JP2003255247A - Multi-beam light source, optical scanner, and method and device for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently configure a signal processing circuit in an image forming device utilizing a multi-beam light source. <P>SOLUTION: In a VCSEL light source group 380 as the multi-beam light source, the total number of VCSELs 380a being light emission points is set to a multiple of 8. A write signal generation part 220 is provided with a modulation signal generation part 224 for generating a laser modulation signal on the basis of image data and a line buffer memory group 226 consisting of 8-bit FIFO memories for coarse adjustment of the write timing of the laser modulation signal from the modulation signal generation part 224. The line buffer memory group 226 is utilized to control the data delay quantity in order to form images of individual light beams emitted from the VCSELs 380a on one line parallel with the sub-scanning direction on a scanned surface. The phase difference between a page synchronizing signal and a main scanning synchronizing signal is finely corrected by a delay adjuster 240 using 8-bit FIFO memories. <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 a multi-beam light source in which a plurality of light emitting points are arranged, an optical scanning device using the multi-beam light source, an image forming method and an image forming apparatus using the optical scanning device.

[0002]

2. Description of the Related Art Due to recent advances in network technology and higher performance of computers, there has been a demand for higher resolution of an image recording apparatus which is an output device thereof. For example, in a printer, in order to output a high-quality image, higher resolution is pursued, and accordingly, the resolution is 400 dp.
i (dot per inch; number of print dots per inch),
It has advanced to 600 dpi and 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.

In addition, in image recording apparatuses, high productivity such as improvement of output speed (printing speed) has been pursued, and in order to meet the demand of writing speed which increases with this, 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.

[0006]

However, when the multi-beam technique is used, the amount of images to be handled is enormous and the handling becomes complicated, and if the conventional technique is applied as it is, a great load may be imposed on the circuit design. It has become clear.

That is, in a laser printer equipped with a multi-beam scanning device, although high-speed machine recording can be performed by the number of beams, the control of the image writing position also becomes rough in units of multiple lines, and There are two problems, that is, the circuit scale related to the access of the image data whose number increases increases. In particular, control of the image writing position is an essential technical subject in a color printer that forms a color image by superposing a plurality of color images.

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. Thirdly, in the dual beam system, as shown in FIG. 21, the system of a plurality of beams may be completely separated, such as the system of two beams being completely separated.

In the first case, since all the operations are performed in units of the number of beams, the transfer rate of image data may be slow, but it is difficult to control the writing position, and the number of beams of the scanning device is increased. The design of the host system must be changed for each case.

In the second case, the higher-order image data generator is equivalent to a one-beam scanning recording device and has a general 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 that 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.

At present, there are almost no line buffer memories capable of directly writing such high-speed data. In reality, if this data is not converted into parallel data while being collected in units of 16 or 32 bits, the line buffer memory should be constructed. Is impossible. Furthermore, parallel-serial conversion is required at the output section, which complicates the circuit configuration.

Further, in this case, although there is no problem in controlling the writing position of the image, a line buffer memory having a complicated structure for each channel as described above is required about twice the number of beams, and the circuit scale is increased. In addition, the cost will be increased.

In the third case, except for the image processing unit which cannot be separated, it is necessary to separately process the image data for the odd beam and the image data for the even beam in the processed image data. . Therefore, the circuit scale is increased and the cost is further increased.

On the other hand, from the viewpoint of circuit design, most of the electronic devices are configured with 8 bits as one unit, so that if the number of beams in the multi-beam system is arbitrarily selected, the circuit configuration becomes complicated. There is a problem that a wasteful circuit must be mounted.

For example, as shown in FIG. 22, 600 dp
i * 8 * 1 dot = 8 bits are 2400 dpi * 1 * 1
When converted to 6 dots = 16 bits, a 600 * 8 input image is converted to 2400 * 1 × 16 pixels. As can be seen from this example, when handling image data, 8
Is the standard for handling amount.

In such a situation, if the total number of light emitting sources and the matrix shape are freely set, an efficient circuit design cannot be performed, the circuit scale is increased, and the cost is further increased. For example, Japanese Patent Laid-Open No. 2001-215423 proposes that the matrix shape of the light emitting points is 6 × 6. In this case, if a circuit design is made based on a multiple of eight, 8-bit input / output devices are used to handle a 6-stage configuration, and 2 bits are wasted in each stage.

Further, by increasing the number of beams, the frequency of the image data (video) to be handled can be lowered, but if it is too large, the wiring pattern will pass between the light emitting points many times. However, problems such as wiring difficulty and yield also occur.

The present invention has been made in view of the above circumstances, and by optimizing the number of light emitting points and the arrangement form,
It is an object of the present invention to provide a multi-beam light source that can improve the efficiency of a circuit and contribute to cost reduction.

Another object of the present invention is to provide an optical scanning device using such a multi-beam light source, and an image forming method and an image forming device using this optical scanning device.

[0022]

That is, in the multi-beam light source according to the present invention, the total number of light emitting points is a multiple of 8. In this multi-beam light source, the light emitting points are arranged in one line, or the light emitting points are arranged in a two-dimensional matrix. It may be either.

When the light emitting points are arranged in a two-dimensional matrix, the number of one of the light emitting points is preferably 2 ^m (m is an integer of 2 or more), and particularly a multiple of 8.

Such a multi-beam light source is configured to be capable of emitting a light beam whose light-emitting point has an optical axis substantially vertical to the surface of the element substrate, for example, VC.
It is preferably a SEL array (surface emitting laser array).

An optical scanning device according to the present invention comprises the above-mentioned multi-beam light source according to the present invention, and an optical system for forming an image of a light beam emitted from each light emitting point of the multi-beam light source on a surface to be scanned. It is a thing.

In the optical scanning device according to the present invention, a plurality of reflecting surfaces are provided, and the light beams emitted from the respective light emitting points are reflected by the reflecting surfaces, so that the respective directions of the light beams are periodically made. It is desirable to have an optical deflector for deflecting the light.

Further, the multi-beam light source has a rectangular outer shape, and is arranged such that the long side of the outer shape is substantially parallel to the sub-scanning direction on the surface to be scanned. desirable.

