming conditions based on the display data D2. Note that the image forming conditions and paper cassette selection information set on the operation panel 48 are output to the MPU 15 as operation data D3.

  In this example, the MPU 15 includes a ROM (Read Only Memory) 94, a CPU (Central Processing Unit) 95, and a work RAM (Random Access Memory) 96. The ROM 94 stores system program data for controlling the entire copying machine. The RAM 96 temporarily stores control commands and the like when executing the image processing mode. When the power is turned on, the CPU 95 reads the system program data from the ROM 94, starts up the system, and controls the entire copying machine.

  For example, the MPU 15 controls the image memory 36 or the like based on the image forming conditions set by the operation panel 48, or performs color processing based on the image data Dy, Dm, Dc, Dk color-converted by the color conversion processing unit 38. The image forming unit 60 is controlled to form an image. In this example, the MPU 15 outputs an image processing control signal S2 to the color conversion processing unit 38.

  In addition, the MPU 15 controls input / output of the correction processing units 32R, 32G, and 32B based on the scaling factor Z set by the operation panel 48 in the ADF mode or the platen mode. For example, the MPU 15 calculates a delay amount for correcting the shift of the decimal line between the reading sensors Lr, Lg, and Lb of each color based on the variable magnification Z when the variable magnification Z ≠ 100%. A timing controller 34 is connected to the MPU 15 and controls the timing controller 34 so as to output read timing signals SHg and SHb in consideration of a delay time.

  The timing controller 34 generates the read timing signals SHg and SHb based on the signal generation command (delay amount) D1 output from the MPU 15 and the read timing signal SHr formed based on the reference clock signal CLK. Made. The read timing signals SHr, SHg, and SHb are output from the timing controller 34 to the image sensor 58 together with the two-phase clock signals φ1A and φ2A, the read clock signal φ2B, the reset signal RS, and the clamp signal CP. The MPU 15 sets the number of FIFO memory delay stages = integer lines for the delay circuit 61G of the correction processing unit 32G and the delay circuit 61B of the correction processing unit 32B.

  In this example, a color conversion processing unit 38 is connected to the memory access control units 33R, 33G, and 33G shown in FIG. In the color conversion processing unit 38, the RGB color image read data Dout (= Dr, Dg, Db) read from the image memory 36 is converted into YMCK color image data Dy, Dm, Color conversion is performed to Dc and Dk. The color conversion processing unit 38 is provided with a lookup table (LUT) (not shown) for color conversion.

  Timing control units 39Y, 39M, 39C, and 39K are connected to the color conversion processing unit 38. The timing control unit 39Y receives the image data Dy from the color conversion processing unit 38 based on the timing control signal S3, performs PWM γ correction processing on the image data Dy, performs frequency conversion processing on the image data Dy, and based on the image data Dy. Thus, index synchronization detection processing is performed, or image data Dy is subjected to PWM (pulse width modulation) processing to output a laser drive signal Sy. The timing control signal S3 is output from the MPU 15 to each timing control unit 39Y, 39M, 39C, 39K.

  Similarly, the timing control unit 39M inputs image data Dm, performs PWM γ correction processing on the image data Dm, performs frequency conversion processing on the image data Dm, performs index synchronization detection processing based on the image data Dm, The image data Dm is PWM-processed to output a laser drive signal Sm.

  Similarly, the timing control unit 39C inputs image data Dc, performs PWM γ correction processing on the image data Dc, performs frequency conversion processing on the image data Dc, performs index synchronization detection processing based on the image data Dc, The image data Dc is PWM-processed to output a laser drive signal Sc.

  Similarly, the timing control unit 39K inputs the image data Dk, performs PWM γ correction processing on the image data Dk, performs frequency conversion processing on the image data Dk, performs index synchronization detection processing based on the image data Dk, The image data Dk is PWM-processed to output a laser drive signal Sk.

  In this example, the MPU 15 outputs an image formation control signal S4 to the image forming unit 60. The image forming unit 60 operates to input a laser drive signal Sy, Sm, Sc, Sk and an image formation control signal S4 to form a color image on a predetermined sheet P. In this example, the image forming unit 60 is provided with laser diodes LDy, LDm, LDc, and LDk. The laser diode LDy generates a laser beam for Y color having a predetermined intensity based on the laser drive signal Sy.

