JPH09174919A - Image forming device and positioning mechanism thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positioning mechanism, with which the fine positioning between a write head and a photosensitive body drum can be mechanically and easily performed, and an image forming device, the image forming part of which is equipped with the positioning mechanism. SOLUTION: Each adjusting abutting member 75 is held horizontally and slidably back and forth on each holding part 68a for holding the photosensitive body drum 25. In addition, one pin 67a of a write head 26 is held by the V-shaped abutting groove 75-1 bored on the top surface of the abutting member 75. By turning an external thread 78 to its pushing-in direction, a main scanning regulating block 77 is lowered, resulting in finely moving the adjusting abutting member 75 towards the inside (the right direction of the figure) of a main scanning direction. By turning the external thread 78 to the direction opposite to the above- mentioned pushing-in direction, the main scanning regulating block 77 is raised by the energizing force of a spiral spring 79, resulting in finely moving the regulating abutting member 75 by the amount corresponding to the gap developed on an abutting surface towards the outside of the main scanning direction by means of the energizing force of a plate spring. The positioning in the sub-scanning direction of the write head 26 is also performed by similarly turning an external thread 82, resulting in vertically moving a sub-scanning regulating block 81 so as to finely move the adjusting abutting member 75 back and forth in its sub- scanning direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning mechanism for determining the position of a writing head in two directions, a longitudinal direction and a lateral direction, and a tandem type image forming apparatus equipped with the positioning mechanism.

[0002]

2. Description of the Related Art Conventionally, there is a color image forming apparatus.
The color image forming apparatus is roughly classified into a single drum type and a multi-stage drum type (tandem type). The single drum type is
For each page of the paper, each color toner such as Y (yellow: yellow) toner, M (magenta: red dye) toner and C (cyan: greenish blue) toner, which are three primary colors of subtractive color mixture, and characters, etc. Since a total of four types of Bk (black: black) toner dedicated to printing are transferred in a superimposed manner, printing (image forming) processing is performed individually for each toner, so the printing process for one page of paper Will be repeated 4 times,
Therefore, the printing process requires a long time. On the contrary,
The tandem type includes one in which four types of toner are sequentially superposed and transferred onto a sheet in one step, and one in which the toner is sequentially superposed and transferred onto an intermediate transfer member and then retransferred onto the sheet at once.
Both have a processing speed almost four times that of the single drum type. For this reason, in recent years, in combination with the miniaturization of the internal device and the relative reduction in cost due to assembly (unitization), a variety of tandem type color image forming apparatuses have been put into practical use. .

FIG. 11 is a front sectional view of a main portion of an image forming portion in a tandem type color image forming apparatus, and FIG. 12 is a side sectional view thereof. 11 and 12
The image forming unit shown in FIG. 1 includes a photosensitive drum 1 carrying a toner image, and a writing head 2 for recording an electrostatic latent image for carrying a toner image on the peripheral surface of the photosensitive drum 1 by exposure.
(The figure shows an LED head) and the head can be freely separated from each other. Then, the photosensitive drum 1 is assembled with the other device (not shown) into the housing 3 to form a small assembly device (unitized), which is detachably attached to the support frame 4 of the apparatus main body (color image forming apparatus). There is. The mounted unit is the rotary shaft 1- of the photosensitive drum 1.
1 is rotatably supported by a bearing of a support frame 4 of the apparatus main body, and is rotationally driven by a drive mechanism (not shown) on the apparatus main body side that engages with a gear 5 fixed to the rotating shaft 1-1. On the other hand, the writing head 2 is provided with a large number of light emitting elements corresponding to the maximum number of pixels in the main scanning direction (paper width direction) of an image extending in the longitudinal direction of the photosensitive drum 1, It is supported and arranged so as to be movable in the upward direction in the drawing.

Interval of the pixels (arrangement of light emitting elements)
Is extremely fine at 300 to 400 dots per inch as a standard, so a stable image cannot be formed unless the relative position between the photosensitive drum 1 and the writing head 2 is constant. In order to position the relative position between the photoconductor drum 1 and the writing head 2 at a constant level, the photoconductor drum 1
In the write head receiving portion 3-1 of the casing 3 for holding, a receiving groove 3-2 having a V-shaped cross section is provided. At both ends of the write head 2, attached pins 7 projecting downward are arranged, and the attached pins 7 abut against the receiving grooves 3-2 of the housing 3 to move the write head 2 to the photosensitive drum 1. Position.

FIG. 13 shows the above-mentioned attached pin 7 and receiving groove 3-.
It is an enlarged view of the contact part with 2. As shown in the figure, the tip of the attached pin 7 forms a circumferential surface or a spherical surface with a radius R. Therefore, the center O of the circumference (or spherical surface) always keeps the same position with respect to the V-shape of the receiving groove 3-2 with which the contact is made. Further, since the contact pin 7 is fixed to the writing head 2, the distance from the light emitting element 2-1 of the writing head 2 to the center O of the tip of the contact pin 7 is always constant. Therefore, if the mounting position of the photoconductor drum 1 to the casing 3 is set so that the peripheral surface of the photoconductor 1 is at the constant position O, the support member 6 is formed as shown by an arrow A in FIGS. 11 and 12. Even if the write head 2 which is supported by and is lowered from the top slightly shifts in the front and rear directions (left and right in the figure) as shown by a double-headed arrow B in FIG.
Since the distance from -1 to the center O of the tip of the attached pin 7, that is, the distance to the peripheral surface of the photoconductor 1 is always constant,
It is possible to record a stable electrostatic latent image without changing the exposure action.

[0006]

By the way, as described above, in order to facilitate the maintenance work, the writing head and the photosensitive drum are separately arranged so that they can be contacted and separated from each other, and in recent years, they have become the mainstream in OA equipment. In order to cope with the trend of downsizing of the existing devices, the configuration in which one of the above-mentioned contactlessly separable parts is a detachable process unit (assembly device) is the most useful form in the future image forming apparatus. . However, like the tandem-type image forming apparatus described above, when there are a plurality of image forming units and the writing head and the photosensitive drum can be moved relative to each other so that they can freely come into contact with and separate from each other, they are moved to the actual position. It is necessary to perform positioning so that they are mutually correct when set to (operating position). Otherwise, if a deviation angle of, for example, one pixel occurs between the Y (yellow) image and the M (magenta) image, for example, clear moire fringes are generated in the finished image, and the image quality is significantly deteriorated.