In the multi-beam light source, the light emitting points are arranged in a two-dimensional matrix, and the number of one light emitting point is 2 ^m (m is an integer of 2 or more), particularly 8
Is preferably a multiple of.

The image forming method according to the present invention uses the optical scanning device according to the present invention, and the total number is 8
A light beam is emitted from a light emitting point that is a multiple of, and an image is formed by forming an image on the surface to be scanned using this light beam.

An image forming apparatus according to the present invention uses the optical scanning device according to the present invention, and the total number is eight.
Is emitted from each individual light emitting point of the multi-beam light source, a drive control unit that drives the light emitting point based on image data, And an optical system for forming an image of the light beam on the surface to be scanned.

The image forming apparatus according to the present invention is 8 or 8
It is desirable to include a signal processing unit that handles image data with a multiple of 1 as a unit.

Further, it is desirable that the signal processing unit processes the input digital image data by using the digital screen method.

Further, in the image forming apparatus according to the present invention, a plurality of reflecting surfaces are provided, and the light beams emitted from the respective light emitting points are reflected by the reflecting surfaces, so that the respective directions of the light beams are cycled. It is desirable to have an optical deflector that selectively deflects light.

In this case, the signal processing section uses an 8-bit FIF.
A data delay by an 8-bit FIFO memory for forming an individual light beam emitted from the light emitting point of the multi-beam light source on the same straight line parallel to the sub-scanning direction on the surface to be scanned. It is desirable to control the amount.

For example, the phase difference between the page sync signal and the main scan sync signal is determined on a line sync signal basis, and margin data is added to the write to the line buffer memory consisting of an 8-bit FIFO memory, whereby k scan lines The image recording position in the sub-scanning direction may be adjusted in units. The phase difference between the page synchronization signal and the main scanning synchronization signal may be determined more finely, and the line buffer memory may be read while bit shifting is performed to control the writing position for each scanning line.

Further, in the image forming apparatus according to the present invention, the signal processing unit causes the light beam to be changed for each main scanning.
Adjacent exposure mode in which the scanning surface is scanned by shifting in the sub-scanning direction by all light emitting points of the multi-beam light source, and the scanning surface is scanned by shifting in the sub-scanning direction by less than the total number of light emitting points. The overlap exposure mode may be configured to be switchable.

Alternatively, the signal processing unit is configured to be capable of switching between the adjacent exposure mode and the overlap exposure mode in which the surface to be scanned is shifted by a distance smaller than the total number of light emitting points in the sub-scanning direction. May be

[0038]

In the above structure, the total number of light emitting points of the multi-beam light source is a multiple of 8. The signal processing unit handles 8 or a multiple of 8 in each unit including a memory as a unit for handling.

[0039]

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 mechanism diagram of an example of a color copying machine equipped with an image recording apparatus for recording an image using a surface emitting semiconductor laser (hereinafter referred to as VCSEL) array which is an example of a light source according to the present invention. .

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 unit 10 comprises a housing 112 and a platen glass (original 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 focus 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.

The ADF device 60 includes a paper feed tray 62, a processing tray 63, and various transport roll pairs 64 such as a registration roll pair 64a and an exit roll pair 64b for forming a transport path for the document G. A guide B is provided at an end portion (left side in the drawing) of the platen glass 11 above the housing 112, and a light-transmissive contact glass (reading glass) is provided in the immediate vicinity thereof.

A guide A is provided on the contact glass. A white reference plate 19 is included in the guide B. A paper sensor 65 that detects the document G is provided at a plurality of predetermined positions on the transport path. By monitoring the detection output of the paper sensor 65, the leading edge or the trailing edge of the document G can be detected.

In the above structure, the image acquisition unit 10 is normally at the home position (in the vicinity of the fixed read image destination position G indicated by the Δ mark 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.

For example, the full rate carriage 134
Moves below the platen glass 11 from the home position in the direction opposite to the arrow X or while performing exposure scanning, and is stopped and locked at the conveyance reading image destination position H indicated by a mark in the figure, and the light receiving unit 13 and the read signal processing unit are locked. 14 is set to the imaging standby state. After that, when an exposure start permission signal (not shown) is transmitted from the main body side CPU to the ADF device 60, the ADF device 60 receiving this permission signal causes the ADF device 60 to print the original (paper) P placed on the paper feed tray 62. Start feeding.

The document G is guided in the directions of the guides A and B through a predetermined transport path formed of various transport roll pairs 64, passes through the registration roll pair 64a, and the leading end of the document reaches the transport read image destination position H. At this time, the document image is started to be read by transmitting the image destination signal from the ADF device 60 side to the image acquisition unit 10 side. Then, the peripheral speed of the transport roll pair 64 such as the registration roll pair 64a and the exit roll pair 64b is controlled to be constant by a drive motor (not shown), so that the document passes on the guides A and B at substantially constant velocity. , Exit roll pair 64b, and is discharged toward the processing tray 63. That is, the color copying apparatus 1 reads a document image while conveying the document at a constant speed.

On the other hand, in the fixed reading method, a manuscript is manually placed on the platen glass 11 serving as a manuscript mounting table (or the ADF device 60 may be used) and fixed at an arbitrary position on the platen glass 11. In the (stop locked) state, the reading optical system is moved at a constant speed in the direction of the arrow X with the fixed read image destination position G as the leading end to expose the document to read the image.

For example, with the original placed on the platen glass 11 covered with the ADF device 60, the light from the light source 12 illuminates the original placed on the platen glass 11, and the reflected light reflects the full rate carriage. The light is split into each color of red, green, and blue through a reading optical system including a 134, a half-rate carriage 138, and a lens 140. Then, the respective color lights are incident on the corresponding line sensors 142 for the respective color lights, and the input image is read at a predetermined resolution, whereby analog captured image signals of red, green, and blue color components are generated. can get.

Then, the picked-up image signal obtained by this reading is converted into digital image data of each color component of red (R), green (G) and blue (B), and the digital image data of red, green and blue is converted into an image. It is sent to the processing unit 20. During this reading, light source 1
The reading optical system including the light source 12 and the light receiving unit 13 are arranged so that the light from 2 irradiates the entire surface of the document and the light receiving unit 13 reads the entire input image through the reading optical system such as the lens 140. Are relatively moved from left to right (sub-scanning direction) in FIG. 1 at a constant speed as indicated by arrow X. That is, the color copying apparatus 1 reads the original image while moving the optical system at a constant speed.

