JP2003266756A - Image processor and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image processor in which a data string having a resolution of high clock rate can be attained while performing desired image processing at a low clock rate. <P>SOLUTION: A pixel data invalidating section 908 buries a white pixel within an effective image range in the main scanning direction except the printing part. A pixel packing part 900 packs the pixel data every 4 pixels. A first image processing section 902 collects the packed pixel data and delays it by N clocks at a first clock CK1. A second image processing section 904 further delays the pixel data, delayed by N clocks at the first image processing section 902, by 1 clock and selects 4 pixels among thus delayed pixel data and image data not yet delayed by 1 clock. A third image processing section 906 transfers the selected pixel data, in units of pixel, to the post-stage at clock CK2 higher than the first clock CK1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image by scanning an object to be scanned with a light beam whose light intensity is modulated based on image data, and an image suitable for this image forming apparatus. Regarding a processing device. In particular, it relates to a technique for controlling an image forming position (drawing position) during image formation, such as color registration correction.

[0002]

2. Description of the Related Art In an image forming apparatus employing an electrophotographic system, a photoconductor as an image carrier is charged with a charger,
A latent image is formed by irradiating the charged photoconductor with light (beam light) according to image information, and the latent image is developed by a developing device, and the developed toner image is transferred to a sheet material or the like to form an image. Is formed.

On the other hand, along with the colorization of images, there have been proposed apparatuses for forming images with various kinds of color materials. In this case, a good full-color image can be obtained by adjusting the printing amount of each color material with high accuracy, but the mixing of the color materials before printing leads to a serious deterioration in image quality. Therefore, a color image forming apparatus of a so-called tandem structure, in which printing units (image forming units) for each image forming process are prepared by the number of color materials and arranged in a line in the sheet conveying direction, are provided. Proposed.

In this tandem image forming apparatus, for example, three kinds of color materials of yellow (Y), magenta (M) and cyan (C), or four kinds of color materials in which black (K) is added are used. Is generally used, and when aiming for higher image quality, more than 3 or 4 types of color materials are used. And, for example, cyan image, magenta image,
A full-color image is formed by forming each color image of a yellow image, more preferably a black image on each image carrier, and superimposing and transferring each color image on the sheet material at the transfer position of each image carrier. This tandem type color image forming apparatus has an image forming unit corresponding to the number of color materials, and is therefore advantageous for speeding up.

However, in the tandem type color image forming apparatus, when the printing positions of the color materials are changed, the overlapping degree of the color materials is changed. Is recognized as That is, the deviation of the print position of each color image appears as a change in color tone. Therefore, the relative position between the image forming units for each color material is accurately adjusted, and further, the adjusted position is maintained so as not to change with time, and the printing positions of the color materials are always kept constant. It is necessary to keep it. In other words, in the tandem system, how to perform good registration (registration) of each color image formed by different image forming units is important for image quality.

As one of the causes of the positional deviation of the transferred image,
There is a difference in the image width of each color in the main scanning direction, or an absolute print position shift. This is because the scanning optical system or the image forming apparatus changes due to the replacement of the image forming unit (for example, the difference in the image delay amount due to the memory), the change in the installation state of the color image forming apparatus, and the change in the temperature and humidity inside the color image forming apparatus. The main reason for this is that the optical path to the photoconductor drum of each part differs between colors. When this occurs, the exposure position of each color shifts, which shifts the printing position of each color, resulting in color shift in the image and image distortion (baud distortion).

Therefore, in the tandem system, a mechanism for aligning (registering) each color image formed by different image forming units is essential.

Here, in order to control the print position, a video clock (pixel clock) is counted on the basis of a main scanning synchronizing signal indicating a reference of scanning scanning, and a line synchronizing signal (LS: Line Syn
1) by outputting the image data in synchronization with c)
Pixel unit control is performed. Further, a technique for more accurate alignment is disclosed in, for example, Japanese Patent Laid-Open No. 11-
129526 and Japanese Patent Laid-Open No. 11-55477.

Here, the method described in Japanese Patent Laid-Open No. 11-129526 adjusts the frequency of the video clock to be counted from the main scanning synchronizing signal to the generation of the line synchronizing signal, so that the resolution is smaller than one pixel. The print position is controlled.

Further, the method described in Japanese Patent Laid-Open No. 11-55477 generates a clock delayed by 1 / N unit of a video clock period, and uses an appropriate clock from the N kinds of clocks as a video clock. By doing so, the print position control is performed in units of 1 / N pixel.

[0011]

However, in a high-speed and high-resolution image forming apparatus, the frequency of the video clock is close to 100 MHz, or 200 MHz or higher is required. Therefore, 1
A very high-speed circuit is required to perform control on a pixel-by-pixel basis, and applying the above two methods to a high-speed and high-resolution device makes it difficult to design the circuit and
It is also disadvantageous in terms of mounting on SI. Of course,
The circuit scale also becomes large, which further increases the cost.

[0012] For example, due to recent advances in network technology and higher performance of computers, there has been a demand for higher resolution of an image recording device as an output device thereof. That is, in order to output a high-quality image, higher resolution is pursued, and the resolution is 400 dpi (dot pe
r inch; number of print dots per inch), 600 dp
i have advanced to 1200 dpi. Further, for example, laser printers are required to improve the scanning density of laser beams in order to cope with higher image quality.

Further, in the image recording apparatus, high productivity such as improvement of output speed (printing speed) has been pursued, and in order to meet the demand of writing speed which is increased accordingly, for example, rotation for scanning a laser beam. The speed of polygon mirrors has been increasing. Furthermore, a multi-beam scanning device that simultaneously scans a plurality of laser beams to form an image of one color has been put into practical use, and high speed and high image quality have been advanced. For example, there are cases in which a dual beam laser scanning optical system using two laser beams is used.

On the other hand, as a writing technique for obtaining finer writing resolution and higher productivity, 10
In case of using multiple beams or more, or VCSEL (Vertical Cavity Sustain) in which multiple light emitting points are two-dimensionally arranged.
rface Emitting Laser: A technology that uses a surface emitting laser as a light source is drawing attention.

In this technique, a plurality of laser beams output from the VCSEL are deflected by a rotating polygon mirror to increase the number of beams simultaneously scanned on the photosensitive member, thereby substantially improving the scanning rate and increasing the speed. -Aiming for higher resolution.

However, when the multi-beam technique is used, the amount of images to be handled is enormous, the handling becomes complicated, and the handling frequency shifts to the high frequency side depending on the number of light emitting points and the process speed. A more specific description is as follows. If the conventional technique is applied as it is, first of all, it is necessary to configure a parallel data channel from the higher order image data generation device corresponding to all channels of the multi-beam. Secondly, it is necessary to completely access the upper image data generation device line by line. That is, it means that access is performed by the line synchronization signal N times within one scanning period.

Here, in the first case, since all the operations are performed in the unit of the number of beams, the transfer rate of the image data may be slow, but it is difficult to control the writing position and the number of beams of the scanning device is required. The design of the host system must be changed for each case. In the second case, as viewed from the higher-order image data generation device, it is equivalent to a one-beam scanning recording device and is versatile as an interface, but higher resolution recording is required as the number of multi-beams increases. Therefore, the data access speed (especially writing to the line buffer memory) becomes strict.

For example, when 2400 dpi, 1-bit image data is recorded with a scanning width of 300 mm on a photosensitive member which moves at 200 mm / s, "200 mm (7.84 inches) → 7.84 × 2400 = 18,898 lines. / Sec → 1 scanning time is 53 μs ”.

During this time, "11.8 inches (300 m
m) × 2400 = 28346 bit ”data transfer requires high-speed data transfer of 28346/53 μs = 535 Mbit / s.

Assuming that a light source with 32 beams is used, a high-speed machine with A4 size and 100-sheet productivity has a write speed of about 80 Mbps for adjacent exposure, and a medium-speed machine of 50-sheet class for about 40 Mbps. Incorporated speed is required. Double exposure gives 160Mbp each
A writing speed of 80 Mbps is required.

