JPH11218991A - Color laser printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color laser printer capable of making alignment of position with respect to a polygon mirror simplified, and attaining the miniaturization and reliability improvement. SOLUTION: This printer is, respectively provided with the one laser unit 1 equipped with a laser diode(LD) capable of successively projecting in order by data for one color on a respective surface of the polygon mirror whose respective mirror surface is inclined for four kind of angle so that the angle of the respective mirror becomes the same by every four surface by making the surfaces of the mirror to the multiple of four. Then, these image laser beams of four colors projected from the LD, is respectively projected on the surface inclined by the specified degrees of the respective polygon mirror surface and deflected, and thereafter scanned on respective photoreceptor drum 11Y, 11M, 11C and 11BK after the respective light path is changed by the first turning back mirrors 5Y, 5M, 5C and 5BK, the second turning back mirrors 6Y, 6M, 6C and 6BK, and the third turning back mirrors 7Y, 7M, 7C and 7BK.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color laser printer mainly applied to a color copying machine, a color facsimile and the like.

[0002]

2. Description of the Related Art Conventionally, as this type of color laser printer, for example, there is one having a configuration as shown in FIG. This color laser printer uses yellow (Y /
Yellow), magenta (M / magenta), cyan (C / blue-green),
It is a tandem type having four developing units for performing printing on four colors of black (BK / black). The photosensitive drum cleaners 65 (Y), 65 (M), 6
Photosensitive drum 61 provided with 5 (C) and 65 (BK)
(Y), a developing device including 61 (M), 61 (C), and 61 (BK), and a mirror having a multiple of 4 (usually 8) so that the same angle is obtained every four surfaces. A laser unit 5 having a polygon mirror (not shown) in which the angle of the mirror surface is inclined to four types (Y degrees, M degrees, C degrees, and BK degrees) and a laser diode for irradiating an image laser beam of a specific color.
1 (Y), 51 (M), 51 (C), 51 (BK),
The laser units 51 (Y), 51 (M), 51 (C),
The laser beams emitted from 51 (BK) are applied to the photosensitive drums 61 (Y), 61 (M), 61 (C), 61, respectively.
(BK) First folding mirrors 55 (Y), 55 (M), 55 for folding over to form an electrostatic image
(C), 55 (BK) and the second folding mirror 56
(Y), 56 (M), 56 (C), 56 (BK), and the photosensitive drums 61 (Y), 61
(M), 61 (C), and development units 60 (Y), 60 (M), 60 for forming toner images on 61 (BK)
(C) and 60 (BK).

Further, this color laser printer has a driving roller 68, a first driven roller 69, and a second driven roller 7 for feeding and transporting a sheet 73 from a sheet feeding unit.
0, a third driven roller 71, a paper feed roller 74, and a transport roller 75, and transports the paper 73 to each of the photosensitive drums 61 (Y), 61 (M), and 61.
(C), a transfer belt 66 provided with a transfer belt cleaner 72 for forming a single toner image by sequentially superimposing single-color toner images formed on 61 (BK) on a sheet 73; A fixing unit 76 for fixing the toner image to the discharged paper 73 by heat and pressure, a discharge unit for discharging the fixed paper 73 to the outside of the apparatus, a discharge tray for stacking the discharged paper 73, and the like. Is done.

The photosensitive drums 61 (Y), 61
In the vicinity of (M), 61 (C), and 61 (BK), main chargers 64 (Y), 64 (M), 64 (C), 64
(BK), and the transfer devices 67 (Y), 67 (M), 67 (C), 67 (B) with the transfer belt 66 interposed therebetween.
K) are provided, and the photosensitive drums 61 (Y), 61
(M), 61 (C), and 61 (BK) are developing rollers 62
(Y), 62 (M), 62 (C), and 62 (BK) to contact toner supply rollers 63 (Y), 63 (M), 63
(C), 63 (BK) and developing rollers 62 (Y), 62
(M), 62 (C), and 62 (BK) are linked to rotate.

