JP4082037B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an electrostatic latent image on a photoreceptor by arranging a plurality of LED heads and performing wide exposure.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known an image forming apparatus that performs wide exposure by arranging a plurality of LED heads in order to form an electrostatic latent image corresponding to a wide original on a photoconductor.
[0003]
FIG. 8 is a schematic view of a conventional mounting structure for three A3 size LED heads.
[0004]
As shown in FIG. 8, each LED head is a first LED head 1a, a second LED head 1b, and a third LED head 1c, respectively, and the three LED heads are arranged as shown in FIG. A0 width exposure is possible.
[0005]
Here, since the second LED head 1b is arranged so as to be shifted from the first LED head 1a and the third LED head 1c in the sub-scanning direction, the first LED head 1a and the third LED head 1c. The shift of the second LED head 1b is corrected by image data processing that takes into account the shift of the second LED head 1b in advance.
[0006]
In FIG. 8, the direction in which the LEDs of the first LED head 1a, the second LED head 1b, and the third LED head 1c are arranged is the main scanning direction, and the direction perpendicular to the main scanning direction is the sub-scanning direction. And
[0007]
Here, when exposure is performed by connecting a plurality of LED heads as shown in FIG. 8, the first LED head 1 a and the third LED head 1 c are attached even if correction in the sub-scanning direction by the image data processing is performed. Since there is a level difference in the error, the two joints cannot be aligned at the same time, so the joint between the first LED head 1a and the second LED head 1b, the second LED head 1b and the third LED head 1c. This causes an image shift at the joint. Further, if the two joints in the sub-scanning direction are processed only by image data processing, a plurality of pieces of image data must be delayed independently, increasing the amount of memory required and increasing the cost. .
[0008]
FIG. 9 is an example of a seam shift that occurs in the developed image when one LED is exposed by connecting the three LED heads shown in FIG.
[0009]
FIG. 9A is an example of the image seam shift that occurs when the first LED head 1a and the third LED head 1c are displaced in the main scanning direction.
[0010]
As shown to Fig.9 (a), since the part exposed by the 1st LED head 1a and the 3rd LED head 1c has shifted | deviated to the main scanning direction, 1st LED head and 2nd LED head The image is interrupted at the joint 27 and the joint 28 between the second LED head and the third LED head.
[0011]
FIG. 9B is an example of the image misalignment that occurs when the second LED head 1b is displaced in the sub-scanning direction.
[0012]
As shown in FIG. 9B, the portion exposed by the second LED head 1b is shifted in the sub-scanning direction, so the joint 27 and the second LED between the first LED head and the second LED head. The image is interrupted at the joint 28 between the head and the third LED head.
[0013]
FIG. 9C is an example of the image seam shift that occurs when the first LED head 1a and the third LED head 1c are displaced in the sub-scanning direction.
[0014]
As shown in FIG. 9C, the exposed portions of the first LED head 1a and the third LED head 1c are shifted in the sub-scanning direction, so that the first LED head and the second LED head The image is interrupted at the joint 27 and the joint 28 between the second LED head and the third LED head.
[0015]
In addition to the joint misalignment caused by the positional deviation of the LED head in the main scanning direction and the sub scanning direction as shown in FIGS. 9A, 9B, and 9C, there are various misalignment joints.
[0016]
Therefore, a technique for preventing such a seam shift has been proposed. For example, Japanese Patent Application Laid-Open No. 6-105071 discloses a method of attaching a plurality of LED heads to a member having the same thermal expansion coefficient as that of the LED heads, in order to prevent joint displacement in the main scanning direction due to thermal expansion.
[0017]
[Problems to be solved by the invention]
However, since the member having the same thermal expansion coefficient as the LED head does not change in temperature uniformly, it is impossible to completely prevent the seam shift. In addition, a method of performing image data processing such as shifting the joint misalignment is also conceivable. However, since the image data of the LED head is usually processed every 4 to 8 dots, the shift in units of 1 dot is a large process. In addition, it is impossible to shift less than 1 dot in the main scanning direction.
[0018]
Therefore, the present invention provides an image forming apparatus capable of adjusting a joint shift without replacing parts even when the position of the LED head is shifted due to an unexpected impact or expansion / contraction at a special use environment temperature. With the goal.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to an image forming apparatus that performs wide exposure by alternately arranging a plurality of exposure apparatuses in a first row and a second row. A first eccentric pin for adjusting the main scanning direction of the exposure apparatus arranged; a first guide pin for restricting movement of the exposure apparatus arranged in the first row in the sub-scanning direction; and the second row. A second eccentric pin for adjusting the sub-scanning direction of the exposure apparatus disposed in the second row, and a second guide pin for restricting movement of the exposure apparatus disposed in the second row in the main scanning direction. Features.