As described above, in the image forming apparatus using the multi-beam light source, the delay control function for correcting the positional deviation of the light emitting point is essential, but the video clock is used so as to make the control difficult. There is the problem of high frequencies. Therefore, it is difficult to apply the above two methods to an image forming apparatus using a multi-beam light source.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image processing apparatus and an image forming apparatus capable of accurately controlling a drawing position while using a low-frequency clock. And

[0023]

That is, an image processing apparatus according to the present invention includes a pixel packing unit that groups a plurality of input pixel data into a group including a predetermined number of pixels, and a pixel packing unit. A first image processing is performed on each pixel data in each group by the first clock having a predetermined frequency.
Image processing section, a second image processing section that performs second image processing on individual pixel data in the group that has been subjected to the first image processing by the first image processing section, and a second image processing section And a third image processing unit for performing third image processing on individual pixel data in the group that has been subjected to the second image processing by the image processing unit with a second clock that is faster than a predetermined frequency. .

The image forming apparatus according to the present invention, in addition to the configuration of the image processing apparatus according to the present invention, modulates the light intensity of the light beam based on the image data processed by the image processing apparatus, An image forming unit is provided which forms an image by scanning the object to be scanned with the beam light whose intensity is modulated.

[0025]

In the above structure, the first image processing section performs the first image processing at the first clock on the individual pixel data in the group put together by the pixel packing section. For example, it is delayed by a predetermined clock. The second image processing unit outputs the second pixel data to the individual pixel data in the group subjected to the first image processing by the first image processing unit.
Image processing of. For example, a predetermined number is selected from the delayed pixel data and the pixel data before the delay. And
The third image processing unit uses the second image processing unit to perform the second
The pixel data in the group that has undergone the image processing of
The third image processing is performed with a clock faster than the clock of. For example, each pixel is transferred to the subsequent circuit.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a mechanical diagram of an example of a color copying machine equipped with an image forming apparatus for recording an image using a surface emitting semiconductor laser (hereinafter referred to as VCSEL) array which is an example of a multi-beam light source.

The color copying apparatus 1 records an image on a predetermined recording medium using xerography, and includes an image acquisition unit 10, an image processing unit 20, and an image output unit 3.
0, and an ADF (Automatic Document Feeder) 60 without a circulation function, which also has the function of a platen cover. The image processing unit 20 is provided on the substrate arranged at the boundary between the image acquisition unit 10 and the image output unit 30.

The color copying apparatus 1 includes a platen glass 11
Depending on whether or not the ADF device 60 provided above is used, the fixed reading method and the conveyance reading method can be selected and used. The ADF device 60 does not have a circulation function, but an automatic document feeder (RDF; Duplex Automatic Document Feeder) having a circulation function can also be used.

The image acquisition section 10 includes a housing 112 and a platen glass (document placing table) 11 made of transparent glass provided on the housing 112. Also, the image acquisition unit 1
Reference numeral 0 denotes a light source 12 that emits light below the inner platen glass 11 of the housing 112 toward the surface (rear surface) of the platen glass 11 opposite to the original mounting surface, and the light emitted from the light source 12. A substantially concave reflecting shade 131 and a reflecting mirror 132 for reflecting the platen glass 11 side, and the platen glass 11
A full rate carriage (F / R-CRG) 134 having a reflection mirror 134a that deflects reflected light from the side in a direction substantially parallel to the platen glass 11 is provided.

As the light source 12, a fluorescent lamp whose longitudinal direction is the main scanning direction (the direction orthogonal to the paper surface in the drawing) is used. Further, the image acquisition unit 10 includes two reflection mirrors 136 arranged in the housing 112 so as to form a substantially right angle.
a half rate carriage (H / R-CRG) 138 having a and 136b and sequentially deflecting the reflected light deflected by the full rate carriage 134 by approximately 90 °. The full-rate carriage 134 and the half-rate carriage 138 are configured to be capable of reciprocating in the sub-scanning direction (the arrow X direction in FIG. 1) and in the opposite direction by interlocking with each other by a stepping motor (not shown).

Further, the image acquisition unit 10 receives, in the housing 112, a lens 140 for condensing the reflected light deflected by the reflection mirror 136b at a predetermined focal position, and the reflected light converged by the lens 140. The image is read in the main scanning direction (the depth direction of the paper surface of FIG. 1) which is substantially orthogonal to the sub scanning direction,
The light receiving unit 13 sequentially outputs image signals (analog electric signals) according to the density.

The light receiving section 13 is a CCD (Charge Coupled Decode).
vice) and a drive circuit 143 such as a CCD driver for driving a line sensor 142 (which will be described later in detail) made of a photoelectric conversion element such as a vice) and the read signal processing unit 14 and the like, and is disposed on the substrate.

Although not shown, the image acquisition unit 10
The housing 112 also includes a wire, a drive pulley, and the like for moving the reading optical system, the light receiving unit 13, and the like under the platen glass 11 in the housing 112. The drive pulley is reciprocally rotated by the drive force of the drive motor, and the wire is wound around the drive pulley by the rotational drive, thereby moving the reading optical system and the like below the platen glass at a predetermined speed.

In the above structure, the image acquisition unit 10 is normally at the home position (in the vicinity of the fixed reading image destination position G indicated by the mark Δ in the figure). In the transport reading method, the document is AD while the reading optical system is fixed (stop locked) at an arbitrary position under the platen glass 11 on the document transport path.
The image is read while being conveyed by the F device 60. On the other hand, when the fixed reading method is used, the ADF device 60
With the original placed on the platen glass 11 serving as the original placing table and fixed (stop locked) at an arbitrary position on the platen glass 11, the fixed read image destination position G is set. As the leading edge reference, the reading optical system is moved at a constant velocity in the direction of arrow X to scan the original to expose the original and read the image.

Each original image in the conveyance reading method or the fixed reading method has its optical path changed by the full rate carriage 134 or the half rate carriage 138, and the lens 14 is moved.
It is reduced by 0 and reaches the light receiving unit 13. Then, it is sent to the image processing unit 20 after being processed by the read signal processing unit 14 and the synchronization processing unit 15.

In this way, when the reading in the conveyance reading method or the fixed reading method is completed, the image processing unit 2
0 obtains a binarized signal for each print color based on the red, green, and blue image data R, G, B from the image acquisition unit 10, and outputs each binarized signal to the image output unit 30. Output.

At this time, for example, image data of the RGB color system is converted into image data of the YCrCb color system, and at least three (preferably four) from the YCrCb color system,
For example, mapping to the CMY color system or CMYK color system is performed to generate color-separated raster data for print output.

In such rasterization processing, undercolor removal (UCR) for reducing the CMY components of a color image or gray component exchange (GCR) for partially replacing the reduced CMY components with K components is performed. To do. Further, in order to adjust the toner image of the output image created in response to the output data (CMYK or the like), linearization of color separation or similar processing is performed.

The image processing unit 20 acquires image data from a client terminal via a communication network (not shown),
The binarized signal for each print color may be obtained after performing a predetermined process based on this image data (a so-called network printer configuration).

The image output section 30 of the present embodiment is an image forming section which is an example of an image recording apparatus using the optical scanning device (raster output scan; ROS) according to the present invention.
This is a so-called tandem structure having four sets corresponding to the colors M and C. Hereinafter, reference numbers K, Y, M, and C indicating respective colors are attached to the reference numbers of the respective members, and in the case of collectively describing, the reference numbers are omitted.