If the positional displacement of the pixel as described above is a positional displacement in the sub-scanning direction (vertical direction of the paper), it can be performed to some extent by the control unit for controlling the image forming process, that is, by software. is there. However, even in the sub-scanning direction, if a plurality of image forming units each cause pixel misalignment by an arbitrary direction (angle) and an arbitrary amount of misalignment, control by the control unit is no problem.

Therefore, it is necessary to first mechanically position the write head and the photosensitive drum. As described above, the pixel spacing is 30 per inch.
0 to 400 dots, that is, 12 to 16 dots per 1 mm (millimeter), which are extremely fine, and the relative positions of the writing head and the photosensitive drum of each image forming unit are machined so that there is no error in the position of these pixels. However, conventionally, there is no positioning mechanism that can easily perform such fine positioning, and therefore, there is no image forming apparatus that can perform such positioning. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a positioning mechanism capable of mechanically and easily positioning the write head and the photosensitive drum in each image forming section, and an image forming apparatus provided with the positioning mechanism. Is.

[0010]

First, an image forming apparatus according to a first aspect of the present invention comprises a plurality of image forming portions each including an image carrier and a pair of positioning means for positioning the image carrier. First supporting means for supporting the plurality of image forming units side by side at predetermined intervals, a plurality of writing heads respectively facing the image carrier to write image information on the surface of the image carrier, Second supporting means for supporting a plurality of write heads in parallel in correspondence with the predetermined spacing, and one of the first supporting means and the second supporting means in the juxtaposed direction with respect to the other. An image forming apparatus including a supporting mechanism that is swingable with one end of the fulcrum as a fulcrum and that is capable of relatively moving the plurality of image forming units and the plurality of writing heads.
Each of the plurality of writing heads is provided with a pair of positioning protrusions having a circumferential surface or a spherical surface at a tip end portion thereof, and is movably supported by the second supporting means. A pair of head positioning members provided with a deep recess corresponding to the pair of positioning projections of the writing head and capable of accommodating the positioning projections;
A corresponding head positioning member is movably supported and is provided with adjusting means for moving the write head in two directions, the longitudinal direction and the lateral direction.

Next, an image forming apparatus according to a second aspect of the present invention includes one image carrier whose position is fixed and a pair of positioning means for positioning each image carrier with the image carrier as a reference. A plurality of image forming portions each including a plurality of image bearing members and a plurality of image forming portions to which the plurality of image bearing members each including the pair of positioning means belong, arranged in parallel at a predetermined interval. Supporting means, a plurality of writing heads for writing image information on the surface of the image bearing member facing the image bearing member provided in the image forming section, and a plurality of image bearing members each having the pair of positioning means. Second supporting means for supporting a plurality of write heads facing the body side by side in correspondence with the predetermined spacing, and one of the first supporting means and the second supporting means with respect to the other With one end in the parallel installation direction as a fulcrum An image forming apparatus comprising a movable mechanism and a supporting mechanism for relatively moving the plurality of image forming units and the plurality of writing heads, wherein each of the plurality of writing heads has a circumferential surface at a tip portion. Alternatively, a pair of positioning projections having a spherical surface is provided and is movably supported with respect to the second supporting means, and the pair of positioning means correspond to the pair of positioning projections of the write head. And a pair of head positioning members each having a narrow recess for accommodating therein, and a corresponding head positioning member movably supported on at least one of the head positioning members so as to move the write head in two directions of a longitudinal direction and a lateral direction thereof. It is configured with means.

Further, for example, as described in claim 3, the position-fixed image carrier is an image carrier carrying a black toner image, and a plurality of other image carriers each having a pair of positioning means. The body is composed of an image carrier that carries toner images of the three primary colors.

According to a fourth aspect of the present invention, an image forming is constructed so that a writing head for writing image information on the surface of the image carrier facing the image carrier can be separated from a position facing the image carrier. It is applied to the positioning mechanism of the writing head of the device.

In the positioning mechanism of the present invention, the write head is provided with a pair of positioning projections having a circumferential surface or a spherical surface at its tip portion, and is movably supported by a head support means for supporting the write head. The pair of support members for supporting the image bearing member include a pair of head positioning members having a deep recess corresponding to the positioning projections and capable of accommodating the positioning projections, and a head corresponding to at least one of the head positioning members. Adjustment means is provided for movably supporting the positioning member and moving the write head in two directions, the longitudinal direction and the lateral direction, and the pair of positioning projections are provided in the pair of deep recesses at the facing position. The write head and the surface of the image carrier are kept in contact with each other to maintain a constant distance, and at least one of the head positioning members is adjusted by the adjusting means. The move to the two directions is configured to perform positioning of the two directions.

The adjusting means comprises, for example, as described in claim 4, a taper member having a tapered surface and an adjusting member for sliding the taper member in the direction of forming the taper. Further, the adjusting member is, for example, in claim 5.
As described above, the taper member includes a male screw and a push spring for urging the male screw in a direction opposite to the screwing direction.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a partially enlarged view of a sectional view of the positioning mechanism in one embodiment as seen from the front, and FIG. 1B is a sectional view taken along the line CC ′ of FIG.
Incidentally, FIG. 1 (a) is a view taken along the line DD 'in FIG. 1 (b).

FIG. 2 (a) is a partially enlarged view of a sectional view of the above-mentioned positioning mechanism as seen from above, and FIG. 2 (b) is a reprint of FIG. 1 (b) for comparison. . FIG. 3 is an external perspective view of an image forming apparatus including the above-mentioned positioning mechanism.
Further, FIG. 4 is a sectional view schematically showing the internal structure of the image forming apparatus. Further, FIG. 5 is an enlarged view showing the configuration of each part of the image forming units arranged in parallel in the tandem type shown in the above internal configuration. Since FIGS. 4 and 5 are sectional views of the central portion, the positioning mechanism disposed on the side portion is not shown.

