JPS63158966A - Image recorder - Google Patents

Abstract

PURPOSE:To manage only with one rotary polygon mirror or f-theta lens and to eliminate the difficulty of positioning, by making incident laser beams with different wavelengths on the rotary polygon mirror fitting for the same optical path, and making it incident on a photosensitive material after separating the optical path of reflected light. CONSTITUTION:Th optical paths of the laser beams with different wavelengths from laser light sources 16 and 17 which emit optical signals by switching them with the time difference of one revolution of the photosensitive material are integrated in one optical path by means of integrating means 20 via collimator lenses 18 and 19 respectively, and it is scanned by the rotary polygon mirror 21. The beam of light is separated to two beams of light by a separating means 23 such as a dichroic mirror, etc., via the f-theta lens 22, and is made incident on the photosensitive material via mirrors 24 and 25. Since the beams of light with different wavelengths are made incident from the same optical path to the polygon mirror 21, it is not required to provide a cylindrical lens behind the f-theta lens 22, and the positioning for exposure can be facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image recording device that can form a composite image by inputting a plurality of scanned laser beams onto a photoreceptor such as an electrophotographic photoreceptor. Regarding.

[Background of the invention]

The conventional image recording device described above, which scans multiple laser beams independently, uses a rotating polygon mirror as a scanning means, an f-theta lens, etc. that corrects the spot incident distribution of the laser beams and focal fluctuations. Not only the number of laser beams is required, but also the spot incident positions of the plurality of laser beams need to be appropriately aligned. It is extremely difficult to accurately and stably perform this alignment because the rotating polygon mirror has variations in rotation speed and surface accuracy.

To solve the above problem, two laser beams are incident on the same surface of one rotating polygon mirror at different angles, and the scanned laser beams are incident on the photoreceptor through a common f-theta lens. In this regard, an image recording device has been proposed in Japanese Patent Application Laid-Open No. 161566/1983, in which the laser light incident obliquely on the rotation axis of the rotating polygon mirror is made incident through a cylindrical lens that corrects the distortion of the scanning line. In addition, two laser beams are incident on different surfaces of one rotating polygon mirror, and the scanned laser beams are incident on each electrophotographic photoreceptor through an f-theta lens,
An image recording device that transferred and synthesized the toner images formed on the electrophotographic photoreceptor onto transfer paper was developed in Japanese Patent Laid-Open No.
This is proposed by Japanese Patent No. 95361. Apart from the fact that the latter laser beams are incident on separate electrophotographic photoreceptors to form toner images, which makes alignment difficult, when comparing the optical systems of the two, the former Because they are incident on the same surface of the rotating polygon mirror, there is less difficulty in alignment due to variations in surface precision than when they are incident on different surfaces, but since the incident angles are different, it cannot be completely eliminated, and correction is required. There is also the problem that a cylindrical lens is required. The latter does not require a cylindrical lens because the two laser beams can be incident at right angles to the rotation axis of the rotating polygon mirror, but as mentioned above, the laser beams are incident on different surfaces, making alignment difficult due to variations in surface precision. In addition to the problem that the f-θ lens is required for each laser beam, there is also the essential problem that the scanning directions of the two laser beams are opposite to each other.

[Purpose of the invention]

The present invention has been made for the purpose of providing an image recording device equipped with an optical system that solves both of the above problems.
Only one lens is required, there is no need for a cylindrical lens after the f-theta lens, and the scanning direction of multiple laser beams is the same, completely eliminating the problem of difficulty in positioning due to variations in the surface accuracy of the rotating polygon mirror. (This provides an image recording device equipped with an optical system.

[Structure of the invention]

The present invention provides an image recording device that forms a composite image by making a plurality of scanned laser beams incident on a photoreceptor surface at different positions. An image recording device characterized in that laser beams are made incident on a rotating polygon mirror by aligning the same optical path with a combining means, and the optical paths of the reflected laser beams are separated again with a separating means so that each beam is incident on a photoreceptor surface. This configuration achieves the above object.

〔Example〕

The present invention will be explained below using illustrated examples.

