JP5807326B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and an image forming apparatus.

  In recent years, as an image reading apparatus used for a copying machine, a scanner, or the like, there are four color line sensors including three color line sensors corresponding to each color component of R (red), G (green), and B (blue), and one monochrome line sensor. By adopting a CCD (Charge Coupled Device) sensor having a line configuration, a technique for reading a color image with high quality and reading a monochrome image at high speed has been proposed (for example, see Patent Document 1).

  The image reading apparatus described in Patent Document 1 employs the above-described four-line CCD sensor, and the number of pixels of the monochrome line sensor is twice the number of pixels of the color line sensor, and the vertical transfer period of the monochrome line sensor. Is set to ½ of the vertical transfer period of the color line sensor, thereby reading a monochrome image at high resolution and at high speed.

  As another image reading apparatus, a monochrome line sensor and a color line sensor having the same number of pixels and a shift register for the monochrome line sensor twice that of the color line sensor are known.

JP 2001-144900 A

[1] A first light receiving element array for reading a monochrome image from an original via an optical system, a second light receiving element array for reading a color image from the original via the optical system, and the first The first light receiving unit sequentially holds the charge received and accumulated by the light receiving element row for each light receiving element, and sequentially outputs from the output terminal, and the charge received and accumulated by the second light receiving element row is received by the light receiving element. A second holding unit that sequentially outputs from the output end, a selection unit that selects a monochrome mode for reading the monochrome image or a color mode for reading the color image, and the optical system for the document. The color mode is selected by the determination unit for determining whether the first reading method for moving and reading the image or the second reading method for reading the image by moving the document relative to the optical system and the selection unit is, and, above-size When the first reading method is determined by the unit, the output of the first reading signal for reading the charge from the first holding unit is stopped, and the first reading method for reading the charge from the second holding unit is stopped. 2 readout signals to sequentially output the charges held by the second holding unit from the output terminal, the color mode is selected by the selection unit, and the second mode is selected by the determination unit. A drive control unit that outputs the first read signal to the first holding unit and outputs the second read signal to the second holding unit when the reading method is determined . Image reading device.

[1] A first light receiving element array for reading a monochrome image from an original via an optical system, a second light receiving element array for reading a color image from the original via the optical system, and the first The first light receiving unit sequentially holds the charge received and accumulated by the light receiving element row for each light receiving element, and sequentially outputs from the output terminal, and the charge received and accumulated by the second light receiving element row is received by the light receiving element. A second holding unit that sequentially outputs from the output end, a selection unit that selects a monochrome mode for reading the monochrome image or a color mode for reading the color image, and the optical system for the document. The color mode is selected by the determination unit for determining whether the first reading method for moving and reading the image or the second reading method for reading the image by moving the document relative to the optical system and the selection unit To the determination unit When the first reading method is determined, the output of the first read signal for reading the charge from the first holding unit is stopped, and the second for reading the charge from the second holding unit. And a drive control unit that sequentially outputs from the output terminal each charge held by the second holding unit.

[2] When the monochrome mode is selected by the selection unit, the drive control unit outputs a first extraction signal to the first light receiving element array at a first period regardless of the determined reading method. To output the charge received and accumulated by each light receiving element of the first light receiving element array to the first holding unit, and to the second light receiving element array longer than the first period. [2] In the above [1], the second extraction signal is output in a second cycle of the cycle, and the charges received and accumulated by the light receiving elements of the second light receiving element array are output to the second holding unit. Image reading apparatus.

[3] The image reading apparatus according to [1] or [2] that reads an image from a document, and the photosensitive member is exposed on the basis of the image read by the image reading apparatus, thereby electrostatically forming on the photosensitive member. An exposure unit that forms a latent image, a developing unit that develops an electrostatic latent image formed on the photosensitive member to form a toner image, a transfer unit that transfers the toner image to a sheet, and a transfer unit that transfers to the sheet An image forming apparatus comprising: a fixing unit that fixes the toner image.

According to the first or third aspect of the invention, in the configuration including the first light receiving element array for reading a monochrome image and the second light receiving element array for reading a color image, the image quality is lowered. Color image can be read without any problem.

  According to the second aspect of the present invention, a black and white image can be read at a higher speed than a color image.