FIG. 6 is a perspective view showing a simplified structure of a main part of the color laser printer. Here, the number of mirror surfaces is set to a multiple of 4 (usually 8 surfaces) and the angles of the mirror surfaces are set to four types (Y degrees, M degrees, C degrees, and BK degrees) so that the angles become the same every four surfaces. In the tilted polygon mirror 52, an image laser beam of a specific color emitted from a laser diode (LD) 53 is applied to the polygon mirror 52.
Is controlled so as to irradiate a surface inclined by a predetermined degree, and after being deflected by the surface and passing through a lens 54, the light path is changed by a first folding mirror 55 and a second folding mirror 56, and then photosensitive. The state of scanning on the drum 61 is shown.

For example, when irradiating a yellow (Y) image laser beam, the surface of the polygon mirror 52 has the same angle for every four mirrors. Irradiation every other time, an electrostatic image is sequentially formed on the photosensitive drum 61 (Y). The electrostatic image is coated with yellow toner by the developing roller 62 (Y) to form a yellow toner image.

The yellow toner image on the photosensitive drum 61 (Y) is first supplied from a paper supply unit by a paper supply roller 74, the position of the paper 73 and the position of the toner image are controlled by a conveyance roller 75, Is transferred to the sheet 73 conveyed by the transfer belt 66 rotating in the direction of the arrow by a transfer unit 67 (Y) provided below the transfer belt 66.

Next, when magenta (M) image data is irradiated from the laser diode 53 to the M-degree inclined surface adjacent to the Y-degree inclined surface of the polygon mirror 52, the photosensitive drum 61 (M) is irradiated as described above. ), The writing timing of the laser diode 53 is controlled so that a magenta toner image is formed and is superimposed on the transfer belt 66 with the yellow toner image on the paper 73. Overlaid on the screen.

Further, when cyan (C) image data is irradiated from the laser diode 53 onto the C-degree inclined surface adjacent to the M-degree inclined surface, the photosensitive drum 61 (C) is irradiated in the same manner as described above.
A cyan toner image is formed on the sheet 73, and the cyan toner image is superimposed on the yellow toner image and the magenta toner image on the sheet 73.

Subsequently, when black (BK) image data is irradiated from the laser diode 53 to the BK-degree inclined surface adjacent to the C-degree inclined surface, the black toner image is formed on the photosensitive drum 61 (BK) in the same manner as described above. Is formed, and the black toner image is superimposed on the yellow toner image, the magenta toner image, and the cyan toner image on the sheet 73.

As described above, when writing image data of four colors by the laser diode 53, the data of the selected color is converted to yellow (Y) data → magenta (M) for one fixed inclined surface of the polygon mirror 52. Data → cyan (C) data → black (BK) data → yellow (Y) data → magenta (M) data →... Are sequentially controlled to irradiate an inclined surface of a selected color.

The sheet 73 on which all four colors are superimposed is fixed by applying heat and pressure by a fixing unit 76. The fixed sheet 73 is discharged out of the apparatus and stacked on a discharge tray.

Incidentally, as a well-known technique relating to such a color laser printer, for example, Japanese Unexamined Patent Publication No.
The image forming apparatus disclosed in Japanese Patent Application Laid-Open No.
For example, a laser color printer disclosed in JP-A-4-3618 is exemplified.

[0014]

In the case of the above-described color laser printer, in a configuration having four laser units, even if each polygon mirror alone is rotating with high precision, the rotation phases of the polygon mirrors are different, and Since it is impossible to accurately match the phase of the laser beam irradiation of each color, the writing phase on the photosensitive drum of each color is uncertain, so that accurate toner image color superposition is not performed and as a result, a correct image cannot be obtained. There is a problem.

In the case of a configuration having four laser diodes with one polygon mirror as in the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 4-313776, three laser diodes and a control function for the laser diodes are provided. In addition to the problem that the cost becomes high and the size of the laser unit becomes large, there is a problem that the device becomes complicated due to the positioning and control of each laser diode, and the reliability thereof is reduced.

