JPH04255818A - Optical recorder - Google Patents

Abstract

PURPOSE:To provide an optical recorder which has the long range of the depth of focus and where the adjustment of the position of the range of the depth of focus is not needed as an optical recorder using a laser which is used for a laser printer, etc. CONSTITUTION:This recorder is constituted so that plural laser beams 3 and 4 emitted from plural laser light sources 1 and 2 are transmitted through an optical system and formed into an image on the same photosensitive body 13 and so that the positions where the respective beam diameters of the plural laser beams 3 and 4 become the minimum are deviated in the length direction of an optical path.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording device using a laser for use in laser beam printers and the like.

0002

2. Description of the Related Art In recent years, devices that record images by scanning laser light onto a photoreceptor have been widely used in laser beam printers and the like.

An example of a conventional optical recording device will be described below with reference to the drawings. FIG. 8 schematically shows a conventional optical recording device. In FIG. 8, 1 is a semiconductor laser, 3 is a laser beam emitted from the semiconductor laser 1, 5 is a collimator lens, 7 is a first imaging lens system,
10 is a polygon mirror, 11 is a motor, 12 is a second imaging lens system, and 13 is a photosensitive drum.

The operation of the optical recording apparatus constructed as described above will be explained below.

First, a laser beam 3 is emitted from a semiconductor laser 1 in response to an image signal, and a laser beam 3 is emitted from a collimator lens 5.
after being converted into parallel light by the first imaging lens system 7
An image is formed on the reflective surface of the polygon mirror 10. The polygon mirror 10 is rotated by a motor 11, and the laser beam 3 is scanned by the polygon mirror 10. Thereafter, the photosensitive drum 1 is
The image is formed on 3.

FIG. 9 shows the intensity distribution of laser light at positions A and B in FIG. In FIG. 9, D indicates the photosensitive level of the photosensitive drum 13, and recording is performed when a laser beam having an energy of D or more is incident on the photosensitive drum 13. Therefore, when the photosensitive surface of the photosensitive drum 13 is at position A and position B, the beam diameters recorded are da and db shown in FIG. 9, respectively.

FIG. 10 is a diagram showing the relationship between the position in the optical axis direction and the recorded beam diameter. Here, if the allowable beam diameter dimension dk is db≦dk≦da, then l from position A to position C is the range in which the permissible recording beam diameter can be obtained (hereinafter referred to as focal depth range). .

[0008]

[Problems to be Solved by the Invention] However, in the conventional optical recording device described above, the depth of focus range is short, and there are also variations in precision of each component such as the lens, so that the front of the photosensitive drum 13 is not located within the depth of focus range. There were many. In order to obtain an allowable recording beam diameter, the first imaging lens system 7, second imaging lens system 12, photosensitive drum 13, etc. are positioned so that the depth of focus range is located on the surface of the photosensitive drum 13. However, this position adjustment mechanism is complicated and requires a large amount of adjustment time.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an optical recording device that has a long depth of focus range and does not require adjustment of the depth of focus range position.

0010

[Means for Solving the Problems] In order to achieve the above object, the optical recording device of the present invention has a configuration in which a plurality of laser beams are imaged on a photoreceptor by an optical system, in which each of the plurality of laser beams is The position of the minimum beam diameter is shifted in the optical axis direction.

[0011]

According to the present invention, with the above-described configuration, the positions at which the plurality of laser beams have their minimum beam diameters are different, so that the combined depth of focus range becomes longer, making it unnecessary to adjust the position of the depth of focus range.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical recording apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an embodiment of an optical recording apparatus according to the present invention. In FIG. 1, 1 and 2 are semiconductor lasers, and 3 and 4 are semiconductor lasers 1 and 2, respectively.
and 2, 5 and 6 are collimator lenses, 7 and 8 are first imaging lens systems, 9
10 is a half mirror, 10 is a polygon mirror, 11 is a motor, 12 is a second imaging lens system, and 13 is a photosensitive drum.

The operation of the optical recording apparatus constructed as described above will be explained below.

First, laser beams 3 and 4 are emitted from semiconductor lasers 1 and 2 in response to an image signal, and are converted into parallel beams by collimator lenses 5 and 6, and then are emitted by first imaging lens systems 7 and 6. 8, the image is formed on the reflective surface of the polygon mirror 10. Here laser beam 4
In this case, the half mirror 9 causes the laser beam 3 to coincide with the optical axis and the timing of incidence on the polygon mirror 10. The polygon mirror 10 is rotated by a motor 11, and the laser beam is scanned by the polygon mirror 10. After that, the second imaging lens system 12
The laser beam 3 is imaged at point E, which is slightly in front of the surface of the photosensitive drum 13 in the optical path length direction, and the laser beam 4 is imaged at point F, which is slightly further back in the optical path length direction from the surface of the photosensitive drum 13, so that the beam diameter is minimized. be done.

FIG. 2 shows the intensity distribution of the laser beam at position E in FIG. Here, P indicates the intensity distribution of the laser beam 3, Q indicates the intensity distribution of the laser beam 4, and P+Q indicates the combined intensity distribution of the above two types of laser beams. In FIG. 2, D1 indicates the photosensitive level of the photosensitive drum 13, and recording is performed when a laser beam having an energy of D1 or more is incident on the photosensitive drum 13. Therefore, the recording beam diameters corresponding to P, Q and P+Q are dp, dq, respectively.
, dp+q.