First, the overall structure will be described. As shown in FIG. 3, this image forming apparatus is a small-sized image forming apparatus of a size that can be mounted on, for example, a desktop type rack for a personal computer. The image forming apparatus includes an apparatus body 10
An opening / closing tray 11 is provided on the front surface (right side in the drawing), and a paper cassette 12 is detachably provided on the lower portion. A paper discharge tray 14 is formed on the upper surface of the upper lid member 13, and image-formed paper discharged from the upper paper discharge port 15 is stacked therein. A power switch 16, a liquid crystal display device 17, a plurality of input keys 18, and the like are arranged on the front side of the upper lid member 14.

As shown in FIG. 4, the inside is provided with a sheet conveying belt 23 which is circulated and moved by being held by the drive rotation roller 21 and the driven rotation roller 22 at substantially the center.
Above the belt 23, the image forming unit 24 (2
4-1, 24-2, 24-3, 24-4) are arranged side by side in a multi-stage manner in the sheet conveying direction. The image forming unit 24 includes photoconductor drums 25 (25-1, 25-2, 25-, respectively).
3, 25-4) and various devices, which will be described later in detail, are installed in the image forming unit 24 so as to surround the photoconductor drum 25. Then, the write heads 26 (26-1, 26-) provided on the back surface of the upper lid member 13 directly above the photoconductor drum 25 (image carrier).
2, 26-3, 26-4) are inserted and arranged by closing the upper lid member 13. The writing head 26 is an LED
Composed of a head. The upper lid member 13 opens and closes around a support shaft 27 behind the device body 10. The photosensitive drum 25 is in contact with the belt 23, and the belt 23
A transfer brush 28 (28-1, 28-2, 28-3, 28-4) is disposed so as to be opposed to the photosensitive drum 25 from the back surface of the transfer brush 28.

A standby roll pair 29 and a sheet detection sensor 31 are disposed on the upstream side (right side in the figure) of the belt 23 in the sheet conveying direction. The upstream side thereof branches laterally (front of the apparatus) and downward, A paper feed roller 32, a separating member 33, and the open / close tray 11 described above are arranged in the lateral direction. In addition, a conveyance path 34 formed of two guide plates is provided below,
Upstream of that, the above-mentioned paper cassette 12 has a large number of paper sheets P.
Is housed inside and the end of the paper is seen. A paper feed roller 35 is disposed above the paper feed end. A separation claw 36, a fixing device 37, a paper ejection roller 38, and a switching lever 39 are provided downstream of the belt 23 in the paper conveyance direction. Fixing device 3
Reference numeral 7 is composed of a pressure contact roller, a heat generating roller, a peripheral surface cleaner, an oil applying roller, a thermistor, etc., which are assembled in a heat insulating casing, and heat-fixes the toner image transferred onto the paper on the paper. The switching lever 39 guides the sheet to the upper discharge path 41 when it is at the lower position as shown in the figure, and guides the sheet to the sheet discharge port 42 opened on the rear surface of the apparatus when it is rotated upward. invite. The downstream side of the above discharge path 41 communicates with the upper discharge port 15 via the discharge roll pair 43.

A cleaner bottle 44 is detachably arranged between the belt 23 and the paper cassette 12. this,
A blade scraper 45 is attached to the top of the cleaner bottle 44.
Is attached, and its tip is in contact with the surface of the lower circulation portion of the transfer transfer belt 23. Blade scraper 45
Cleans the transfer transfer belt 23 by scraping off the toner remaining on the surface of the transfer transfer belt 23, and stores the scraped unnecessary toner in the cleaner bottle 44.

The belt 23 is used for the image forming unit 2
A portion between 4-1 and 24-3 is supported by a fixed support roll 46 and a movable support roll 47. Fixed support roll 46
Is rotatably fixed to the frame of the main body of the apparatus, and the movable roll 47 is held at the other end of a support member 48 that swings around a support shaft of the fixed roll 46. Support member 4
A cam 49 is engaged with the lower portion of the shaft 8 to selectively pivot left and right between the position shown in the figure and the position rotated 90 degrees in the clockwise direction. When the cam 49 rotates clockwise by 90 degrees from the position shown in the drawing, the support member 48 slightly rotates downward, and the moving roll 47 moves downward. As a result, the photoconductor drums 25-1 to 25- of the image forming units 24-1 to 24-3.
An image forming unit 2 is released from contact with the belt 23 and is separated from the image formation, and is in charge of image formation of black toner.
Only 4-4 is supported between the drive rotation roller 21 and the fixed roller 46 and comes into contact with the belt 23 whose position is immovable so that image formation can be performed.

FIG. 5 shows the image forming unit 24 (2
4-1, 24-2, 24-3, 24-4) is an enlarged view. The image forming units 24 have the same configuration except that the colors of the toners contained therein are different. As shown in the figure, the image forming unit 24 includes the photosensitive drum 2
5, a cleaner 51 surrounding the photosensitive drum 25 along its peripheral surface, an initialization charger 52, and a developing device 53. The developing device 53 also serves as a toner container, and forms one casing of the image forming unit 24. Then, the photoconductor drum 25, the cleaner 51, and the initialization charger 52.
The various devices are held by a frame forming the other casing of the image forming unit 24.

The developing device 53 has a developing roller 54 at the lower opening.
Is rotatably held, and contains toner T inside. Each developing device 53 contains Y (yellow), M (magenta), C (cyan), or Bk (black) toner, respectively. A toner stirring member 55 is disposed below the inside of the developing device 53, and the toner stirring member 55 is disposed.
Rotates as shown by the chain double-dashed line in the figure to feed the toner T to the lower supply roller 56 while stirring the toner T. The supply roller 56 is made of a sponge member, is in pressure contact with the developing roller 54, and rubs the toner T sent from the stirring member 55 so as to rub the developing roller 54.
Supply to the peripheral surface. A leaf spring-shaped doctor blade 57 is in contact with the circumferential surface of the developing roller 54 in the rotation direction, and imparts a triboelectric charge to the toner T to promote the adherence to the developing roller 54 and, at the same time, keeps the adhered toner layer constant. Reduce to thickness.

