JP4014161B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a writing optical system unit used in an image forming apparatus such as a digital copying machine and a facsimile, and a method for correcting the center position of a reading optical system unit.
[0002]
[Prior art]
In an image forming apparatus using electrophotography, an electrostatic latent image (charge image) is obtained by uniformly charging the surface of a photosensitive drum and irradiating the charged surface of the photosensitive drum with light based on predetermined image information. ) And developing the electrostatic latent image using a developer containing toner charged to a predetermined polarity, and transferring the resulting toner image onto the surface of a transfer sheet such as paper or an OHP film. Image formation is performed by thermally fixing the image with a heat roller (fixing roller). In such an image forming process, formation of an electrostatic latent image by light irradiation on the surface of a charged photosensitive drum, that is, writing of image information, is a writing unit using a laser beam called a so-called LSU (Laser Scanner Unit). Or using an LED array head in which a plurality of LED elements are arranged in the main scanning direction.
Image information is read by irradiating an original with a light source and receiving reflected light with a CCD element through an optical system such as a lens.
[0003]
[Problems to be solved by the invention]
In the writing optical system unit used in such an image forming apparatus, the center position of the image obtained on the predetermined transfer sheet with respect to the main scanning direction varies from machine to machine due to, for example, unit attachment errors. Therefore, when the machine is assembled or when the writing optical system unit is replaced, it is necessary to correct the center position. Conventionally, as shown in FIG. 3, the sheet is conveyed to the center position in the main scanning direction set by default. Write the reference line in the direction and measure the amount of deviation from the center of this image with a metal ruler, etc., for example, enter the correction amount from the operation unit, write the reference line again, and this reference until the reference line comes to the center position. There is a problem that it is necessary to repeat the correction, which is extremely troublesome and takes time.
[0004]
Further, when the machine is assembled or when the reading optical system unit is also replaced at the same time, it is necessary to adjust the center position of the reading optical system unit, and the center position is adjusted after completion of the correction of the center position of the writing optical system unit. The original is read by a scanner, output to a predetermined transfer sheet, the amount of deviation from the center of the image is measured with a metal ruler, etc., for example, the correction amount is input from the operation unit, and the original is read and written again. It is necessary to repeat this correction until the reference line comes to the center position, and there is a problem that it is very troublesome and takes time.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a correction method capable of obtaining and correcting the correction amount of the center position with extremely simple means in the writing optical system unit and the reading optical system unit in the image forming apparatus. .
[0006]
[Means for Solving the Problems]
According to the present invention, in an image forming apparatus provided with a writing optical system unit for performing image writing by irradiating light on a uniformly charged photoreceptor surface based on image information, in the main scanning direction in advance. The center position reference image information arranged so as to change the position stepwise and having a length of a plurality of lines in the sub-scanning direction is stored, and the center position reference image information is stored in a predetermined optical system unit using a writing optical system unit. An apparatus for identifying a correction amount of the center position of the writing optical system unit from the center position reference image information output to the sheet, and further comprising an image information reading scanner, the center position reference The paper on which the image information is output is read by the scanner, and is output to a predetermined paper by using the writing optical system unit. The image forming apparatus is provided and identifies the amount of correction centers position.
[0007]
That is, in the present invention, the correction amount of the center position of the writing optical system unit can be specified by one output to the paper, and the center position of the reading optical system unit can be corrected by one reading and output to the paper. Since the amount can be specified, the correction can be easily performed without taking time, and the correction can be easily performed without taking time.
[0008]
In addition, it is further easy to specify the correction amount by providing a dividing line in the main scanning direction for each length of the plurality of lines and writing the correction amount of the writing optical system unit on the predetermined sheet. become.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on specific examples shown in the accompanying drawings. FIG. 1 is a schematic diagram showing the overall structure of an image forming apparatus having an image information reading scanner and a writing optical system unit (LSU). FIG. 2 shows center position reference image information used in the present invention. FIG.