According to a second aspect of the present invention, in the first aspect of the present invention, the second eccentric pins are provided at both ends in the main scanning direction of the exposure apparatus arranged in the second row.
According to a third aspect of the present invention, in the first aspect of the invention, the second eccentric pin is provided at one end in the main scanning direction of the exposure apparatus arranged in the second row, and the end It is characterized in that the end on the opposite side is fixed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an image forming apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
[0021]
FIG. 1 is a schematic view of a mounting structure of three LED heads by an image forming apparatus according to the present invention.
[0022]
As shown in FIG. 1, each LED head is a first LED head 1a, a second LED head 1b, and a third LED head 1c, respectively, and these three LED heads 1a, 1b, 1c are shown in FIG. By arranging in this way, exposure to a photoconductor corresponding to a wide original is performed.
[0023]
Here, the second LED head 1b is arranged so as to be shifted from the first LED head 1a and the third LED head 1c in the sub-scanning direction, and an image by each LED head is processed by image data processing in consideration of this shift. Correct the deviation.
[0024]
However, in this embodiment in which complete correction of the deviation is difficult even by the image data processing, the main scanning is performed by restricting the movement of the first LED head 1a and the third LED head 1c in the sub-scanning direction. A first adjustment mechanism that adjusts the arrangement position in the direction is provided, and the second LED head 1b is provided with a second adjustment mechanism that regulates the arrangement position in the sub-scanning direction by restricting movement in the main scanning direction.
[0025]
FIG. 2 is a schematic view showing details of the first adjustment mechanism provided in the first LED head 1a and the third LED head 1c.
[0026]
In FIG. 2, the first LED head 1a and the third LED head 1c include an eccentric pin 2 for adjusting in the main scanning direction and two guide pins for restricting movement of the LED head in the sub-scanning direction. (5, 7) are provided, the eccentric pin 2 is fitted to the eccentric pin guide 4 that is vacant in the frame for mounting the LED head, and the two guide pins (5, 7) are the frame for mounting the LED head. The guides (6, 8) which are vacant are respectively fitted.
[0027]
Here, as shown in FIG. 2, the eccentric pin 2 is provided at a position where the shaft 3 is slightly shifted from the center of the eccentric pin 2, and when the eccentric pin 2 is turned in the direction of the arrow A in the drawing, The main body comes into contact with the left side of the eccentric pin guide 4, and the LED head can be moved in the main scanning direction indicated by the arrow C in the drawing.
[0028]
Further, when the eccentric pin 2 is turned in the direction of the arrow B, the main body of the eccentric pin 2 comes into contact with the right side of the eccentric pin guide 4 and the LED head can be moved in the main scanning direction of the arrow D in the figure.
[0029]
Here, when the fixed positions of the first LED head 1a and the third LED head 1c are adjusted in the main scanning direction by turning the eccentric pin 2, the guide pins (5, 7) are used in the sub scanning direction of the LED head. Since the movement is restricted, the first LED head 1a and the third LED head 1c do not move in the sub-scanning direction.
[0030]
FIG. 3 is a schematic view showing details of the second adjustment mechanism provided in the second LED head 1b.
[0031]
3, the second LED head 1b includes an eccentric pin 9 for adjusting the left end of the LED head in the sub scanning direction, an eccentric pin 12 for adjusting the right end of the LED head in the sub scanning direction, and the LED head. Guide pins 15 for restricting the movement of the LED head in the main scanning direction are provided, and the eccentric pins (9, 12) are respectively fitted to the eccentric pin guides (11, 14) vacant in the frame to which the LED head is attached. The guide pins 15 are fitted on guides 16 that are vacant in the frame to which the LED head is attached.
[0032]
Here, as shown in FIG. 3, the eccentric pin 9 is provided at a position where the shaft 10 is slightly shifted from the center of the eccentric pin 9. Therefore, when the eccentric pin 9 is turned in the direction of the arrow E in FIG. The main body of the pin 9 comes into contact with the upper side of the eccentric pin guide 11, and the left end of the LED head can be moved in the sub-scanning direction indicated by the arrow G in the drawing. When the eccentric pin 9 is turned in the direction of the arrow F, the main body of the eccentric pin 9 comes into contact with the lower side of the eccentric pin guide 11, and the left end of the LED head can be moved in the sub-scanning direction of the arrow H in the figure. .
