JP2010039425A - Laser beam scanner and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the generation of a main scanning-directional beam positional shift to a low level, even when forming an image by a plurality of laser beam emitting elements, in a laser beam scanner. <P>SOLUTION: A scanning part 17 scans respective laser beams emitted from the laser beam emitting elements LD1, LD2 on a face to be scanned of a rotary photoreceptor 15, and forms the image for one line at once. A light beam emission driving part 19 light-emission-drives the laser beam emitting elements LD1, LD2. One of the laser beam emitting elements LD1, LD2 is a predetermined laser beam emitting element located in a rear side of an image area in one scan, and lit on for detecting scan start timing. A laser beam emitting element having a light beam emission length longer than that of the predetermined laser beam emitting element LD1 is selected as the other laser beam emitting element LD2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser beam scanning apparatus and an image forming apparatus, and more particularly to a laser beam scanning apparatus mounted on a copying machine, a multifunction peripheral (MFP), and an image forming apparatus using the same.

  In this type of image forming apparatus, a laser beam emitted from a laser light emitting element based on image data from a document image is polarized and scanned on a rotating photoconductor for each line by a polygon mirror to form a latent image. An image is formed by attaching a toner agent to the image.

  In addition, in order to increase the number of latent images formed for each line and improve the efficiency of image formation, two laser light emitting elements are arranged for one polygon mirror, and two lines of latent images are simultaneously formed. Has been proposed.

  However, in each laser light emitting diode that is frequently used as a laser light emitting element, there is a difference in the lighting period for each line, so there is also a difference in temperature rise due to this light emission, which shifts to the beam spot position in the main scanning direction. Is likely to cause image degradation.

  Therefore, for example, a laser beam scanning device disclosed in Japanese Patent Laid-Open No. 10-148782 (Patent Document 1) has been proposed.

  This Patent Document 1 discloses a plurality of laser light sources, a scanning unit that forms an image by scanning each laser beam emitted from these laser light sources on a surface to be scanned, a light emission driving unit for driving the light source, A single photodetector that is located outside the image forming area and detects at least one of the laser beams emitted from each laser light source, and the light emission drive after a predetermined time from when the photodetector detects the laser beam A control signal is sent to the light emission drive section for sending all the laser light sources for a certain period of time after the image formation signal is sent to the section and after the image formation signal has been sent and until the light detection element detects the laser beam. And a control circuit for sending, the wavelength difference between the plurality of light sources is suppressed, and the magnification difference of the written image between the light beams is reduced.

That is, as shown in FIG. 3, in this patent document 1, after the laser light emitting diodes LD1 and LD2 are turned on based on image data in an image area in one scanning period, both of them are outside the image area in one scanning period. After the laser light emitting diodes LD1 and LD2 are forcibly lit for a predetermined forced lighting period T1, only the laser light emitting diode LD1 is continuously lit for the synchronization detection period T2 for the next image writing position detection, and both laser light emitting diodes LD1 and LD2 are lit. The lighting periods are to be aligned.
Japanese Patent Laid-Open No. 10-148782

  However, in the configuration of Patent Document 1 described above, after both the laser light emitting diodes LD1 and LD2 are forcibly lit for the forced lighting period T1, only the laser light emitting diode LD1 is continued for the synchronization detection period T2 for the next image writing position detection. Since the laser light emitting diode LD2 is turned off while being turned on, the lighting period of the laser light emitting diode LD1 is overwhelmingly long and becomes dominant with respect to the temperature rise, and the laser light emitting diode LD1 has a time difference of the synchronization detection period T2. However, the shift amount toward the long wavelength side tends to increase.

  For this reason, there is a limit in suppressing the difference in the beam spot position in the main scanning direction from the difference in temperature rise due to the difference in lighting period, and it is desired to improve image degradation.

  Therefore, as a result of diligent observation and consideration of laser light emitting diodes used as non-defective products, the present inventor frequently uses laser light emitting diodes having a wavelength of about 660 to 680 nm due to variations in mass production. Focusing on the fact that if laser light emitting diodes having a wavelength difference corresponding to the light emission period difference are combined, the laser beam during one line scan will easily have the same wavelength, and the positions in the main scanning direction will be aligned. Completed the invention.