The present invention has been made to solve such a problem, and its technical problem is that the number of laser units can be reduced as much as possible to simplify the alignment with respect to the polygon mirror. Another object of the present invention is to provide a color laser printer capable of improving the color laser printer.

[0017]

According to the present invention, in a tandem type color laser printer having four developing units, the number of mirrors is set to a multiple of four so that the mirrors are formed at the same angle every four surfaces. A color laser printer having one laser unit having a polygon mirror with four different surface angles and one laser diode for sequentially irradiating one color data to one surface of the polygon mirror is obtained. Can be

Further, according to the present invention, in the above color laser printer, four types of image laser beams of a specific color emitted from a laser diode are irradiated on a polygon mirror surface inclined at a predetermined angle and deflected. Thus, a color laser printer having three types of folding mirrors for changing the optical path for scanning on the photosensitive drum for the dedicated color can be obtained.

Further, according to the present invention, in the above color laser printer, a beam detector for detecting an image laser beam of a specific color and outputting a beam detection signal is provided on the photosensitive drum for a dedicated color. A diode laser irradiates the polygon mirror based on the beam detection signal.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color laser printer according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a side sectional view showing a basic structure of a color laser printer according to one embodiment of the present invention.
This color laser printer is also a tandem type having four developing units for printing on four colors of yellow (Y), magenta (M), cyan (C), and black (BK). Drum cleaner 15
(Y), 15 (M), 15 (C), and 15 (BK) attached to photosensitive drums 11 (Y), 11 (M), 11
(C), and four types (Y degrees) of the developing device including 11 (BK) and a mirror surface number which is a multiple of 4 (usually 8 surfaces) and have the same angle every four surfaces. , M degrees,
(C degrees, BK degrees), a laser unit 1 having a polygon mirror (not shown) tilted at 4 degrees and a laser diode for irradiating four-color image laser beams, and a laser beam emitted from the laser unit 1
(Y), 11 (M), 11 (C), 1st folding mirrors 5 (Y), 5 (M), 5 (C) for folding back on 11 (BK) to form an electrostatic image. 5 (BK) and second folding mirrors 6 (Y), 6 (M), 6 (C), 6
(BK) and third folding mirrors 7 (Y), 7
(M), 7 (C), 7 (BK), and the photosensitive drums 11 (Y), 11 (M), 11
(C), 10 (Y), 10 (M), 10 (C), 10 (B) for forming toner images on 11 (BK)
K).

This color laser printer has a driving roller 18, a first driven roller 19, and a second driven roller 2 for feeding and conveying a sheet 23 from a sheet feeding unit.
0, a third driven roller 21, a paper feed roller 24, and a transport roller 25, and transports the paper 23 to the respective photosensitive drums 11 (Y), 11 (M), 11
(C), a transfer belt 16 provided with a transfer belt cleaner 22 for sequentially superimposing single-color toner images formed on 11 (BK) on a sheet 23 to form one toner image; A fixing unit 26 for fixing the toner image to the discharged paper 23 by heat and pressure, a discharge unit for discharging the fixed paper 23 to the outside of the apparatus, a discharge tray for stacking the discharged paper 23, and the like. Is done.

The photosensitive drums 11 (Y), 11
In the vicinity of (M), 11 (C), and 11 (BK), main chargers 14 (Y), 14 (M), 14 (C), 14
(BK), and the transfer devices 17 (Y), 17 (M), 17 (C), and 17 (B) with the transfer belt 16 interposed therebetween.
K) are provided, and the photosensitive drums 11 (Y), 11
(M), 11 (C), and 11 (BK) indicate the developing roller 12
(Y), 12 (M), 12 (C), and 12 (BK) to contact toner supply rollers 13 (Y), 13 (M), 13
(C), 13 (BK) and developing rollers 12 (Y), 12
(M), 12 (C), and 12 (BK) are linked to rotate.

