JPH0872308A - Image forming device - Google Patents

Abstract

PURPOSE: To obtain an image forming system whose scanning width can be increased without enlarging the entire system. CONSTITUTION: All elements are constructed so that multiple light beams radiated from multiple light sources 1a, 1b are guided to the same scanned face 8 through different multiple light guiding means 12a, 12b, deflecting means 4a, 4b, and image forming means 5a, 5b, and optical scanning can be made for the same scanning area of the scanned face.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, it uses a plurality of light beams to share the same scanning area on the same surface to be optically scanned to thereby reduce the scanning width in the main scanning direction. The present invention relates to an image forming apparatus which is increased and records image information such as characters and images, which is suitable for a printing apparatus or the like.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a printing apparatus, a laser unit (light source means) has been used as shown in FIG.
The light-modulated light beam (laser light) from 41 is guided to a polygon mirror (scanning mirror) 44 as an optical deflector via a collimator lens 42 and a cylindrical lens 43, and is deflected and reflected by the polygon mirror 44. The formed light beam is guided to the surface of the photosensitive drum 48 as the surface to be scanned through the folding mirror 47 by the image forming means (image forming optical system) including the toric lens 45 and the image forming lens 46. Then, a beam spot diameter (spot diameter) having a predetermined size is formed on the surface of the photosensitive drum 48, whereby image information is sequentially formed on the surface of the photosensitive drum 48.

The photosensitive drum 48 is uniformly charged by a primary charging unit 49 and is subjected to scanning exposure with a light beam at an exposure position to form an electrostatic image. The latent image is developed by the developing unit 50. Then, the image is a copy sheet 5 fed from a sheet feeding cassette (not shown) between the photosensitive drum 48 and the transfer unit 51.
3 is transferred to the photosensitive drum 4 by the separation unit 54.
Separated from 8. Then, after being conveyed to the fixing unit 55, the image is fixed and discharged to a discharge tray (not shown),
Next, the transfer material of the toner image left after the transfer is removed by the drum cleaning unit 56.

In such an image forming apparatus, it has been desired in recent years that users can print image information such as characters and images on a larger sheet. For that purpose, it is necessary to further widen the scanning width (scanning area in the main scanning direction) of the light beam on the surface to be scanned as compared with the scanning width of the conventional image forming apparatus.

Therefore, in the conventional image forming apparatus, as a method of increasing the scanning width, for example, the focal length of the image forming optical system is lengthened or the number of polygon mirrors (rotating polygon mirrors) as an optical deflector is reduced. Widening the scanning angle was considered.

[0006]

However, when the focal length of the imaging optical system is increased, the size of the entire apparatus becomes large, which makes it difficult to make the size of the apparatus compact. Further, if the number of faces of the polygon mirror is reduced and the scanning angle is widened, for example, in order to obtain the same resolution as that of the conventional image forming apparatus, it is necessary to increase the rotation speed of the drive motor for driving the polygon mirror. However, there was a problem in that this was mechanically limited and very difficult to realize.

A first object of the present invention is to guide a plurality of light beams emitted from a plurality of light source means onto the same surface to be scanned through a plurality of different light guide means, deflecting means, and image forming means. However, the present invention is to provide an image forming apparatus capable of increasing a scanning width by sharing the same scanning area of the surface to be scanned with the plurality of light beams and performing optical scanning.

A second object of the present invention is to simultaneously guide a plurality of light beams emitted from a plurality of light source means to different deflecting surfaces of a single deflecting means through different light guiding means, and to obtain the different deflecting surfaces. The plurality of light beams deflected and reflected by the optical path are guided to the same surface to be scanned through one set of image forming means, and the plurality of light beams share the same scanning area of the surface to be scanned. An object of the present invention is to provide an image forming apparatus capable of increasing the scanning width by scanning.

[0009]

The image forming apparatus of the present invention comprises (1-1) a plurality of light guide means, a deflecting means, and an image forming means which are different from each other for a plurality of light beams emitted from a plurality of light source means. Each element is configured so that light is guided to the same scanned surface via the same and the same scanning area of the scanned surface is shared and optically scanned.