  The present invention has been made to solve such a problem, and a laser beam scanning apparatus that can easily suppress the occurrence of beam position deviation in the main scanning direction even when the lighting times of the respective laser light emitting elements are different. Another object is to provide an image forming apparatus.

  In order to solve such a problem, in the laser beam scanning apparatus according to the present invention, a plurality of laser light emitting elements and each laser beam emitted from these laser light emitting elements are scanned on the surface to be scanned for a plurality of lines. A scanning unit that forms an image at a time and a light emission driving unit that drives the laser light emitting elements to emit light, and one of the laser light emitting elements starts the next scan outside the image area in one scan. A specific laser light-emitting element that is turned on for timing detection is selected, and the other laser light-emitting element having a long light emission length is selected for the specific laser light-emitting element.

  In the laser beam scanning device of the present invention, a configuration in which those laser light emitting elements having a wavelength difference corresponding to a lighting period difference is selected is also possible.

  In the laser beam scanning apparatus of the present invention, it is possible to adopt a configuration in which a plurality of these laser light emitting elements are lit in common before lighting for the next scan start timing detection outside the image area in one scan.

  In the laser beam scanning apparatus of the present invention, another laser light emitting element having a wavelength of about 1% longer than the light emission length of the specific laser light emitting element may be selected.

  The image forming apparatus according to the present invention includes these laser beam scanning devices and has a configuration for forming an image based on image data.

  In such a laser beam scanning apparatus according to the present invention, one of the plurality of laser light emitting elements is a specific laser light emitting element that is turned on for detection of the next scanning start timing outside the image area in one scan. Since the other laser light emitting elements having a longer light emission length are selected for this specific laser light emitting element, even if the lighting time of each laser light emitting element is different, the beam position deviation in the main scanning direction occurs. It is easy to keep the value small.

  In the laser beam scanning apparatus of the present invention, when the laser light emitting elements having a wavelength difference corresponding to the lighting period difference are selected, the occurrence of beam position deviation in the main scanning direction can be reliably suppressed to be small. It becomes easy.

  In the laser beam scanning apparatus of the present invention, in a configuration in which a plurality of these laser light emitting elements are commonly lit before the next scan start timing detection is performed outside the image area in one scan, the laser light emitting elements are forced. Therefore, even if the common lighting is performed, it is easy to suppress the occurrence of beam position deviation in the main scanning direction.

  In the laser beam scanning apparatus of the present invention, in the configuration in which the other laser light emitting elements are selected to have a wavelength of about 1% longer than the light emission length of the specific laser light emitting element, the main scanning is more reliably performed. It is easy to suppress the occurrence of the beam position deviation in the direction.

  Embodiments of a laser beam scanning apparatus and an image forming apparatus according to the present invention will be described below with reference to the drawings. The laser beam scanning apparatus according to the present invention will be described in the course of describing the image forming apparatus according to the present invention.

FIG. 1 is a schematic block diagram showing the configuration of an image forming apparatus A according to the present invention.
In FIG. 1, the image forming apparatus A includes an image reading unit 3, a storage unit 5, an operation panel unit 7, a printing unit 9, and a communication unit 11 connected to the main control unit 1. It is a multifunction device. The image forming apparatus A has other constituent elements than these, but is not a main part of the present invention, and thus description and illustration thereof are omitted. The function of the main control unit 1 will be described later.

  The image reading unit 3 is a known scanner that optically reads an image from a document under the control of the main control unit 1 and generates electronic image data subjected to filter processing or the like as a print job. The pages are sequentially stored in the storage unit 5.

  The storage unit 5 stores a print job from the image reading unit 3 or the communication unit 11, an operation application program of the main control unit 1, operation screen information for operating the multifunction peripheral A, and the like under the control of the main control unit 1. For example, it is a readable / writable hard disk (HDD).

  The operation panel unit 7 is an input / output unit that also serves as, for example, a known liquid crystal display and a touch switch arranged in the image forming apparatus A. Under the control of the main control unit 1, the operation state and various data in the image forming apparatus A And a function of receiving an operation instruction input of the apparatus A.