That is, in this color laser printer,
One laser unit for one surface of a polygon mirror in which the number of mirror surfaces in one laser diode 1 is a multiple of 4 and the angle of each mirror surface is inclined to four types so that the same angle is set every four surfaces. Irradiates the data one color at a time.

FIG. 2 is a simplified perspective view showing the structure of the main part of the color laser printer. Here, the number of mirror surfaces is set to a multiple of 4 (usually 8 surfaces), and the angles of the mirror surfaces are set to four types (Y degrees, M degrees, C degrees, and BK degrees) so that the angles become the same every four surfaces. The tilted polygon mirror 2 is controlled so that the image laser beams of the four colors emitted from the laser diode (LD) 3 are irradiated onto the surfaces of the polygon mirror 2 which are tilted by a predetermined degree, and are deflected by those surfaces. 4 (Y), 4 (M), 4
After passing through (C) and 4 (BK), the first folding mirrors 5 (Y), 5 (M), 5 (C) and 5 (BK) and the second folding mirrors 6 (Y) and 6 (BK) M), 6 (C), 6 (B
K) and the third folding mirrors 7 (Y), 7 (M), 7
(C) and 7 (BK), the optical paths of which are respectively changed, and then the photosensitive drums 11 (Y), 11 (M), 11
(C) and 11 (BK) are shown as being scanned along the direction of the arrow.

In other words, the image laser beam of a specific color emitted from the laser diode 3 is applied to the surface of the polygon mirror 2 inclined at a predetermined angle and deflected to form four types of photosensitive drums 11 for exclusive colors. (Y), 11 (M), 11
(C), three types of folding mirrors that change the optical path for scanning on 11 (BK), the first folding mirrors 5 (Y), 5 (M), 5 (C), and 5 (BK) deflect. The reflected beam is reflected to form a second folding mirror 6 (Y),
In 6 (M), 6 (C), and 6 (BK), the reflected beam is reflected again, and the third folding mirrors 7 (Y), 7 (Y),
In (M), 7 (C), and 7 (BK), the re-reflected beam is used as the photosensitive drum 11 (Y), 11 (M), 11 for a dedicated color.
(C) Scan on 11 (BK).

For example, when irradiating a yellow (Y) image laser beam, the surface of the polygon mirror 2 is Y
3A, the laser diode 3 transmits yellow (Y) image data to the lens 4 as shown in FIG.
(Y), the laser beam is controlled so as to be irradiated on the Y-degree inclined surface every four surfaces of the polygon mirror 2, and the irradiated laser beam is emitted by the Y-degree inclined surface of the polygon mirror 2 rotating in the illustrated direction. Deflected, first folding mirror 5
(Y), the second turning mirror 6 (Y), and the third turning mirror 7 (Y) change the optical path, and scan the photosensitive drum 11 (Y) in the direction of the arrow to sequentially form an electrostatic image. Form. The formed electrostatic image is applied to the developing roller 12.
The yellow toner is adhered by (Y) to form a yellow toner image.

The yellow toner image on the photosensitive drum 11 (Y) is first supplied from a paper supply unit by a paper supply roller 24, the position of the paper 23 and the position of the toner image are controlled by a conveyance roller 25, Is transferred by the transfer unit 17 (Y) provided below the transfer belt 16 to the sheet 23 conveyed by the transfer belt 16 rotating in the direction of.

Next, as shown in FIG. 3B, the magenta (M) image data from the laser diode 3 is applied to the lens 4 (M) on the M-degree inclined surface next to the polygon mirror Y-degree inclined surface.
Illuminated, the emitted laser beam is deflected by the M-degree inclined surface of the polygon mirror 2 rotating in the direction shown in the figure, and the first folding mirror 5 (M) and the second
The optical path is changed by the turning mirror 6 (M) and the third turning mirror 7 (M) of the photosensitive drum 11.
(M) Scanning is performed in the direction of the arrow above to sequentially form an electrostatic image.