The image output unit 30 first includes image forming units 31K, 31Y, 31M and 31C for K, Y, M and C, which are sequentially arranged in one direction at regular intervals, and a paper feed cassette 41. And a leading edge detector 44 provided in proximity to a conveyance path of a document conveyed to each image forming unit 31. The leading edge detector 44 optically detects, for example, the leading edge of the document sent from the paper feed cassette 41 onto the transfer belt 43 through the registration rollers 42 to obtain a leading edge detection signal, and the leading edge detection signal is sent to the image processing section 20. send. The image processing unit 20 synchronizes with K, in synchronization with the input leading edge detection signal.
On / off binarized signals of Y, M and C colors are sequentially obtained at regular intervals.

The transfer belt 43 is provided above the transfer belt 43 and on the downstream side of the image forming section 31C in the sheet conveying direction.
A pattern detection unit 614 for detecting a resist pattern (test pattern for alignment) formed on both upper sides is provided. In this pattern detection unit 614, for example, three registration correction sensors are provided on the belt 30.
4 are arranged in a line in the direction (in the main scanning direction) perpendicular to the transport direction.

The transfer belt 43 not only conveys the sheet but also has a function as a recording body on which the resist pattern is directly printed. When a resist pattern is formed on the transfer belt 43, this sensor detects the amount of color shift of the K, Y, M, and C images in the main / sub-scanning directions, and the drawing position control unit 600 described later corrects the drawing position. By performing image distortion correction, color deviation of K, Y, M, C images on a sheet (paper) is prevented.

The transfer belt 43 is made to function as an intermediate transfer belt, and is sequentially transferred to the transfer belt 43 having the function as the intermediate transfer belt in the image forming section 31 of each color, and then the image is transferred. By passing the sheet between the transfer belt 43 and the transfer roller, the transfer belt 4
It is also possible to adopt a mode in which the image on No. 3 is transferred to a sheet.

The image forming section 31 is a semiconductor laser 38 including a VCSEL light source group which is an example of the light source according to the present invention.
And a polygon mirror (rotating polygonal mirror) 39 for reflecting a laser beam (laser beam) emitted from the semiconductor laser 38 toward a photosensitive drum 32 which is an example of a photosensitive member. There is.

Although not shown in the drawing, in addition to the polygon mirror 39, various lenses such as a collimator lens and a scanning lens which form an optical system, or VC
A half mirror or the like for causing the laser light emitted from the SEL 380a to enter the light amount sensor is arranged on the optical axis of the laser light.

For example, a black (K) image forming section 3
In 1K, first, the semiconductor laser 38K is connected to the image processing unit 20.
Driven by the black on / off binary signal from, the black on / off binary signal is converted into an optical signal, and the converted laser light is irradiated toward the polygon mirror 39. This laser light is further reflected by the reflection mirror 4
An electrostatic latent image is formed on the photosensitive drum 32K by scanning on the photosensitive drum 32K charged by the primary charger 33K via 7K, 48K, and 49K.

This electrostatic latent image is made into a toner image by the developing device 34K to which black toner is supplied, and the original toner image on the transfer belt 43 is the photosensitive drum 32K.
Is transferred onto the original by the transfer charger 35K while passing through the sheet. After the transfer, the cleaner 36K removes excess toner from the photosensitive drum 32K.

Similarly, the semiconductor lasers 38Y, 38M, 3
8C is driven by the corresponding on / off binarization signals of the respective colors Y, M, and C, which are sequentially obtained from the image processing unit 20 with respect to the black on / off binarization signal at regular intervals, so that 8C The on / off binary signal is converted into an optical signal, and the converted laser light is irradiated toward the polygon mirror 39.

This laser light is further reflected by the reflection mirror 47Y.
Through 49Y, 47M to 49M, 47C to 49C, the corresponding photoconductor drums 32Y, 32M, and 32C charged by the primary chargers 33Y, 33M, and 33C are scanned to scan the photoconductor drums 32Y, 32M, and 32C. An electrostatic latent image is sequentially formed on it.

Each electrostatic latent image is sequentially made into a toner image by the developing devices 34Y, 34M and 34C to which toners of respective colors are supplied, and each toner image is made to correspond to the photosensitive drum 32Y, which corresponds to the original on the transfer belt 43. While passing through 32M and 32C, they are sequentially transferred onto the original by corresponding transfer chargers 35Y, 35M and 35C.

The original on which the K, Y, M, and C toner images are sequentially transferred in this manner is separated from the transfer belt 43, the toner is fixed by the fixing roller 45, and the toner is fixed to the outside of the copying machine. Is discharged.

The image output unit 30 uses K, Y, M, and K on one photosensitive drum by one laser light scanner.
An electrostatic latent image of each color of C is sequentially formed, and the electrostatic latent image is sequentially formed by a developing device provided around the photosensitive drum and supplied with toners of each color of K, Y, M, and C, respectively. Alternatively, the toner images may be sequentially and multiple-transferred onto the original document adsorbed on the transfer drum.

FIG. 2 is a diagram showing an example of the configuration of the image forming section 31. In addition, here, the reflecting mirrors 47 to 49 will be omitted. Each light emitting point of the VCSEL light source group 380 that constitutes the semiconductor laser 38 shown in FIG.
The plurality of laser beams L emitted from the CSEL 380a are collimated (collimated) by a collimator lens 382 into laser beams having a predetermined beam diameter. This laser light enters the polygon mirror 39 through the cylindrical lens 387, is reflected by the reflecting surface (there are six surfaces in the figure) as the polygon mirror 39 rotates, and is deflected.

The laser light L reflected and deflected by the polygon mirror 39 passes through a toroidal lens 388 having a tilt correction function and a scanning lens group 384 having an fθ function, and is exposed as an image carrier on the surface to be scanned. An image is formed on the spot 386 on the surface to be scanned of the body drum 32.

At a position within the deflection range of the laser light L and which is not involved in scanning the surface to be scanned, the reflection mirror 391 and the photodetector 392, and the laser light L1 reflected by the reflection mirror 391 is detected by the photodetector 392. It is arranged to be incident on. In order to detect the laser beam L1 by the photodetector 392, the laser is turned on immediately before the laser beam L1 is deflected by the photodetector 392 during the scanning period and turned off before the scanning range necessary for the original scanning. Control is performed. The main scanning synchronization signal output from the photodetector 392 controls the start of laser light modulation in accordance with the image data.

The VCSEL light source group 380 includes the semiconductor substrate 3
A VCSEL 380a as a light source is arranged on the surface of 81 in a two-dimensional matrix, or a large number of one line (in-line) is arranged.

FIG. 3 is a diagram showing the relationship between the scanning line and the image formation spot on the surface to be scanned by the laser beam emitted from the VCSEL light source group 380. Illustrated VCSE
The L light source group 380 includes the VCSEL 38 on the surface of the semiconductor substrate.
0a is arranged in a two-dimensional manner so that the vertical length is 8 × horizontal length 4. Here, the vertical arrangement of the VCSEL light source group 380 (eight in this example) is compared with the polygon mirror 39.
It is arranged so that it is in the vertical direction, that is, it is optically parallel to the sub-scanning direction on the photoconductor that is the surface to be scanned. This arrangement form is hereinafter referred to as vertical arrangement. In addition, VCSE
A configuration in which the L light source groups 380 are arranged vertically so as to be in a horizontal direction with respect to the polygon mirror 39, that is, are arranged to be optically parallel to the sub-scanning direction on the photoconductor that is the surface to be scanned. , Hereinafter referred to as horizontal arrangement.

As shown in the figure, the VCSEL light source group 380 includes a main scanning direction and an arbitrary line in the main scanning direction (main scanning line).
VCSEL 380a on the main scanning line having an angle φ with respect to
An array pattern is defined by a base line (an inclined line indicated by a chain line in the figure) passing above. Each of the VCSELs 380a is formed on a single semiconductor substrate, and eight VCSELs 380a are arranged at equal intervals along an arbitrary line (sub-scanning line) in the sub-scanning direction and four at equal intervals along the main scanning line, for a total of eight. × 4 VCSELs 380a are arranged in a two-dimensional matrix. Reference symbols L1 to
L32 indicates a sub scanning line.