(1-2) In particular, each of the plurality of deflecting means comprises an optical deflector having a plurality of deflecting surfaces, is driven by the same driving means, and emits light emitted from the plurality of light source means. The beams share and radiate the laser drive signals created from the image information for one line developed on the memory, and the beams are emitted in the sub-scanning direction with respect to the deflection surfaces of the plurality of optical deflectors. Arranging optical means having a plurality of light source means and a light guide means, using a plurality of light beams emitted from the plurality of light source means to simultaneously optically scan a plurality of lines in the sub-scanning direction, The light beams emitted from the light source means provided in the sub-scanning direction with respect to the deflection surfaces of the plurality of optical deflectors respectively emit laser drive signals generated from image information of a plurality of lines developed on the memory. Sharing to have characterized such that it is radiated.

The image forming apparatus of the present invention comprises: (2-1) A single optical deflector having a plurality of deflecting surfaces for a plurality of light beams emitted from a plurality of light source means via different light guide means. The light beams are respectively guided to different deflecting surfaces of the deflecting means, and the plurality of light beams deflected and reflected by the different deflecting surfaces are guided to the same scanned surface by one set of image forming means, and the same scanned surface is provided. It is characterized in that each element is configured to perform optical scanning by sharing the respective scanning areas.

(2-2) In particular, the light beams emitted from the plurality of light source means share the laser drive signals generated from the image information for one line developed on the memory and emit the respective laser drive signals. Alternatively, optical means having a plurality of light source means and a light guide means are respectively arranged in different sub-scanning directions on different deflecting surfaces of the light deflector, and a plurality of light beams emitted from the plurality of light source means are used. Optical scanning of a plurality of lines in the sub-scanning direction at the same time, and the light beams emitted from a plurality of light source means respectively provided in the sub-scanning direction with respect to different deflecting surfaces of the optical deflector are stored in the memory. It is characterized in that the laser drive signals created from the image information of the developed plural lines are respectively shared and emitted.

[0013]

Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention.

In the figure, reference numerals 1a and 1b denote light source means (laser units), each of which is composed of, for example, a semiconductor laser, and emits a light beam (laser light) optically modulated based on an image signal. In this embodiment, a laser drive signal is created from the image information for one line developed on the memory, and the laser drive signal is divided by half in each of the light source means 1a, 1a.
b, and two light beams simultaneously emitted from the respective light source means 1a and 1b, respectively, outside the same scanning area on the surface of the photosensitive drum 8 as the surface to be scanned, as will be described later (end portions).
Image scanning of data for one line is performed by optically scanning from 8A and 8C toward the inner side (central portion) 8B.

Reference numerals 2a and 2b denote collimator lenses, which convert the light beams emitted from the light source means 1a and 1b into substantially parallel light beams. Cylindrical lenses 3a and 3b each have a predetermined refractive power only in the sub-scanning direction. In this embodiment, the collimator lens 2a (2
b) and the cylindrical lens 3a (3b) constitute the light guiding means 12a (12b), and the light guiding means 1
The optical means 1 includes the light source means 1a (1b) and the light source means 1a (1b).
1a (11b) is configured.

Optical deflectors 4a and 4b each serve as a deflecting means, and are composed of, for example, a polygon mirror (rotating polygonal mirror) having a plurality of deflecting surfaces (reflection surfaces). In this embodiment, the same motor such as a motor is used. It is rotated at a predetermined speed in the direction of arrow C by the drive means (power device) 10 via the respective transmission parts 20a and 20b.

Reference numerals 5a and 5b denote image forming means (image forming optical systems) each having an f-θ characteristic, and the toric lenses 5a1 and 5a1.
5b1 and imaging lenses 5a2 and 5b2, the light beams A and B deflected and reflected by the optical deflectors 4a and 4b are imaged on the surface of the photosensitive drum 8 through a single folding mirror 7. ing.

The photosensitive drum 8 is rotated at a predetermined speed in the arrow E direction (sub-scanning direction) by a driving means (not shown) such as a motor, and image information is written as a latent image on the surface of the photosensitive drum 8. Incidentally, around the photosensitive drum 8, there are arranged a charging means, a developing means, a transfer means, and the like, which are not shown, as electrophotographic process means.

In this embodiment, a laser drive signal is created from the image information for one line developed in the memory, and the laser drive signal is sent to each of the light source means 1a and 1b in half, and the two light source means are provided. Two light beams A and B simultaneously emitted from 1a and 1b are made into substantially parallel light beams by the corresponding collimator lenses 2a and 2b, and are made incident on the respective cylindrical lenses 3a and 3b.