[0033]
Further, since the shaft 13 of the eccentric pin 12 is provided at a position slightly deviated from the center of the eccentric pin 12, when the eccentric pin 12 is turned in the direction of the arrow I, the main body of the eccentric pin 12 becomes the eccentric pin guide. 14, the right end of the LED head can be moved in the sub-scanning direction indicated by the arrow K in the figure.
[0034]
Further, when the eccentric pin 12 is turned in the direction of the arrow J, the main body of the eccentric pin 12 comes into contact with the lower side of the eccentric pin guide 14 and the right end of the LED head can be moved in the sub-scanning direction of the arrow L in the figure. .
[0035]
Here, when the eccentric pin (9, 12) is turned to adjust the fixed position of the second LED head 1b in the sub-scanning direction, the guide pin 15 regulates the movement in the main scanning direction. The LED head 1b does not move in the main scanning direction.
[0036]
FIG. 4 is a diagram illustrating a specific example of adjusting the shift of the joint between images.
[0037]
In FIG. 4 (a), it is originally desired to form a single linear image parallel to the main scanning direction, but at the joint 17 between the first LED head and the second LED head in the main scanning direction and the sub scanning direction. An image shift occurs, and an image shift in the main scanning direction and the sub-scanning direction occurs at the joint 18 between the second LED head and the third LED head.
[0038]
Here, as shown in FIG. 4B, the first LED head 1a is moved in the main scanning direction indicated by the arrow M and the third LED head 1c is moved in the main scanning direction indicated by the arrow N. The image deviation in the main scanning direction between the first LED head 1a and the second LED head 1b and the image deviation in the main scanning direction between the second LED head 1b and the third LED head 1c are adjusted. be able to.
[0039]
Next, the left end of the second LED head 1b is moved in the sub-scanning direction indicated by the arrow O, and the right end of the second LED head 1b is moved in the sub-scanning direction indicated by the arrow P in FIG. As shown in FIG. 2, the image shift in the sub-scanning direction between the first LED head 1a and the second LED head 1b and the image in the sub-scanning direction between the second LED head 1b and the third LED head 1c The shift can be adjusted, and the images at the joint 17 between the first LED head and the second LED head and the joint 18 between the second LED head and the third LED head can be joined.
[0040]
FIG. 5 is a diagram illustrating another example of adjusting the shift of the joint between images.
[0041]
As shown in FIG. 5 (a), it is originally desired to form a single linear image parallel to the main scanning direction. An image in the sub-scanning direction is formed at the joint 19 between the first LED head and the second LED head. A shift occurs, and an image shift in the sub-scanning direction occurs at the joint 20 between the second LED head and the third LED head.
[0042]
Here, by moving the left end of the second LED head 1b in the sub-scanning direction indicated by the arrow Q and moving the right end of the second LED head 1b in the sub-scanning direction indicated by the arrow R in FIG. As shown in FIG. 2, the image shift in the sub-scanning direction between the first LED head 1a and the second LED head 1b and the image in the sub-scanning direction between the second LED head 1b and the third LED head 1c The shift can be adjusted, and the images at the joint 19 between the first LED head and the second LED head and the joint 20 at the second LED head and the third LED head can be joined. At this time, although it is not a straight line image, it becomes a bent line, but since this is minute, it is not regarded as a problem.
[0043]
FIG. 6 is a schematic view showing details of another embodiment of the second adjustment mechanism provided in the second LED head 1b.
[0044]
As shown in FIG. 6, the second LED head 1 b is provided with an eccentric pin 21 for adjusting the right end of the LED head in the sub-scanning direction, and the left end of the LED head is fixed by a fixing portion 24.
[0045]
Here, as shown in FIG. 6, the shaft 22 of the eccentric pin 21 is provided at a position slightly deviated from the center of the eccentric pin 21, and the eccentric pin 22 is used when the right end of the LED head is adjusted in the sub-scanning direction. Is rotated in the direction of the arrow S in the drawing, the main body of the eccentric pin 21 contacts the upper side of the eccentric pin guide 23, and the right end of the LED head can be moved in the sub-scanning direction of the arrow U in the drawing. However, in this embodiment, since the left end of the LED head is fixed by the fixing portion 24, the right end of the LED head is moved in the sub-scanning direction of the illustrated arrow U by turning the eccentric pin 22 in the direction of the illustrated arrow U. Strictly speaking, the right end of the LED head rotates around the fixed portion 24 in the sub-scanning direction indicated by the arrow U in the drawing.
[0046]
Further, when the eccentric pin 21 is rotated in the direction of the arrow T shown in the drawing and the eccentric pin 21 rotates about the shaft 22, the main body of the eccentric pin 21 contacts the lower side of the eccentric pin guide 23, and the right end of the LED head is fixed to the fixing portion. 24 can be moved in the sub-scanning direction indicated by the arrow V in the figure.