When the above-mentioned image forming unit 24 is mounted on the apparatus main body 10, the supporting shaft projecting from the unit side surface of the photosensitive drum 25 to the outside is held by the bearing portion of the apparatus main body 10 and fixed in position. A drum gear formed on the photosensitive drum engages with a drive mechanism (not shown) of the apparatus main body 10 and is rotationally driven. The drive systems of the devices incorporated in the unit together with the photoconductor drum 25 are connected to the drive system of the photoconductor drum, and the photoconductor drum 25 is connected to the main body 1 of the device.
When driven by 0, it is driven in conjunction with this.

The writing head 26 disposed on the upper lid member 13 is provided between the initialization charger 52 and the developing roller 54.
However, the two-dot chain line 58 (5
8-1, 58-2, 58-3, 58-4), an arcuate locus is drawn to descend and be localized at the image forming position.
When the upper lid member 13 is opened and the writing head 26 is pulled up, the image forming unit 24 can be individually taken out of the machine in a straight line direction inclined obliquely to the upper right as indicated by a two-dot chain line 59 in the figure. Maintenance work such as replacement of the photoconductor drum and removal of paper jam can be performed. Also,
In this way, when the image forming unit 24 is taken out, the protective lid 61 slides counterclockwise to cover the exposed lower surface of the photosensitive drum 25 and protect it.

In the image forming apparatus 10 having such a configuration (see FIG. 4), when the power is turned on and the number of sheets, full-color printing (image formation), and other designations are keyed in, the sheet feed roller 35 is set to the sheet form. The sheet P placed and accommodated in the cassette 12 is fed to the standby roll pair 29 via the conveyance path 34. Alternatively, the paper feed roller 32 feeds the paper placed on the open / close tray 11 to the pair of standby rolls 29. The sheet detection sensor 31 detects the fed sheet P. The pair of standby rolls 29 stops rotating, and the leading edge of the paper P is brought into contact with the nip portion to stand by.

The drive rotation roller 21 starts to rotate in the counterclockwise direction, and the driven rotation roller 22 is driven to start to rotate in the counterclockwise direction as well. This makes the belt 23
, The upper circulation portion comes into contact with the four photoconductor drums 25, and the entire circulation movement is counterclockwise.

At the same time, the image forming unit 24 is sequentially driven in accordance with the print timing, and the photosensitive drum 25 is sequentially rotated clockwise in accordance with the driving. Then, the write heads 26 corresponding to the respective image forming units 24 are sequentially driven. Then, first, the initialization charging brush 52 (see FIG. 5) is connected to the photosensitive drum 25.
The write head 26 exposes the peripheral surface of the photosensitive drum in accordance with an image signal to form an electrostatic latent image on the peripheral surface of the photosensitive drum. Developing roller 5
Reference numeral 4 transfers the toner T to the low potential portion of the electrostatic latent image to form (develop) a toner image on the peripheral surface of the photosensitive drum.

At the timing when the leading edge of the toner image on the peripheral surface of the most upstream photosensitive drum 25-1 is rotatably conveyed to the facing point with the belt 23, the print start position of the paper P coincides with the facing point. As described above, the pair of standby rolls 29 starts rotating to feed the paper P to the paper carry-in entrance of the image forming unit. The driven rotation roller 22 and the pressing roll 62 sandwich the fed paper P together with the conveyor belt 23 to convey the paper P. The sheet P is adsorbed to the conveyance belt 23 and conveyed as it is even after the nip between the driven rotation roller 22 and the pressing roll 62 is released. Then, the paper P is sequentially transferred onto the paper surface by the electric fields formed between the photoconductor drums 25 and the transfer brushes 28 while being conveyed in this way.

The paper P on which the four color toner images of Y (yellow), M (magenta), C (cyan) and Bk (black) have been transferred is separated from the conveyor belt 23 by the separation claw 36 and fixed by the fixing device 37. Be delivered to. After the toner image is heat-fixed on the sheet P by the fixing device 37, the toner image is transferred from the rear paper ejection port 42 to the top or the toner image is transferred from the upper paper ejection port 15 to the bottom by the paper ejection roller 38. It is discharged outside the aircraft.

By the way, the photosensitive drum 25 is positioned by the support shaft being held by the bearing of the apparatus main body 10 and the drum gear of the photosensitive drum 25 being engaged with the drive mechanism of the apparatus main body. , The lid member 13
The upper cover member 13 is opened and closed, and the upper cover member 13 is opened and closed to rotate about its supporting shaft 27, and its relative position to the photosensitive drum 25 is unstable. On the other hand, in the tandem type developing system as described above, the print dot positions by the image forming units are not set to overlap each other within half a dot,
Moire fringes are generated, so a clean print result cannot be obtained. Therefore, the positions of the paper P, the photosensitive drum 25, and the writing head 26 must be accurately set.

However, in this case, paying attention to the overlap of the dot positions of the printing result, even if the main scanning direction is oblique with respect to the paper (inclined with respect to the width direction of the paper),
If the relative positions of the write head 26 and the photoconductor drum 25 can be aligned so that the print dots of all the image forming portions have the same inclination, then Y (yellow), M
If the output timing of image formation of (magenta), C (cyan), and Bk (black) is electrically corrected and interpolation dots are inserted in the dots in the main scanning direction, the apparent displacement of the print dots can be eliminated. .

However, there is a limit to the control by the control unit, and from the viewpoint of shortening the processing time, it can be said that it is desirable to perform mechanical positioning as much as possible, especially in the case of a small machine. .

In the image forming apparatus 10 described above, the writing head 26 is positioned with respect to the photoconductor drum 25 by holding the support shaft of the photoconductor drum 25 and fixing the position of the support shaft, that is, the photoconductor drum shaft ( The drum holding portion of the frame of the apparatus body 10 (where the photosensitive drum 25 is positioned) is provided with a receiving groove integrally formed with the drum holding portion, and is attached to the writing head 26 by closing the upper lid member 13. The head pin fits into the receiving groove to perform positioning. This positioning is performed by adjusting the inclination of the write head 26 (inclination of each write head in the paper traveling direction with respect to the width direction of the paper) to be the same and the position of the write head 26 in the main scanning direction (dot alignment of the write head). There are two adjustments to make. These two adjustments are made by the receiving groove. Hereinafter, this will be described.