In addition, the VCSEL light source group 380 includes
The SEL 380a (that is, the light emitting point) is located at each vertex of the parallelogram, and is tilted at an appropriate angle to form a scanning line of a predetermined resolution (for example, 2400 dpi) on the photoconductor. For example, when the interval in the main scanning direction of the VCSEL 380a is SL, the interval Δ between the sub scanning lines is set to SL × tan φ.

That is, the imaging spot of the laser beam periodically moves in the main scanning direction (from the left to the right in the figure) at a substantially constant speed, the scanning lines are scanned at equal intervals with a pitch Δ, and each time the scanning line is scanned. The surface to be scanned moves in the sub-scanning direction in FIG. Regardless of the positional relationship of the positions of the spots to be scanned, the movement of the surface to be scanned in the sub-scanning direction is 32 scanning line segments per main scanning period. It should be noted that the drawing shows the main scanning for two times, and the positions of the first and second VCSEL light source groups 380 are shown shifted in the main scanning direction, but this is for convenience of illustration. hand,
Actually, scanning starts from the same position.

During scanning, the laser is turned on / off according to the image data or the intensity modulation is performed according to the image density. This modulation or start of lighting control is started by the photodetector 39.
This is performed with reference to the main-scanning synchronization signal output from S2. At this time, a total of 32 laser beams of 8 × 4 operate simultaneously. Then, by repeating this operation, the entire surface to be scanned is completely covered with the scanning lines at equal intervals to realize two-dimensional scanning. This type of scanning is called adjacent exposure. Of course, not only the adjacent exposure but also the multiple exposure mode in which a part of them are overlapped (overlapped) for exposure can be used.

If the distance measured from one spot to another spot in the sub-scanning direction is divided by the scanning line pitch Δ and the remainders divided by the number of scanning lines simultaneously scanned are natural numbers different from each other. It is possible to fill the surface to be scanned with scanning lines at regular intervals without overlapping. The interval SL between the spots in the main scanning direction is the interval Δ = S between the sub-scanning lines.
It can be arbitrarily set as long as L × tan φ is satisfied.

Here, since the VCSEL 380a is arranged so that the image forming position in the main scanning direction is shifted by SL,
A delay control unit (for example, 4) is provided so that each light beam emitted from the VCSEL 380a, which is a light emitting point, corresponding to one row on the image data is imaged substantially on one row in the sub-scanning direction.
Each VCSE by bit FIFO or 8-bit FIFO)
By performing delay control on the modulated signal of L380a, 32 (4 × 8) laser lights on the signal are simultaneously scanned adjacently.

The VCSEL 3 is arranged in a two-dimensional matrix.
In the case of the arrangement of 80a, the interval SL in the main scanning direction,
The shape may be a rectangle depending on the relationship with the sub-scanning line interval Δ. In this case, the VCSEL light source group 380
The polygon mirror 39 may be arranged in a horizontally long shape or a vertically long shape in the sub-scanning direction.

At this time, if the VCSEL light source group 380 is arranged with respect to the polygon mirror 39 so that the shape becomes laterally long in the sub-scanning direction, from the viewpoint of the optical system,
It is necessary to increase the width of each mirror surface of the polygon mirror 39 (that is, the width of the polygon mirror 39). Further, not only the load of a polygon motor (not shown) for driving the polygon mirror 39 is increased, but also the operating noise of the machine is increased.

On the other hand, if the shape is vertically long in the sub-scanning direction, the width of each mirror surface of the polygon mirror 39 can be reduced. In addition, the load on the polygon motor and the operating noise of the machine can be reduced. That is, it is preferable to arrange the VCSEL light source group 380 to have a vertically long shape that is long in the sub-scanning direction.

FIG. 4 shows a VCSEL light source group 38 having the above structure.
FIG. 3 is a diagram illustrating an outline of a processing circuit (image recording control unit) for forming an image in the image forming unit 31 including 0. The image recording control unit is the image acquisition unit 10 or the network 9
An image data generation unit 20 for acquiring image data from a client terminal 8 such as a personal computer via the
0, a write signal generator 220 that generates a laser modulation signal for each VCSEL 380a based on the image data from the image data generator 200, and this write signal generator 2
And an output memory 242 for delivering the laser modulation signal from the laser drive circuit 20 to the laser drive circuit 300.

The image data generation unit 200 includes the image acquisition unit 1
Image data of RGB color system input from 0 etc. is YC
Converted to image data of rCb color system, and further converted to YCrCb
Raster data (halftone data) representing a halftone image or a character image having a resolution of 600 dpi / multi-tone (for example, 8 bits), which is color-separated for print output, is mapped from the color system to the CMYK color system. It is generated and passed to the write signal generator 220.

At this time, undercolor removal (UCR) for reducing the CMY components of the color image and gray component exchange (GCR) for partially exchanging the reduced CMY components with the K components are performed. Also, output data (CMYK, etc.)
In order to adjust the toner image of the output image created in response to the above, processing such as linearization of color separation is performed.

The write signal generation section 220 includes an I / F (interface) section 222 that functions as an interface with the image data generation section 200, and a modulation signal generation section 224 that generates a laser modulation signal (light beam modulation signal). A line buffer memory group 226 which has a plurality of line buffer memories 226a and adjusts the write timing (drawing position) with respect to the laser modulation signal from the modulation signal generation unit 224.
With. The line buffer memory group 226 functions as a delay control unit having a position correction function for controlling the print position (drawing position) peculiar to the VCSEL light source group 380 shown in FIG. 3 (details will be described later).

Further, the write signal generation section 220 includes the I / F section 2
22, a memory controller 228 for controlling the modulation signal generation unit 224, and the line buffer memory group 226,
The I / F unit 222, the modulation signal generation unit 224, the line buffer memory group 226, and the timing signal generator 230 that controls the memory controller 228 are provided.

Further, the image recording control section includes the image forming section 31.
Of the color copying apparatus 1 and a sync signal generator 260 for generating a main-scan sync sync signal SOS which is a reference signal for controlling write timing (that is, scan scan) based on a detection signal obtained from the photodetector 392 of FIG. A machine controller 270, which is a functional portion for controlling the whole, is provided.

The drawing position controller 600 controls the image position during image formation, and adjusts the image position and image size in the main scanning direction / sub scanning direction. In the present embodiment, the modulation signal generation unit 224, the line buffer memory group 226, and the memory controller 228 that controls them are responsible for the functional part of the image forming process in that function. The functional portion for detecting the deviation of the image position and the image size in the main scanning direction / sub scanning direction will be described later (see FIG. 5). The functional part of the image forming process is
Based on the detection result of the amount of deviation from the function part to be detected,
Scales an image and controls the writing position on a sheet.

The timing signal generator 230 outputs a main scanning synchronization signal SOS indicating that the scanning beam has reached the position immediately before entering the photosensitive drum 32, and a print request signal for instructing the start of image recording output by the machine controller 270. Various control signals are generated from PRQ and supplied to each unit. For example, the write reference signal ROS_PS, the write enable signal ROS_LS, the page synchronization signal Page, the line synchronization signal LS (LineSync), the subline synchronization signal Line corresponding to the number of FIFO memories, the pixel clock PCK, or the like.

The timing signal generator 230 also outputs a page synchronization signal Pag for instructing the start of image recording in the sub-scanning direction.
The phase difference between e and the main scanning synchronization signal SOS is determined and the memory controller 228 is controlled. Memory controller 2
28 indicates each line buffer memory 2 according to this phase difference.
Margin data is added to the writing to the data 26a, and the image recording position (drawing position) on the photosensitive drum 32 in the sub-scanning direction is adjusted. Then, through the output memory 242, a modulation signal corresponding to N laser beams for the multi-beam scanning device is supplied to the image forming unit 31.