  Similarly, the laser diode LDm generates a laser beam for M color having a predetermined intensity based on the laser drive signal Sm. The laser diode LDc generates a laser beam for C color having a predetermined intensity based on the laser drive signal Sc. The laser diode LDk generates a BK color laser beam having a predetermined intensity based on the laser drive signal Sk. An example of the internal configuration of the image forming unit 60 has been described with reference to FIG.

  In this example, the sheet feeding means 20 is connected to the system bus 29, and the sheet feeding cassettes 20A to 20C shown in FIG. 10 are controlled based on the sheet feeding control signal S5. For example, the paper feed unit 20 selects one of the paper feed cassettes 20A, 20B, and 20C based on the paper feed control signal S5, and transports the paper P fed from the paper feed cassette 20A, 20B, or 20C to the image forming system. To be made. The paper feed control signal S5 is supplied from the MPU 15 to the paper feed means 20.

  The communication means 19 is connected to a communication line such as a LAN, and is used when performing communication processing with an external computer or the like. For example, when a document image having a desired variable magnification Z read by the color copying machine 200 is image-formed and output by an external printer or the like, the communication means 19 transmits print data Dout ′ to the external printer. . The print data Dout 'is subjected to color conversion processing by the color conversion processing unit 38, and a color image can be formed on the basis of the variable magnification Z even in an external multi-function peripheral or printer.

Next, an example of image formation in the color copying machine 200 will be described. FIG. 12 is a flowchart showing an example of image formation in the color copying machine 200.
In this embodiment, it is assumed that a color image is formed by reading a color image from an arbitrary document 30 according to the setting of the zoom ratio Z. In the color scanner 100, a one-dimensional image sensor 58 is used in which the RGB scanning sensors Lr, Lg, and Lb have a distance of 4 lines in the sub-scanning direction. In this example, the RGB color timing correction units 34R, 34G, and 34B are arranged in the sub-scanning direction of the read sensors Lr, Lg, and Lb for detecting light of R, G, and B colors with respect to the light information read by the image sensor 58. A misalignment is corrected. With these as image forming conditions, the MPU 15 waits for a copy request in step Q1 of the flowchart shown in FIG.

[Platen mode]
For example, the user opens the ADF 40 on the platen glass upward, places the document 30 with the image forming surface down on the platen glass, and then operates the ADF 40 downward to cover the platen cover 50. As a result, the document 30 placed on the platen glass is covered with the platen cover 50 with the image forming surface facing downward. The presence / absence of a document on the platen glass is output to the MPU 15 by a paper detection signal. The MPU 15 recognizes the copy request based on the paper detection signal.

  If there is a copy request, the process proceeds to step Q2, and the MPU 15 inputs and sets the zoom ratio Z and other image forming conditions. Here, the user operates the operation panel 48 to input image forming conditions such as the variable magnification Z, the paper size, and the number of copies. The variable magnification Z can be input as an integer and a decimal point. The default value of the scaling factor Z is 100%. For example, 90% or the like is set as the scaling factor Z of the decimal point.

  In step Q3, the MPU 15 branches the control based on the ADF mode or the platen mode. In this example, since the platen mode is set, the process proceeds to step Q4, and the control is branched by pressing the start or stop button. If the start button is pressed, the process proceeds to step Q5, and the optical system drive control unit 37 uses the paper detection signal and the start-on signal generated by pressing the start button as a trigger, and the motor 59 ′ of the optical system drive unit 59 receives a motor. The control signal S1 is output to start moving the optical drive system in the sub-scanning direction relative to the document 30.

  In step Q6, the image sensor 58 executes image reading processing of the document 30. At this time, the image sensor 58 reads light information of R color, G color, and B color in time series at the same position in the sub-scanning direction of the document 30 irradiated with light from the light source 53. An RGB color image reading signal Sout obtained by reading the document 30 is output from the image sensor 58 to the control unit 35 ′. The image reading signal Sout is output in units of one page of the document 30.

  The control unit 35 'receives the image reading signal Sout from the image sensor 58, and A / D converts the image reading signal Sout by the analog signal processing units 31R, 31G, and 31B of the RGB color channels. In this example, the image reading data Dr output from the analog signal processing unit 31R for the R color channel, the image reading data Dg output from the analog signal processing unit 31G for the G color channel, and the analog signal processing unit 31B for the B color channel. With respect to the output image read data Db, the delay between lines is corrected.