FIG. 1 is a diagram illustrating a configuration example of an image reading apparatus according to a first embodiment of the present invention. FIG. 2 is a front view illustrating a configuration example of the surface line sensor unit. FIG. 3 is a block diagram illustrating a main part of a control system of the image reading apparatus. 4A is a diagram illustrating an example of a document, and FIG. 4B is a timing chart illustrating output timings of timing signals and drive signals in the image reading apparatus. FIG. 5 is a diagram illustrating a configuration example of an image forming apparatus according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, about the component which has the substantially same function, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

  FIG. 1 is a diagram illustrating a configuration example of an image reading apparatus according to a first embodiment of the present invention.

  The image reading apparatus 1 is provided in a document transport unit 2 that transports the document 20 to a document placement table 36, which will be described later, a surface image reading unit 3 that optically reads an image on the surface 20a of the document 20, and a document transport unit 2. And a back image reading unit 4 that optically reads an image on the back surface 20b of the document 20. The document feeder 2 is also called an ADF (Aoto Document Feeder).

  The document transport unit 2 and the back image reading unit 4 are provided on a document cover 24 that can be opened and closed with respect to the document placement table 36.

  Further, as the reading method, the image reading apparatus 1 moves the optical carriages 37A and 37B in the sub-scanning direction A with respect to the document 20 on the document placement table 36, and reads an image from the document 20 as “first”. A “second reading method” in which the document 20 is conveyed in the sub-scanning direction A by the document conveying unit 2 with respect to the optical carriages 37A and 37B of the optical system of the surface image reading unit 3. And have. The first reading method is also called a platen scan method, and the second reading method is also called a CVT (Constant Velocity Transport) method.

  Further, the image reading apparatus 1 has, as reading modes, a “monochrome mode” for reading a monochrome image from the document 20, a “color mode” for reading a color image from the document 20, and a “single-side mode” for reading an image from the front surface 20a of the document 20. And “double-sided mode” for reading an image from both the front surface 20 a and the back surface 20 b of the document 20. Normally, the “monochrome mode” and the “single-sided mode” are often initially set.

(Original transport section)
The document transport unit 2 includes a paper feed tray 21 on which a document 20 on which an image is recorded is disposed, a paper discharge tray 22 from which the transported original 20 is discharged, and a document 20 from the paper feed tray 21 to a paper discharge tray 22. And a paper sensor 25 that detects the document 20 on the paper feed table 21.

  The transport mechanism 23 separates the document 20 one by one from a bundle of a plurality of documents 20 arranged on the sheet feed table 21, a transport roll 231 that transports the separated document 20, and the document 20 as a first. A reading roll 232 that conveys the original 20 to the back surface image reading unit 4, and a discharge roll 234 that discharges the original 20 to the paper discharge tray 22.

(Surface image reading unit)
The front surface image reading unit 3 guides the illumination light from the light sources 30A, 30B and the light sources 30A, 30B to the first or second reading regions 3a, 3b by a pair of left and right white LED lamps that generate illumination light. Body 31 and first to third mirrors 32A to 32C for reflecting the reflected light reflected by the surface 20a of the document 20 in the first or second reading area 3a, 3b by illumination light from the light sources 30A, 30B; Lens 33 of the reduction optical system that condenses the reflected light guided to first to third mirrors 32A to 32C, and a surface line sensor unit that is an example of a light receiving unit that receives the light collected by lens 33 34.

  For example, a CCD (Charge Coupled Device) line sensor having a 4-line configuration can be used as the surface line sensor unit 34, but the surface line sensor unit 34 is not limited to this, and other surface sensors such as CMOS (Complementary Metal-Oxide Semiconductor) image sensors can be used. A solid-state image sensor may be used.

  The surface image reading unit 3 includes a housing 35 that houses the light sources 30A and 30B, the light guide 31, the first to third mirrors 32A to 32C, the lens 33, and the surface line sensor unit 34. An original placement table 36 made of a light transmissive member such as glass is provided on the top of the body 35.

  The light sources 30A, 30B, the light guide 31, and the first mirror 32A are fixed to a first carriage 37A that can move in the sub-scanning direction A, and the second mirror 32B and the third mirror 32C It is fixed to the carriage 37B. The second carriage 37B moves half as much as the first carriage 37A so that the optical path length from the document surface on the document placement table 36 to the light receiving surface of the front line sensor unit 34 is always kept constant. It is configured to be movable in the sub-scanning direction A by the amount. Further, the first and second carriages 37A and 37B, when reading an image on the surface 20a of the document 20 placed on the document placement table 36, use the position shown in FIG. 1 as a home position and a motor (not shown). It is configured to move in the sub-scanning direction A.