FIG. 6 is a front sectional view of the image forming apparatus in which only the components relating to the positioning mechanism are left and the other components described above are omitted. Figure 1 shown earlier
(a) is an enlarged view of a portion indicated by a circle A in FIG. 6.

FIG. 7 is a cross-sectional view as seen from the left side surface of FIG. FIG. 1 (b) described above is an enlarged view of a portion indicated by a circle B in FIG. 8 shows a sectional view seen from the right side surface of FIG. 6, and FIG. 9 shows a sectional view seen from the upper surface.

In FIGS. 1 and 2 and FIGS. 6 to 9 shown here, the upper lid member 13 is rotated downward about the support shaft 27 from the open position of the chain double-dashed line 13 '. Closed and locked by the lock lever 65 (see FIG. 7).
8 and FIG. 8), the tips of the head pins 67a and 67b projecting downward at both ends of the write head holder 66 have the drum holder 68a of the frame of the apparatus main body 10.
And 68b are pressed against each other via a butting groove described later. The writing head 26 (see FIGS. 1a and 6) is arranged on the upper lid member 13 by attaching members 71 (FIGS. 1 (b), 7 and 8) fixed to both sides of the upper lid member 13, respectively. ), The write head holding portion 66 is held so as to be finely movable back and forth and left and right. A pressing spring 72 is interposed between the writing head holding portion 66 and the upper lid member 13, which urges the writing head holding portion 66 downward, and by closing the upper lid member 13 described above, the head pins 67a and 67b are held by the drum. Parts 68a and 68
They are pressed against each other via b butting grooves.

The drum holding portions 68a and 68b, on the other hand, hold the photosensitive drum shaft 73 (see FIGS. 6, 8 and 9), by which the photosensitive drum 25 is positioned. The writing head holding portion 66, that is, the spherical tip of one head pin 67b of the writing head 26 is
The drum holding portion 68b is brought into pressure contact with the drum holding portion 68b by coming into contact with the valley of the abutment groove 74 (see FIGS. 6 and 8) formed directly above the drum holding portion 68b. The abutting groove 74 is V-shaped when viewed from the side (see FIG. 8), and therefore the head pin 67b is fixed in the front and rear positions with respect to the apparatus main body 10 constantly. Further, the length of the abutting groove 74 is formed to be slightly longer than the diameter of the head pin 67b from the front side of the V-shape to the side facing the V-shape (in the width direction of the apparatus main body 10) (see FIG. 6). As a result, the head pin 67b, that is, one end of the write head 26 has room for fine movement in the width direction of the apparatus body 10.

The head pin 67a at the other end of the write head 26 is inside the circle A in FIG. 6 (see FIG. 1 (a)).
Further, as shown in the circle B in FIG. 7 (see FIG. 1B), the drum holding portion 68a is pressed against the drum holding portion 68a via the adjusting abutting member 75 of the drum holding portion 68a. The adjusting abutting member 75 positions (positions) the writing head 26 with respect to the photosensitive drum 25. Hereinafter, the configuration related to the adjusting abutting member 75 will be described with reference to FIGS. 1 and 2.

The adjusting abutment member 75 is provided with an abutment groove 75-1 (see FIG. 1B) having a V-shaped side cross section on its upper surface, and is slightly slid forward, backward, leftward and rightward by the holding portion 68a. It is supported as closely as possible. The spherical tip of the other head pin 67a comes into pressure contact with the valley of the butting groove 75-1. As a result, the other head pin 67a is fixed in the front-rear position (left-right direction in FIG. 1B) with respect to the adjusting abutting member 75.
That is, the angle formed by the straight line connecting the other head pin 67a and the one head pin 67b with the main scanning direction with the one head pin 67b as the center (fulcrum) is fixed. That is, as a result, the write head 26 (see FIGS. 1A and 6) has one end attached to the photosensitive drum 25 via the write head holding portion 66, the head pin 67b, the abutting groove 74, and the holding portion 68b. The other end is fixed to the photosensitive drum 2 via the write head holding portion 66, the head pin 67a, the adjusting abutting member 75, and the holding portion 68a.
By being fixed with respect to 5, the inclination angle of the write head 26 with respect to the main scanning direction of the photoconductor drum 25 is fixed.

The abutting groove 75-1 of the adjusting abutting member 75 is formed so that one side in the left-right direction (left side in the figure) is closed and the other end (right side in the figure) is open. One of the left and right head pins 67a of the write head 26 abuts on the closing opening of the abutment groove 75-1, and the other abuts on the abutment groove 75-.
1 and the side support wall 68a-1 of the holding portion 68a are urged toward the closing opening by the upper return spring portion of the leaf spring 76, which causes the adjustment abutting member 7 to move.
The position in the left-right direction with respect to 5 is fixed. As a result, the positions of the two head pins 67a and 67b in the main scanning direction are fixed. That is, as described above, the write head 26 has one end fixed to the photosensitive drum 25 via the write head holding portion 66, the head pin 67b, the abutting groove 74, and the holding portion 68b, and the other end is the same. Through the holding portion 66, the head pin 67a, the adjusting abutting member 75, and the holding portion 68a, the photosensitive drum 2
In this case, the position of the write head 26 with respect to the main scanning direction of the photoconductor drum 25, that is, the print dot position, is fixed by being fixed with respect to No. 5. The angle formed by the writing head 26 with respect to the fixed main scanning direction and the print dot position in the main scanning direction can be finely adjusted.
This will be described below.

First, the positioning of the write head 26 in the main scanning direction will be described. As shown in FIG. 1A, the adjusting abutting member 75 has a lower end portion slidably closely supported by a holding portion 68a, and right and left side supporting walls 68a-1 and 68a- of the holding portion 68a. There is a slight gap between each of them. The side surface of the abutting groove 75-1 on the opening end side is the side support wall 68a- of the holding portion 68a.
1 is urged toward the outer side in the main scanning direction (leftward in the drawing) by the lower folded spring portion of the leaf spring 76 interposed between the leaf spring 76 and the sheet spring 1. The outer surface of the adjustment abutting member 75 in the main scanning direction is
As shown in FIG. 1 (a), the cross section constitutes an inclined surface 75-2 which forms a taper in the upward direction, whereby the holding portion 68a is formed.
A divergent gap is formed upward between the side support wall 68a-2 and the side support wall 68a-2. The lower part of the key mold of the main scanning adjustment block 77 having a key-shaped cross section is fitted in this gap.