Further, the image forming section 31 has an output memory 242.
VCSEL light source group 3 based on the laser modulation signal from
Laser driving circuit (multi-LDD) 300 for driving 80 individual VCSELs 380a, and individual VCSs
The drive control unit 310 controls various control signals for controlling the drive current of the EL 380a and the amount of rotation of the photosensitive drum 32 (the amount of rotation in the sub-scanning direction).

The drive control unit 310 determines whether to use a temperature sensor (not shown), the number of mirrors used by the polygon mirror 39 (the number of used mirrors; 6 in this example), a print mode indicating the screen type, or an external input. A light amount setting condition selection unit 304 that generates a light amount control level change signal for setting the light amount of each VCSEL 380a is included. In addition, the drive control unit 310 uses the light amount sensor 3
02, the light amount detection signal indicating the light amount of each VCSEL 380a, the light amount control level change signal generated by the light amount setting condition selection unit 304, and the light amount setting signal from the machine controller 270 are changed. Level changing unit 306 and this level changing unit 306
Drive amount setting signal for controlling the drive current of each VCSEL 380a (1 corresponding to each).
To n) and a drive amount control unit 308 that generates a drive signal for controlling the light amount. Further, the drive control unit 310 includes a rotation control unit 309 that controls the amount of rotation of the photosensitive drum 32 in the sub-scanning direction and the surface skipping of the polygon mirror 39 based on the timing signal from the timing signal generator 230.

If the light quantity of the beam is not constant, the density of the formed image will not be constant and the image quality will not be stable. Further, when forming an image with a plurality of light beams, if the light amount of each light beam is not constant, density unevenness occurs in the formed image, which deteriorates the image quality. The light amount sensor 302 detects the light amount of each VCSEL 380a and controls the laser drive amount so that the light amount becomes constant (APC: Auto Power Controller).
It is for this reason that a mechanism is provided.

In the present embodiment, the write signal generator is provided so that the functional portion of the optical scanning device in the image forming unit 31 is a multi-beam scanning device that simultaneously scans N light beams that can be independently modulated. In 220, first, N light beams are grouped into k groups, and while the multi-beam scanning device scans the N light beams once on the photosensitive drum 32 serving as a recording medium, image data for k lines is recorded. The process of capturing one scan in the order of scanning pixels is repeated N / k times. Then, the data for N lines in the sub-scanning direction substantially orthogonal to the optical scanning are aligned, and then recording is performed by the N multi-beam scanning devices.

Specifically, when the scanning density of the N main beams in the sub-scanning direction is nndpi (dots / inch) and the resolution of image data to be recorded is mmdpi, k = nn / mm and a divisor of N. The multi-beam scanning device generates N / k sub-line synchronization signals Line during one cycle of the main scanning synchronization signal generated each time the N-number of beams scans the photosensitive drum 32 once. Then, the modulation signal generation unit 224
From the upper image data generation unit 200 that stores the image data to be recorded via the I / F unit 222.
Image data is received according to the sub-line synchronization signal Line.

Next, the modulation signal generator 224 outputs the mmdpi
A laser modulation signal for k lines is generated in the sub-scanning direction for each / 1 pixel and sequentially written in the line buffer memory 226. And finally, after the data for N lines are aligned in the sub-scanning direction in the output memory 242, the individual VCs of the VCSEL light source group 380 are controlled by the laser drive circuit 300.
An image (an electrostatic latent image in this example) is recorded on the photosensitive drum 32 by driving the SEL 380a. At this time, VC
The amount of delay in the main scanning direction of the SEL 380a (S shown in FIG.
(Corresponding to L) is controlled using a 4-bit FIFO.

The modulated signal generation section 224 receives 600 from the image data generation section 200 via the I / F section 222.
The dot image data (16 bits) of the bitmap of 2400 dpi is generated for each pixel of the multi-valued data of dpi.
Then, the modulation signal generation unit 224 outputs the halftone dot image data to the line buffer memory 226a in units of k (4) bits.
Write to (FIFO memory).

In order to process image data by such a method, it is necessary to store data for 4 lines of 2400 dpi. If the scan width is 300 mm, then (300 / 25.4) × 2400≈28,300, which requires a FIFO memory with a capacity of about 30 kwords × 4 bits. There are many methods for generating halftone image data, such as the dither matrix method and the error diffusion method, and any technique may be used here.

The line buffer memory 226a, under the control of the memory controller 228, simultaneously outputs the modulated signal at a predetermined timing. That is, the modulation signals for the 32 laser lights used in the VCSEL light source group 380 are simultaneously output, and the output timing of the image data to the light source (VCSEL 380a) is the same. And eight light sources (VCSEL380a) vertically (process direction)
With 8x4 matrix structure
The light source group 380 can function as a light source for 32 line beam simultaneous scanning.

Therefore, by having eight light sources in the vertical direction (process direction), the read timing from the 4-bit FIFO memory can be set to the same, so that the output timing can be adjusted without waste by using the 4-bit FIFO memory. can do. Also, by having a FIFO memory in a form that matches it with the matrix of the light source in the main scanning direction,
The number of beams can be expanded without waste.

FIG. 5 is a diagram for explaining a drawing position control, more specifically, a method of controlling the printing position of each color (color registration correction) at the time of forming a color image. Here, FIG.
(A) is a schematic diagram showing an outline of an image forming mechanism focusing on the function of the drawing position control unit 600, particularly, the drawing position correction in the main scanning direction. In addition, FIG.
5 is a diagram for explaining the deviation of the drawing position of each color.

As shown in FIG. 5A, the color copying apparatus 1 is a copying machine which outputs four colors simultaneously for one scan.
In the image output unit 30 having the tandem configuration, black (K),
The image forming units 31K, 31Y, 31M, and 31C for the four colors of yellow (Y), magenta (M), and cyan (C) are arranged in a line vertically in the paper transport direction (see also FIG. 1).
Then, in the tandem configuration, it is necessary to transfer the K, Y, M, and C toner components onto the paper fed onto the transfer belt 43 without any color shift.

However, as schematically shown in FIG. 5B, color shift occurs due to various factors. The developing timings of the K, Y, M, and C toners deviate by a time corresponding to the distance between the photoconductor drums 32 because the photoconductor drums 32 of the respective colors are arranged at substantially equal intervals with respect to the transfer belt 43. Will be performed. Therefore, by using the sub-scanning delay module, the photosensitive drum 3 is moved in the sub-scanning direction for each of K, Y, M, and C.
Delay control is performed by an amount corresponding to two intervals.

However, as shown in (B1), if the drawing position of C shifts in the sub-scanning direction, color shift occurs. In addition to this, the printing start position shift (B5) in the main scanning direction due to beam scanning of each color, the main scanning partial magnification distortion (B4),
Baud distortion in the sub-scanning direction (B3) and skew distortion (B3) due to the deviation of the parallelism between the arrangement of the photosensitive drum 32 and the beam scanning.
2) occurs, which causes color misregistration. These phenomena are prevented by the drawing position control unit 600 by performing position correction and image correction on K, Y, M, and C data to prevent color misregistration. In the present embodiment, among the above positional deviations, the correction of the printing start positional deviation (B5) in the main scanning direction will be mainly described.

The drawing position control unit 600 corrects the drawing position of each color, so that a predetermined resist detection test pattern (hereinafter referred to as a resist pattern) is used as a reference of the drawing position.
A resist pattern generation unit 621 that generates a signal for forming each color at a predetermined position on the transfer belt 43 is provided. Downstream of the image forming unit 31C in the sheet conveying direction,
A pattern detection unit 614 for detecting resist patterns formed on both sides of the transfer belt 43 is provided.

In order to correct the input image data Vy, Vm, Vc, Vk of each color based on the detection result obtained by the pattern detection unit 614, the color shift correction units 613Y, 613M, 61
3C and 613K are input image data Vy, Vm, Vc and V
It is provided corresponding to each of k. A clock is input from the clock generation unit 622 to the color misregistration correction units 613Y, 613M, 613C, and 613K. The K, Y, M, and C image data transferred from the image processing unit 20 are color shift correction units 613Y, 613M, 613C, and 61.
Input to 3K.