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, the 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;
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.

First, the image output section 30 starts from the image forming sections 31K, 31Y, 31M and 31C of K, Y, M and C, which are arranged in parallel in one direction at regular intervals, and the original cassette 41. The leading edge detector 44 is provided in proximity to the conveyance path of the document conveyed to each image forming unit 31. The leading edge detector 44 optically detects, for example, the leading edge of the document fed onto the transfer belt 43 from the document cassette 41 through the registration roller 42 to obtain a leading edge detection signal, and sends this leading edge detection signal to the image processing section 20. . 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 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
By scanning on the photosensitive drum 32K charged by the primary charger 33K via 7K, 48K, and 49K,
An electrostatic latent image is formed on the photosensitive drum 32K.

This electrostatic latent image is made into a toner image by the developing device 34K to which black toner is supplied, and this toner image is the original on the transfer belt 43 as 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 photoconductor 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 in which the toner images of K, Y, M, and C are sequentially transferred in this manner is peeled off from the transfer belt 43, and the toner is fixed by the fixing roller 45 to the outside of the copying machine. Is discharged.

It should be noted that 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 the toroidal lens 388 having the tilt correction function and the scanning lens group 384 having the 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 view for explaining the arrangement of the VCSELs 380a that make up the VCSEL light source group 380.
Here, FIG. 3A illustrates an example in which a large number of VCSELs 380a are arranged in one line (inline),
FIG. 3B shows an example in which the VCSELs 380a are arranged in a two-dimensional matrix.

In this embodiment, whether it is in-line,
VCSEL regardless of whether it is a two-dimensional matrix
The total number of 380a is 10 or more and a multiple of 8. In the case of the in-line arrangement, since the required number of VCSELs 380a are arranged and driven at the same time in the main scanning direction, it goes without saying that the polygon mirror 39 which is a functional portion for scanning the beam light in the main scanning direction is not required. Absent.

For example, in the case of an in-line arrangement, as shown in FIG. 3A, (8 × p) pieces (p is 1
The above integers), and one line is arranged in the horizontal direction. Again 2
In the case of a two-dimensional matrix arrangement, as shown in FIG. 3B, when the length is 2 ^m × horizontal (2 ⁿ × q), m is 2 or more,
n is 0 or more, q is an integer of 1 or more, and VCSEL3
The total number of 80a is set to be a multiple of 8.

For example, in the case of a two-dimensional matrix arrangement, four vertical types a1, a2, ... Series, eight vertical types b1, b2 ,. , C2, ...

FIG. 4 shows a VCSEL light source group 3 of type a1.
FIG. 8 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 80. Reference numerals P1 to P8 in the drawing are scanning spots (the same applies to FIGS. 5 to 7 described later).

The type a1 VCSEL light source group 380 is
The VCSEL 380a is two-dimensionally arranged on the surface of a semiconductor substrate so as to have a length of 4 × width 2. here,
Vertical arrangement of this VCSEL light source group 380 (four in this example)
Are arranged in the vertical direction with respect to the polygon mirror 39, that is, in such a manner that they are 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. The VCSEL light source group 380 is arranged vertically such that it is in the horizontal direction with respect to the polygon mirror 39, that is, it is arranged so as to be optically parallel to the sub-scanning direction on the photoconductor that is the surface to be scanned. The form is 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 (main scanning line) in the main scanning direction.
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 four VCSELs 380a are equally spaced along any line (subscanning line) in the subscanning direction and two equally spaced along the main scanning line. A total of 4 × 2 VCSELs 380a are arranged in a two-dimensional matrix. Reference symbols L1 to L16 indicate sub-scanning lines.

Further, 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, and the scanning lines are scanned at equal intervals with a pitch Δ, and further, each time. The surface to be scanned moves in the sub-scanning direction in FIG. Regardless of the positional relationship of the spots to be scanned, the movement of the surface to be scanned in the sub-scanning direction is 8 scanning line segments per main scanning period. It should be noted that the figure shows main scanning for two times, and V for the first and second times
Although the position of the CSEL light source group 380 is shown shifted in the main scanning direction, this is for convenience of explanation in the drawing, and the scanning actually starts from the same position (see FIGS. 5 to 7 described later).
The same).

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 8 laser beams of 4 × 2 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.

If the distance from one spot to another spot measured 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,
By performing delay control on the modulation signal of each VCSEL 380a so that each light beam emitted from the VCSEL 380a, which is a light emitting point, corresponding to one row on the image data forms an image in one row in the sub-scanning direction. Is n × 8 (8
Laser light of a multiple) is simultaneously and adjacently scanned.

In addition to the total number of VCSELs 380a being a multiple of 8, by controlling the delay amount (corresponding to SL) in the main scanning direction using an 8-bit electronic device, bit waste occurs. Not configuring an efficient circuit. This point is applied to any of vertical 4 × horizontal 4 vertical arrangement, vertical 8 × horizontal 4 vertical arrangement, and vertical 8 × horizontal 2 horizontal arrangement, which will be described later.

FIG. 5 shows V of the type a2, which is 4 × 4.
It is a figure which shows the relationship between the scanning line and the imaging spot in the to-be-scanned surface by the laser beam emitted from the CSEL light source group 380. Here, it is assumed that the four vertical rows are vertically arranged with respect to the polygon mirror 39.

When the first main scan is completed, the adjacent exposure is repeated with a shift of 16 scanning lines in the sub-scanning direction.
Type a1 VCSEL light source group 38
Similar to 0, 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.

FIG. 6 shows V of type b4, which is 8 × 4.
It is a figure which shows the relationship between the scanning line and the imaging spot in the to-be-scanned surface by the laser beam emitted from the CSEL light source group 380. Here, it is assumed that the vertical 8 lines are arranged vertically with respect to the polygon mirror 39.

When the first main scan is completed, the adjacent exposure is repeated with a shift of 32 scanning lines in the sub-scanning direction.
Type a1 VCSEL light source group 38
Similar to 0, 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.