[0012]
In FIG. 1 schematically showing the overall structure of an image forming apparatus having an image information reading scanner and a writing optical system unit (LSU), a photosensitive drum 1 is rotatably mounted on the apparatus. Around the photosensitive drum 1, a main charging device 2, a developing device 3, a transfer and paper separating device 4 and a cleaning device 5 are provided along the rotation direction. Although not shown, a static eliminator is provided between the transfer and paper separation device 4 and the cleaning device 5 or between the cleaning device 5 and the main charging device 2. That is, the surface of the photosensitive drum 1 is uniformly charged with a predetermined polarity by the main charging device 2, and then an electrostatic image is formed by light irradiation based on predetermined image information (an optical path is indicated by L). . The electrostatic latent image formed on the surface of the photoconductor is developed by the developing device 3, thereby forming a toner image corresponding to the image information. The toner image is transferred onto a transfer sheet (not shown) such as paper conveyed between the photosensitive drum 1 and the transfer and paper separation device 4, and the transfer toner image is formed on the surface of the transfer sheet. Is supplied to a fixing device (not shown), the toner image is fixed on the transfer sheet by heat, pressure, etc., and the transfer sheet on which the toner image is fixed is discharged out of the device. In addition, after the toner image is transferred, the remaining toner is cleaned by the cleaning device 5 on the surface of the photosensitive drum 1, and the charge is removed. Thus, one cycle of image formation is completed.
[0013]
On the other hand, a scanner 10 for obtaining the image information described above is provided above, and below the scanner (reading optical system) 10 is an LSU for irradiating the surface of the photosensitive drum 1 with light based on the image information. A (writing optical system unit) 12 is disposed. Although not shown, an openable / closable cover is attached to the upper portion of the scanner 10, and an automatic document feeder is provided on the cover. Although not shown, the scanner 10 is provided with a setting key for setting various modes such as the number of copies and enlargement / reduction, and an operation unit including a display unit.
[0014]
When the scanner 10 is outlined, a contact glass for placing an original is attached to the upper surface, and a light source, an optical system such as a mirror and a lens, and a CCD provided below the contact glass so as to be capable of scanning drive. The element is accommodated. That is, light is irradiated from a light source to a document placed on or passing through the contact glass, and reflected light from the document is received by a CCD element through an optical system such as a lens, so that image information of the document is changed. The structure is such that it can be read.
[0015]
Based on the image information read by the CCD element as described above, the LSU 12 irradiates the surface of the photosensitive drum 1 with laser light, and image formation is performed according to the above-described image process. The LSU 12 includes a laser light source 12a such as a laser diode, a rotating polygon mirror 12b (usually a polygonal plate mirror such as a hexagon), and further includes a reflection mirror 12c as necessary. That is, based on the image information, the surface of the photosensitive drum 1 is irradiated with laser light from the laser light source 12a through at least the polygon mirror 12b that rotates. In FIG. 1, the optical path of the laser beam is indicated by L.
[0016]
When the surface of the photosensitive drum 1 is irradiated with laser light using the LSU 12 as described above, that is, writing is performed, the irradiated laser light normally has an image that is the same size as the original image on a predetermined sheet. The surface of the photosensitive drum 1 must be irradiated so as to be formed at the position. When the machine is assembled or the LSU 12 is replaced, the center position in the main scanning direction is displaced by the machine. It is necessary to correct the timing of laser light irradiation. Similarly, when the document is read by the scanner 10, a deviation of the center position when the image information of the document is read occurs due to variations in mounting of the optical system such as a mirror and a lens and the CCD element. For this reason, in the present invention, the center position reference image information arranged so as to change the position in the main scanning direction stepwise and have a length of a plurality of lines in the sub scanning direction is stored in a memory such as a ROM. deep. That is, the center position is corrected based on the output information when the reference image is output by the LSU 12 to be corrected.
[0017]
That is, in FIG. 2A showing the output information of the reference image using the LSU 12, this reference image is a plurality of lines in the sub-scanning direction by changing the position in the main scanning direction step by step in a predetermined sheet. It is arranged to have a length of Preferably, first, the reference line (20) at the current center position setting value (default value at the time of machine assembly) is printed on the leading edge of the sheet. Next, the center position set value is shifted by one unit at the back side in the machine direction and printed. After printing a predetermined number of times (four times in the embodiment), the center position set value is then shifted by one unit in the reverse direction from the reference line in the same way on the front side in the machine direction, and printed a predetermined number of times (in the example, five times). At this time, a dividing line (21) as printed by a broken line in FIG. 2A is provided for each line, and the center position setting value (22) of the line belonging to the dividing line and the current state are set in each dividing line. The set amount deviation (23) from the center position set value is printed. With this reference image, for example, in the case of A4 size paper, the line located at 105 mm from the edge of the paper is the center position, so if measuring with a metal ruler, etc., it is only necessary to select a line that matches the distance of 105 mm. It becomes. Further, since the correction value of the selected line is entered for each line, the correction value can be determined at a glance. Furthermore, it is possible to quickly cope with the fact that the position where the fold line and the line overlap can be determined as the center position by folding the sheet in half without using a metal scale or the like.