  For example, as shown in FIG. 8, in the G color channel correction processing unit 32G, in order to correct the integer lines by the delay circuit 61G, the image read data Dg for three lines is read from the FIFO memory by the FIFO memory. Delay several stages. Further, the B color channel correction processing unit 32B delays the image read data for 7 lines with respect to the image read data Db in order to correct 7 integer lines with the delay circuit 61B.

  The above-described RGB color three-channel image read data Dr, Dg, Db is encoded and compressed by the memory access control units 33R, 33G, 33B, etc., and is temporarily stored in the image memory 36. The image reading data Din is stored in units of one page, and an end of flag (EOF) is added to the image reading data Din of the page.

  Then, the process proceeds to step Q7 to execute image forming processing. At this time, the memory access control units 33R, 33G, 33B, etc. read the RGB color three-channel image read data Dr, Dg, Db from the image memory 36, decode the image read data Dr, Dg, Db, and decompress them. The decompressed image read data Dr, Dg, and Db are transferred to the color conversion processing unit 38 under the control of the memory access control units 33R, 33G, and 33B.

  The color conversion processing unit 38 converts the RGB color image read data Dr, Dg, Db read from the image memory 36 into YMCK color image data Dy, Dm, Dc, Dk based on the image processing control signal S2. Color conversion is made. The color-converted image data Dy, Dm, Dc, and Dk are output to the timing controllers 39Y, 39M, 39C, and 39K. At this time, the MPU 15 outputs a timing control signal S3 to each timing control unit 39Y, 39M, 39C, 39K.

  In the timing control unit 39Y, the image data Dy is input from the color conversion processing unit 38 based on the timing control signal S3, the image data Dy is subjected to PWM γ correction processing, and then subjected to frequency conversion processing. Further, the timing control unit 39Y detects an index signal based on the image data Dy and performs an index synchronization detection process in order to align the timing of the laser beam. Further, the timing control unit 39Y generates a laser drive signal Sy by subjecting a predetermined pulse signal to PWM (pulse width modulation) processing based on the image data Dy.

  Similarly, the timing control unit 39M inputs the image data Dm, performs PWM γ correction processing, frequency conversion processing, and index synchronization detection processing, or performs PWM processing on the image data Dm and outputs the laser drive signal Sm. Made. Similarly, the timing control unit 39C also receives the image data Dc, performs PWM γ correction processing, frequency conversion processing, index synchronization detection processing, or PWM-processes the image data Dc to output the laser drive signal Sc. Made. Similarly, the timing control unit 39K also receives the image data Dk, performs PWM γ correction processing, frequency conversion processing, and index synchronization detection processing, or performs PWM processing on the image data Dk and outputs a laser drive signal Sk. Made.

  These laser drive signals Sy, Sm, Sc, and Sk are output to the image forming unit 60 together with the image formation control signal S4. The image forming unit 60 operates to input a laser drive signal Sy, Sm, Sc, Sk and an image formation control signal S4 to form a color image on a predetermined sheet P. For example, the laser diode LDy generates a laser beam for Y color having a predetermined intensity based on the laser drive signal Sy. The Y-color laser beam is scanned in the main scanning direction based on the image formation control signal S4, and is irradiated onto the photosensitive drum 1Y shown in FIG. An electrostatic latent image is exposed on the photosensitive drum 1Y by a laser beam for Y color (image writing). The electrostatic latent image exposed on the photosensitive drum 1Y is developed with a Y-color toner. The developed Y color toner image is transferred to the intermediate transfer belt 6.

  Similarly, the laser diode LDm generates a laser beam for M color having a predetermined intensity based on the laser drive signal Sm. The laser beam for M color is scanned in the main scanning direction based on the image formation control signal S4, and is irradiated onto the photosensitive drum 1M. The photosensitive drum 1M is exposed to an electrostatic latent image by an M color laser beam. The electrostatic latent image exposed on the photosensitive drum 1M is developed with an M color toner. The developed M color toner image is transferred to the intermediate transfer belt 6 and superimposed on the other colors on the belt.