FIG. 7 shows V of type b2, which is 8 × 2 in length.
It is a figure which shows the relationship between the scanning line and the imaging spot in the to-be-scanned surface by the laser beam emitted from the CSEL light source group 380. Here, it is assumed that the arrangement of 8 columns is a horizontal arrangement with respect to the polygon mirror 39 in the horizontal direction.

The number of arrays in the main scanning direction is eight, but when the first main scanning is completed, the adjacent exposure is repeated with a shift of 16 scanning lines in the sub-scanning direction, which is the same as the embodiment shown in FIG. As in the case of the type a1 VCSEL light source group 380, the interval of the VCSEL 380a in the main scanning direction is SL.
Then, the sub-scanning line interval Δ is set to SL × tan φ.

The VCSEL 3 is arranged in a two-dimensional matrix form.
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. 8 shows a VCSEL light source group 38 having the above structure.
FIG. 3 is a diagram showing an outline of a signal processing circuit for forming an image in the image forming unit 31 including 0. Here, VCSE
As the L light source group 380, the VCSEL 380a is 8 × 4
An example of the configuration when using the type b4 arranged in a two-dimensional matrix (total number = 32) will be described.

The image processing unit 20 converts the image data from the image data generating unit 200, which acquires image data from the client terminal 8 such as a personal computer, via the image acquiring unit 10 or the network 9. A write signal generation unit 220 that generates a laser modulation signal for each VCSEL 380a based on it, and a delay adjuster 240 that adjusts the write timing for the laser modulation signal from the write signal generation unit 220 are provided.

The adjustment of the delay amount according to the arrangement position of the VCSEL 380a is performed by the adjustment (coarse adjustment) by the write timing or the read timing of the line buffer memory group 226 and the adjustment (fine adjustment) by the delay adjuster 240.
The line buffer memory group 22
6 or only the delay adjuster 240 may be used. If coarse adjustment and fine adjustment are combined, VCSEL
In order to form the individual light beams emitted from 380a on the same straight line parallel to the sub-scanning direction on the surface to be scanned,
Using the line buffer memory group 226, the phase difference between the page sync signal and the main scan sync signal can be finely corrected by the delay adjuster 240 using an 8-bit FIFO memory.

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 that has a plurality of line buffer memories 226a and roughly adjusts the write timing with respect to the laser modulation signal from the modulation signal generation unit 224. The line buffer memory group 226 and the delay adjuster 240 connected to the subsequent stage thereof function as a data delay unit according to the present invention.

Further, the write signal generator 220 has the I / F unit 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 processing section 20 includes an image forming section 31.
Main scanning synchronization signal S which is a reference signal for controlling the writing timing based on the detection signal obtained from the photodetector 392 of
A synchronization signal generator 260 that generates an OS and a machine controller 270 that is a functional portion for controlling the entire color copying apparatus 1 are provided.

The timing signal generator 230 outputs a main scanning synchronizing 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, FI
Sub-line synchronization signal Line corresponding to the number of FO memories,
Alternatively, it is a 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 on the photosensitive drum 32 in the sub-scanning direction is adjusted.

The delay adjuster 240 receives the fine phase difference that cannot be adjusted by writing the margin data in the line buffer memory 226a.
When the data is read from 6, the bit shift corresponding to the fine phase difference is performed, and the modulation signal corresponding to the N laser beams for the multi-beam scanning device is supplied to the image forming unit 31.

The image forming section 31 uses the laser modulation signal whose output timing is adjusted by the delay adjuster 240, based on the individual VCSELs 380 of the VCSEL light source group 380.
Laser driving circuit for driving a (multi-LDD)
300, and a half mirror 3 arranged on the optical path of the laser light as a functional portion for controlling the image forming unit 31.
The laser light reflected by 94 is supplied to each VCSEL 380a.
And a light amount sensor 302 for receiving light.

Further, the image forming section 31 is based on 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, for example, 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.

Further, the image forming section 31 includes the light amount sensor 30.
2, 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 machine controller 2
Based on the light amount setting signal from 70, a level changing unit 306 that changes the light amount level, and under the control of this level changing unit 306, a drive amount setting signal for controlling the drive current of each VCSEL 380a (each Corresponding 1 ~
n) and a drive amount control unit 308 that generates a drive signal for controlling the light amount.

FIG. 9 shows the flow of image data (video path).
3A and 3B are diagrams illustrating resolution conversion. Note that FIG.
(TR) "TRC LUT", which is the functional unit on the left side of the middle, is a color correction process (TRC process; Tone Reproduction Correctio).
n; Look-up table (LUT) for use in, for example, JP-A-6-101799).

In the configuration shown in FIG. 8, the VCSEL3
The total number of 80a N = 32 (that is, the total number of laser beams is 3)
2), scanning resolution nn = 2400 dpi, halftone data of the image data generation unit 200 has resolution mm = 600 dpi,
Each pixel has a density value of 8 bits. Scanning resolution
nn = 2400 and data resolution mm = 600.

Here, considering the handling of data,
It is efficient to handle with 8 bits in terms of circuit configuration. For example, an electronic device basically has a bus width and a capacity that are multiples of 8. Therefore, in an exposure method using a plurality of light beams, the number of beams is set to be a multiple of 8.
As shown in (A), handling of an image is simplified and an electronic device or the like can be used efficiently.

In addition, for example, when a screen is applied to a multi-valued image of 600 dpi to output it on a digital screen of 2400 dpi, 600 dpi is 240
When converting to 0 dpi, as shown in FIG.
Four inputs will produce four outputs. That is, resolution conversion is required.

Here, by setting the shape of the matrix arranged in the main scanning direction to the power of 2n, the resolution conversion and the handling of the video signal become very simple. That is, when obtaining 2400 dpi / 32 lines of output data shown in FIG.
By setting the delay amount in the main scanning direction for each number (4 in this case) after resolution conversion, it is possible to create a stream of video signals without waste. For example, FIG. 9 (B)
As shown in, there are eight 600 dpi × 8 bit inputs, and each output is 2400 × 8 output (2400 × 4
2 sets of outputs) are separated into 8-bit FIs shown in FIG.
A 32 beam video path is completed by putting it in the FO memories 227-1 to 224.