  First and second white reference plates 38A and 38B are provided at both ends of the first reading area 3a of the document placement table 36, and along the main scanning direction B in the vicinity of the second reading area 3b. A third white reference plate 38C is provided.

  As the first to third white reference plates 38A to 38C, for example, a white resin plate, a white painted metal plate, or the like can be used.

(Back side image reader)
The back surface image reading unit 4 includes a light source 40 that generates illumination light, a rod lens array 41 of an equal-magnification optical system that collects reflected light reflected from the back surface 20b of the document 20 by the illumination light from the light source 40, and a rod lens. The back surface line sensor 42, which is an example of a light receiving unit that receives the reflected light collected by the array 41, the substrate 43 on which the back surface line sensor 42 is mounted, and the rod lens array 41 through the conveyance path. The white reference plate 44 is arranged.

  As the light source 40, for example, a fluorescent lamp, a xenon lamp, or a plurality of LEDs (Light Emitting Diodes) arranged along the main scanning direction can be used.

  For example, a CCD (Charge Coupled Device) line sensor can be used as the back surface line sensor 42, but the present invention is not limited to this, and other solid-state imaging devices such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor may be used. .

  As the white reference plate 44, for example, a white resin plate, a white painted metal plate, or the like can be used.

(Surface line sensor)
FIG. 2 is a front view illustrating a configuration example of the surface line sensor unit 34. The front surface line sensor unit 34 includes a substrate 340. On the substrate 340, a monochrome line sensor 341 that reads a monochrome image from the document 20, a red line sensor 342R that reads a color image from the document 20, and a green line sensor. 342G and a blue line sensor 342B. The monochrome line sensor 341 is an example of a first light receiving element array, and the red line sensor 342R, the green line sensor 342G, and the blue line sensor 342B are examples of a second light receiving element array.

  The surface line sensor unit 34 includes a first and second shift registers 343a and 343b for holding charges output from the monochrome line sensor 341, a red line sensor 342R, and a green line sensor on the substrate 340. Shift registers 344R, 344G, and 344B for holding charges output from the 342G and the blue line sensor 342B, respectively. The first and second shift registers 343a and 343b are examples of a first holding unit, and the shift registers 344R, 344G, and 344B are examples of a second holding unit.

  The surface line sensor unit 34 amplifies the output signals of the shift registers 343a, 343b, 344R, 344G, and 344B at the output terminals of the shift registers 343a, 343b, 344R, 344G, and 344B. 346G and 346B are provided.

  A monochrome image reading unit 34a is configured by the monochrome line sensor 341, the first and second shift registers 343a and 343b, and the amplifiers 345a and 345b. A color image reading unit 34b is configured by the red line sensor 342R, the green line sensor 342G, the blue line sensor 342B, the shift registers 344R, 344G, 344B, and the amplifiers 346R, 346G, 346B.

The monochrome line sensor 341 includes photoelectric conversion elements 347 as a plurality of light receiving elements arranged along the main scanning direction B, and a filter that transmits green component light is provided on the light receiving side of each photoelectric conversion element 347. Monochrome line sensor 341, first and second shift registers 343a and charges photoelectric conversion element 347 is accumulated in accordance with the amount of the received light in synchronism with a vertical transfer signal phi _V, and outputs the 343b. The odd-numbered (ODD) photoelectric conversion element 347 of the monochrome line sensor 341 outputs charges to the first shift register 343a, and the even-numbered (EVEN) photoelectric conversion element 347 outputs charges to the second shift register 343b. It is configured to output. The reason why a filter that transmits green light is used for the monochrome line sensor 341 is to avoid output saturation of the monochrome line sensor 341.

  In the present embodiment, the number of photoelectric conversion elements 347 of the black and white line sensor 341 is the same as that of the color line sensors 342R, 342G, and 342B, but more than 342R, 342G, and 342B, for example, twice. Also good.

The red line sensor 342R includes a plurality of photoelectric conversion elements 347 arranged in the main scanning direction B, and a filter that transmits red component light is provided on the light receiving side of each photoelectric conversion element 347. Red line sensor 342R is output to the shift register 344R in synchronization charges photoelectric conversion element 347 is accumulated in accordance with the amount of the red component of the received light to the vertical transfer signal phi _V.

