JP2000155283A - Image forming device using helical mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing cost without lowing image forming speed. SOLUTION: A helical mirror 1 is formed into a shape by which a projected line 1b is spirally provided at the outer peripheral surface of a columnar body 1a, and both side surfaces of the projected line 1b is made as a reflection surface 1c, and the reflection surface 1c is crossed with an axial line by 45 deg.. Two laser elements 2 are arranged so that a laser beam is made incident on the reflection surface 1c in parallel with the axial line on the concentric circle of the helical mirror 1 on both end sides in an axial direction. Photoreceptor drum 3 are respectively arranged in both directions in which the laser beams from the laser elements 2 are reflected by the helical mirror 1, and a developing unit is arranged for each image in the vicinity of the photoreceptor drum 3, and a transfer belt is linearly arranged between the photoreceptive drums 3. Scanning by four laser beams is simultaneously executed by one helical mirror 1, so that the transfer belt is linearly provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applicable to a copying machine, a laser beam printer, and the like, and reflects laser beams from a plurality of laser elements by a helical mirror.
The present invention relates to an image forming apparatus using a helical mirror that forms a full-color image by electrophotography on a photosensitive drum.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for forming a full-color image by electrophotography deflects and scans a laser beam from a plurality of laser elements with a polygon mirror to form a latent image on a photosensitive drum, and forms this latent image. The image is developed by a developing device and transferred to a recording medium. The laser element separately forms images of different colors of magenta, cyan, yellow and black, and transfers these images to a recording medium to form a full-color image, which is transferred from the photosensitive drum to the recording medium. In doing so, any one of the three methods described below is employed.

In the first method, images of different colors of magenta, cyan, yellow and black are formed on four photosensitive drums, respectively, and these four different colors are transferred to the same recording medium. The second method is to form images of different colors of magenta, cyan, yellow or black on the four photosensitive drums, respectively, as in the first method. And the transferred image of the intermediate transfer member is transferred to a recording medium. And the third method is to apply magenta, cyan,
An image of one color of yellow or black is developed and transferred to a recording medium, and the image of each color is sequentially transferred by rotating the recording medium four times.

The image forming apparatus provided with such a plurality of photosensitive drums has an advantage that a conveying path of a recording medium can be set linearly and an image can be formed at a high speed. Further, by providing a plurality of laser elements and one polygon mirror for a plurality of photosensitive drums,
This has the advantage that the number of parts of an expensive polygon mirror can be reduced, thereby suppressing an increase in manufacturing cost. On the other hand, an image forming apparatus having one photosensitive drum reduces the number of components of an expensive photosensitive drum and a polygon mirror,
There is an advantage that an increase in manufacturing cost can be suppressed.

[0005]

However, an image forming apparatus provided with a plurality of photosensitive drums can form an image at a high speed, but requires a plurality of expensive photosensitive drums. There is a problem of rising.

In an image forming apparatus having one photosensitive drum, the number of components of an expensive photosensitive drum and a polygon mirror is small, but the number of transfer processes is large and complicated, and the image forming speed is increased. Is difficult.

Therefore, in any case, it is difficult to balance the manufacturing cost with the image forming speed.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an image forming apparatus using a helical mirror, which can reduce a manufacturing cost without lowering an image forming speed by using the helical mirror.

[0009]

In order to achieve the above object, an image forming apparatus using a helical mirror according to the present invention uses a side surface of a spiral ridge provided on an outer peripheral surface of a cylindrical body as a reflecting surface. A helical mirror, driving means for driving the helical mirror to rotate at a predetermined speed, a plurality of laser elements for emitting laser light from different positions on the circumference concentric with the axis of the cylinder, and the helical mirror. At least one photoconductor means arranged in the traveling direction of the reflected laser light, a developing means for developing a latent image formed on the photoconductor means, and transferring an image developed by the developing means to a recording medium And a transfer unit.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 is a side view of the embodiment, and FIG. 2 is a partial plan view. Two laser elements 2 for emitting image information are arranged at both ends in the axial direction of one helical mirror 1. The laser beams emitted from these laser elements 2 are reflected by the helical mirror 1 two by two on the opposite side. In the traveling direction of the left and right laser beams reflected by the helical mirror 1, one photosensitive drum 3 is arranged, and each photosensitive drum 3 is provided with a primary charging unit for forming a latent image from the laser beam. . An imaging lens 4 is arranged between the helical mirror 1 and the photosensitive drum 3 for each image, and a developing device 5 is arranged near the photosensitive drum 3 for every four images. A transfer belt 6 for transporting a recording medium (not shown) is provided between the photosensitive drums 3.