[0047]
FIG. 7 is a diagram illustrating a specific example in which the shift of the joint of the image is adjusted using the second adjustment mechanism illustrated in FIG. 6.
[0048]
Here, for the convenience of the arrangement of the LED heads, it is necessary to make the exposure timing of the image of the second LED head 1b different from the other two. FIG. 7A shows a state in which the sub-scanning direction of the joint 25 between the first LED head and the second LED head is adjusted by adjusting the exposure timing in advance. Accordingly, an image shift in the main scanning direction occurs at the joint 25 between the first LED head and the second LED head, and a main scanning direction and a sub scanning direction occur at the joint 26 between the second LED head and the third LED head. There is an image shift.
[0049]
Here, the first LED head 1a is moved in the main scanning direction indicated by the arrow W and the third LED head 1c is moved in the main scanning direction indicated by the arrow X by the adjusting means shown in FIG. As shown in FIG. 7B, the image shift in the main scanning direction between the first LED head 1a and the second LED head 1b and the main scanning between the second LED head 1b and the third LED head 1c. It is possible to adjust the image shift in the direction.
[0050]
Next, by moving the right end of the second LED head 1b in the sub-scanning direction indicated by the arrow Y in the figure, as shown in FIG. 7C, the second LED head 1b and the third LED head 1c are moved. The image shift in the sub-scanning direction can be adjusted, and the images at the joint 25 between the first LED head and the second LED head and the joint 26 between the second LED head and the third LED head are connected. Can do.
[0051]
Here, the LED head is provided with an LED head fixing mechanism (not shown), and when the adjustment of the LED head is completed, each LED head is fixed by the LED head fixing mechanism.
[0052]
In the configuration shown in FIG. 6, the configuration in which the fixing portion 24 is provided at the left end of the LED head has been described. However, the configuration in which the fixing portion 24 is provided at the right end of the LED head may be used.
[0053]
Also in the case of an exposure apparatus using two LED heads, the adjustment in the sub-scanning direction can be made by adjusting the exposure timing or by the second adjusting means.
[0054]
【The invention's effect】
As described above, according to the present invention, even when the position of the LED head is displaced due to an unexpected impact or expansion / contraction at a special use environment temperature, it is possible to adjust the joint displacement without replacing parts.
[Brief description of the drawings]
FIG. 1 is a schematic view of a mounting structure of three LED heads by an image forming apparatus according to the present invention.
FIG. 2 is a schematic view showing details of a first adjustment mechanism provided in the first LED head 1a and the third LED head 1c.
FIG. 3 is a schematic view showing details of a second adjustment mechanism provided in the second LED head 1b.
FIG. 4 is a diagram illustrating a specific example of adjusting a shift of a joint between images.
FIG. 5 is a diagram illustrating another example of adjusting the shift of a joint between images.
FIG. 6 is a schematic view showing details of another embodiment of the second adjustment mechanism provided in the second LED head 1b.
7 is a diagram showing a specific example of adjusting the shift of the joint of the image using the second adjustment mechanism shown in FIG.
FIG. 8 is a schematic view of a conventional mounting structure of three A3 size LED heads.
FIG. 9 is an example of a seam shift generated in a developed image when one LED is exposed by connecting the three LED heads shown in FIG. 8;
[Explanation of symbols]
1a 1st LED head 1b 2nd LED head 1c 3rd LED head 2, 9, 12, 21 Eccentric pins 3, 10, 13, 22 Axes 4, 11, 14, 23 Eccentric pin guides 5, 7, 15 Guide pins 6, 8, 16 Guides 17, 19, 25, 27 Joints 18, 20, 26, 28 between the first LED head and the second LED head Joints between the second LED head and the third LED head 24 fixed part

Claims (3)

In an image forming apparatus that performs wide exposure by alternately arranging a plurality of exposure devices in a first row and a second row,
A first eccentric pin for adjusting the main scanning direction of the exposure apparatus arranged in the first row;
A first guide pin that regulates movement of the exposure apparatus arranged in the first row in the sub-scanning direction;
A second eccentric pin for adjusting the sub-scanning direction of the exposure apparatus arranged in the second row;
An image forming apparatus comprising: a second guide pin for restricting movement of the exposure apparatus arranged in the second row in the main scanning direction. The image forming apparatus according to claim 1, wherein the second eccentric pins are provided at both ends in the main scanning direction of the exposure apparatus arranged in the second row. Providing the second eccentric pin at one end in the main scanning direction of the exposure apparatus disposed in the second row;
The image forming apparatus according to claim 1, wherein an end opposite to the end is fixed.

Images