Of the parallel light beams incident on the cylindrical lenses 3a and 3b, the parallel light beams are emitted as they are in the main scanning section, and are converged in the sub scanning section to be deflected by the respective optical deflectors 4a and 4b. Surface (reflection surface) 4a
The images are formed on 1, 4b1 as substantially line images.

After that, the deflection surface 4 of each optical deflector 4a, 4b
The two light beams A and B deflected and reflected by a1 and 4b1 are imaged on the same surface of the photosensitive drum 8 through the single folding mirror 7 by the corresponding imaging optical systems 5a and 5b.

By rotating each of the light deflectors 4a and 4b in the direction of arrow C in the figure via the transmission units 20a and 20b by the single power unit 10, the respective light beams A and B are transferred to the surface of the photosensitive drum 8. The same scanning area is simultaneously scanned from outside (end portions) 8A and 8C to inside (center portion) 8B as indicated by arrow D. Then, when the optical scanning is performed up to the central position 8B on the surface of the photosensitive drum 8, the exposure of one line is completed (the exposure of one line is completed), and the image information for one line is recorded.

In the present embodiment, since the driving device (power device) 10 for driving the respective light deflectors 4a and 4b is used as a single device, the same rotation speed can be maintained and the light beam can be maintained. There is an advantage that the scanning times are all the same.
As a result, a good image without jitter is obtained.

As described above, in the present embodiment, as described above, a plurality of light beams emitted from a plurality of light source means are used to share the same scanning area on the same surface to be scanned and perform optical scanning simultaneously. The scanning width (scanning area in the main scanning direction) can be increased, whereby image information such as characters and images can be formed using a large paper in the main scanning direction.

FIG. 2 is a schematic view of the essential portions of Embodiment 2 of the present invention. In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

This embodiment is different from the above-mentioned embodiment 1 in that the light deflector and the image forming means are each composed of one set of elements, and the different deflecting surfaces of the light deflector emit light from each light source means. A light beam is made incident respectively, and two light beams deflected and reflected by the two different deflecting surfaces share the same scanning area of the surface to be scanned through one set of image forming means to perform optical scanning. Is. Other configurations and optical functions are substantially the same as those of the first embodiment, and the same effect is obtained.

That is, in the present embodiment, a laser drive signal is created from the image information for one line developed on the memory, and the laser drive signal is divided by half in each of the light source means 1a, 1a.
b, and the two light beams A and B simultaneously emitted from the two light source means 1a and 1b are converted into substantially parallel light beams by the corresponding collimator lenses 2a and 2b, and are made incident on the cylindrical lenses 3a and 3b. ing.

Of the parallel light beams incident on the cylindrical lenses 3a and 3b, the parallel light beams are emitted in the state of parallel light beams in the main scanning cross section as they are, and in the sub scanning cross section they are converged and converged on different deflecting surfaces of the optical deflector 24 ( Reflective surface) 24
The images are formed as substantially linear images on a and 24b, respectively.

After that, each deflection surface 24a of the optical deflector 24,
The two light beams A and B deflected and reflected by 24b are imaged on the same photosensitive drum 8 surface by the imaging optical system 15 via the single folding mirror 7.

The optical deflector 24 is driven by a driving means (not shown).
By rotating in the direction of arrow C in the figure, the light beam A of the two light beams A and B is optically scanned from the central portion 8B to the end portion 8A of the photosensitive drum 8 as indicated by arrow D1 in the figure, and the other light beam A is scanned. The light beam B is optically scanned from the end portion 8C of the photosensitive drum 8 toward the central portion 8B as indicated by an arrow D2 in the figure.
Then, when the light beam A optically scans to the end portion 8C of the photosensitive drum and the light beam B optically scans to the central portion 8B of the surface of the photosensitive drum 8, one line of exposure is completed (one line exposure is completed). By this, image information for one line is recorded.

In this embodiment, as described above, a plurality of deflection surfaces of a single polygon mirror are used at the same time, and a plurality of light beams deflected and reflected by the plurality of deflection surfaces are used to optically scan the surface to be scanned. Therefore, it is possible to smoothly obtain the sync signal for writing the scan without causing the scanning deviation of the light beam in the sub-scanning direction.