As shown in FIG. 1, in the color copying apparatus 1 using the xerographic technique, there is a large problem in that the normal image quality has a large variation with respect to the environment, especially from the viewpoint of maintaining the image quality. There is. One method of solving these problems is to stabilize the image quality by using a digital screen.

However, when an image is formed using a digital screen with a low resolution, the number of screen lines is reduced, and it cannot be said that the maximum performance of the image forming apparatus is necessarily obtained. To solve these problems, it is desirable to have a resolution of 2400 dpi or higher, which is well known in printing.

Therefore, in order to realize 2400 dpi, the following conditions must be satisfied. That is, 1) Considering the output efficiency (ROS efficiency) in the image forming unit 31, a writing speed equivalent to about 1.5 G (G: giga) points is required for A4 size × 1 surface, 2) A4 size With a high-speed machine with a productivity of 100 sheets, adjacent exposure is about 2.5 Gbps (Bit Per Sec),
A writing speed of about 1.25 Gbps is required even for a medium-speed machine of 50 sheets class. 3) Furthermore, if double exposure is performed,
Double the writing speed is required.

That is, assuming that a light source with 32 beams is used, in a high-speed machine having an A4 size and a productivity of 100 sheets, adjacent exposure is about 80 Mbps, 50
A writing speed of about 40 Mbps is required even for a medium-speed machine of the sheet class. Double exposure gives 160Mbp each
A writing speed of 80 Mbps is required.

Assuming that a light source having 16 beams is used, a writing speed of about 160 Mbps for adjacent exposure in a high-speed machine of A4 size and 100 sheets class productivity, and a writing speed of about 80 Mbps for a medium speed machine of 50 sheets class. You will need it. When double exposure is performed, 320 Mbps,
A writing speed of 160 Mbps is required.

If, for example, 40 dots = 40 times with a single beam, 40 dots = 20 times with a dual beam, the driving frequency rises, transmission technology becomes difficult, and EMC noise is generated. There is also a problem such that sticking is likely to occur and the light energy per time decreases.

By increasing the number of beams, the frequency of image data (video) to be handled can be suppressed to 200 Mbps or less. For example, if the matrix shape is set to 8 × 8 (that is, 64 beams), the wiring pattern becomes VCSE.
It has been pointed out that the number of lines passing through the L380a causes a problem in semiconductor manufacturing, and further, the yield is extremely reduced when the size of the chip becomes 64 beams.

Considering these points, A4 size is 2
In a medium- to high-speed machine that produces a productivity of about 5 to 200 sheets, the frequency of image data (video) to be handled can be suppressed to about 200 Mbps by setting the number of beams to 16 or 32, which is very efficient. You can set up a system. That is, the matrix shape is 8 × 4 (ie 32
If the VCSEL light source group 380 of (main beam) or 8 × 2 or 4 × 4 (that is, 16 beams) is used, wiring on the chip can be facilitated and the yield can be increased.

FIG. 10 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 modulation signal generation unit 224. Here, as shown in FIG. 9, an 8-bit FIFO memory 227 is used as each line buffer memory 226a.
A line buffer memory group 226 is configured by using four lines (numbers 1 to 4).

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 (FI
Write to FO memory 227).

In order to process image data by such a method, it is necessary to store data for 8 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 approximately 30 kwords × 8 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 modulated signals 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), it is possible to set the same read timing from the 8-bit FIFO memory 227.
The output timing can be adjusted without waste by using the bit FIFO memory 227. In addition, the FIFO memory 2 is arranged in a form that matches it with the matrix of the light source in the main scanning direction.
By having 27, the number of beams can be expanded without waste.

Although FIG. 10 shows only the correspondence between the halftone data and the laser modulation signal, in actual processing, for example, color registration correction (positional deviation correction) and density correction are performed. Various image processing is performed.
Sometimes these processes are done with multi-valued data,
It may also be done with digitized data.

FIG. 11 is a diagram showing a first example around the memory controller 228. The line buffer memory group 226 of this example has two sets of FIFO groups (each having A and B) having four 8-bit FIFO memories 227 as line buffer memories.

The timing signal generator 230 receives various control signals (ROS_PS, ROS_LS, Lin) from the main scanning synchronization signal SOS and the print request signal (PRQ).
e, Page, PCK, etc.) are generated and supplied to each unit.

The memory controller 228 has a clock generator 228a and a 1/4 frequency divider 228b, and stores the four 8-bit FIFO memories 227 (A-1 to A-4) forming the FIFO group A. Write clock FIF
O_WCK is generated by the clock generator 228a, and 1 /
In the divide-by-4 frequency divider 228b, this write clock FIFO_
A transfer clock is generated by dividing WCK by four. And
This transfer clock is sent to the image data generation unit 200 via the I / F unit 222.

When the page sync signal Page and the sub-line sync signal Line are activated, the image data generator 200 synchronizes with the transfer clock to generate 8-bit image data through the I / F unit 222 and the modulated signal generator 224.
Send to.

The modulation signal generating section 224 generates 16-bit bitmap data from the 8-bit halftone data of one pixel, and outputs the 16-bit bitmap data to the FIFO memory 2 in 8-bit units.
Write in 27. Further, FIFO_WCK having a frequency four times as high as the transfer clock is used as a write clock.

At this time, the output of the modulation signal generator 224 is connected to the inputs of all the FIFO memories 227 of the FIFO memory 227 groups A and B, and the memory controller 228.
Are sequentially controlled by controlling the write enable terminal.

Image data is read from the FIFO memory 227 in synchronization with the pixel clock PCK with the write enable signal ROS_LS generated from the main scanning synchronization signal SOS as a read reference. FIFO memory 22 at this time
The memory controller 228 is used to switch between the A group and the B group in FIG.
By controlling the read enable terminal and the output enable terminal of each FIFO memory 227.

FIG. 12 is a diagram showing an outline of a second example of the signal processing circuit. Here, the modulation signal generator 224 is included in the image data generator 200. However, the original image data processed by the modulation signal generation unit 224 in the image data generation unit 200 is image information having a predetermined resolution and density value, and is simply designed in the data transfer circuit in the I / F unit 222. Only the above difference occurs.