FIG. 1 is a schematic side view of the configuration of an example of the image recording device of the present invention, FIG. 2 is a partial plan view of FIG. 1, and FIG. 3 is another example of an optical system for combining two types of laser beams. The perspective view and FIG. 4 are spectral characteristic graphs of the multilayer film plate.

The image recording apparatus shown in FIGS. 1 and 2 is an electrophotographic recording apparatus in which a drum-shaped photoreceptor 1 rotates in the direction of the arrow.
A developing device 4 whose surface is charged by a charger 2, and a laser beam 3 scanned onto the charged surface is incident to form an electrostatic image, and the electrostatic image is formed using toner of a different color as a developer. or 5, the surface having the toner image is charged again by the charger 6, and the scanned laser beam 7 is incident on the charged surface to form an electrostatic image again. is developed into a toner image by the developing device 8 or 9 which uses toner of different colors as a developer, thereby forming an image consisting of a composite of two color toner images on the surface of the photoreceptor 10, and the composite image The transfer device 11. whose surface has been placed in an inactive state. When it passes through the separator 12 and the cleaning device 15 and reaches the charger 2 again, it is charged again by the charger 2, and the scanned laser beam 3 is incident on the charged surface again to form an electrostatic image. The electrostatic image is developed by a different developing device 5 or 4, thereby forming an image consisting of a composite of three color toner images on the surface of the photoreceptor 1, and the surface on which the composite image exists is The charged surface is charged again by the charger 6, and the laser beam 7 scanned again is incident on the charged surface to form another electrostatic image, and the electrostatic image is converted into a toner image by a different developing bag W, 9 or 8 A color image is formed by combining four color toner images, and the color image is transferred by the transfer device 11 to the recording paper P fed by the paper feeder 10, and the transferred recording paper P is separator 1
2, the photoconductor 1 is separated from the photoconductor 1 by a conveyance device 13, and sent to a fixing device 14 by the fixing device 14, where the color image is fixed and the photoconductor 1 is discharged outside the machine. 15, the remaining toner is removed and the state returns to the state where the next image forming process is repeated again.

The above is a case of recording a color image consisting of a composite of four-color toner images, but when recording a composite image of two-color toner images, transfer, etc. is performed at the stage when the composite image is formed. Needless to say, the charger 6
Of course, it is also possible to record a monochromatic image or a three-color image by not performing charging by electrification or incidence of the laser beam 7, etc. Therefore, the developing devices 4.5 and 8.9 are equipped with a non-contact developing system that can perform development without damaging the previously formed toner image and can be easily switched to a non-operating state. is preferably used.

In addition, a scorotron corona discharger is preferably used as the chargers 2 and 6 because it is less affected by previous charging (it can provide stable charging), and the cleaning device 15 is equipped with a cleaning blade or a fur brush in an inactive state. Photoreceptor 1
A material that moves away from the surface is used.

The optical system includes a laser light source 16 equipped with a drive circuit that switches and emits optical signals based on color-specific image data that produce electrostatic images developed by the developing devices 4 and 5 at a time difference of one rotation of the photoreceptor 1; , a color that produces an electrostatic image that is similarly developed in the developing devices 8 and 9 at a timing delayed by the time that the surface of the photoreceptor l moves the distance between the incident positions of the laser beams 3 and 7. Laser beams with different wavelengths emitted from similar laser light sources 17 that emit optical signals based on different image data with a time difference of one rotation of the photoreceptor 1 are passed through collimator lenses 18 and 19, respectively, and then the polarizing beam splitter The optical paths are combined into one by the combining means 20, and the combined output light from the combining means 20 is incident on the rotating polygon mirror 21, and the reflected light scanned by the rotating polygon mirror 21 is passed through the f-theta lens. 22, the laser beams 3 and 7 are separated again into two laser beams 3 and 7 by a separating means 23 such as a multilayer plate such as a gicroic mirror, and these laser beams 3 and 7 are sent to a photoreceptor by mirrors 24 and 25, respectively. incident on l. In this way, two types of laser beams are combined into one by a combining means, scanned by a rotating polygon mirror, and then separated into two again, each of which is made incident on the photoreceptor 1. Therefore, both laser beams can be incident at the same position in the direction perpendicular to the rotation axis of the rotating polygon mirror 1, the scanning direction is the same, and the problem of difficulty in alignment due to variations in surface accuracy is eliminated, and f- 〇There is no need to provide a cylindrical lens after the lens, making it easier to align the exposure, and if it is separated after passing through the f-theta lens 22 as shown in the example, the f-theta lens can be Only one laser beam is required for each laser beam.