As in the case described above, the polygon mirror 2 has an inclined surface of M degrees every fourth mirror, so that the laser diode 3 irradiates magenta (M) image data every four mirrors and the photosensitive drum 11 (M). An electrostatic image is sequentially formed thereon. Magenta toner is adhered to the formed electrostatic image by the developing roller 12 (M) to form a magenta toner image.

The writing timing of the laser diode 3 is controlled so that the magenta toner image on the photosensitive drum 11 (M) is superimposed on the transfer belt 16 with the yellow toner image on the transfer belt 16. Is superimposed on the yellow toner screen on the sheet 23 transferred to the sheet 23.

Further, as shown in FIG. 3C, when cyan (C) image data is radiated from the laser diode 3 through the lens 4 (C) to the C-degree inclined surface adjacent to the M-degree inclined surface, A cyan toner image is formed on the photosensitive drum 11 (C), and the cyan toner image is superimposed on the yellow image and the magenta toner image on the sheet 23 conveyed to the transfer belt 16.

Subsequently, as shown in FIG.
When the black (BK) image data is radiated from the laser diode 3 through the lens 4 (BK) to the BK-degree inclined surface adjacent to the BK-degree inclined surface, a black toner image is formed on the photosensitive drum 11 (BK), and the black toner is formed. The image is superimposed on the yellow image, the magenta toner image, and the cyan toner image.

FIG. 4 is a timing chart showing processing signals when writing such four-color image data.

That is, when four color image data are written by the laser diode 3, data of a specific color is converted into yellow (for one fixed inclined surface of the polygon mirror 2) according to the timing of the BD signal obtained by the reference clock. Y) data → magenta (M) data → cyan (C) data → black (BK) data → yellow (Y) data → magenta (M) data →. Will do.

The paper 23 on which all four colors are superimposed is fixed by applying heat and pressure by the fixing unit 26. The fixed paper 23 is discharged out of the apparatus and stacked on a paper discharge tray.

By the way, the laser diode 3 has to irradiate image data of a specific color to a predetermined inclined surface of the polygon mirror 2 rotating at a high speed. Hereinafter, the photosensitive drums 11 (BK), 11 ( C), 11
The timing of writing electrostatic images to (M) and 11 (Y) will be described with reference to the configuration of FIG.

Here, a beam detector 9 and a beam detect mirror 8 are installed on the writing side of the photosensitive drum 11 (BK) in the laser beam scanning direction. According to such a configuration, when a black (BK) image laser beam enters the beam detector 9, a beam detection signal is output from the beam detector 9, so that the laser diode 3 operates based on the output beam detection signal. Then, the screen data of yellow (Y) can be accurately irradiated to the next Y-degree inclined surface of the polygon mirror 2, and a predetermined position on the photosensitive drum 11 (Y) can be irradiated with the laser beam.

Therefore, by adopting such a configuration, the laser beams of each color from the laser diode 3 are sequentially and accurately irradiated on the inclined surface of the polygon mirror 2, and the photosensitive drums 11 (Y), 11 (M), 11 (C), 11 (B
K) It becomes possible to irradiate a predetermined position on the laser beam.

[0040]

As described above, according to the color laser printer of the present invention, the number of mirror surfaces is set to a multiple of four and the angle of each mirror surface is set to four so that the same angle is obtained every four surfaces. Since one laser unit having one laser diode for sequentially irradiating one color data on one surface of the inclined polygon mirror is provided, the conventional apparatus has a laser unit for four colors. Instead of scanning the laser beam on the photosensitive drum with the laser unit for each color, the laser beam can be scanned on the photosensitive drum with one laser unit, and the laser unit can be reduced as much as possible to simplify the alignment with the polygon mirror. Therefore, it is possible to reduce the size of the device and improve the reliability.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a basic configuration of a color laser printer according to an embodiment of the present invention.

