JPH01262568A - Image forming device - Google Patents

Abstract

PURPOSE:To miniaturize a device and to form a high quality image by providing a slit having a prescribed slit width on an original supporting member in order to limit the exposing area of an image carrier. CONSTITUTION:The slit (a) having the prescribed slit width is provided on the original supporting member 3 to limit the exposing area of the image carrier (photosensitive drum) 6. Thus, when an original optical image is formed and exposed on the image carrier, its luminous flux is limitted by means of the slit (a); moreover, the exposing area of the image carrier contracts to decrease a difference between the optical path lengths, which is caused by the form of the image carrier. In this case, since the slit (a) is provided on the original supporting member 3, a special member forming the slit is not needed. In addi tion, since the slit (a) adheres to the original, an illuminating light passes through between them to scan the original.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to: 1 an image forming apparatus such as a copying machine, in particular, an image forming apparatus that forms an image by regulating image light with a slit and exposing it to an image on an image carrier; The present invention relates to an image forming apparatus.

(Prior Art) Conventionally, in image forming apparatuses such as copying machines, the image forming apparatus shown in FIG.
), a document 101 placed on a moving document table 100 is illuminated by a lamp 102, and the reflected image light is transmitted to mirrors 103, 104, 105, 106, an imaging lens,
It is known to form a latent image on a photosensitive drum 108 by scanning an image on the photosensitive drum 108 via a photosensitive drum 107, thereby copying an original image. In this case, in order to regulate the image light in a straight line along the photosensitive drum 108, a slit member 10 is installed near the mirror 103 or the photosensitive drum 108.
9 will be installed.

In addition, as shown in FIG. 3(b), the moving document table 11
By illuminating the original 111 on 0 with a lamp 112 and using the reflected image light with a refractive index distribution type lens array 113, linear light is imaged and scanned on the photosensitive drum 114 without providing a slit member. A device has also been devised.

(Problems to be Solved by the Invention) In recent years, various measures have been taken to reduce the size of this type of device. For example, since the gradient index lens array 113 has a short focal length, in the apparatus shown in FIG. This allows the device to be made into a small star. Along with this, the photosensitive drum 114
In recent years, photosensitive drums as small as 30 mm in diameter have been put into practical use.

However, since the photosensitive drum 114 has such a small diameter,
When the image light of the original 111 is image-formed and exposed, the drum 11
For example, the 3rd LI! As shown in J(C), a difference in optical path length occurs between the reading area n of the original 111 and the exposure area Xo' on the drum 114 due to the curvature of the photosensitive drum 114.
As a result, one image is distorted and the resolution is reduced, leading to deterioration in image quality. Incidentally, in the example shown in FIG. 3(c), as shown in Table 1, the difference Δ in the optical axis direction on the drum surface becomes as large as the depth of focus of the maximum lens array 113.

Table I L1 = 17.35 mm, R 15 layers Therefore, in order to prevent image quality deterioration due to this wide range of image exposure, it may be considered to limit the luminous flux of the image light with a member such as a slit.

However, in this type of small device, because the diameter of the photosensitive drum is small, the charging device, developing device, etc. for image formation are crowded near the optical path between the imaging lens system and the photosensitive drum. Therefore, there is no room to provide a new member such as a slit member in this space.

On the other hand, in the space between the document table and the imaging lens, it is necessary to ensure a space for guiding the document illumination light from the lamp so that this illumination light is not blocked.

Therefore, devices that use such small-diameter photosensitive drums have the problem that there is no space for arranging slit members, and it is difficult to achieve both miniaturization and high image quality of the device. Ta.

Therefore, the present invention has been made in order to solve the above-mentioned problems of the prior art, and its purpose is to provide a slit member that restricts the image light without requiring a special space. An object of the present invention is to provide an image forming apparatus that can achieve miniaturization and high-quality image formation.