With the above-described structure, first, a predetermined pattern (for example, Japanese Patent Application Laid-Open No. 2) generated in the resist pattern generating section 621 is generated.
000-15870, JP 2001-5245, etc.) Resist pattern data Ry, Rm, Rc, Rk
On the transfer belt 43, the resist patterns corresponding to the respective colors are sequentially detected by the pattern detection unit 614 arranged further downstream of the most downstream image forming unit 31C. The detection results are given to the color misregistration correction units 613Y, 613M, 613C and 613K, respectively.

Color misregistration correction units 613Y, 613M, 613
In C and 613K, the color shift amount is detected based on the detection result detected by the pattern detection unit 614, and the input image data Vy, Vm, and V are detected based on the detected color shift amount.
c and Vk are respectively corrected, and the corrected image data Qy, Qm, Qc and Qk are output to the corresponding image forming unit 31. That is, in order to correct the deviation of the development timing according to the interval between the photoconductor drums 32, the position of the K component is corrected based on the drawing position in the image forming unit 31K (K developing unit) arranged in the most upstream. However, for the other color components, position correction on the sub-scanning side is performed for the K component.

Next, the positions of the other colors are corrected with respect to the K component, so that the main scanning start position shift due to the mounting error amount of the image forming units 31Y, 31M and 31C with respect to the main scanning image forming unit 31K. To correct. Here, the correction of the main scanning start position shift is performed by resolution conversion and subsequent control of the line buffer memory (FIFO), which will be described below. That is, the modulation signal generation unit 224 and the line buffer memory group 226 form a part of the drawing position control unit 600.

FIG. 6 is a diagram showing the correspondence relationship between the halftone data generated by the image data generation unit 200 and the laser modulation signal generated by the write signal generation unit 220 (particularly the modulation signal generation unit 224). Is. Here, as shown in FIG. 4, the line buffer memory group 226 is configured by using eight 4-bit FIFO memories (numbers 1 to 8) as the individual line buffer memories 226a.

When image data is output at high speed, a memory (output memory 242 in FIG. 4) is prepared on the output side as a mechanism for handling the image data at a frequency as low as possible before the output side. In the first stage, 1
It is configured to be handled by the clock. In this example, the modulation signal generation unit 224 receives the 600d signal received from the I / F unit 222.
The dot image data (16 bits) of the bitmap of 2400 dpi is generated for each pixel of the multi-valued data of pi. Then, the modulation signal generation unit 224 uses the halftone dot image data in the line buffer memory 226a in units of k (= 4) bits.
Write to (FIFO memory). Hereinafter, a method of writing to the line buffer memory 226a (FIFO memory) in units of k (= 4) bits is called k pixel packing. In this example, since k = 4, 4 pixel packing is performed.

In the figure, 600 dpi / 8 bit / 40M
Multi-valued data of Hz is speed-converted using a FIFO, resolution is converted to binary data of 2400 dpi / 1 bit, and 4 pixels are packed, and then 2400 dpi / bit.
The case of outputting at 200 MHz to the output memory 242 in the subsequent stage is illustrated. Since the output (area B) is 200 MHz and the preceding stage (area A) is 4 pixel packing, the area A can be handled at a frequency of 200 MHz / 4 = 50 MHz (Min).

Conventionally, the image print position control is performed by controlling the data read timing from the image memory in the area B, but if the same thing is attempted in FIG. A high-speed circuit of 200 MHz is required. In the present embodiment, the image processing is performed in the area (area A) from the reading of each FIFO of the line buffer memory group 226 shown in FIG. 6 to the writing to the output memory 242 (image memory) of the output stage, whereby the area B It is possible to eliminate the need for a high speed circuit.

FIG. 7 is a diagram for explaining the operation when the print position control is performed in the area A, that is, the operation of the drawing position control section 600. Here, the format of the image data in the areas A and B will be described on the assumption that the format shown in FIG. 7A is used to correct 11 pixels in units of 2400 dpi.

FIG. 7B is a diagram showing the relationship between the line synchronization signal LS for one line, the image data before correction, and the image data after correction. The line synchronization signal LS is an example of the index signal according to the present invention.

As described above (see FIG. 4), when the image data is output at high speed, as a mechanism for handling the image data at a frequency as low as possible before the output side,
A memory (the output memory 242 in FIG. 4) is prepared on the output side, and the preceding stage has a configuration in which a plurality of pixels are collectively handled in one clock.

First, the timing signal generator 230 generates a line synchronization signal LS including the number of pixels to be corrected in synchronization with the main scanning synchronization signal SOS which is a timing signal for starting scanning in the main scanning direction. Here, “including the number of pixels to be corrected” means that the effective image range width is equal to or larger than the maximum range for correcting the print position within one period of the main scanning synchronization signal SOS, that is, This means that the active period is the line synchronization signal LS having a margin of the maximum correction amount (number of pixels) or more. When correcting the main scanning magnification error, the maximum magnification (enlargement side) at that time is also taken into consideration when setting. In other words, the line synchronization signal LS should be equal to or larger than the maximum magnification (enlargement side) + position correction amount, that is, the active period should be a line synchronization signal LS having a margin equal to or larger than both position correction and magnification correction (number of pixels). means.

In the area A, the drawing position control section 600 first determines, for the original image data, the effective image data portion which is the printing period in the effective image range (ON) of the line synchronization signal LS (hereinafter referred to as the uncorrected horizontal printing area). In addition to the above, a predetermined flag is set. For example, pre-correction image data is generated by embedding data (white pixel data) meaning a white pixel in the flag pixel portion. The range width of the pre-correction image data including the flag pixel and the print image data portion is the effective period width of the pre-correction image data. By embedding the flag pixel, the effective period width of the pre-correction image data and the effective image range of the line synchronization signal LS are substantially equalized.

In the area B, the output memory 242 sets the image data including this flag pixel (preferably white pixel) to 1
Read as line. That is, in the main scanning direction, the same number of pixels as the number of pixels in the effective image range of the line synchronization signal LS are handled. Since the amount of flag pixels is adjusted in the area A, the print position can be corrected without adjusting the read timing in the area B.

FIG. 7C is a diagram showing a position correction method in the area A for the uncorrected image data b0 to b3 packed with 4 pixels. 1 clock in area A (VC
LK; video clock) correction amount is 2400d
Since pi is 4 pixels, it is possible to correct 8 pixels in 2 clocks (rough adjustment). Then, the rough adjusted data is delayed by one clock to generate data, and the delay amount is corrected in bit units depending on which bit is selected from the combined 8-bit data (fine adjustment).

This is an example of the case where 11 pixels are corrected in units of 2400 dpi. Since 8 pixels have been corrected in coarse adjustment, the number of finely adjusted pixels becomes 3 pixels, and as shown in FIG. The bit data b0 and the bit data b1 to b3 further delayed by one clock are selected.

As described above, by combining the "coarse adjustment" performed in the region A in 1-clock units and the "fine adjustment" in which the correction is performed in bit units, the output resolution can be corrected in 1-pixel units. . In other words, by performing printing position control while handling a plurality of pixels in one clock, a low-speed circuit (50 MHz in the previous example)
The print position can be controlled in units of one pixel of output resolution. Further, a timing generation circuit for high-speed print position control at the output stage is not required, and at the same time, the timing generation circuit can be controlled at a speed lower than the image data output rate.

FIG. 8 is a diagram for explaining a method of adjusting the print position in the main scanning direction when the VCSEL light source group 380 is used. Here, in FIG.
An example of a two-dimensional array of CSEL light source groups, FIG. 8 (B) is an example of a two-dimensional array for memory reading, FIG. 8 (C).
Shows respective examples when the array correction is performed by writing in the memory.

