JPH07242019A - Electrophotographic apparatus and printing method thereof - Google Patents

Abstract

PURPOSE:To easily change over resolving power without adjusting an optical part such as a roof prism or a cylindrical lens. CONSTITUTION:When printing is performed with resolving power of 600 dpi, four multi-beams are applied to a photosensitive drum 11 in matching relation to printing data. When resolving power is changed over from 600 psi to 300 dpi, the photosensitive drum is irradiated with two adjacent scanning beams using the same printing data without adjusting a roof prism or cylindrical lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus using a multi-beam optical scanning device having a resolution switching function and a printing method thereof.

[0002]

2. Description of the Related Art In recent years, in the field of high speed printers, it has been proposed to connect two continuous paper printers to perform double-sided printing. In that case, the deterioration of the printing paper and the fixability of toner are poor. High-speed printing cannot be performed compared to single-sided printing on a stand. Therefore, a variable speed printer has been proposed so that high-speed printing can be performed during single-sided printing and low-speed printing can be performed during double-sided printing by connecting two units. On the other hand, there is an increasing need for high resolution to support image processing. But,
Achieving high-speed printing and high resolution has limitations due to control limitations and the like. So in high-speed printing, low resolution (for example,
300 dpi, high resolution for low speed printing (eg 60
A printer for printing at 0 dpi) is presented.

FIG. 2 is a block diagram showing an example of an electrophotographic apparatus using a conventional multi-beam optical scanning apparatus. First, the laser light 2 emitted from the laser light source 1 is incident on the multi-beam generating grating 3. The grating 3 is for allowing low-order to high-order diffracted light to be emitted with a uniform light intensity. 4 generated in grating 3
The multi-beam of the book is focused by the spherical lens 4 and enters the multi-channel acousto-optic light modulator 5. The four multi-beams, which are respectively modulated, become parallel light by the spherical lens 6 and are arranged in a predetermined beam by the dove prism 7.
The multi-beam is reflected by the mirror 13, and the cylindrical lens 8,
After changing the beam diameters 9 and 14, the rotary polygon mirror 10 optically scans the photosensitive drum 11. The lens 12 is for uniformizing the beam diameter and scanning speed of the multi-beam scanning the photosensitive drum 11. FIG. 3 shows a state of scanning light on the photosensitive drum 11 during oblique line printing.
As shown in FIG. 3, when the resolution is 600 dpi, the pitch interval between scanning beams and the width of one dot are about 42 μm. When switching the resolution from 600 dpi to 300 dpi, it is necessary to set the pitch interval between scanning beams and the width of one dot to about 85 μm, but the pitch interval between scanning beams changes the rotation speed of the rotary polygon mirror 10, and It is changed by adjusting the rotation angle of the dove prism 7. The width of one dot is changed by adjusting the scanning time per dot. Further, by adjusting the cylindrical lenses 8, 9 and 14, the beam diameter on the photosensitive drum 11 is expanded to one suitable for 300 dpi.

[0004]

In an electrophotographic apparatus using a conventional multi-beam optical scanning device, when the resolution is switched, the Dove prism and the cylindrical lens are adjusted.
Adjustment time is required, and there is a problem that the electrophotographic apparatus cannot be used during that time.

Therefore, an object of the present invention is to provide an electrophotographic apparatus capable of easily switching resolutions without adjusting optical components such as a Dove prism and a cylindrical lens.

[0006]

SUMMARY OF THE INVENTION The above object is to provide an electrophotographic apparatus for scanning a plurality of light beams onto a recording material by a single rotating polygonal mirror, and to adjust the plurality of light beams to print data during high resolution printing. This is achieved by irradiating the recording material and irradiating two adjacent scanning lights with the same print data at the time of low resolution printing, thereby performing printing with two kinds of resolutions.