(Means for Solving Problem W1) In order to achieve the above object, the present invention includes forming and exposing an optical image of a document moving on a document support member onto an image carrier through a slit. The image forming apparatus for forming an image is characterized in that a slit having a predetermined slit width is provided in the document support member to limit an exposure area on the image carrier.

(Function) In the present invention having the above configuration, when the optical image of the original is formed and exposed on the image carrier, the light flux is limited by the slit to reduce the exposure area on the image carrier, To reduce the difference in optical path length due to the shape of an image carrier.

In this case, since the slit is provided in the document support member,
There is no need for a special location for the member forming the slit, and since the slit is in close contact with the document, the illumination light can pass between them to scan the document.

(Example) The present invention will be explained below based on illustrated embodiments.

7 FIG. 1 shows a schematic configuration of main parts of a first embodiment of an image forming apparatus according to the present invention. In the figure, reference numeral 1 denotes a sheet-like original, which is in close contact with the original transport roller 2. This original l is moved between the a-roller 2 and the transparent sheet for placing the original by the rotation of the original transport roller 2 in the direction of arrow P. It is conveyed between the supporting member 3 in the direction of arrow Q. Here, a conveyor belt may be used as the roller 2 for conveying the document.

Reference numeral 4 denotes a lamp for illuminating the original, and the reflected image light of the original l illuminated by this lamp 4 is transmitted through a lens array 5 provided below the support member 3 to an image carrier provided below the array 5. The image is formed on the photosensitive drum 6. here,
The lens array 5 and the photosensitive drum 6 extend in a direction perpendicular to the direction Q in which the document l is conveyed, and each has substantially the same length as the support member 3. As this lens array 5, for example, a gradient index rod lens array such as a SELFOC lens (trade name of Nippon Sheet Glass Co., Ltd.) is used. 12 corners
A glass with a conjugate length of 48.5° was used.

The photosensitive drum 6 is a cylindrical photosensitive member with an outer diameter of 30 layers,
The distance between the lens array 5 and the drum 6 is 111IL=113
5- It is arranged with a thorn. Further, around the photosensitive drum 6, means for forming an image using an electrophotographic method is provided. That is, 7 is a primary charger that charges the surface of the photosensitive drum 6 with static electricity, 8 is a developer that visualizes the latent image of the document formed on the surface of the drum 6, and 9 is a device that records a visible image on the surface of the drum 6. Transfer charger for transferring to paper, IO is drum 6
This is a cleaner for erasing residual toner on the surface, and is also provided with a fixing device (not shown) for fixing the toner image on the recording paper.

Incidentally, in this embodiment, in order to increase the amount of transmitted light through the lens array 5, a wide aperture angle of 12 degrees is used, and an image is formed on a small photosensitive drum 6 with an outer diameter of 30 mm. It is structured as follows. For this reason, as explained based on FIG. 3(C), there is a difference in the optical path length between the document l and the surface of the drum 6, which causes the image around the exposed surface of one image to deteriorate. That will happen.

Therefore, in this embodiment, a light shielding member S is used as a field stop to regulate the reflected image light on the support member 3 for carrying the original.
This is provided. This light shielding member S is provided on the upper surface of the support member 3 in a portion illuminated by the lamp 4, and has a slit a having approximately the same length as the lens array 5, and furthermore, the slit width is approximately 6 mm. This is set to be smaller than the width of the reading surface on the original 1. Here, as the light shielding member S, in addition to painting a predetermined area on the upper surface of the support member 3 black, a recess is provided on the support member 3, and a black plate is placed in the recess so as not to interfere with the conveyance of the original l. It may also be configured to attach a member.

In the above configuration, when the lamp 4 is turned on to copy an image of the document 1 conveyed in the direction of the arrow Q, the image light reflected by the document 1 is regulated by the light shielding member S to the slit width,
The illumination width on the surface of the photosensitive drum 6 in the drum rotation direction is regulated to be narrow. In other words, as shown in Figure 1,
The visual field indicated by the dotted line A when the light shielding member S is not provided is as follows:
By providing the light shielding member S, light in the vicinity of the exposure area X of the image light irradiated onto the photosensitive drum 6, which is sandwiched between the range shown by the solid line A, is cut off.