As described above, a vertical 8 × horizontal 4 VCS
In the configuration in which the EL light source groups 380 are arranged in the vertical direction with respect to the polygon mirror 39, by using four 8-bit FIFO memories 227 for each group,
The exposure control circuit can be efficiently configured without wasting the bits of the IFO memory 227.

In other words, by setting the number of light emitting sources to be a multiple of 8, for example, the number of FIFO memories 227 as line buffer memories can be reduced and the control of the image writing position can be simplified, whereby the circuit scale can be reduced. Can be made smaller. Therefore, it can also contribute to cost reduction.

Next, special points for dealing with the 8-bit FIFO memory 227 will be described. In the above example, the vertical 8 × horizontal 4 (type b4) VCSEL light source group 38
Although the drive timing in the configuration in which 0 is arranged in the vertical direction with respect to the polygon mirror 39 has been described, even when the VCSEL light source group 380 of another type is used, the vertical arrangement or the horizontal arrangement is adopted. The 8-bit FIFO memory 227 can be used regardless of whether

Note that the pixel position of the image data (data series to be taken into the FIFO memory) and each VCSEL 380a of the VCSEL light source group 380 are changed in accordance with the change of the vertical arrangement / horizontal arrangement.
The corresponding number will change. Along with this, the handling of the write clock / read clock of the FIFO memory or the handling of the delay adjuster 240 is changed. A detailed description of these changes is omitted.

Even in such a modified embodiment, V
The delay amount (corresponding to SL shown in FIGS. 4 to 7) of the CSEL 380a in the main scanning direction can be controlled, and the 8-bit F
The exposure control circuit can be efficiently configured without wasting the bits of the IFO memory 227.

For example, the vertical 4 × horizontal 2 (type a1) VCSEL light source group 380 shown in FIG. 4 is arranged vertically, and the vertical 4 × horizontal 4 (type a2) VCSE shown in FIG.
A configuration in which the L light source group 380 is arranged vertically, and the vertical 8 shown in FIG.
8-bit FI in any of the case where the horizontal 2 (type b2) VCSEL light source group 380 is horizontally arranged
The FO memory 227 can be used to efficiently configure a circuit for exposure control.

Further, in the above example, the VCSEL 380a is set to 2
Although an example using the VCSEL light source group 380 arranged in a three-dimensional matrix has been described, the exposure control circuit can be efficiently configured using the 8-bit FIFO memory 227 even in the in-line arrangement. it can. In this case, the required resolution pitch in the main scanning direction is a VC that is a multiple of 8.
The SEL 380a is arranged and drives individual VCSELs 380a by converting serial data into parallel data. Then, an 8-bit FIFO memory may be used for the serial-parallel conversion unit that converts serial data into parallel data.

FIG. 13 shows an 8-bit FIF of the vertical 4 × horizontal 4 (type a2) VCSEL light source group 380 shown in FIG.
It is a figure which shows the structure (video path) of a drive circuit at the time of driving using O memory 227, and an example of a timing. In this case, eight VCSELs 380a on each of the left half and the right half of the VCSEL light source group 380 in the figure are provided as one 8-bit F.
It is configured to be driven by the IFO memory 227. Also VCS
In order to perform delay control so as to correct the interval SL in the main scanning direction of the EL 380a, the VCSEL light source group 380 and each 8
Delay adjuster 240 between bit FIFO memory 227
To provide.

FIG. 14 is a diagram for explaining a configuration example of a drive circuit when the VCSEL light source group 380 is horizontally arranged (a horizontally long chip is used). In this figure, the vertical 8 × horizontal 2 (type b2) VCSEL light source group 380 shown in FIG.
Are horizontally arranged and used as sub 2 × main 8. In this embodiment, for example, two methods can be adopted: a first example handled by grouping indicated by A1 and A2 in the figure and a second example treated by grouping indicated by B1 and B2 in the figure.

In the first example, the simply created bitmap images are sequentially placed in the 8-bit FIFO memory 227 for each grouping indicated by A1 and A2 in the figure, and the VCSEL light source group 3 is set by the delay adjuster (Delay) 240.
It is synchronizing with 80. On the other hand, in the second example, the bitmap image created to minimize the delay adjuster 240 is put into the 8-bit FIFO memory 227 for each grouping indicated by B1 and B2 in the figure due to the early / late scan timing. Is the way. In FIG. 14, a matrix of sub 2 × main 8 is shown as an example, but not limited to this, for example, sub 2 × main 16, ..., Sub 2 × main (n × 8; n is an integer of 3 or more). In the case of), it can be dealt with by extending it as well.

In the above description, the movement of the surface to be scanned in the sub-scanning direction is divided into scanning line segments for the total number of VCSELs 380a per main scanning period, and the scanning lines are equally spaced.
Adjacent exposure was used to realize dimensional scanning. However, in order to deal with deformation such as printing on thick paper, for example, the process speed may be changed. For example, 1 / n speed is obtained by overlapping scans n times,
For example, by skipping the n-plane, the speed is 1 / n.

FIG. 15 is a diagram showing a difference between the adjacent exposure and the overlap exposure as a scanning mode. This Figure 1
The scanning mode shown in FIG. 5 is a double exposure mode in which two overlap scans are executed.

As shown in FIG. 15, the movement of the surface to be scanned in the sub-scanning direction is set to half the total number of VCSEL 380a scanning lines per main scanning period, so that the latent image pattern is formed twice on the paper surface. To be formed. Also in this case, 32 beams are simultaneously driven every time so that the flow of the video signal does not have to be changed even when the process speed is changed by the two kinds of exposure.

FIG. 16 is a diagram showing a first configuration example of a drive circuit compatible with overlap scan (double exposure in this example). VCSE for two overlap scans
The image drawn by the pixels 17-32 of the L light source group 380 is scanned again by the pixels 1-16 at the next scan, so the image data is shifted by the image generation circuit 280 (corresponding to the modulation signal generation unit 224) in FIG. 8 bit FIFO memory 227.