FIG. 3 is a schematic view of the essential portions of Embodiment 3 of the present invention. In the figure, the same elements as those shown in FIG. 2 are designated by the same reference numerals.

The present embodiment differs from the above-mentioned second embodiment in that it has a light source means in the sub-scanning direction with respect to different deflection surfaces of the optical deflector, and a light guide means composed of a collimator lens, a cylindrical lens or the like. Two optical means are provided, and a plurality of lines (two lines) in the sub-scanning direction can be optically scanned at the same time by using the light beam from each optical means. Other configurations and optical functions are substantially the same as those of the second embodiment, and the same effect is obtained.

That is, in the figure, 31a (31b, 31
c, 31d) is an optical means, and is a light source means 1a (1b,
1c, 1d) and the light source means 1a (1b, 1c, 1d)
Collimator lens 2a (2b, 2c, 2d) for converting a light beam emitted from the laser beam into a parallel light beam, and a cylindrical lens 3a (3 having a predetermined refractive power only in the sub-scanning direction.
b, 3c, 3d) and light guide means 32a (32b,
32c, 32d). Of the plurality of optical means 31a, 31b, 31c, 31d, the optical means 31
As shown in the figure, a and 31c are juxtaposed in the sub-scanning direction with respect to the same deflection surface of the optical deflector 34, and the other optical means 31b and 31d sub-scan with respect to the deflection surface different from the above. It is juxtaposed in the direction.

In this embodiment, a laser drive signal is created from the image information for two lines developed on the memory by such a configuration, and the signal for the first one line is divided into two light source means 1a and 1b. To the other two light source means 1c and 1d. And four light source means 1a, 1b, 1c, 1d
Four light beams A1, B1, A2 emitted simultaneously from
Collimator lenses 2a, 2b, 2 corresponding to B2 respectively
The light beams are made to be substantially parallel by c and 2d and are made incident on the respective cylindrical lenses 3a, 3b, 3c and 3d.

Each of the cylindrical lenses 3a, 3b,
Of the parallel light beams incident on 3c and 3d, the parallel light beams are emitted as they are in the main scanning cross section, and are converged in the sub scanning cross section. And four light beams A
Two light beams A1, A2 of 1, B1, A2, B2
Is formed as a substantially linear image on the deflection surface (reflection surface) 34a of the optical deflector 34, and the other two light beams B1 and B2 are deflected on the deflection surface 3
The image is formed as a line image on 4b.

In this embodiment, the two light beams reflected by the same deflecting surface are reflected at positions separated by one dot in the sub-scanning direction, so that exposure for two lines can be performed simultaneously. There is.

After that, each deflection surface 34a of the optical deflector 34,
Four light beams A1, A2, B deflected and reflected by 34b
Images 1 and B2 are imaged on the same surface of the photosensitive drum 8 through a single folding mirror 7 by a pair of imaging optical systems 15.

The optical deflector 34 is driven by a driving means (not shown).
Of the four light beams A1, A2, B1, B2 by rotating them in the direction of arrow C in the figure by
A2 performs optical scanning from the central portion 8B of the photosensitive drum 8 toward the end portion 8A as indicated by an arrow D1 in the figure, and other light beams B1 and B2
Indicates an optical scan from the end portion 8C of the photosensitive drum 8 toward the central portion 8B as indicated by an arrow D2 in the figure. And the light beam A1,
A2 optically scans to the end 8A, and another light beam B1,
When B2 optically scans to the central portion 8B of the surface of the photosensitive drum 8, the exposure of two lines is completed (two-line exposure is completed), and the image information for two lines is recorded.

As described above, in the present embodiment, different deflecting surfaces of a single polygon mirror are used at the same time, and a plurality of light beams deflected and reflected by the different deflecting surfaces form a plurality of lines in the sub-scanning direction as described above. By optical scanning at the same time,
The scanning width is increased and the image processing speed is increased.

In the first embodiment described above, only one optical means is provided for the deflection surface of each optical deflector. However, as in the third embodiment, for example, a sub-device is provided for the deflection surface of the optical deflector. By arranging a plurality of optical means in parallel in the scanning direction, a plurality of lines in the sub-scanning direction can be optically scanned at the same time, which makes it possible to increase the scanning width and speed up image processing.