The green line sensor 342G includes a plurality of photoelectric conversion elements 347 arranged in the main scanning direction B, and a filter that transmits green component light is provided on the light receiving side of each photoelectric conversion element 347. Green line sensor 342G outputs to the shift register 344G synchronously charges photoelectric conversion element 347 is accumulated in accordance with the amount of green component of the received light to the vertical transfer signal phi _V.

The blue line sensor 342B has a plurality of photoelectric conversion elements 347 arranged in the main scanning direction B, and a filter that transmits blue component light is provided on the light receiving side of each photoelectric conversion element 347. Blue line sensor 342B outputs to the shift register 344B synchronously charges photoelectric conversion element 347 is accumulated in accordance with the amount of blue component of the received light to the vertical transfer signal phi _V.

Shift register 343, in synchronization with the holding to have electric charges to the horizontal transfer signal phi _H sequentially transferred to the output end side of the shift register 343 is output from the amplifier 345 to the outside as the signal S _WB.

The shift register 344 sequentially transferred to the output terminal of the shift register 344 in synchronization with the holding to have electric charges to the horizontal transfer signal phi _H, output from the amplifier 346 the signal _{S R,} S G, to the outside as _{S B.}

  Since the heat generation amount on the output end side of the shift registers 343 and 344 is relatively large, in order to disperse the heat generation amount, the output direction of the monochrome line sensor 341 and the output direction of the color line sensors 342R, 342G, and 342B are reversed. I have to.

(Control system)
FIG. 3 is a block diagram showing the main part of the control system of the image reading apparatus 1. Sample the image reading apparatus 1 includes a CPU10 for controlling each section of the image reading apparatus 1, which holds a drive control unit 11 that drives the surface line sensor unit 34, the signal S _WB output from the black-and-white image reading unit 34a The ring hold (SH) circuit 12a, the sampling hold (SH) circuit 12b that holds the signals S _R , S _G , and S _B output from the color image reading unit 34b, and the output signals of the SH circuits 12a and 12b are amplified. Amplifying circuits 13a and 13b, A / D converting circuits 14a and 14b for converting the output signals of the amplifying circuits 13a and 13b into digital signals, and a memory for storing the output data of the A / D converting circuits 14a and 14b as digital image data 15a and 15b and shading correction for performing shading correction on the digital image data stored in the memories 15a and 15b. Comprising Ingu correction circuit 16a, and 16b, and stripe correction circuit 17, an image processing unit 18, an operation panel 19 of the reading mode can be selected.

  The CPU 10 operates according to a stored program such as an HDD (Hard Disk Drive) to control each part of the image reading apparatus 1 and move the optical system carriages 37A and 37B relative to the document 20 in a first manner. Or a second reading method for moving the document 20 with respect to the optical system.

  The determination unit reads the document 20 on the document placement table 36 when the start button of the operation panel 19 is pressed when the paper sensor 25 provided in the document transport unit 2 does not detect the document 20. It is determined that the reading method is selected. The determination unit determines that the second reading method for automatically conveying the document 20 is selected when the start button is pressed when the paper sensor 25 detects the document 20.

  The drive control unit 11 includes a timing generator 110 that generates various timing signals, a black and white driving unit 111 that drives a black and white image reading unit 34 a of the front line sensor unit 34, and a color image reading of the front line sensor unit 34. And a color driving unit 112 that drives the unit 34b.

The timing generator 110, a vertical synchronizing signal _{S V,} generates a timing signal such as a horizontal synchronizing signal _{S H,} and outputs the black-and-white driving unit 111 and the color drive unit 112. Further, the timing generator 110, a first read mode, the second read method, regardless of the monochrome mode and color mode, and outputs a vertical synchronizing signal S _V to be output to the monochrome drive unit 111 to the color drive unit 112 than the vertical sync signal _{S V} output at a cycle of 1/2. Further, the timing generator 110 of the present embodiment is to output a horizontal sync signal S _H between the vertical synchronizing signal S _V, particular reading the document 20 on the document placing stand 36 in the color mode by the first reading type in mode stops the output of the horizontal sync signal _{S H} to the monochrome drive unit 111 under the control of the CPU 10. The timing generator 110, a color mode when the first read method and / or the second reading method, the vertical for outputting a vertical synchronizing signal S _V to be output to the monochrome drive unit 111 to the color drive unit 112 in the period equal to the synchronizing signal S _V may output.