When a light emitting point arrayed in a two-dimensional matrix such as the VCSEL light source group 380 (see also FIG. 3) is used, the light emitting point (light source) is arranged in accordance with the two-dimensional array ( In FIG. 8A, it is necessary to control the printing position in the main scanning direction for each line) (sub 4 × main 3).

When performing the two-dimensional array correction by the conventional technique, it is necessary to change the timing of reading from the memory in the area B for each beam, as shown in FIG. 8B. Therefore, in order to perform the array correction on a pixel-by-pixel basis, in the case of FIG.
Timing control circuit is required.

On the other hand, when "coarse adjustment" and "fine adjustment" are combined in the same manner as in the print position control shown in FIG. 7 and the array correction is performed by the number of white pixels, the memory is changed from the area A (output memory 242). Array correction has been completed at the stage of writing
As shown in FIG. 8C, when reading from the memory in the area B, it is only necessary to read the image data corresponding to all the beams at the same timing without considering the two-dimensional array.

As described above, even when the light source in which the light emitting points are arranged in a two-dimensional matrix is used, "rough adjustment" is performed.
By performing array correction with the number of white pixels that is a combination of "and fine adjustment", a two-dimensional array correction of light emitting points (correction of intervals between light emitting points) is performed in one pixel unit of output resolution in a slow circuit
Can be done. Further, at the time of data output (reading of the output stage memory), data of all beams can be handled at the same timing without being aware of the two-dimensional array. Therefore, a timing generation circuit for high-speed array correction at the output stage is unnecessary.

FIG. 9 is a diagram for explaining an edge erasing process, which is another form of the process for controlling the drawing position. Here, the “edge erasing process” means a process of invalidating (erasing) the data on the image side edge in the main scanning direction.

In the area A, in addition to the line synchronization signal LS, the erasing main scanning synchronization signal ALS (Area Line Syn
c) is generated. The edge-erasing main scanning synchronization signal ALS is a gate signal that leaves image data only in the active period and makes white pixel data otherwise, and is an example of an index signal according to the present invention.

As shown in FIG. 9A, the edge-erasing main scanning synchronization signal ALS can only be adjusted in units of the video clock (pixel clock) VCLK of the area A. For this reason, first, the erasing process is performed in units of 4 pixels by the gate process using the erasing main scanning synchronization signal ALS. Thereafter, erasing of less than 4 pixels is performed by bit processing.

FIG. 9B is a diagram showing an example of erasing 50 pixels. 48 which is a multiple of 4 (= 4 × 1
2) It can be seen that the pixel portion is gated by the erasing main scanning synchronization signal ALS and the remaining 2 pixels are processed by bit processing. That is, the gated signal corresponding to the coarse adjustment stage is set to 1
It is delayed by the clock and bit data b0, b
By selecting 1 and bit data b2 and b3 delayed by 1 clock, 50 pixels are erased. By performing the processing in this way, it is possible to perform the erasing processing on a pixel-by-pixel basis.

Comparing with the printing position control method shown in FIGS. 7 and 8, the gate by the erasing main scanning synchronization signal ALS in the erasing process corresponds to the "coarse adjustment" of the position control.
Since the bit processing corresponds to “fine adjustment”, the erasing processing can be said to be the same as the print position control in concept.

As described above, by performing the erasing process by the method shown in FIG. 9, it is possible to perform the erasing process on a pixel-by-pixel basis of the output resolution with a low-speed circuit. In order to perform the erasing on a pixel-by-pixel basis in the output stage, the erasing main scanning synchronization signal must be generated at the same speed as the image data output rate. However, by using the method shown in FIG. It is not necessary to use a special synchronization signal generation circuit.

As described above, according to the image position control function of the above-described embodiment, a low-speed circuit (a low-frequency video clock can be used) is used, and the output resolution is 1 pixel unit.
The control of the image writing position in the main scanning direction and the erasing process can be performed. Further, since these processes can be performed based on the same line synchronization signal LS, it is possible to obtain an image with high print quality without causing an increase in circuit scale and cost.

FIG. 10 is a block diagram briefly showing the image processing apparatus. In the above embodiment, the image processing apparatus having the multi-beam light source is described as a mode suitable for controlling the drawing position, but the applicable range is not limited to the above example. In short, Figure 10 (A)
As shown in FIG. 3, a pixel packing unit 900 that collects a plurality of input pixel data into a group including a predetermined number of pixels, and each pixel data in each group collected by the pixel packing unit On the other hand, the first image processing unit 902 that performs the first image processing with the first clock CK1 having the predetermined frequency, and the individual pixel data in the group that has been subjected to the first image processing by the first image processing unit 902. To the second image processing unit 904 that performs the second image processing, and the individual pixel data in the group that has been subjected to the second image processing by the second image processing unit 904 to the first clock CK1. Third image processing unit 906 that performs third image processing with the second clock CK2 that is faster than the predetermined frequency
Anything with and can be used.

A preferred application example in this case is shown in FIG.
As shown in 0 (B), in the pixel packing unit 900,
Individual pixel data in the group is collected into 4 pixels (4 pixel packing), and the first image processing unit 902 delays the first clock CK1 (50 MHz) by N clocks as the first image processing. In the second image processing unit 904,
As the second image processing, individual pixel data in the group delayed by the predetermined N clocks from the first image processing unit 902 and before delay (one clock before the pixel data delayed by N clocks) From among the individual pixel data in the group, 4 pixels are selected by an arbitrary combination,
The image processing unit 906 of the second clock CK2 (100
(MHz) to transfer at high speed.

At this time, for each group assembled by the pixel packing unit 900, a pixel data invalidation unit 908 is provided for allocating white pixels to unnecessary portions represented by the index signal in the scanning direction. A drawing position adjustment function can be provided. For example, an image writing position control and an edge erasing processing function can be provided. In correspondence with the above embodiment, the pixel packing unit 900 and the first image processing unit 90
2, the modulated signal generation unit 224 and the line buffer memory group 226 are in charge of the respective units of the second image processing unit 904 and the pixel data invalidation unit 908. In addition, the third image processing unit 9
The output memory 242 is in charge of 06. The memory controller 228 functions as a part that controls these.

Although the present invention has been described with reference to the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various changes or improvements can be added to the above-described embodiment, and a mode in which such changes or improvements are added is also included in the technical scope of the present invention. Also,
The above embodiments do not limit the claimed invention, and all combinations of the features described in the embodiments are not necessarily essential to the solution of the invention.

For example, in the above embodiment, the relationship between the effective image range of the line synchronization signal and the image data in the mechanism for preventing the phenomenon that appears as a color shift in the tandem color image forming apparatus has been described.
It can also be applied to other than tandem configurations. For example, when the mechanism for correcting the image position in the main scanning direction is provided to correct the deviation of the drawing position in the main scanning direction with respect to the absolute reference, if the first example or the second example of the above embodiment is applied, The correction processing of the drawing position (main scanning direction) can be performed with reference to the line synchronization signal of the same effective image range / position. Of course, it can also be applied to print position control in an apparatus for monochrome printing. Further, the present invention can be applied not only to the main scanning direction but also to the drawing position control in the sub scanning direction.

In the above embodiment, the multi-beam light source in which the VCSELs are arranged in a two-dimensional matrix of vertical 8 × horizontal 4 is arranged vertically with respect to the polygon mirror (in the sub-scanning direction). I explained it as an example of using it,
Not limited to this, for example, vertical 4 × horizontal 4, vertical 8 × horizontal 2 vertical layout, vertical 8 × horizontal 2 horizontal layout, or vertical 8 × horizontal 4 horizontal layout, such as VCSEL on the semiconductor substrate. Also, the arrangement form in the sub-scanning direction is free.

In the above embodiment, the polygon mirror (rotating polygon mirror) is used as the deflecting device.
If the direction of light can be periodically deflected, such as a galvanometer mirror or a hologram disc, the same effect as the above example can be obtained. Further, the collimator lens, the scanning lens, and the tilt correction optical system are not essential in the configuration of the optical system, and the presence or absence thereof does not affect the above effects.