[0042]

According to the present invention, as described above, a plurality of light beams simultaneously emitted from a plurality of light source means are transmitted through different light guide means, deflecting means, and image forming means on the same surface to be scanned. By configuring each element so that the same scanning area of the surface to be scanned is shared and optical scanning is performed, a driving device for driving the optical deflector can be provided without enlarging the entire device. It is possible to achieve an image forming apparatus that can easily increase the scanning width without increasing the number of rotations.

Further, according to the present invention, as described above, a plurality of light beams simultaneously emitted from a plurality of light source means are passed through different light guide means to different deflecting surfaces of a single deflecting means having a plurality of deflecting surfaces. A plurality of light beams that are respectively guided and deflected and reflected by the different deflecting surfaces are guided to the same scanned surface by one set of image forming means, and the same scanning area of the scanned surface is shared. By configuring each element to perform optical scanning by means of optical scanning, it is possible to achieve an image forming apparatus that can easily increase the scanning width without increasing the size of the entire apparatus.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a schematic view of the essential portions of Embodiment 2 of the present invention.

FIG. 3 is a schematic view of the essential portions of Embodiment 3 of the present invention.

FIG. 4 is a schematic view of a main part of a conventional image forming apparatus.

[Explanation of symbols]

 1a. 1b, 1c, 1d light source means 2a. 2b, 2c, 2d Collimator lens 3a. 3b, 3c, 3d Cylindrical lens 4a, 4b, 24, 34 Deflection means 5a, 5b, 15 Imaging means 7 Folding mirror 8 Photosensitive drums 11a, 11b Optical means 31a, 31b, 31c, 31d Optical means 12a, 12b Light guiding means 32a, 32b, 32c, 32d Light guide means

Claims (9)

[Claims] 1. A plurality of light beams emitted from a plurality of light source means are guided to the same scan surface via a plurality of different light guide means, deflection means, and image forming means, and the scan surface is scanned. The image forming apparatus is configured such that each element is configured to perform optical scanning by sharing the same scanning area. 2. The image forming apparatus according to claim 1, wherein each of the plurality of deflecting means comprises an optical deflector having a plurality of deflecting surfaces, and is driven by the same driving means. 3. The light beams emitted from the plurality of light source means share the respective laser drive signals generated from the image information of one line developed on the memory and emit the laser drive signals. The image forming apparatus according to claim 1. 4. Optical means having a plurality of light source means and a light guide means in the sub-scanning direction are respectively arranged on the deflection surfaces of the plurality of light deflectors, and a plurality of light sources emitted from the plurality of light source means are provided. The image forming apparatus according to claim 2, wherein a plurality of lines in the sub-scanning direction are optically scanned at the same time by using a light beam. 5. A light beam emitted from light source means provided in the sub-scanning direction with respect to the deflection surfaces of the plurality of light deflectors is a laser generated from image information of a plurality of lines developed on a memory. The image forming apparatus according to claim 4, wherein the drive signals are shared and emitted. 6. A plurality of light beams emitted from a plurality of light source means are respectively guided to different deflecting surfaces of a single deflecting means composed of an optical deflector having a plurality of deflecting surfaces through different light guiding means. , A plurality of light beams deflected and reflected by the different deflecting surfaces are guided to the same scanned surface by one set of image forming means, and the same scanning area of the scanned surface is shared and optically scanned. An image forming apparatus in which each element is configured as described above. 7. The light beams emitted from the plurality of light source means share the laser drive signals generated from the image information for one line developed on the memory, and emit the laser drive signals. The image forming apparatus according to claim 6. 8. Optical means having a plurality of light source means and a light guide means in the sub-scanning direction are respectively arranged on different deflecting surfaces of the optical deflector, and a plurality of lights emitted from the plurality of light source means are provided. 7. The image forming apparatus according to claim 6, wherein a plurality of lines in the sub-scanning direction are simultaneously optically scanned using a beam. 9. Light beams emitted from a plurality of light source means respectively provided in different sub-scanning directions on different deflecting surfaces of the optical deflector are created from image information of a plurality of lines developed on a memory. 9. The image forming apparatus according to claim 8, wherein the laser drive signals are shared and emitted.