Monochrome drive unit 111, in synchronization with the vertical synchronizing signal S _V outputted from the timing generator 110 generates a vertical transfer signal (a first extraction signal) phi _V as the driving signal, the black-and-white image the vertical transfer signal phi _V The data is output to the reading unit 34a. Further, black-and-white driving unit 111, in synchronization with the horizontal synchronizing signal S _H output from the timing generator 110 generates a horizontal transfer signal (first read signal) phi _H as a drive signal, a horizontal transfer signal phi _H The data is output to the first and second shift registers 343a and 343b.

Color driving unit 112, in synchronization with the vertical synchronizing signal S _V outputted from the timing generator 110 generates a vertical transfer signal (second extraction signal) phi _V as the drive signal, the color of the vertical transfer signal phi _V The image is output to the image reading unit 34b. The color drive unit 112 in synchronism with the horizontal synchronizing signal S _H output from the timing generator 110 generates a horizontal transfer signal phi _H as a drive signal, a horizontal transfer signal (a second read signal) phi _H The data is output to the shift registers 344R, 344G, 344B.

  The SH circuits 12a and 12b sample and hold the signals output from the line sensors 341, 342R, 342G, and 342B to detect a peak, and output a signal indicating the peak.

  The amplifier circuits 13a and 13b amplify the signals indicating the peaks output from the SH circuits 12a and 12b with a predetermined amplification factor.

  The memories 15a and 15b are configured to store the input digital image data when the enable signal from the CPU 10 is at a high level and not to store the input digital image data when the enable signal is at a low level. .

  The shading correction circuits 16a and 16b perform corrections for sensitivity variations of the line sensors 341 and 342 and corrections corresponding to the light amount distribution characteristics of the reading optical system.

  In the second reading method, the streak correction circuit 17 determines that the streak is in the same position in both the read color image and the black-and-white image, determines that it is a streak, corrects the color image, and erases the streak. Make corrections.

  The image processing unit 18 performs various image processing such as enlargement / reduction processing for enlarging or reducing the digital image data, and then outputs the digital image data to an HDD or the like.

(Operation of the first embodiment)
Next, the operation of the first embodiment will be described.

(1) Color Mode, First Reading Method First, the case where the color mode and the first reading method are selected will be described with reference to FIG.

  4A is a diagram illustrating an example of a document, and FIG. 4B is a timing chart illustrating output timings of timing signals and drive signals in the image reading apparatus.

(Comparative example)
First, a comparative example will be described. In this comparative example, the timing generator 110, in any of the color mode and monochrome mode also, the horizontal sync signal _{S H} shift register 344R between the vertical sync signal _{S V,} 344 g, is configured to output to 344B.

  When the user places the document 20 on the document placement table 36, operates the operation panel 19 to select a color mode, and presses a start button (not shown) provided on the operation panel 19, the CPU 10 causes the document transport unit 2. Since the paper sensor 25 does not detect the document 20, it is determined that the first reading method has been selected, and reading control is started on the document 20 on the document placement table. That is, the CPU 10 controls a motor (not shown) to move the first and second carriages 37A and 37B to the home position shown in FIG. Subsequently, the CPU 10 moves the first and second carriages 37A and 37B in the sub-scanning direction A.

The timing generator 110, under the control of the CPU 10, the vertical sync signal _{S V,} generates a timing signal such as a horizontal synchronizing signal _{S H,} and outputs the black-and-white driving unit 111 and the color drive unit 112. Further, the timing generator 110, also in the original 20 on the original placing stand 36 color mode, and outputs a horizontal synchronizing signal S _H between the vertical synchronizing signal S _V.

Color driving unit 112 generates a vertical transfer signal phi _V as the driving signal in synchronization with the vertical synchronizing signal S _V outputted from the timing generator 110, and outputs the vertical transfer signal phi _V in the color image reading unit 34b. The color drive unit 112 in synchronism with the horizontal synchronizing signal _{S H} output from the timing generator 110 generates a horizontal transfer signal phi _H as the driving signal, the horizontal transfer signal phi _H shift registers 344R, 344G, 344B Output to.

Monochrome drive unit 111 generates a vertical transfer signal phi _V as the driving signal in synchronization with the vertical synchronizing signal S _V outputted from the timing generator 110, and outputs the vertical transfer signal phi _V to a black-and-white image reading unit 34a. Further, black-and-white driving unit 111, in synchronization with the horizontal synchronizing signal S _H output from the timing generator 110 generates a horizontal transfer signal phi _H as the driving signal, the first and second shift horizontal transfer signal phi _H The data is output to the registers 343a and 343b.