  Under the control of the main control unit 1, the printing unit 9 primarily feeds printing paper from a paper feed stage (not shown) and secondary feeds transported printing paper, while image data read from the storage unit 5. Is developed into image image data, and laser beams are emitted by laser light emitting diodes LD1 and LD2 to be described later on the basis of the image data, and this laser beam is output by a polygon mirror 13 to a rotating photosensitive member 15 (both described later). A known printing engine that forms a toner image by forming a latent image by performing polarization scanning every time, and transferring and fixing the toner image on a secondary fed printing paper to form an image by monochrome or full color printing. There is a laser beam scanning device B of the present invention. Details of the laser beam scanning device B will be described later.

  The communication unit 11 is connected to an external electronic device such as an image forming apparatus (both not shown) via a network under the control of the main control unit 1, and an external image according to a predetermined image data transmission protocol. This is an interface for transmitting and receiving e-mails and facsimiles to and from the forming apparatus.

  The main control unit 1 includes a CPU, a ROM that stores a startup program for the CPU, and the like. The image reading unit 3, the storage unit 5, the operation panel unit 7, the printing unit 9, and the application program stored in the storage unit 5 It consists of a control computer that controls the communication unit 11 and has the following functions.

  Based on the application program and setting information (not shown), the main control unit 1 stores the image data from the image reading unit 3 and the communication unit 11 in the storage unit 5, and passes the image data to the printing unit 9. It has a function of printing control (image formation control) and a function of data communication with an external image forming apparatus.

  Next, the laser beam scanning device B according to the present invention will be described with reference to FIG. This configuration will be described using monochrome printing as an example.

  In other words, a polygon mirror (rotating mirror body) 13 is arranged above the rotating photosensitive member 15 with a lens L therebetween, and two lasers as laser emitting elements that emit and emit a laser beam based on image data. The light emitting diodes LD1 and LD2 are arranged toward the mirror peripheral surface of the polygon mirror 13.

  Of the two laser light emitting diodes LD1 and LD2, one laser light emitting diode LD1 has a synchronization detection period for detecting the next scanning start timing after the image area in one scan as shown in FIG. It is a specific laser light emitting diode that is turned on at T2, and the other laser light emitting diode LD2 has a longer laser light emission length than this specific laser light emitting diode LD1, and preferably has a wavelength difference corresponding to the difference in lighting period. Is selected.

  Generally, there are laser light emitting diodes LD1 and LD2 that are frequently used as non-defective products and have a wavelength of about 660 to 680 nm due to variations in mass production. LD2 having a laser wavelength of 677 nm may be selected.

  That is, the specific laser light emitting diode LD1 has a laser wavelength that is about 1% longer than that of the laser light emitting diode LD2.

  Laser beams from the laser light emitting diodes LD1 and LD2 are emitted toward a polygon mirror 13 that rotates at a constant speed by a brushless motor (not shown), reflected by the mirror peripheral surface of the polygon mirror 13, converged by a lens L, and converged by a motor M. A scanning unit 17 is formed by performing polarization scanning on the rotating photosensitive member 15 driven to rotate by two lines.

  The light emission control unit 19 has a function of controlling light emission of the laser light emitting diodes LD1 and LD2.

  That is, the light emission control unit 19 controls the main control unit 1 based on the image image data for each horizontal scanning line developed from the image data read from the storage unit 5 in the image area in FIG. The laser light emitting diodes LD1 and LD2 are controlled to emit the laser beam line by line, and both the laser light emitting diodes LD1 and LD2 are forcibly lit for a predetermined forced lighting period T1 outside the image area after the lighting. For the image writing position detection, light emission control is performed so that only the laser light emitting diode LD1 is continuously turned on for the synchronization detection period T2.

  The rotating photoconductor 15 is polarized and scanned every two lines by a laser beam emitted from the laser light emitting diodes LD1 and LD2 and reflected by the polygon mirror 13 based on the image data, and a toner agent is formed on the latent image. It has a function of transferring and fixing the toner image formed by adhering to the printing paper 21 at a position rotated half a turn.

  Moreover, in order to increase the number of latent images to be formed for each line and improve the efficiency of image formation, two laser light emitting elements are arranged for one polygon mirror, and latent images for two lines are simultaneously displayed. An image forming apparatus to be formed has been proposed.