  Further, the laser diode LDc generates a laser beam for C color having a predetermined intensity based on the laser drive signal Sc. The laser beam for C color is scanned in the main scanning direction based on the image forming control signal S4, and is irradiated onto the photosensitive drum 1C. An electrostatic latent image is exposed on the photosensitive drum 1C by a C-color laser beam. The electrostatic latent image exposed on the photosensitive drum 1C is developed with a C-color toner agent. The developed C color toner image is transferred to the intermediate transfer belt 6 and superimposed on the other Y and M colors on the belt.

Furthermore, the laser diode LDk generates a BK color laser beam having a predetermined intensity based on the laser drive signal Sk. The laser beam for BK color is scanned in the main scanning direction and irradiated to the photosensitive drum 1K. An electrostatic latent image is exposed on the photosensitive drum 1K by a laser beam for K color. The electrostatic latent image exposed on the photosensitive drum 1K is developed with a BK toner. The developed BK color toner image is transferred to the intermediate transfer belt 6. The color toner image superimposed on the intermediate transfer belt 6 is transferred onto a predetermined paper P. The paper P is fed out from a paper feed cassette 20A, 20B, or 20C controlled by the paper feed means 20 based on a paper feed control signal S5. The paper feed control signal S5 is supplied from the MPU 15 to the paper feed means 20.
[ADF mode]
When the user sets the document 30 on the ADF 40 in step Q1, a paper detection signal indicating that “the document is set on the ADF 40” is output to the MPU 15. In step Q2, the MPU 15 inputs and sets the zoom ratio Z and image forming conditions from the user in the same manner as in the platen mode. Thereafter, the process proceeds to step Q3, and the MPU 15 branches the control based on the ADF mode or the platen mode. In this example, since the ADF mode is set, the process proceeds to step Q8, and the control is further branched by pressing the start or stop button.

  In this example, when the start button is pressed, the process proceeds to step Q9 and the document 30 is started to be fed by the roller 43. At this time, the optical system drive control unit 37 uses a paper detection signal and a start-on signal by pressing the start button as a trigger, and the optical system drive control unit 37 sends a motor control signal S1 to the motor 59 ′ of the optical system drive unit 59. Then, the document 30 is fed in the sub-scanning direction relative to the optical system including the image sensor 58.

  Thereafter, the process proceeds to step Q10 to execute an image reading process. In this example, when the document 30 reverses the roller 43 in a U shape, the image sensor 58 reads the surface of the document 30. At this time, the image sensor 58 reads the light information of the R color, the G color, and the B color at the same time at different positions in the sub-scanning direction of the document 30 irradiated with light from the light source 53. The image reading signal Sout is output from the image sensor 58 to the control unit 35 '.

  Similarly to the platen mode, the control unit 35 ′ inputs the image reading signal Sout from the image sensor 58, and the image reading signal Sout is A / D processed by the analog signal processing units 31 R, 31 G, and 31 B of the RGB color channels. Convert. Even in the ADF mode, the inter-line delay is corrected for the RGB color three-channel image read data Dr, Dg, and Db output from the RGB color channel analog signal processing units 31R, 31G, and 31B.

  The image read data Dr, Dg, Db are encoded and compressed by the memory access control units 33R, 33G, 33B, etc., and stored in the image memory 36 in the same manner as in the platen mode. The image reading data Din is stored in units of one page, and an end of flag (EOF) is added to the image reading data Din of the page.

  Then, the process proceeds to step Q10 to execute image forming processing. At this time, the memory access control units 33R, 33G, 33B, etc. read the image reading data Dr, Dg, Db of the RGB color three channels from the image memory 36 in the same manner as in the platen mode, and the image reading data Dr, Dg, Decrypt and decompress Db. The decompressed image read data Dr, Dg, and Db are transferred to the color conversion processing unit 38 under the control of the memory access control units 33R, 33G, and 33B.

  The color conversion processing unit 38 converts the RGB color image read data Dr, Dg, Db read from the image memory 36 into YMCK color image data Dy, Dm, Dc, Dk based on the image processing control signal S2. Color conversion is made. The color-converted image data Dy, Dm, Dc, and Dk are output to the timing controllers 39Y, 39M, 39C, and 39K.

  At this time, the timing control units 39Y, 39M, 39C, and 39K receive the image data Dy, Dm, Dc, and Dk from the color conversion processing unit 38 based on the timing control signal S3. These image data Dy, Dm, Dc, and Dk are subjected to PWM γ correction processing by the respective timing controllers 39Y, 39M, 39C, and 39K, and then subjected to frequency conversion processing.