The red line sensor 342R, the green line sensor 342G, and the blue line sensor 342B of the color line sensor vertically accumulate the charges accumulated according to the red component, the green component, and the blue component of the light received by the photoelectric conversion element 347. shift register 344R in synchronization with the transfer signal phi _V, outputs 344 g, the 344B.

Monochrome line sensor 341, the shift register 343a in synchronism charges photoelectric conversion element 347 is accumulated in accordance with the amount of green component of the received light to the vertical transfer signal phi _V, and outputs the 343b.

Shift register 344R for color, 344 g, 344B outputs sequentially output in synchronization with the holding to have electric charges to the horizontal transfer signal phi _H, amplifiers 346R, 346G, after being amplified by 346B, the output signal _{S R} , S _G and S _B are output.

Shift register 343a for black and white, 343b outputs sequentially output in synchronization with the holding to have electric charges to the horizontal transfer signal phi _H, amplifiers 345a, after being amplified by 345b, and output as an output signal _{S WB} .

The signals S _R , S _G , and S _B output from the color image reading unit 34b are held by the SH circuit 12b, the peak is detected, and the signal indicating the peak is amplified by the amplifier circuit 13b, and then A / D converted. The circuit 14b converts the analog signal into a digital signal and stores it as digital image data in the memory 15b. The digital image data stored in the memory 15 b is subjected to shading correction by the shading correction circuit 16 b and output to the image processing unit 18 via the streak correction circuit 17. The image processing unit 18 performs various types of image processing such as enlargement / reduction processing for enlarging or reducing the digital image data output from the line correction circuit 17, and then outputs the digital image data to an HDD or the like.

In the case of the comparative example, the scanning line _{L 1} shown in FIG. 4 (a), since the black region 20c is continuous, the output signal _S R of the output signal _{S WB} monochrome line sensor 341 is a line sensor 342 for color, S _G and S _B do not wrap around as unnecessary noise. However, the scanning line _{L 2} shown in FIG. 4 (b), the output signal _S R of the line sensor 342 of the output signal _{S WB} for the white area 20d is a _color, and a S G, _{S B} crosstalk (noise) Sn wraparound May occur.

(This embodiment)
In the present embodiment, when the document 20 placed on the document placement table 36 is read in the color mode by the first reading method, the output of the horizontal transfer signal φ _H for the monochrome line sensor 341 is stopped. Therefore, in the reading position the scanning line _{L 2,} the output signal _S R of the line sensor 342 for the color at the timing when the monochrome line sensor 341 reads the white area _20d, S G, thereby preventing the noise _{S B} are mixed.

(2) Color Mode, Second Reading Method Next, a case where the color mode and the second reading method are selected will be described.

  When the user places the document 20 on the paper feed tray 21, operates the operation panel 19 to select a color mode, and presses a start button (not shown) provided on the operation panel 19, the CPU 10 causes the paper in the document transport unit 2 to be printed. Since the sensor 25 detects the document 20, it is determined that the second reading method has been selected, and reading control using the document conveying unit 2 is started.

If the color mode and the second reading mode, from the timing generator 110 under the control of the CPU 10, the vertical sync signal _{S V} to the color image reading unit 34b and the black-and-white image reading unit 34a, and outputs a horizontal synchronizing signal _{S H.} Accordingly, the color image reading unit 34b and the monochrome image reading unit 34a read the color image and the monochrome image by driving the color driving unit 112 and the monochrome driving unit 111, respectively, and the signals S _R , S from the color image reading unit 34b. _{G, S B} is output, the signal _{S WB} is output from the black-and-white image reading unit 34a. When the same position streak is included in both the color image read by the color image reading unit 34b and the black and white image read by the black and white image reading unit 34a, the streak correction circuit 17 determines that the streak is a streak and Correction for erasing is performed, and a color image without a streak is output from the image processing unit 18.

(3) Monochrome Mode, Second Reading Method Next, a case where the monochrome mode and the second reading method are selected will be described.

  When the user places the document 20 on the paper feed tray 21, operates the operation panel 19 to select the monochrome mode, and presses a start button (not shown) provided on the operation panel 19, the CPU 10 causes the paper in the document transport unit 2 to be printed. Since the sensor 25 detects the document 20, it is determined that the second reading method has been selected, and reading control using the document conveying unit 2 is started.