  The motor drive unit 23 controls the rotation of the motor M that rotationally drives the rotary photoconductor 15.

  As described above, the image forming apparatus of the present invention scans the two laser light emitting diodes LD1 and LD2 and the laser beams emitted from the laser light emitting diodes LD1 and LD2 on the surface to be scanned of the rotating photoconductor 15. A scanning unit 17 that forms an image for one line at a time and a light emission drive unit 19 that drives the laser light emitting diodes LD1 and LD2 to emit light are provided. One of the laser light emitting diodes LD1 and LD2 is 1 The specific laser light-emitting diode LD1 that is turned on for detection of the next scan start timing after the image area in the scan for the number of times of scanning is used, and the other laser light-emitting diodes LD2 emit light with respect to the specific laser light-emitting diode LD1. The long one is selected.

  For this reason, even if the laser lighting period of the specific laser light emitting diode LD1 is longer than the others and the temperature rises and the wavelength of the laser beam emitted from the specific laser light emitting diode LD1 shifts to the longer wavelength side, It is easy to match the wavelength of the laser beam emitted by the diode LD2, and even if the lighting times of the laser light emitting diodes LD1 and LD2 are different, it is easy to suppress the occurrence of beam position deviation in the main scanning direction.

  Moreover, even if the plurality of laser light emitting diodes LD1 and LD2 are commonly lit in the forced lighting period T1 before the lighting for the next scanning start timing detection outside the image area in one scan, the beam position in the main scanning direction It becomes easy to suppress the occurrence of deviation.

  In the laser beam scanning device of the present invention, a laser beam having a longer emission length than the wavelength of the laser beam emitted from another laser light emitting diode LD2 is selected as the wavelength of the laser beam emitted from the specific laser light emitting diode LD1. However, it is more preferable to select one having a wavelength difference corresponding to the lighting period difference, and it is more accurate if one having a long wavelength of 1% is selected. It is preferable because the wavelength can be easily aligned. The wavelength difference does not have to be strictly 1%, but is about 1% including a width corresponding to a slight error and a difference in light emission period between the laser light emitting diodes LD1 and LD2.

  The laser beam scanning apparatus according to the present invention can be implemented in various laser light emitting elements in addition to the laser light emitting diodes LD1 and LD2.

  However, since the image forming apparatus A according to the present invention is equipped with the laser beam scanning apparatus B described above, it is possible to form a good image based on the effects described above.

1 is a schematic block diagram showing an outline of an image forming apparatus including a laser beam scanning device according to the present invention. It is a principal schematic diagram showing the principal part of the laser beam scanning device concerning the present invention. It is a figure explaining general operation | movement of a laser beam scanning apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main control part 3 Image reading part 5 Memory | storage part 7 Operation panel part 9 Printing part 11 Communication part 13 Polygon mirror (rotating mirror body)
DESCRIPTION OF SYMBOLS 15 Rotating photoconductor 17 Scanning part 19 Light emission drive part 21 Printing paper 23 Motor drive part LD1, LD2 Laser light emitting diode (laser light emitting element)
L Lens M Motor A Image forming device B Laser beam scanning device

Claims (5)

A plurality of laser light emitting elements;
A scanning unit that scans the surface to be scanned with each laser beam emitted from these laser light emitting elements to form an image for a plurality of lines at once;
A light emission driving unit for driving the laser light emitting element to emit light;
Comprising
One of the plurality of laser light emitting elements is a specific laser light emitting element that is turned on for detection of a start timing of the next scan outside the image area in one scan. The other laser light emitting element is selected from those having a long light emission length. 2. The laser beam scanning apparatus according to claim 1, wherein a plurality of laser light emitting elements having a wavelength difference corresponding to a lighting period difference are selected. 3. The laser beam scanning device according to claim 1, wherein the plurality of laser light emitting elements are commonly lit before the next lighting for detecting the start timing outside the image area in one scan. The laser beam scanning device according to any one of claims 1 to 3, wherein another laser light emitting element having a wavelength of about 1% longer than a light emission length of the specific laser light emitting element is selected. An image forming apparatus comprising the laser beam scanning device according to claim 1 and forming an image based on image data.

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