Therefore, in the exposure area X on the surface of the small-diameter photosensitive drum 6, the difference in distance between the center and the end of the lens array 5 is not very large, and as a result, there is a large difference in the projection magnification of each part on the exposure area X. Since this does not occur and does not cause a decrease in resolution, it is possible to prevent deterioration of image quality and form a clear image. In this case, since the light shielding member S is provided integrally with the support member 3 that supports the document, it is possible to achieve miniaturization of the apparatus without requiring a special space, and the light shielding member S is provided in close contact with the document L. Therefore, the illumination light from the lamp 4 is not blocked, and desired reflected image light can be obtained.

Furthermore, this transparent support member 3 is included in the main body of the device including the lamp 4 and the lens array 5.

If the light intensity distribution in the longitudinal direction of the slit (a) is adjusted during optical adjustment of the main body of the apparatus, even if the cartridge containing the photosensitive drum 6, charger 7g, and developer 9 is replaced, the area near the photosensitive drum of a conventional cartridge can be adjusted. There is also the advantage that there is no need to perform light amount correction every time the cartridge is replaced, unlike devices provided with slit members.

FIG. 2 shows a second embodiment of the image forming apparatus according to the present invention, and hereinafter, the same parts as in the first embodiment will be described with the same reference numerals. This support member supports the 1M document 1 and guides image light to the photosensitive drum 6 by using mirrors 20, 21, 22, 23 and an inverted real image imaging system continuously variable magnification lens 24 instead of the lens array 5. 3, a light shielding member S similar to that of the previous embodiment is provided. In this case, since the reading width of the original 1 is determined to be the optimum width, compared to the case where the slit member is arranged near the mirror 20 to avoid the original illumination light as in the conventional example,
It is possible to prevent the exposed area on the surface of the photosensitive drum 6 from spreading due to the penumbra of the slit, and it is possible to form a high-quality image similar to that of the embodiment described above, as well as to achieve miniaturization of the apparatus. The other configurations and operations are the same as those of the first embodiment, so their explanation will be omitted.

(Effects of the Invention) In the present invention having the above-described configuration and operation, a slit having a predetermined slit width is provided in the document support member to limit the exposure area on the image carrier. Even when an image is formed on a drum-shaped photoreceptor, it is possible to prevent deterioration in image quality and form a clear image.

Further, since the three and three are provided on the document support member, there is no need to secure a special space for arranging the slit, and the apparatus can be miniaturized.

Furthermore, since the slit is in close contact with the document, it does not block illumination light, and provides various effects such as being able to obtain desired reflected image light.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a main part of a first embodiment of an image forming apparatus according to the present invention, FIG. 2 is a schematic diagram showing a main part of a second embodiment of an image forming apparatus according to the present invention, Figure 3(a),
(b) and (c) show a conventional image forming apparatus, and (a) is a schematic configuration diagram showing the main parts of an apparatus that performs exposure using a mirror, an imaging lens, and a slit. FIG. 1B is a schematic diagram showing the main parts of an exposure apparatus using a lens array, and FIG. 1C is an explanatory diagram showing the principle of image deterioration when a small-diameter photosensitive drum is used. Explanation of symbols l... Original 3... Supporting member (original supporting member) 5... Lens array 6... Photosensitive drum (image carrier) A, B... Field of view a... Slit S. ...Canon Co., Ltd., patent applicant for light shielding member. Agent: Patent Attorney Kazunobu Sera; Figure 1

Claims (1)

[Scope of Claims] An image forming apparatus that forms an image by exposing an optical image of a document moving on a document support member onto an image carrier through a slit, comprising: an exposure area on the image carrier; An image forming apparatus characterized in that a slit having a predetermined slit width is provided in the document supporting member to limit the amount of slit.