For monochrome mode and a second read method, the timing generator 110 under the control of the CPU 10, and outputs a vertical synchronizing signal _{S V} at a period of 1/2 than the color image reading unit 34b for monochrome image reading unit 34a . Thus, black-and-white image reading unit 34a outputs a signal S _WB at half the speed of the color image reading unit 34b, the reading of a monochrome image is performed at high speed.

[Second Embodiment]
FIG. 5 is a diagram illustrating a configuration example of an image forming apparatus according to the second embodiment of the present invention. The image forming apparatus 5 includes the image reading apparatus 1 according to the first embodiment and a main body 5A.

  The main body 5A includes an image forming unit 6 that prints a document image read by the image reading device 1 on a sheet 70 as a recording medium, and a tray unit 7 that supplies the sheet 70 to the image forming unit 6.

  The operation panel 19 is provided with a touch panel 191 and operation buttons 192 such as a start button for instructing reading of an original and printing of an image and a stop button for instructing to stop reading of an original and printing of an image.

  The image forming unit 6 prints an original image on a sheet by an electrophotographic method. The endless intermediate transfer belt 60 circulates, and the intermediate transfer belt 60 has yellow (Y), magenta (M), cyan ( C), black (K) first to fourth image forming units 61Y, 61M, 61C, 61K for transferring toner images of the respective colors, and first to fourth laser beams modulated based on the image information. An optical scanning device 62 is provided as an exposure unit that forms an electrostatic latent image on the photosensitive drum 610 by exposing a photosensitive drum 610 (described later) of the image forming units 61Y, 61M, 61C, and 61K.

  Each of the image forming units 61Y, 61M, 61C, and 61K is formed by the photosensitive drum 610, the charger 611 that uniformly charges the surface of the photosensitive drum 610, and the optical scanning device 62 on the surface of the photosensitive drum 610. A developing unit 612 as a developing unit that develops the electrostatic latent image with toner of each color to form a toner image, and a primary transfer roller 613 that presses the intermediate transfer belt 60 against the photosensitive drum 610.

  The intermediate transfer belt 60 is driven by a driving roller 63 connected to a motor (not shown), and is formed by a first driven roller 64A, a second driven roller 64B, and a tension roller 65 that applies tension to the intermediate transfer belt 60. Rotate along the circulation path.

  The image forming unit 6 is disposed at a position facing the second driven roller 64B across the intermediate transfer belt 60, and the toner image formed on the intermediate transfer belt 60 is applied to the sheet supplied from the tray unit 7. A secondary transfer roller 66 as a transfer unit for transferring, a fixing unit 67 as a fixing unit for transferring the toner image transferred onto the paper onto the paper, and the paper 70 that has passed through the fixing unit 67 are discharged to a discharge table 69. And a discharge roller 68.

  The fixing unit 67 includes a fixing roller 671 with a built-in heater, and a pressure roller 672 that is pressed against the fixing roller 671.

  The tray unit 7 includes first to third trays 71 to 73 that accommodate sheets 70 having different orientations, sizes, paper quality, and the like. The tray unit 7 corresponds to each of the first to third trays 71 to 73, and picks up rollers 74 </ b> A to 74 </ b> C for taking out the stored paper 70 and the plurality of papers 70 when they are taken out. Separation rollers 75A to 75C for separation, and registration rollers 76A to 76C for conveying the paper 70 further downstream are provided. The registration rollers 76 </ b> A to 76 </ b> C operate in synchronization with the timing of image formation by the image forming unit 6, and the sheet 70 taken out from the first to third trays 71 to 73 along the conveyance path 77 and the secondary transfer roller 66. It is configured to guide between the intermediate transfer belt 60.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, although the determination unit by the CPU 10 is realized by a program, it may be realized by using hardware such as an ASIC (Application Specific IC).