Below the key mold of the main scanning adjustment block 77,
The surface of the holding portion 68a that is in contact with the side support wall 68a-2 is vertical, and the surface of the adjustment abutting member 75 that is in contact with the sloped surface 75-2 forms a sloped surface 77-1 whose section is a taper downward. . The angle formed by the inclined surface 77-1 of the main scanning adjustment block 77 with the vertical plane and the angle formed by the inclined surface 75-2 of the adjustment abutting member 75 with the vertical plane are the same. As a result, the lower part of the key mold of the main scanning adjustment block 77 comes into close contact with the side support wall 68a-2 of the holding portion 68a on one surface, and the other surface (slope 77-).
In 1), the slant surface 75-2 of the adjusting abutting member 75 is in close contact with the slant surface. A screw receiving hole is formed in the upper portion of the key mold of the main scanning adjustment block 77. In this screw receiving hole, male screw 7
8 is inserted, and the threaded portion at the tip of the male screw 78 penetrates the spiral spring 79 and is screwed with the female threaded portion of the holding portion 68a. A spiral spring 79 interposed between the lower surface of the upper portion of the key die of the main scanning adjustment block 77 and the female screw portion of the holding portion 68a.
Is a push spring and biases the main scanning adjustment block 77 upward.

When the male screw 78 is rotated in the pushing direction using a driver, the main scanning adjusting block 77 is lowered downward against the pushing force of the spiral spring 79, and the cross section forms a taper downward. The inclined surface 77-1 pushes the adjusting abutting member 75 inward in the main scanning direction. The adjustment abutting member 75 moves inward in the main scanning direction against the urging force of the lower return spring portion of the leaf spring 76 by the amount of this pushing.
On the other hand, when the male screw 78 is turned in the pull-out direction, the main scanning adjustment block 77 is rotated by the spiral spring 79 by the pulled-out amount.
It rises due to the pushing force of. That is, slope 77-1
Rises to generate a gap on the contact surface with the adjusting abutting member 75, and the adjusting abutting member 75 is moved outward by the biasing force of the lower return spring portion of the leaf spring 76 in the main scanning direction by the amount of the generated gap. Move to.

In the movement of the write head 26 in the main scanning direction, one end portion thereof is the head pin 6 as described above.
7b and the abutment groove 74, the head pin 6
Since 7b has a room for fine movement in the width direction (main scanning direction) of the apparatus main body 10, the above movement can be performed without any trouble.

Thus, the fine movement of the adjusting abutting member 75 in the main scanning direction can be performed by rotating the male screw 78 and moving the main scanning adjusting block 77 back and forth accordingly. The amount of movement of the adjustment abutting member 75 for fine movement in the main scanning direction is one dot per rotation of the male screw 78 when the resolution of the writing head 26 is 300 dpi (dots / inch), for example. To do this, for example,
The pitch of the screw threads of No. 8 may be set to 0.7 mm (millimeter), and the inclination angles of the slopes 75-2 and 77-1 may be set to about 83.1 °. If the inclination angles of the slopes 75-2 and 77-1 are constant, the amount of movement is increased by increasing the pitch of the thread of the male screw 78, and is decreased by decreasing the pitch of the thread. Further, if the pitch of the threads of the male screw 78 is constant, the amount of movement is increased by increasing the inclination angle of the slopes 75-2 and 77-1, and is decreased by decreasing the inclination angle.

Next, positioning of the write head 26 in the sub-scanning direction (setting of an angle formed with the head pin 67b as a fulcrum with respect to the main scanning direction) will be described with reference to FIG. 2 (b) and FIG. 1 (b) again. . In FIG. 2 (b), as described above, the adjustment abutting member 75 whose lower end is slidably and closely supported by the holding portion 68a has a rear surface (left side in the drawing) in the sub-scanning direction,
Form a slope 75-3 whose cross section forms a taper in the upward direction,
As a result, a divergent gap is formed upward between the holding portion 68a and the rear support wall 68a-3. The lower part of the key mold of the sub-scanning adjustment block 81 having a key-shaped cross section is fitted in this gap. The surface of the lower part of the key of the sub-scanning adjustment block 81, which is in contact with the rear support wall 68a-3 of the holding portion 68a, is vertical, and the surface of the adjustment abutting member 75, which is in contact with the inclined surface 75-3, has a downward cross section. A slope 81-1 forming a taper is formed. Also in this case, the angle formed by the inclined surface 81-1 of the sub-scanning adjustment block 81 with the vertical plane is the same as the angle formed by the inclined surface 75-3 of the adjusting abutting member 75 with the vertical plane. As a result, the lower part of the key mold of the sub-scanning adjustment block 81 is in close contact with the rear support wall 68a-3 of the holding portion 68a on one surface, and the adjustment abutting member 75 is on the other surface (slope 81-1). Slope 75
It closely touches -3.

A screw receiving hole is formed in the upper part of the key mold of the sub-scanning adjusting block 81, and a screw 82 is inserted into the screw receiving hole, and the screw portion at the tip of the male screw 82 is the spiral spring 8.
3 and is screwed into the female thread portion of the holding portion 68a. The spiral spring 83 biases the sub-scanning adjustment block 81 upward.

An abutting portion 75-4 is provided above the front portion of the adjusting abutting member 75 so as to regulate the amount of movement of the holding portion 68a with the front support wall 68a-4. A pushing spiral spring 84 is interposed in a slightly large gap between the front portion of the adjusting abutting member 75 formed below the abutting portion 75-4 and the front supporting wall 68a-4 of the holding portion 68a. The spiral spring 84 biases the adjusting abutting member 75 rearward in the sub-scanning direction.

