JP2949522B2 - Exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] An exposure apparatus which is a part of a recording unit of an image forming apparatus such as a printer, a copying machine, a facsimile, etc., which uses an electrophotographic system, performs a uniform angular velocity movement on a latent image forming light. The purpose is to convert the latent image forming light from constant angular velocity motion to constant velocity linear motion, with the aim of enabling correct information to be formed on the image carrier even if the accuracy of processing the reflecting surface of the rotating or rotating mirror is low. In a latent image forming exposure apparatus provided with an fθ lens for incidence on the image carrier, at least a part of each surface excluding the entrance surface and the exit surface of the fθ lens is formed by rough surface processing, whereby The n-th light incident on the fθ lens is diffused.

[Industrial applications]

The present invention relates to a printer, a copier,
The present invention relates to an exposure device that is a part of a recording unit of an image forming apparatus such as a facsimile.

In an image forming apparatus of this type, for example, an electrophotographic printer, the surface of a rotating image carrier is uniformly charged by corona discharge using a charger. Next, a light corresponding to the recorded information is irradiated from the exposure device on this to form a latent image (potential image) on the surface of the photoconductor. Next, a toner image is formed by attaching toner particles charged by being stirred by the developing device to the latent image. On the other hand, the recording paper is fed to the transfer position at a predetermined timing from the rotation of the photoconductor from the paper feeding unit, and comes into contact with the toner image at the position. Then, the toner image is attracted to the paper by corona discharge from the back of the paper by the transfer device. In this case, the paper is electrically attracted to the photoreceptor, so that a high-voltage AC potential is discharged from the back of the paper by a separation transfer device that performs corona discharge, and the paper is electrically neutralized. Then, the paper is separated from the photoreceptor by gravity, and then sent to a fixing device to fix the toner image. The residual toner remaining on the photoreceptor is removed by the cleaner brush, and the process returns to the charging step.

In the above-described exposure apparatus used for forming a latent image in an image forming apparatus having such a configuration and operation, it is necessary to irradiate the photosensitive member only with light corresponding to the record information. It is essential to shut off.

[Conventional technology]

FIG. 3 is a schematic diagram illustrating the configuration of an exposure apparatus. In the figure, reference numeral 1 denotes an image carrier (photosensitive drum), and 2 denotes an exposure apparatus.

The exposure device 2 includes a light source such as a laser (not shown), a polygon mirror 4, an fθ lens 4, and a reflection mirror 5.

The above-described latent image formation on the image carrier 1 is performed by guiding the constant angular velocity scanning light emitted from the light source and reflected on the reflecting surface of the rotating mirror 3 to the fθ lens 4, and passed through the fθ lens 4 at a constant velocity straight line. The motion scanning light is reflected by the reflection mirror 5 and the reflected light 6 is irradiated on the image carrier 1.

[Problems to be solved by the invention]

In such an exposure apparatus, if the processing accuracy of the reflecting surface of the rotating mirror 3 is low, as shown in FIG. 4 (a), a part of the light corresponding to the recorded information is irregularly reflected, and correct information is transferred to the image carrier. 1
It cannot be formed on the top. FIG. 4 (b) shows a printing state when n-order light 7 (see FIG. 4 (a)) such as diffusely reflected light or stray light is generated.

Therefore, the processing of the reflecting surface of the rotating mirror 3 requires high precision, the yield of the mirror is reduced, and the processing time is prolonged.
Was very expensive. This problem is the same when a swinging mirror is used instead of a rotating mirror.

SUMMARY OF THE INVENTION The present invention provides an exposure apparatus capable of forming correct information on an image carrier even if the swinging or rotating mirror has a low reflection surface processing accuracy for causing a latent image forming light to perform a constant angular velocity movement. It is intended to be.

[Means for solving the problem]

In order to achieve the above-described object, the present invention provides a latent image forming exposure apparatus including an fθ lens for converting a latent image forming light from a constant angular velocity motion to a constant velocity linear motion to be incident on an image carrier. At least a part of each surface of the fθ lens other than the incident surface and the outgoing surface is formed by roughening, thereby diffusing n-order light incident on the fθ lens.

(Operation)

If the accuracy of the reflecting surface of the oscillating or rotating mirror that generates the constant angular velocity scanning light is low, n-order light such as stray light generated by the mirror enters the fθ lens, but the incident surface and the exit surface of the fθ lens Since each surface or a part thereof is roughened (pear-skinned) and has low surface accuracy, the n-order light is diffused. Therefore, it is possible to prevent the energy from being concentrated on the characteristic portion on the image carrier, and to prevent the image from being adversely affected.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 and FIG.

FIG. 1 is a diagram for explaining the operation of the fθ lens of the exposure apparatus of the present embodiment. In the drawing, reference numeral 11 denotes an fθ lens. Reference numeral 3 denotes a polygon mirror as in the prior art.

The light reflected by the reflecting surface of the rotating mirror 3 is incident on the fθ lens 11, and the light passing through the fθ lens 11 is reflected by a reflection mirror (not shown) to irradiate the image carrier to form a latent image. Will be

fθ lens 11 has a low surface accuracy because each surface or a part of the surface except the entrance surface 12 and the exit surface 13 is roughened such as a matte surface, and the accuracy of the reflection surface of the rotating mirror 3 is low. The n-order light 7 such as stray light incident on the incident surface 12 of the fθ lens 11 is diffused. Accordingly, it is possible to prevent energy from being concentrated on a specific portion on the image carrier, and to prevent an adverse effect on an image.

FIG. 2 shows a printing state when the fθ lens 11 is used.
Even when the n-th light is incident on the image carrier, good printing is realized by forming light corresponding to correct recording information on the image carrier.

〔The invention's effect〕

As described above, according to the present invention, even if n-order light such as stray light is incident on the fθ lens, it can be diffused and prevented from adversely affecting the image.
There is no need to increase the precision of the reflecting surface of the oscillating or rotating mirror, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view for explaining the operation of the fθ lens of the exposure apparatus according to the embodiment of the present invention, FIG. 2 is a view for explaining the effect of the present invention, FIG. 3 is a schematic view for explaining the configuration of the exposure apparatus, and FIG. And (b) are diagrams for explaining the problems of the conventional exposure apparatus, where 1 is an image carrier, 3 is a rotating mirror, 7 is an n-order light, 11 is an fθ lens, 12 is an entrance surface, and 13 is an exit surface. It is.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takao Sugano 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 26/10

Claims (1)

(57) [Claims] 1. A latent image forming exposure apparatus comprising: an fθ lens (11) for converting a latent image forming light from a constant angular velocity movement to a constant velocity linear movement to be incident on an image carrier; (11) entrance surface (12) and exit surface (13)
At least a part of each surface except for is formed by rough surface processing,
Thus, the exposure apparatus is configured to diffuse the n-order light incident on the fθ lens (1).