FIG. 2 is a simplified perspective view showing a configuration of a main part of the color laser printer shown in FIG. 1;

FIG. 3 is a perspective view showing a detailed state of a laser unit included in a main part shown in FIG. 2; FIG. 3A illuminates yellow image data onto a Y-degree inclined surface of a polygon mirror by a laser diode; FIG. 4B shows the case where magenta image data is irradiated on the M-degree inclined surface of the polygon mirror by the laser diode, and FIG. 4C shows the case where cyan image data is FIG. 4D relates to a case in which black image data is irradiated to a BK-degree inclined surface of a polygon mirror by a laser diode.

FIG. 4 is a timing chart showing processing signals when writing four-color image data by the color laser printer shown in FIG. 1;

FIG. 5 is a side sectional view showing a basic configuration of a conventional color laser printer.

FIG. 6 is a simplified perspective view showing a configuration of a main part of the color laser printer shown in FIG. 5;

[Explanation of symbols]

1, 51 (Y), 51 (M), 51 (C), 51 (B
K) Laser unit 2,52 Polygon mirror 3,53 Laser diode (LD) 4 (Y), 4 (M), 4 (C), 4 (BK), 54 Lens 5 (Y), 5 (M), 5 (C), 5 (BK), 55, 5
5 (Y), 55 (M), 55 (C), 55 (BK) First folding mirror 6 (Y), 6 (M), 6 (C), 6 (BK), 56,5
6 (Y), 56 (M), 56 (C), 56 (BK) Second folding mirror 7 (Y), 7 (M), 7 (C), 7 (BK) Third folding mirror 8 Beam Detect mirror 9 Beam detector 10 (Y), 10 (M), 10 (C), 10 (BK),
60 (Y), 60 (M), 60 (C), 60 (BK)
Developing units 11 (Y), 11 (M), 11 (C), 11 (BK),
61, 61 (Y), 61 (M), 61 (C), 61 (B
K) Photosensitive drums 12 (Y), 12 (M), 12 (C), 12 (BK),
62 (Y), 62 (M), 62 (C), 62 (BK)
Developing rollers 13 (Y), 13 (M), 13 (C), 13 (BK),
63 (Y), 63 (M), 63 (C), 63 (BK)
Toner supply rollers 14 (Y), 14 (M), 14 (C), 14 (BK),
64 (Y), 64 (M), 64 (C), 64 (BK)
Main charger 15 (Y), 15 (M), 15 (C), 15 (BK),
65 (Y), 65 (M), 65 (C), 65 (BK)
Photosensitive drum cleaners 16, 66 Transfer belts 17 (Y), 17 (M), 17 (C), 17 (BK),
67 (Y), 67 (M), 67 (C), 67 (BK)
Transfer device 18, 68 Driving roller 19, 69 First driven roller 20, 70 Second driven roller 21, 71 Third driven roller 22, 72 Transfer belt cleaner 23, 73 Paper 24, 74 Feed roller 25, 75 Transport rollers 26, 76 Fixing unit

Claims (3)

[Claims] 1. A tandem type color laser printer having four developing units, wherein the number of mirror surfaces is a multiple of 4 and the angle of each mirror surface is inclined to four types so that the mirror surface has the same angle every four surfaces. A color laser printer comprising: a mirror; and one laser unit having one laser diode for sequentially irradiating one surface of the polygon mirror with data of one color at a time. 2. The color laser printer according to claim 1, wherein the image laser beam of a specific color emitted from the laser diode is irradiated on a surface of the polygon mirror surface inclined at a predetermined angle and deflected. A color laser printer comprising three types of folding mirrors for changing the optical path for scanning on the photosensitive drum for the dedicated color. 3. The color laser printer according to claim 2, wherein a beam detector for detecting the image laser beam of the specific color and outputting a beam detection signal is provided on the photosensitive drum for the dedicated color, A color laser printer, wherein a laser diode irradiates the polygon mirror based on the beam detection signal.