Further, driving means (not shown) for driving the helical mirror 1, the photosensitive drum 3 and the transfer belt 6 are provided, respectively, and control for controlling these driving means, the laser element 2 and the developing device 5 is provided. Means are provided. The helical mirror 1 is driven to rotate at a high speed clockwise as shown in FIG.
The laser element 2 separately forms images of different colors of magenta, cyan, yellow and black on the photosensitive drum 3. The helical mirror 1, the laser element 2, and the photosensitive drum 3 are controlled synchronously.

As shown in the perspective view of FIG. 3, in the helical mirror 1, a ridge 1b is spirally formed on an outer peripheral surface of a cylindrical body 1a, and both side surfaces of the ridge 1b are reflection surfaces 1c. For example, when two laser elements 2 are arranged at different positions on one end side of the helical mirror 1 in the axial direction, FIG.
As shown in (1), the laser beams L1 and L2 respectively emitted from the laser element 2 are incident on different positions on the reflection surface 1c of the helical mirror 1 and are respectively reflected in different directions.
Therefore, the direction in which the laser beams L1 and L2 are reflected depends on the position of the laser element 2 on the circumference concentric with the axis of the helical mirror 1.

FIG. 5 also shows a case where one laser element 2 is disposed at each end of the helical mirror 1 in the axial direction.
As shown in the figure, the laser light L emitted from the laser element 2
1, L2 are incident on different positions on the reflection surface 1c of the helical mirror 1 and are reflected in different directions. Therefore,
Depending on which side of the helical mirror 1 the laser element 2 is arranged, the direction of reflection of the laser beams L1 and L2 changes.

For this reason, in the embodiment, the helical mirror 1 is formed such that the reflection surface 1c intersects the axis at 45 °. Further, the laser element 2 is arranged on a circumference concentric with the axis of the helical mirror 1 so that the laser beam travels in parallel with the axis of the helical mirror 1 and enters different positions on the reflection surface 1c.

In the image forming apparatus having such a configuration, FIG.
As shown in the figure, the helical mirror 1 rotates at a high speed in the CW direction, that is, clockwise, and the laser light emitted from the laser element 2 travels in parallel to the axis of the helical mirror 1 and enters the reflecting surface 1c, And is reflected in a direction orthogonal to. Note that the dashed line in the figure indicates the optical path of the laser light emitted from the upper laser element 2, and the straight line indicates the optical path of the laser light emitted from the lower laser element 2.

The laser beam reflected by the helical mirror 1 passes through the imaging lens 4 while maintaining the reflection direction, enters the photosensitive drum 3, and forms a latent image on the photosensitive drum 3.
At this time, since the helical mirror 1 is rotating, FIG.
As shown in FIG. 8, the laser beam reflected by the helical mirror 1 moves in parallel in the axial direction with the passage of time, and
Two latent images of different colors are formed on each photosensitive drum 3. Then, these latent images are developed by the developing device 5 and the developed images are sequentially transferred to a recording medium moving on the transfer belt 5 to form a full-color image.

As described above, in the first embodiment, the laser beams from the four laser elements 2 can be simultaneously scanned by one helical mirror 1, so that only one helical mirror 1 is used for scanning. In addition, since the number of components of the photosensitive drum 3 is reduced as compared with the related art, the manufacturing cost is reduced. In addition, the reduction in the number of parts simplifies the structure and allows the entire apparatus to be downsized. And
Since the transfer belt 6 is arranged linearly, the image forming speed does not decrease.