[0007]

When a high resolution printing is performed, a plurality of lights are applied to the recording material in accordance with the print data, and when the low resolution printing is performed, two adjacent scanning lights are applied using the same print data, so that the low resolution is obtained. Since two adjacent scanning lights can be considered as approximately one scanning light at the time of printing, the pitch interval between the scanning beams and the pitch interval between the scanning beams corresponding to the low resolution without changing the beam diameter. And the beam diameter can be realized.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. An electrophotographic apparatus according to the present invention will be described with reference to FIG. Further, FIG. 1 shows a state of scanning light on the photosensitive drum 11 at the time of oblique line printing by the electrophotographic apparatus of the present invention. When printing at high resolution, for example, when printing at a resolution of 600 dpi, control is performed so that the four multi-beams irradiate the photosensitive drum 11 in accordance with print data. When switching from high resolution printing to low resolution printing, for example, 300 dpi resolution, the Dove prism 7, the cylindrical lenses 8, 9 and 14 are not adjusted, and two adjacent scanning lights are exposed using the same print data. The control is performed so that the drum 11 is irradiated. In addition, the width of 1 dot can be changed to 85μ by changing the scanning time of 1 dot.
Set to about m. In this case, the two adjacent scanning lights can be considered approximately as one scanning light, and therefore the pitch interval between the scanning beams and the beam diameter are equal to 85 μm.
It can be expanded to those suitable for 300 dpi.

Further, in an electrophotographic apparatus capable of switching between two types of printing speed, high speed and low speed, it is preferable to perform printing at low resolution during high speed printing and at high resolution during low speed printing.

In the present embodiment, the number of multi-beams is 4, the high resolution is 600 dpi, and the low resolution is 300 dpi. However, in the high resolution printing of the present invention, a plurality of lights are respectively matched with print data on the photosensitive drum 11. It is needless to say that the same effect can be obtained as long as the number of multi-beams and the resolution are established by irradiating two adjacent scanning lights with the same print data during low-resolution printing.

[0011]

According to the present invention, in an electrophotographic apparatus using a multi-beam optical scanning device, at the time of high resolution printing, a plurality of lights are irradiated onto a recording material in accordance with print data, and low resolution printing is performed. At times, two adjacent scanning lights are emitted by using the same print data, so that it is not necessary to change the pitch interval between the scanning beams when switching the resolution in accordance with the switching of the printing speed. This eliminates the need for adjustment of the Dove prism and the adjustment of the lens because there is no need to change the beam diameter on the recording material, so the electrophotographic device will not be unavailable for a long time due to the adjustment. It was

Further, since the beam diameter for scanning at the time of low resolution printing is the same as the beam diameter at the time of high resolution printing, there is an effect that thin lines and halftones are clearly produced. Further, needless to say, when the resolution is switched in the electrophotographic apparatus that switches the resolution at the same printing speed as in the present invention, it is not necessary to change the rotation speed of the rotary polygon mirror.

[Brief description of drawings]

FIG. 1 is a diagram showing a state of scanning light on a recording material during oblique line printing by an electrophotographic apparatus of the present invention.

FIG. 2 is a configuration diagram showing an example of a conventional electrophotographic apparatus.

FIG. 3 is a diagram showing a state of scanning light on a recording material during oblique line printing by a conventional electrophotographic apparatus.

[Explanation of symbols]

1 ... Laser light source, 2 ... Laser light, 3 ... Grating,
4 ... Spherical lens, 5 ... Multi-channel acousto-optic light modulator, 6 ... Spherical lens, 7 ... Dove prism, 8, 9, 14
... Cylindrical lens, 10 ... Rotating polygon mirror, 11 ... Photosensitive drum,
12 ... Lens, 13 ... Mirror

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoji Hirose 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Co., Ltd. (72) Inventor Yuuo Nakajima 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Co., Ltd. (72) Inventor Susumu Saito 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Co., Ltd. (72) Inventor Keiji Kataoka 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Co., Ltd.

Claims (2)

[Claims] 1. An electrophotographic apparatus for scanning a plurality of light beams onto a recording material by means of a single rotating polygonal mirror, wherein at the time of high resolution printing, the plurality of light beams are irradiated onto the recording material in accordance with print data, respectively. An electrophotographic apparatus, which performs printing with two kinds of resolutions by irradiating two adjacent scanning lights with the same print data at the time of resolution printing. 2. An electrophotographic apparatus for scanning a plurality of light beams onto a recording material by means of one rotating polygonal mirror, wherein the printing speed is switched between two types, high speed and low speed, and printing is performed at low resolution at the high speed side printing speed. A printing method for an electrophotographic apparatus, wherein printing is performed at high resolution at a low printing speed.