[0018]
FIG. 2A shows an initial reference image at the time of assembling the machine, and a reference line (20) with a default center position setting value (in this case, 0) is output at the tip. At this time, if the third line (24) from the tip of FIG. 2 (a) is the center position (25) as a result of the measurement by the metal scale or the discrimination by the crease, the center within the third line break is indicated. Since the value +2 of the position setting value (22) is a correction value, this correction value is set by the operation unit. Thus, it can be determined at a glance how much the correction value for the center position should be set.
[0019]
Next, FIG. 2B shows an output example of a reference image when the LSU 12 is exchanged in the machine. The reference line (20) at the center position setting value before replacement (in this case +2) is output at the tip, and the center position setting value (22) of the line belonging to the section is output as +2, and the current center position setting value is output. The amount of deviation (23) of the set value from 0, that is, 0 is printed. Since the center position setting value is shifted by one unit from the next line, the center position setting value (22) is output as +3, and the deviation (23) of the setting value from the current center position setting value. That is, +1 is printed. The method for obtaining the correction value is the same as in the machine assembly.
[0020]
Next, a case where the correction amount of the center position of the image information reading scanner is specified will be described. After correcting the center position of the writing optical system unit, the reference image is output. The reference image is read as an original by an image information reading scanner, written by the writing optical system unit, and an image is output. If an image similar to that shown in FIG. 2B is obtained at this time, since the center position of the writing optical system unit is corrected in this image, the center of the image information reading scanner is corrected. The amount of deviation from the current setting value of the position is shown. That is, when it is determined that the center position is the third line (24) by the same method as that for correcting the center position of the writing optical system unit, the amount of deviation of the set value from the current center position set value ( The value +2 of 23) represents the amount of deviation from the current center position correction value of the scanner for reading image information. This correction amount is added to the current set value, and a correction value is set on the operation unit.
[0021]
In the above embodiment, when specifying the correction amount of the center position of the scanner for reading image information, the output of the reference image after correcting the center position of the writing optical system unit is used as it is. After the correction of the center position, the center position set value of the image information reading scanner and the deviation of the set value from the current center position set value of the image information reading scanner may be printed. Accordingly, it can be determined at a glance how much the correction value should be set in the same manner as the correction of the center position of the writing optical system unit.
In the embodiments described above, the laser beam is used as the writing optical system unit. However, it is also possible to use the LED array head in which a plurality of LED elements are arranged in the main scanning direction. It is obvious.
[0022]
【The invention's effect】
According to the present invention, in the writing optical system unit and the reading optical system unit of the image forming apparatus, it is possible to obtain the correction amount of the center position and perform the correction by outputting the reference image by a very simple means. Labor such as man can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a structure of an image forming apparatus including an LSU.
FIG. 2 is a diagram showing an output image of a reference image used in the present invention.
FIG. 3 is a diagram showing an output image of a conventional reference image.
[Explanation of symbols]
1: Photosensitive drum 12: LSU
20: Reference line 25: Center position

Claims (2)

In an image forming apparatus equipped with a writing optical system unit that writes light by irradiating light on a uniformly charged photoconductor surface based on image information, the position in the main scanning direction is changed stepwise in advance. And storing center position reference image information arranged so as to have a length of a plurality of lines in the sub-scanning direction, and outputting the center position reference image information to a predetermined sheet using a writing optical system unit, An image forming apparatus that specifies a correction amount of the center position of the writing optical system unit from the center position reference image information output to the paper , further comprising a scanner for reading image information, and the center The paper on which the position reference image information is output is read by the scanner, and is output to a predetermined paper by using the writing optical system unit. Image forming apparatus characterized by specifying the amount of correction of the center position of the scanner. 2. The image forming apparatus according to claim 1, wherein a dividing line is provided in the main scanning direction for each length of the plurality of lines, and the correction amount of the writing optical system unit is written on the predetermined sheet.

Images