FIG. 9 is a side view of the second embodiment, in which four laser elements 12 on one end of one helical mirror 11 are different on the circumference concentric with the axis of the helical mirror 11. Is located in the position. The helical mirror 12
One photosensitive drum 13 is arranged in the traveling direction of the laser light reflected by the helical mirror 12, one laser light reflected by the helical mirror 12 is directly incident on the photosensitive drum 13, and the other three laser lights are Each is incident on a different position of the photosensitive drum 13 via the mirror 14. In the vicinity of the photosensitive drum 13, a developing unit 15 is arranged for each image, and a transfer belt (not shown) is arranged.

In the second embodiment, the laser element 12
Are reflected at different positions of the helical mirror 11, one reflected laser beam is directly incident on the photosensitive drum 13, and the other three reflected laser beams are reflected by the mirror 13 and are the same. At different positions on the photosensitive drum 13. Other operations are the same as those of the first embodiment.

In the second embodiment, the helical mirror 1
1 is a single-sided reflection surface, and the number of components of the photosensitive drum 13 is smaller than that of the first embodiment. Otherwise, the same effects as in the first embodiment can be achieved.

[0021]

As described above, in the image forming apparatus using the helical mirror according to the present invention, a plurality of laser elements are arranged at different positions on the circumference concentric with the axis of the cylindrical body of the helical mirror. A plurality of laser beams can be simultaneously scanned on the photosensitive member means by one helical mirror. Therefore, the number of components of the scanning mirror and the photoconductor means is reduced, and the manufacturing cost is reduced. In addition, since the number of parts is reduced, the structure is simplified and the entire device is reduced in size.
Further, since the recording medium can be transported linearly, the image forming speed is not reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a first embodiment.

FIG. 2 is a partial plan view.

FIG. 3 is a perspective view of a helical mirror.

FIG. 4 is an explanatory diagram of a reflection direction of a helical mirror.

FIG. 5 is an explanatory diagram of a reflection direction of a helical mirror.

FIG. 6 is an operation explanatory view.

FIG. 7 is an operation explanatory view.

FIG. 8 is an operation explanatory view.

FIG. 9 is a side view of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11 Helical mirror 1a Cylindrical body 1b Ridge 1c Reflection surface 2,12 Laser element 3,13 Photosensitive drum 4 Imaging lens 5,15 Developing device 6 Transfer belt 14 Mirror

Claims (4)

[Claims] 1. A helical mirror having a side surface of a spiral ridge provided on an outer peripheral surface of a cylindrical body as a reflecting surface, driving means for rotating the helical mirror at a predetermined speed, and an axis of the cylindrical body. A plurality of laser elements for emitting laser light from different positions on a concentric circumference; and at least one laser element arranged in a traveling direction of the laser light reflected by the helical mirror.
Individual photoreceptor means, developing means for developing a latent image formed on the photoreceptor means, and transfer means for transferring an image developed by the developing means to a recording medium. Image forming apparatus using a helical mirror. 2. The laser beam from the laser element is made incident on the reflection surface in parallel with the axis, and the helical mirror is rotated about the axis. 2. An image forming apparatus using a helical mirror according to claim 1, wherein the light incident parallel to the axis is scanned in a direction orthogonal to the axis. 3. The method according to claim 1, wherein one helical mirror is interposed between the two helical mirrors.
2. A method according to claim 1, wherein said plurality of photoconductor means are arranged, and two laser elements are arranged at both ends of said helical mirror.
An image forming apparatus using the helical mirror according to 1. 4. One helical mirror and one photoconductor means are arranged, and four laser elements are arranged on one end side of the helical mirror, and reflected by the reflection surface of the helical mirror. 2. An image using a helical mirror according to claim 1, wherein one of the laser beams is directly incident on the photoconductor means, and the remaining three laser beams are incident on the photoconductor means via a mirror. Forming equipment.