FIG. 17 is a diagram showing a second configuration example of the drive circuit corresponding to the overlap scan (double exposure in this example). The second example is an example in which shift is performed by the 8-bit FIFO memory 227 instead of the image generation circuit 280.
This will be described together with the application in FIG. 9 (C). One 8-bit FIFO memory 2 in FIG. 9 (C)
17, the circuit configuration is such that the data corresponding to the pixels 17-32 is written again in the pixels 1-16, as shown in FIG. 17, so that only the 8-bit FIFO memory 227 portion corresponds to the overlap scan. Will be possible. At this time, in the adjacent scan, the image generation circuit 28
The image output corresponding to the pixels 1-16 output from 0 is stopped.

FIG. 18 is a diagram showing a third configuration example of a drive circuit compatible with overlap scan (double exposure in this example). This third example describes an example corresponding to the application in FIG. In this case, pixel 1-1
6 and the 8-bit FIFO memory 227 corresponding to the pixels 17-32 are completely independent. Therefore, as shown in FIG. 18, the data corresponding to the pixels 17-32 is the pixel in units of the 8-bit FIFO memory 227. It becomes possible to make a configuration such that the data is written again in 1-16. 8-bit F
Overlap scan can be supported only by the IFO memory 227 portion. At this time, the image output corresponding to the pixels 1-16 output from the image generation circuit 280 during the adjacent scan is stopped.

FIG. 19 is a diagram showing the difference between the adjacent exposure and the surface skipping exposure as scanning modes. The scanning form shown in FIG. 19 is a form of one-sided skip exposure in which the polygon mirror 39 is used for every other surface, and a latent image pattern similar to that in the adjacent exposure is formed on the paper surface at the time of face skip exposure. I am trying to do it. Also in this case, 32 beams are simultaneously driven each time so that the flow of the video signal does not have to be changed even when the process speed is changed by the one-side skip exposure.

In other words, even if the normal adjacent exposure is switched to each of the overlap exposure and the surface skipping exposure, the basic element of the drive timing, that is, 32 beams are simultaneously driven, is not changed. I'm done, so
According to the basic circuit configuration shown in FIG. 8 and the like, the processing of the image processing circuit can be commonly used in each mode.

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, "8" is set to 1
As an example of handling as a unit, the description was made mainly on the use of an 8-bit FIFO.
C (Application Specific Integrated Circuit), FPGA (Field Prgramble Gate Arr)
In ay), DSP (Digital Signal Processor), etc., the library is often configured with "8" as one unit, and it is needless to say that it is effective as in the case of using the 8-bit FIFO.

Further, in the above embodiment, as an example of handling "8" as one unit, an example of using the VCSEL light source group 380 in which the VCSEL 380a is two-dimensionally arranged was mainly described, but the VCSEL 380a is a multiple of "8". As long as it is (including “8” itself), it is not limited to the VCSEL light source group 380 described above, and may have another configuration. In short, the VCSEL light source group 3 in which the total number of VCSELs 380a is 8 × n (n is an integer of 1 or more)
It may be 80. For example, as shown in FIG.
X1 VCSEL light source group 380, 8-bit FIFO4
It may be in the form of an 8-beam video path driven by 00.

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 the VCSEL, and an edge emitting laser array or LEDs may be arranged. In addition, 2 which arranged VCSEL
In the case of a light source group of a three-dimensional array, two on one semiconductor chip
It can be a monolithic structure in which light emitting portions are arranged in a dimension. Further, in the VCSEL, since 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 small.

Therefore, a compact light source can be obtained. Further, in such a surface emitting semiconductor laser, current and light can be efficiently confined in the laser resonator, so that heat generation per one light emitting portion is reduced and at the same time, a plurality of light emitting portions are adjacent to each other. Mutual optical in the case,
Electrical and thermal interference can be reduced. Therefore, the distance between the light emitting portions can be made smaller than that of the conventional semiconductor laser.

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 arrangement of the imaging spots with respect to the scanning lines in the above embodiment is only a few examples, and if the light source that satisfies the condition that the total number of light emitting points is a multiple of 8 is used, It has a sufficient effect compared with the conventional technology.

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

[0166]

As described above, according to the present invention, since the total number of light emitting points is a multiple of 8, the circuit system for driving this light source can handle 8 as a unit, In an electronic circuit such as a memory, 8 bits can be handled as a unit. In other words, it has become possible to efficiently construct a circuit by deriving a significantly advantageous condition to the circuit design side having the number of light emitting points and the arrangement shape.

[Brief description of drawings]

FIG. 1 is a mechanism diagram of an example of a color copying apparatus equipped with an image recording device that records an image using a surface-emitting type semiconductor laser array. FIG. 1 is a mechanism diagram of an example of a color copying machine equipped with an example of an image processing apparatus of the present invention.

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

FIG. 3 is a diagram illustrating an arrangement form of VCSELs that constitute a VCSEL light source group.

FIG. 4 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 4 × 2 array / vertical VCSEL light source group.

FIG. 5 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 4 × 4 array VCSEL light source group.

FIG. 6 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 an 8 × 4 array / vertical VCSEL light source group.

FIG. 7 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 of 8 × 2 array / horizontal arrangement.

FIG. 8 is a diagram illustrating an outline of a first example of a signal processing circuit for forming an image in an image forming unit including a VCSEL light source group.

FIG. 9 is a diagram illustrating a flow of image data (video path) and resolution conversion.

FIG. 10 is a diagram showing a correspondence relationship between the halftone data generated by the image data generation unit and the laser modulation signal generated by the modulation signal generation unit.

FIG. 11 is a diagram showing a first example around a memory controller.

FIG. 12 is a diagram showing an outline of a second example of the signal processing circuit.

FIG. 13 is a diagram showing an example of the configuration and timing of a drive circuit in the case of driving a vertical 4 × horizontal 4 VCSEL light source group using an 8-bit FIFO memory.

FIG. 14 is a diagram illustrating a configuration example of a drive circuit when a VCSEL light source group is horizontally arranged.

FIG. 15 is a diagram showing a difference between adjacent exposure and overlap exposure.

FIG. 16 is a diagram showing a first configuration example of a drive circuit compatible with overlap scan.