Further, the present invention is not limited to the VCSELs arranged in a two-dimensional matrix, but can be applied to a case where a large number of VCSELs arranged in one line (inline) are used. In this case, since a required number of VCSELs are arranged in the main scanning direction and driven simultaneously, it goes without saying that a polygon mirror (rotating polygon mirror) which is a functional portion for scanning the beam light in the main scanning direction is not required.

Further, in the above embodiment, the VCSE is set at the light emitting point.
Although L is arranged, the effect of the above embodiment is not limited to that of the VCSEL and the arrangement of edge emitting laser arrays, LEDs, and the like does not change. In the case of a two-dimensional array of light source groups in which VCSELs are arranged, a monolithic structure in which light emitting portions are two-dimensionally arranged on one semiconductor chip can be used. Also,
In the VCSEL, the cross-sectional area of the emitting portion of the laser light can be made larger than that of the conventional edge emitting semiconductor laser.
The divergence angle of the laser light becomes smaller.

Further, it is needless to say that the present invention can be applied not only to a printing device such as a printer or a copying machine but also to a facsimile or a display, and has the same effect.

[0132]

As described above, according to the present invention, first,
A functional portion (pixel packing unit) that handles a plurality of pixels in one clock is provided, and the pixel data collected by the pixel packing unit is collectively subjected to the first image processing for a plurality of pixels at a low speed clock. Next, the second image processing is performed on the pixel data group subjected to the first image processing. Finally, the third image processing is performed for each bit with a high-speed clock.

As a result, basically, it is possible to obtain a data string having a high-speed clock resolution while performing desired processing with a low-speed clock. For example, it is possible to control the print position in units of one pixel with an output resolution corresponding to a high speed clock with a low speed circuit. Further, when applied to an image forming apparatus that uses a multi-beam light source in which light emitting points are arranged in a two-dimensional matrix, delay adjustment for the positional deviation of the light emitting points can be realized with a low-speed circuit, and the memory of the output stage can be read. At this time, data of all beams can be handled at the same timing without being aware of the two-dimensional array.

Further, even when the edge erasing process for erasing the image side edge in the main scanning direction is performed, the edge erasing process can be performed on a pixel-by-pixel basis of the output resolution with a low-speed circuit.

[Brief description of drawings]

FIG. 1 is a mechanism diagram of an example of a color copying apparatus equipped with an image forming apparatus.

FIG. 2 is a diagram illustrating a configuration example of an image forming unit.

FIG. 3 is a diagram showing a relationship between a scanning line and an imaging spot on a surface to be scanned by a laser beam emitted from a VCSEL light source group.

FIG. 4 is a diagram showing an outline of a processing circuit for forming an image in an image forming unit including a VCSEL light source group.

FIG. 5 is a diagram illustrating drawing position control.

FIG. 6 is a diagram showing a correspondence relationship between halftone data generated by an image data generation unit and a laser modulation signal generated by a write signal generation unit.

FIG. 7 is a diagram illustrating an operation when print position control is performed in area A.

FIG. 8 shows a case where a VCSEL light source group is used.
It is a figure explaining the method of controlling the printing position of the main scanning direction.

FIG. 9 is another form of the processing for controlling the drawing position,
It is a figure explaining an edge erasing process.

FIG. 10 is a block diagram briefly showing an image processing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Color copying device, 10 ... Image acquisition part, 11 ... Platen glass, 12 ... Light source, 13 ... Light receiving part, 20 ... Image processing part, 30 ... Image output part, 31 ... Image forming part, 32 ... Photosensitive drum, 38 ... Semiconductor laser, 39 ... Polygon mirror, 200 ... Image data generating section, 220 ... Write signal generating section, 222 ... I / F section, 224 ... Modulation signal generating section, 22
6 ... Line buffer memory group, 228 ... Memory controller, 230 ... Timing signal generator, 240 ... Delay adjuster, 260 ... Synchronous signal generator, 270 ... Machine controller, 300 ... Laser drive circuit, 304 ... Light amount setting condition selection unit , 306 ... Level changing unit, 308 ... Drive amount control unit, 380 ... VCSEL light source group, 380a ... VCSE
L, 392 ... Photodetector, 600 ... Drawing position control unit, 61
4 ... Pattern detection unit, 621 ... Resist pattern generation unit, 900 ... Pixel packing unit, 902 ... First image processing unit, 904 ... Second image processing unit, 906 ... Third image processing unit, 908 ... Pixel data Invalidation section

Continued front page    (72) Inventor Yasuhiro Arai             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Co., Ltd. Ebina Office (72) Inventor Kenji Koizumi             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Co., Ltd. Ebina Office (72) Inventor Kazuhiro Hama             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Co., Ltd. Ebina Office F term (reference) 2C362 AA07 AA13 AA16 CB75 CB78

Claims (8)

[Claims] 1. A pixel packing unit that collects a plurality of input pixel data into a group including a predetermined number of pixels, and for each group collected by the pixel packing unit, individual pixel data in the group. A first image processing unit that performs a first image processing with a first clock having a predetermined frequency, and an individual image in the group that has been subjected to the first image processing by the first image processing unit. A second image processing unit that performs second image processing on pixel data, and individual pixel data in the group that has been subjected to the second image processing by the second image processing unit, to the predetermined image data. An image processing apparatus, comprising: a third image processing unit that performs a third image processing with a second clock that is faster than the frequency. 2. The third image processing unit applies pixel data in the group, which has been subjected to the second image processing, to a subsequent processing unit connected to the third image processing unit in pixel units. The image processing apparatus according to claim 1, wherein the transfer is performed by the output unit. 3. The first image processing unit, as the first image processing, collectively delays individual pixel data in the group by a predetermined clock with the first clock, The second image processing unit, as the second image processing,
Individual pixel data in the group delayed by the predetermined clock from the first image processing unit is delayed by one clock by the first clock for each group, and is further delayed by this one clock. Selecting the predetermined number of pixels by any combination from individual pixel data in the group and individual pixel data in the group delayed by the predetermined clock from the first image processing unit The image processing apparatus according to claim 1, wherein 4. The first image processing unit, as the first image processing, collectively delays individual pixel data in the group by a predetermined clock with the first clock, The second image processing unit, as the second image processing,
Individual pixel data in the group delayed by the predetermined clock from the first image processing unit, and individual pixel data in the group one clock before the pixel data delayed by the predetermined clock 2. The image processing apparatus according to claim 1, wherein the predetermined number of pixels are selected by an arbitrary combination. 5. Pixel data excluding a print effective range of pixel data in the group within the effective image range of an index signal indicating an effective image range in the scanning direction for each group collected by the pixel packing unit. And a pixel data invalidation unit that changes the pixel data into substantially invalid pixel data in image formation, wherein the first image processing unit includes the first image with respect to the pixel data from the pixel data invalidation unit. The image processing apparatus according to claim 1, wherein the image processing apparatus adjusts an image position in the scanning direction by performing processing. 6. Pixel data excluding the effective range of an index signal indicating an effective range in the scanning direction, out of individual pixel data in the group, for each group grouped by the pixel packing unit, in image formation. A pixel data invalidation unit for changing into substantially invalid pixel data, wherein the first image processing unit performs the first image processing on the pixel data from the pixel data invalidation unit, The image processing apparatus according to any one of claims 1 to 4, wherein the image on the peripheral portion of the image in the scanning direction is erased by the above. 7. The image processing apparatus according to claim 1, wherein the light intensity of the light beam is modulated based on the image data processed by the image processing apparatus. An image forming apparatus, comprising: an image forming unit that forms an image by scanning an object to be scanned with a modulated light beam. 8. An image distortion detecting unit that detects an image distortion amount that may occur when the image forming unit forms the image, and an image in a scanning direction based on the image distortion amount detected by the image distortion detecting unit. The image forming apparatus according to claim 7, further comprising a drawing position control unit that controls a position.