DESCRIPTION OF SYMBOLS 1 ... Image reading apparatus, 2 ... Document conveyance part, 3 ... Front image reading part, 3a ... 1st reading area, 3b ... 2nd reading area, 4 ... Back surface image reading part, 5 ... Image forming apparatus, 5A ... Main unit, 6 ... Image forming unit, 7 ... Tray unit, 10 ... CPU, 11 ... Drive control unit, 12a, 12b ... Sampling hold (SB) circuit, 13a, 13b ... Amplifying circuit, 14a, 14b ... A / D conversion Circuit, 15a, 15b ... Memory, 16a, 16b ... Shading correction circuit, 17 ... Line correction circuit, 18 ... Image processing unit, 19 ... Operation panel, 20 ... Original, 20a ... Front side, 20b ... Back side, 20c ... Black area, 20d ... White area, 21 ... Paper feed tray, 22 ... Discharge tray, 23 ... Conveyance mechanism, 24 ... Document cover, 25 ... Paper sensor, 30A, 30B ... Light source, 31 ... Light guide, 32A-32C ... Mirror, 33 ... Lens, 3 ... line sensor unit for surface, 34a ... black and white image reading unit, 34b ... color image reading unit, 35 ... housing, 36 ... original placement table, 37A, 37B ... carriage, 38A to 38C ... white reference plate, 40 ... light source, DESCRIPTION OF SYMBOLS 41 ... Rod lens array, 42 ... Line sensor for back surface, 43 ... Substrate, 44 ... White reference board, 60 ... Intermediate transfer belt, 61Y, 61M, 61C, 61K ... Image forming unit, 62 ... Optical scanning device, 63 ... Drive Roller, 64A, 64B ... driven roller, 65 ... tension roller, 66 ... secondary transfer roller, 67 ... fixing unit, 68 ... discharge roller, 69 ... discharge table, 70 ... paper, 71-73 ... tray, 74A-74C ... Pickup roller, 75A to 75C ... Separation roller, 76A to 76C ... Registration roller, 77 ... Conveyance path, 110 ... Timing generator, 111 ... Black drive unit, 112 ... color drive unit, 191 ... touch panel, 192 ... operation button, 230 ... separation roll, 231 ... transport roll, 232 ... reading roll, 233 ... guide roll, 234 ... discharge roll, 340 ... substrate, 341 ... monochrome line sensor, 342R ... red line sensor, 342G ... green line sensor, 342B ... blue line sensor, 343a ... first shift register, 343b ... second shift registers, 344R, 344G, 344B ... Shift register, 345a, 345b ... amplifier, 346R, 346G, 346B ... amplifier, 347 ... photoelectric conversion element, 610 ... photosensitive drum, 611 ... charger, 612 ... developer, 613 ... primary transfer roller, 671 ... fixing roller, 672 ... pressing roller, A ... sub scanning direction, B ... main scanning _{direction, L 1,} L ₂ Scanning lines, S V _... vertical synchronization signal, S H _... horizontal sync _{signal, S R, S G, S} B ... signal, S _{WB ...} signal, phi _H ... horizontal transfer signal, phi _V ... vertical transfer signal

Claims (3)

A first light receiving element array for reading a black and white image from an original via an optical system;
A second light receiving element array for reading a color image from the original document via the optical system;
A first holding unit that sequentially outputs from the output end after holding the charge received and accumulated by the first light receiving element row for each light receiving element;
A second holding unit that sequentially outputs from the output end after holding the charge received and accumulated by the second light receiving element row for each light receiving element;
A selection unit for selecting a monochrome mode for reading the monochrome image or a color mode for reading the color image;
A determination unit that determines whether the first reading method for reading an image by moving the optical system with respect to the document or the second reading method for reading an image by moving the document with respect to the optical system;
When the color mode is selected by the selection unit and the first reading method is determined by the determination unit, the output of the first read signal for reading the charge from the first holding unit is stopped. And outputting a second read signal for reading out the charge from the second holding unit to sequentially output each charge held in the second holding unit from the output terminal, When the color mode is selected and the determination unit determines the second reading method, the first reading signal is output to the first holding unit, and the second holding unit is configured to output the first reading signal. An image reading apparatus comprising: a drive control unit that outputs a second read signal.   The drive control unit outputs a first extraction signal to the first light receiving element array at a first cycle regardless of the determined reading method when the selection unit selects the monochrome mode. The charge received and accumulated by each light receiving element in the first light receiving element array is output to the first holding unit, and the second light receiving element array has a period longer than the first period. 2. The image reading apparatus according to claim 1, wherein a second extraction signal is output at a period of 2 to cause each of the light receiving elements of the second light receiving element array to receive and accumulate charges that are accumulated in the second holding unit. . The image reading apparatus according to claim 1 or 2, wherein an image is read from a document.
An exposure unit that forms an electrostatic latent image on the photosensitive member by exposing the photosensitive member based on an image read by the image reading device;
A developing unit that develops an electrostatic latent image formed on the photoreceptor to form a toner image;
A transfer portion for transferring the toner image onto a sheet;
An image forming apparatus comprising: a fixing unit that fixes the toner image transferred to the paper.

Images