FIG. 17 is a diagram illustrating a second configuration example of a drive circuit compatible with overlap scan.

FIG. 18 is a diagram illustrating a third configuration example of a drive circuit compatible with overlap scan.

FIG. 19 is a diagram showing a difference between adjacent exposure and surface skipping exposure.

FIG. 20 shows an 8 × 1 VCSEL light source group with an 8-bit F
FIG. 3 is a diagram showing a form of an 8-beam video path driven by an IFO.

FIG. 21 is a diagram illustrating a problem of a conventional multi-beam system.

FIG. 22 is a diagram illustrating a reference amount when handling image data.

[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

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[Procedure amendment]

[Submission date] March 26, 2002 (2002.3.2)
6)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

FIG. 16

[Figure 5]

[Figure 6]

[Figure 7]

[Figure 9]

FIG. 14

FIG. 20

[Figure 8]

[Figure 10]

FIG. 11

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FIG. 18

[Fig. 12]

[Fig. 13]

FIG. 15

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   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C362 AA07 AA14 BA48 BA63                 2H045 AA01 BA02 BA23 BA33 CB65                 5C051 AA02 CA07 DA06 DB11 DB22                       DB24 DB30 DC07                 5C072 AA03 BA03 DA02 DA21 HA02                       HA06 HA09 HA13 HB08 HB11                       UA11 XA05                 5F073 AB05 AB16 AB25 BA07 EA29                       GA24 GA37

Claims (23)

[Claims] 1. A multi-beam light source having a plurality of light-emitting points that can be independently modulated, wherein the total number of the light-emitting points is a multiple of 8. 2. The multi-beam light source according to claim 1, wherein the light emitting points are arranged in one line. 3. The multi-beam light source according to claim 1, wherein the light emitting points are arranged in a two-dimensional matrix. 4. The multi-beam light source according to claim 3, wherein the number of the light emitting points on one side of the two-dimensional matrix is 2 ^m (m is an integer of 2 or more). 5. The multi-beam light source according to claim 3, wherein the number of the light emitting points of at least one of the two-dimensional matrices is a multiple of 8. 6. The light emitting point is configured to be capable of emitting a beam of light having an optical axis substantially perpendicular to the surface of the element substrate.
A multi-beam light source according to item. 7. A multi-beam light source having a total number of multiples of 8, each of which can be independently modulated, and a light beam emitted from each of the light-emitting points of the multi-beam light source to be scanned. An optical scanning device comprising an optical system for forming an image on a surface. 8. A light deflection device comprising a plurality of reflecting surfaces, wherein the light beams emitted from each of the light emitting points are reflected by the reflecting surface to periodically deflect each direction of the light beams. 8. An optical system is provided, and the optical system forms an image of the beam light deflected by the optical deflector on the surface to be scanned.
The optical scanning device according to. 9. The multi-beam light source has a rectangular outer shape, and is arranged such that a long side of the outer shape is optically parallel to a sub-scanning direction on the surface to be scanned. The optical scanning device according to claim 8, characterized in that 10. The optical scanning device according to claim 8, wherein the light emitting points of the multi-beam light source are arranged in a two-dimensional matrix. 11. The optical scanning device according to claim 10, wherein the number of the light emitting points on one side of the two-dimensional matrix is 2 ^m (m is an integer of 2 or more). 12. The optical scanning device according to claim 10, wherein the number of the light emitting points of at least one of the two-dimensional matrices is a multiple of 8. 13. The multi-beam light source is arranged so that the number of the light emitting points is a multiple of 8 in the sub-scanning direction on the surface to be scanned. Optical scanning device. 14. The optical scanning device according to claim 7, wherein the multi-beam light source has 32 or 16 light emitting points. 15. A light beam is emitted from a multi-beam light source having a total number of multiples of 8, each of which is capable of being independently modulated, and an image is formed on a surface to be scanned using this light beam. An image forming method characterized by forming an image by doing so. 16. A multi-beam light source having a total number of multiples of 8, each of which is capable of being independently modulated, a drive controller for driving the light-emitting point based on image data, and the multi-beam. An image forming apparatus comprising: an optical system for forming an image of a light beam emitted from each of the light emitting points of a light source on a surface to be scanned. 17. The image forming apparatus according to claim 16, further comprising a signal processing unit that handles the image data in units of 8 or a multiple of 8. 18. The image forming apparatus according to claim 17, wherein the signal processing unit processes the input digital image data by using a digital screen method. 19. A light deflection device comprising a plurality of reflecting surfaces, wherein the light beams emitted from each of said light emitting points are reflected by said reflecting surface to periodically deflect each direction of said light beam. 2. An optical system, wherein the optical system forms an image of the beam of light deflected by the optical deflector on the surface to be scanned.
The image forming apparatus according to any one of 6 to 18. 20. The signal processing unit directs individual light beams, which are emitted from the light emitting points of the multi-beam light source and correspond to one row on the image data, in a main scanning direction or a sub scanning direction on a surface to be scanned. 20. The image forming apparatus according to claim 19, further comprising a data delay unit that controls a delay amount of the input image data to form an image on the same straight lines. 21. The data delay unit comprises an 8-bit FIF.
The image forming apparatus according to claim 20, further comprising an O memory. 22. The signal processing unit, wherein the light beam is
Adjacent exposure mode in which the scanned surface is scanned while being shifted in the sub-scanning direction by the amount of all the light emitting points of the multi-beam light source for each main scanning, and the number of light emitting points is less than the total number of the light emitting points. The image forming apparatus according to any one of claims 19 to 21, wherein the image forming apparatus is configured to be switchable between an overlap exposure mode in which the surface to be scanned is deviated in the sub-scanning direction. 23. The signal processing unit, wherein the light beam is
Adjacent exposure mode in which the scanned surface is scanned while being shifted in the sub-scanning direction by the amount of all the light emitting points of the multi-beam light source for each main scanning, and the number of light emitting points is less than the total number of the light emitting points. The image forming apparatus according to any one of claims 19 to 21, wherein the image forming apparatus is configured to be switchable between an overlap exposure mode in which the surface to be scanned is deviated in the sub-scanning direction.