When a polarizing beam splitter is used as the combining means 20, the laser light sources 16, 17 are arranged such that their p-n junction planes are orthogonal to each other with respect to the polarizing beam splitter. The output light can be made to pass through collimator lenses 18, 19 and then directly enter the polarizing beam splitter as shown in FIG. 1.2. Further, as shown in FIG. 3, the laser light source 16
．． Assuming that the semiconductor laser 17 is arranged such that the p-n junction plane is parallel to the combining means 20, that is, the polarizing beam splitter, the emitted light of the semiconductor laser 16, for example, is emitted after passing through the collimator lens 18. Rotate the plane of polarization by 90@ rotation means 2 such as a wave plate
The zero-combining means 20, which may be made to enter the polarizing beam splitter after passing through the polarizing beam splitter 6, is not limited to the above-mentioned polarizing beam splitter, but may also be one having the same configuration as the separating means 23.

In the illustrated example, a multilayer film plate is used for the separation means 23, but the present invention is not limited to this, and a prism having a multilayer film or a polarization beam splinter similar to the combining means 20 may also be used. Wavelength 800 n+s as shown in the figure
When using a multilayer film plate with spectral characteristics that separate the laser light sources 16 and 17 with the wavelength 800 nm at the center,
A laser that emits light with a wavelength shorter than 800 nm, for example 780 nm, and a laser that emits light with a wavelength longer than 800 nm, for example 810 nm.
If a laser that emits light of n+ wavelength is used, both laser beams can be completely separated.

The multilayer plate shown in FIG. 4 exhibits a transmittance close to 100% at an incident angle of 90'' regardless of the wavelength of the incident light.

The image recording apparatus of the present invention is not limited to the illustrated example, and may be one that is equipped with two optical systems as shown in FIG. Alternatively, it may be equipped with an optical system as shown in FIG. For example, the system may be configured such that three laser beams of different wavelengths are combined, then incident on a rotating polygon mirror for scanning, and then separated into three beams and incident on the photoreceptor.

It uses two uniting means and two separating means, and
The combination and separation may be performed in stages.

〔Effect of the invention〕

In the image recording apparatus of the present invention, only one rotating polygon mirror or one f-theta lens is required for the plurality of laser beams, no cylindrical lens is required after the f-theta lens, and the scanning direction of the plurality of laser beams can be adjusted. Similarly, there is no problem of difficulty in positioning due to variations in the surface precision of the rotating polygon mirror, and therefore the device can be configured small and inexpensively, and it is possible to easily record multicolor images without color shift. You can get excellent results.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of the configuration of an example of the image recording device of the present invention, FIG. 2 is a partial plan view of FIG. 1, and FIG. 3 is another example of an optical system for combining two types of laser beams. The perspective view, FIG. 4, is a spectral characteristic graph of the multilayer wainscot. 1... Photoreceptor, 2.6-... Charger, 3.
7... Laser light, 4.5.8.9-... Developing device, 10-... Paper feeding device, 11... Transfer device, 1
2-... Separator, 13... Conveying device, 14
... Fixing device, 15... Cleaning device, 16, 17... Laser light source, 18.19... Collimator lens, 20... Combining means, 21... Rotating polygon mirror,
22...f-theta lens, 23-...separation means, 2
4, 25--mirror, 26--rotating means. Figure 1 Figure 2 Figure 3 Device 4: Beggar

Claims (2)

[Claims] (1) In an image recording device that forms a composite image by making a plurality of scanned laser beams incident on a photoreceptor surface at different positions, the plurality of laser beams use laser beams with different wavelengths, and the plurality of laser beams An image recording device characterized in that the beams are made to be incident on a rotating polygon mirror along the same optical path by a combining means, and the optical paths of the reflected laser beams are separated again by a separating means so that each beam is incident on a photoreceptor surface. (2) The image recording apparatus according to claim 1, wherein the separation by the separation means is performed after passing through an f-theta lens.