  In addition, in order to align the timings of the laser beams for the respective colors, index signals relating to the laser beams for the respective colors are detected based on the image data Dy, Dm, Dc, and Dk, and index synchronization detection processing is performed. Further, in each of the timing controllers 39Y, 39M, 39C, and 39K, a predetermined pulse signal is subjected to PWM (pulse width modulation) processing based on the image data Dy, Dm, Dc, and Dk, and laser drive signals Sy, Sm, Sc and Sk are generated.

  These laser drive signals Sy, Sm, Sc, and Sk are output to the image forming unit 60 together with the image formation control signal S4. In the same manner as in the platen mode, the image forming means 60 operates to input a laser drive signal Sy, Sm, Sc, Sk and an image formation control signal S4 to form a color image on a predetermined sheet P (step). Q7).

  Thereafter, the process proceeds to step Q12, and the MPU 15 determines whether or not the original 30 is the last page based on the detection of the paper detection signal. If the original 30 is not the last page, that is, if the original 30 remains on the original placement portion 41, the paper detection signal indicates “paper present”, so the process returns to step Q10 to perform the above-described image forming process. It is made to repeat. If the original 30 is the last page, the process proceeds to step Q13 after completing the image forming process. Note that the number of formed images (number of printed sheets) is counted by a counter (not shown).

  If the stop button is pressed in steps Q4 and Q8 described above, the process proceeds to step Q13, and the MPU 15 makes an end determination regarding the image forming process. For example, the power-off information is detected and the image forming process is terminated. If power-off information is not detected, the process returns to step Q1 to wait for a copy request. Thereafter, the above-described processing is repeated.

  As described above, according to the image forming apparatus as the second embodiment of the present invention, when a color image formed on an arbitrary document 30 is read and a color image is formed on a predetermined sheet P, the present invention is applied. The scanner 100 according to the above is applied.

  Therefore, a color image can be formed based on the light information of each color at the same position in the sub-scanning direction read in time series in the order of the reading sensors Lr, Lg, and Lb arranged in the sub-scanning direction. Thereby, even when the variable magnification (reading magnification × sensor line interval) Z is set to have a value below the decimal point, a high-quality image that is not colored by a black thin line or the like can be formed.

  Further, regarding the image forming means 60, image forming units 10Y, 10M, 10C, and 10K that form toner images of Y color, M color, C color, and BK color on the photosensitive drums 1Y, 1M, 1C, and 1K, and these The case of having the image transfer belt 6 for transferring the toner image formed on the photosensitive drums 1Y, 1M, 1C, and 1K for each color has been described, but the present invention is not limited to this, and the present invention is not limited to one transfer. The present invention can also be applied to a color copying machine that forms a color image on transfer paper by superimposing colors on a material conveying belt.

  The present invention is very suitable when applied to a tandem type color printer, a color copying machine, a color facsimile machine, a multi-function machine thereof, or the like that reads a document including a color image in a black and white document to form a color image.

1 is a conceptual diagram illustrating a configuration example of a color scanner 100 as a first embodiment of the present invention. 3 is a conceptual diagram illustrating a configuration example of an image sensor 58. FIG. 3 is a block diagram showing an example of the internal configuration of an image sensor 58. FIG. 2 is a block diagram illustrating a configuration example of a control system of the color scanner 100. FIG. 3 is a block diagram illustrating an example of an internal configuration of a timing controller 34. FIG. A and B are time charts showing an example of a delay relationship between the reading sensor Lr and the sensor Lg during document reading. A and B are time charts showing an example of the relationship between the reading sensor Lr and the reading sensor Lb during document reading. It is a figure which shows the example of correction | amendment of the delay between lines in the correction process parts 32R, 32G, and 32B at the time of variable magnification Z = 90%. 3 is a flowchart illustrating an example of image reading in the color scanner 100. It is a conceptual diagram which shows the structural example of the color copying machine 200 as a 2nd Example which concerns on this invention. 2 is a block diagram illustrating a configuration example of a control system of a color copying machine 200. FIG. 3 is a flowchart illustrating an example of image formation in the color copying machine 200. It is a figure which shows the example of a delay correction of the image reading data Dr, Dg, Db by the image sensor 58 which concerns on a prior art example. It is a figure which shows the linear interpolation example of the image reading data Dr, Dg, and Db at the time of variable magnification decimal point setting.