When the male screw 82 is rotated in the pushing direction using a driver, the sub-scanning adjusting block 81 descends downward against the pushing force of the spiral spring 83, and the cross section forms a taper downward. 81-1 pushes the adjusting abutting member 75 forward (in the drawing, rightward) in the sub-scanning direction. The adjustment abutting member 75 moves forward in the sub-scanning direction against the pressing biasing force of the pressing spiral spring 84 by the amount of this pushing-out.

On the other hand, when the male screw 82 is turned in the pull-out direction, the sub-scanning adjustment block 81 is raised by the pushed-out amount by the pushing biasing force of the spiral spring 83, that is, the inclined surface 81-1 is raised and adjusted. A gap is created on the contact surface with the working abutting member 75, and the adjusting abutting member 75 is moved rearward in the sub-scanning direction by the pressing biasing force of the pressing spiral spring 84 by the amount of the created gap. As described above, the fine movement of the adjusting abutting member 75 in the sub-scanning direction can be performed by rotating the male screw 82 and moving the sub-scanning adjusting block 81 forward and backward accordingly.
The amount of movement of the adjustment abutting member 75 that slightly moves in the sub-scanning direction is the same as the above-described setting of the amount of movement in the main scanning direction.

As described above, the positioning of the write head 26 in the main scanning direction and the sub scanning direction of the photosensitive drum 25 by the fine movement of the adjusting abutting member 75 is performed by the holding portion 68a as shown in FIG. 2 (a). The above-mentioned male screw 78 exposed to the outside of the
And, by using a Phillips screwdriver formed in the head of the male screw 82 to rotate the screw 78 or the male screw 82 by an appropriate amount, a dot position is set at a desired position in the main scanning direction. The angle with respect to the main scanning direction can be easily set to a desired angle.

Then, after the setting is completed, (a) and (b) in FIG.
By turning the set screws 85 and 86 shown in FIG. 2 in the tightening direction, the stop portion that is integrally formed by projecting forward and backward on the upper portion of the adjustment abutting member 75 is fastened to the holding portion 68a of the apparatus body 10. The set screws 85 and 86 are such that the adjustment abutting member 75 moves forward and backward in a screw receiving hole provided in the overhang preventing portion.
Or, it is inserted with enough play to allow slight movement to the left and right. By tightening the upper screws of the setscrews 85 and 86, the setting in which the positioning has been completed is fixed.

As described above, the fine positioning of the writing head 26 with respect to the photosensitive drum 25 in the horizontal and vertical directions can be easily performed. In the above-described embodiment, the positioning mechanism is set to Y (yellow), M (magenta),
Although it is provided for each of the C (cyan) and Bk (black) image forming units, the fine adjustment by positioning is originally performed with respect to the reference. Therefore, for example, the positional relationship between the write head of the Bk (black) image forming unit and the photosensitive drum is fixed, and a positioning mechanism is provided only for the other Y (yellow), M (magenta), and C (cyan) image forming units. It may be provided. Further, since such positioning is performed with respect to the reference as described above,
For example, even in the case of only one image forming apparatus such as a black printer, it can be applied for positioning with respect to a fixed reference. Further, in the above-described embodiment, the writing head is described as an LED, but the writing head is not limited to this, and any type can be used as long as it can be downsized and disposed on the rotating member. It may be one.

FIG. 10 shows an example of a small-sized laser head which can be arranged on the opening / closing member. The image forming unit 90 shown in the figure includes a photosensitive drum 91, a cleaner 92 arranged in a clockwise direction along the peripheral surface of the photosensitive drum 91,
The initialization charger 93, the laser head 94, and the developing roller 95 are shown. The laser head 94 is thus independently configured for each image forming unit, and the light emitting unit 94-
1, a rotary reflecting mirror 94-2, a converging lens 94-3, an optical path changing plate 94-5, and an irradiation port 94-6 are integrally assembled. The laser head 94 is arranged on an opening / closing member (not shown) and moves in the vertical direction as indicated by a double-headed arrow E in the figure. When the laser head 94 descends and is localized at the image forming position, the irradiation port 94-6 can be positioned with respect to the photosensitive drum 91 using the above-described positioning mechanism.

[0057]

As described above, according to the present invention,
Since a finely adjustable adjusting abutting member, a main scanning adjusting block and a sub-scanning adjusting block having a taper surface that abuts on the photosensitive drum holding portion of the apparatus main body are provided in the vertical and horizontal directions, these are advanced and retracted by a male screw. By combining the thread pitch of the male screw and the inclination angle of the taper surface of the adjustment block, the position of the writing head with respect to the photosensitive drum can be set to 1
Fine adjustment can be performed in dot units, and therefore fine positioning of the writing head and the photosensitive drum can be performed mechanically and easily.

[Brief description of the drawings]

FIG. 1A is an enlarged view of a part of a sectional view of a positioning mechanism according to an embodiment as seen from the front (a portion indicated by a circle A in FIG. 6), and FIG. FIG. 8 is an enlarged view of a portion (portion indicated by a circle B in FIG. 7).

2A is a partially enlarged view of a cross-sectional view of the positioning mechanism as seen from above, and FIG. 2B is a view showing FIG. 1B again for comparison.

FIG. 3 is an external perspective view of an image forming apparatus including a positioning mechanism.

FIG. 4 is a cross-sectional view schematically showing the internal configuration of the image forming apparatus.

FIG. 5 is an enlarged view showing the configuration of each unit of the image forming units arranged in parallel in a tandem type.

FIG. 6 is a cross-sectional view of the image forming apparatus as viewed from the front, in which only the components related to the positioning mechanism are left and other components are omitted.

7 is a cross-sectional view seen from the left side of FIG.

8 is a cross-sectional view seen from the right side of FIG.

9 is a cross-sectional view seen from the upper surface of FIG.

FIG. 10 is a diagram showing an example of a small-sized laser head that can be arranged on an opening / closing member.

FIG. 11 is a front sectional view of a main portion of an image forming unit in a conventional tandem type color image forming apparatus.

FIG. 12 is a side sectional view of FIG. 11;

FIG. 13 is an enlarged view of the contact portion of FIG.