At this time, if the allowable beam diameter dk for forming a clear image is db≦dk≦da, then
Only dp has a beam diameter within this range. Therefore, laser beam 3 alone forms an acceptable beam diameter, but laser beam 4 alone and laser beam 3 or 4 combined form an acceptable beam diameter. Not formed.

Here, when the photosensitive level of the photosensitive drum 13 is changed to D2 in FIG. 2, only dp+q becomes the allowable beam diameter.
Although a beam diameter having an allowable size is formed by combining, a beam diameter having an allowable size is not formed by using the laser beams 3 or 4 alone.

FIG. 3 shows the intensity distribution of laser light at position E when the output of semiconductor lasers 1 and 2 is halved. In this case, as in the case where the photosensitive level of the photosensitive drum 13 is changed to D2 in FIG. A beam diameter of dimensions is not formed.

FIG. 4 shows the intensity distribution of the laser beam at position F in FIG. 1, and FIG. 5 shows the output of semiconductor lasers 1 and 2
The intensity distribution of the laser beam at position F is shown when the intensity is reduced to 1/1. As in the case at position E, unless the photosensitive level of the photosensitive drum 13 is changed or the output of the semiconductor lasers 1 and 2 is changed, an allowable beam diameter will be formed with the laser beam 4 alone, but the laser beam 3 A beam diameter of permissible size cannot be formed by combining the laser beams 3 and 4 alone or by combining the laser beams 3 and 4.

[0021] Here, as in the case at the above position E,
When the photosensitive level of the photosensitive drum 13 is changed to D2 in FIG. 4, or when the output of the semiconductor lasers 1 and 2 is halved as shown in FIG. is formed, but the laser beam 3
Or, if 4 is used alone, an acceptable beam diameter cannot be formed.

Therefore, although it was not possible to obtain the permissible beam diameter at both positions E and F using laser beam 3 or 4 alone in any of the above cases, the sensitivity level of the photosensitive drum 13 was changed to D2 in FIGS. 2 and 4. It is possible to obtain the permissible beam diameter at both positions E and F only when the output of the semiconductor lasers 1 and 2 is changed to 1/2 as shown in FIGS. 3 and 5. At this time, the allowable beam diameter is similarly obtained in the vicinity of both positions E and F.

FIG. 6 shows the depth of focus range when the laser beams 3 or 4 are used alone, and FIG. 7 shows whether the sensitivity level of the photosensitive drum 13 is changed to D2 in FIGS. The output of 2 is shown in Figures 3 and 5.
It shows the depth of focus range of laser beams 3 and 4 combined when the depth is changed to 1/2. From FIGS. 6 and 7, when the photosensitive level of the photosensitive drum 13 is changed or the output of the semiconductor lasers 1 and 2 is changed, the focal depth range in the combination of laser beams 3 and 4 is as follows: Laser beam 3 or 4 alone The depth of focus range is longer than that in .

As described above, according to this embodiment, the positions at which the laser beams 3 and 4 have the minimum beam diameter are shifted in the optical axis direction, and the sensitivity level of the photosensitive drum 13 or the semiconductor laser 1 and By adjusting in advance the output level of laser beam 2 to a level different from that when semiconductor laser 1 or 2 is used alone, the depth of focus range for combining laser beams 3 and 4 can be adjusted to the depth of focus for laser beam 3 or 4 alone. It is possible to make it longer than the range.

[0025]

As described above, the present invention provides an optical recording apparatus configured to transmit a plurality of laser beams through an optical system and form an image on a photoreceptor, in which each of the plurality of laser beams has a minimum beam. By configuring the radial position to be shifted in the optical axis direction, the combined depth of focus range becomes longer, and it is possible to realize an optical recording device that does not require adjustment of the depth of focus range position.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of an optical recording device of the present invention.

[
Figure 2: Intensity distribution diagram of laser light at position E shown in Figure 1

[Figure 3] Laser light intensity distribution diagram at position E when the output of semiconductor lasers 1 and 2 is halved

[Figure 4] Intensity distribution diagram of laser light at position F shown in Figure 1

[Figure 5] Laser light intensity distribution diagram at position F when the output of semiconductor lasers 1 and 2 is halved

[Figure 6] Diagram showing the depth of focus range of laser beam 3 or 4 alone

[Figure 7] Diagram showing the depth of focus range when laser beams 3 and 4 are combined

[Figure 8] Schematic diagram of a conventional optical recording device

[FIG. 9] A diagram showing the intensity distribution of laser light at position A and position B shown in FIG. 8.

[Fig. 10] Diagram showing the depth of focus range in the conventional example

[Explanation of symbols]

1, 2 Semiconductor laser (laser light source) 3, 4
Laser beams 5, 6 Collimator lenses 7, 8 First imaging lens system 9 Half mirror 10 Polygon mirror 12 Second imaging lens system

Claims (1)

[Claims] Claim 1: A plurality of laser light sources are provided, a plurality of laser beams emitted from these laser light sources are configured to be imaged on the same photoreceptor by an optical system, and each of the plurality of laser beams is An optical recording device characterized in that the position where the beam diameter is minimum is shifted in the optical axis direction.