Explanation of symbols

1Y, 1M, 1C, 1K Photosensitive drum 3Y, 3M, 3C, 3K Image writing unit (image forming means)
4Y, 4M, 4C, 4K developing device (image forming means)
6 Intermediate transfer belt 10Y, 10M, 10C, 10K Image forming unit (image forming means)
DESCRIPTION OF SYMBOLS 11 Scanner part 11a Scanner main body 14 Operation part (setting means)
15 MPU (control means)
17 Fixing device 18 Display (setting means)
19 Communication means 20 Paper feed means 34 Timing controller (control means)
35, 35 'control unit (control means)
40 Automatic document feeder (ADF)
48 Operation panel 60 Image forming means 61B, 61G Delay circuit 100 Color scanner 101 Copier body 200 Color copier

Claims (8)

An apparatus for reading a color image formed on an arbitrary sheet,
A light source for irradiating the sheet with light;
Line-shaped reading sensors for detecting red, green, and blue, which are configured by arranging a plurality of light receiving elements in the main scanning direction, are arranged at a predetermined distance in the sub-scanning direction orthogonal to the main scanning direction, and A one-dimensional image sensor that reads light information of each color at the same position in the sub-scanning direction of the sheet irradiated with light by the light source in time series;
Moving means for relatively moving the image sensor or the sheet in the sub-scanning direction;
Control means for controlling input / output of the image sensor and moving means,
The control means includes
The moving means is controlled at a sub-scanning speed corresponding to a preset document reading magnification, and the reading sensors for each color are independently controlled by a reading control signal corresponding to the document reading magnification. Image reading device. Setting means for setting a document reading magnification when reading the sheet;
The control means includes
A sub-scanning speed control signal based on the document reading magnification set by the setting unit is output to the moving unit;
The image reading apparatus according to claim 1, wherein a reading timing signal based on the document reading magnification is independently output to the reading sensor for each color. The control means includes
Calculating a delay amount for correcting a deviation of a decimal line between the reading sensors of each color based on the document reading magnification;
The image reading apparatus according to claim 1, wherein the reading timing signal based on the delay amount is created.   A delay circuit that corrects an integer line shift between the reading sensors for detecting each color with respect to the optical information obtained by reading the image sensor from the sheet moved by the moving unit; The image reading apparatus according to claim 1. A method for reading a color image formed on an arbitrary sheet,
A plurality of light receiving elements are arranged in the main scanning direction, and red, green, and blue color detection reading sensors are arranged at a predetermined distance in the sub scanning direction orthogonal to the main scanning direction, and Using a one-dimensional image sensor that reads light information of each color at the same position in the scanning direction in time series,
Set the document scanning magnification when scanning the sheet,
The sheet or image sensor is moved relatively in the sub-scanning direction at a sub-scanning speed based on the set original reading magnification, and each reading sensor for each color is independently set by a reading control signal based on the original reading magnification. Control to
An image reading method characterized by irradiating the sheet with light and reading optical information returned from the sheet. Calculating a delay amount for correcting a shift of a decimal line between the reading sensors of each color based on the set document reading magnification;
6. The image reading method according to claim 5, wherein a read timing signal is created based on the calculated delay amount.   6. The image according to claim 5, wherein a deviation corresponding to an integer line between the reading sensors for detecting each color is corrected with respect to the optical information obtained by reading from the moved sheet by the image sensor. Reading method. An apparatus for reading a color image formed on an arbitrary sheet to form a color image,
An image reading device for reading a color image formed on the sheet;
Image forming means for forming a color image based on color image information obtained by reading with the image reading device;
The image reading device includes:
A light source for irradiating the sheet with light;
A plurality of light receiving elements are arranged in the main scanning direction, and red, green, and blue color detection reading sensors are arranged at a predetermined distance in the sub-scanning direction orthogonal to the main scanning direction, and the light source A one-dimensional image sensor that reads light information of each color at the same position in the sub-scanning direction of the sheet irradiated with light in time series,
Moving means for relatively moving the image sensor or the sheet in the sub-scanning direction;
Control means for controlling input / output of the image sensor and moving means,
The control means includes
The moving unit is controlled at a sub-scanning speed corresponding to a document reading magnification set in advance, and the reading sensor for each color is independently controlled by a reading control signal corresponding to the document reading magnification. Image forming apparatus.

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