[Explanation of symbols]

1 Photosensitive Drum 1-1 Rotating Shaft 2 Exposure Head (LED Head) 2-1 Light Emitting Element 3 Enclosure 3-1 Exposure Head Receiving Section 3-2 Receiving Groove 4 Support Frame 5 Gear 6 Support Member 7 Attached Pin O Tip Shape center R Tip radius 10 Device body 11 Open / close tray 12 Paper cassette 13 Upper lid member 14 Paper ejection tray 15 Upper paper ejection port 16 Power switch 17 Liquid crystal display device 18 Input key 21 Drive rotation roller 22 Driven rotation roller 23 Paper conveyance Belt (belt) 24 (24-1, 24-2, 24-3, 24-4) Image forming unit 25 (25-1, 25-2, 25-3, 25-4) Photoreceptor drum 26 (26- 1, 26-2, 26-3, 26-4) Writing head 27 Spindle 28 (28-1, 28-2, 28-3, 28-4) Transfer brush 29 Standby low 31 Pair of paper detection sensor 32 Paper feed roller 33 Separation member 34 Conveyance path P Paper 35 Paper feed roller 36 Separation claw 37 Fixer 38 Discharge roller 39 Switch lever 41 Discharge path 42 Discharge port 43 Discharge roll pair 44 Cleaner bottle 45 Blade Scraper 46 Fixed Support Roll 47 Moving Support Roll 48 Supporting Member 49 Cam 51 Cleaner 52 Initializing Charger 53 Developing Device 54 Developing Roller 55 Toner Stirring Member 56 Supply Roller 57 Doctor Blade 61 Protective Lid 62 Pressing Roll 65 Lock Lever 66 Writing Head holding portion 67a, 67b Head pin 68a, 68b Drum holding portion 68a-1, 68a-2 Side support wall 68a-3 Rear support wall 68a-4 Front support wall 71 Mounting member 72 Push spring 73 Photoconductor drum shaft 74 Protrusion Contact groove 75 key Abutting member 75-1 abutting groove 75-2 main scanning direction inclined surface 75-3 sub-scanning direction inclined surface 75-4 abutting portion 76 leaf spring 77 main scanning adjustment block 77-1 inclined surface 78 male screw 79 spiral spring 81 Sub-scanning adjustment block 81-1 Slope 82 Male screw 83 Spiral spring 84 Push spiral spring 85, 86 Set screw

Claims (6)

[Claims] 1. A plurality of image forming units each comprising an image carrier and a pair of positioning means for positioning the image carrier, and a plurality of image forming units arranged in parallel at predetermined intervals. First supporting means, a plurality of writing heads facing the image carrier to write image information on the surface of the image carrier, and the plurality of writing heads arranged in parallel in correspondence with the predetermined interval. Second supporting means for supporting, and one of the first supporting means and the second supporting means capable of swinging with respect to the other with one end in the juxtaposed direction as a fulcrum, and the plurality of image forming sections. An image forming apparatus comprising: a support mechanism that allows the plurality of writing heads to move relative to each other, each of the plurality of writing heads having a pair of positioning protrusions having a circumferential surface or a spherical surface at a tip end portion thereof. And a pair for supporting the second supporting means. At least one of a pair of head positioning members provided with a deep recess corresponding to the pair of positioning projections of the write head and capable of accommodating the pair of positioning projections. An image forming apparatus, further comprising adjusting means for movably supporting a corresponding head positioning member and moving the writing head in two directions of a longitudinal direction and a lateral direction thereof. 2. A plurality of images composed of one image carrier fixed in position and a plurality of other image carriers each having a pair of positioning means for positioning each image carrier with the image carrier as a reference. An image forming unit; a first supporting unit configured to support a plurality of image forming units to which a plurality of image carriers each including the pair of positioning units belong side by side at a predetermined interval; and an image included in the image forming unit. The plurality of writing heads for respectively writing image information on the surface of the image carrier facing the carrier and the plurality of write heads facing the plurality of image carriers each having the pair of positioning means are predetermined. A second supporting means for supporting in parallel with each other at a predetermined interval, and one of the first supporting means and the second supporting means swinging with respect to the other with one end in the juxtaposing direction as a fulcrum. Freely and in front of the plurality of image forming units An image forming apparatus comprising: a support mechanism that allows a plurality of write heads to move relative to each other, wherein each of the plurality of write heads has a pair of positioning protrusions having a circumferential surface or a spherical surface at a tip portion thereof. And a pair of positioning means, each of which is movably supported with respect to the second support means, has a deep recessed portion corresponding to a pair of positioning projections of the write head and capable of accommodating the projection. An image forming method comprising: a pair of head positioning members; and at least one of the head positioning members movably supporting a corresponding head positioning member, and adjusting means for moving the writing head in two directions of a longitudinal direction and a lateral direction thereof. apparatus. 3. The position-fixed image carrier is an image carrier that carries a black toner image, and a plurality of other image carriers each having a pair of positioning means carry toner images of respective three primary colors. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image carrier. 4. A write head positioning mechanism of an image forming apparatus, wherein a write head for writing image information on the surface of the image carrier facing the image carrier is separable from a position facing the image carrier. The writing head is provided with a pair of positioning protrusions having a circumferential surface or a spherical surface at a tip portion thereof, and is movably supported by a head supporting unit that supports the writing head, and supports the image carrier. The pair of supporting members are provided with a pair of head positioning members corresponding to the positioning protrusions and having a recessed recess for accommodating the positioning protrusions, and at least one of the head positioning members movably supports the corresponding head positioning member. Adjustment means for moving the head in two directions of a longitudinal direction and a lateral direction is provided, and the pair of positioning projections are provided with the pair of deep recesses at the facing position. While maintaining a constant distance between the writing head and the surface of the image carrier, the adjusting means moves at least one of the head positioning members in the two directions to perform the positioning in the two directions. A write head positioning mechanism characterized by the above. 5. The positioning device according to claim 3, wherein the adjusting means includes a taper member having a tapered surface and an adjusting member for sliding the taper member in a direction in which the taper is formed. mechanism. 6. The adjusting member includes a male screw screwed into the taper member, and a push spring for urging the male screw in a direction opposite to the screwing direction. 4. The positioning mechanism described in 4.