JPH065414B2 - Electrophotographic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an image forming apparatus using an electrostatographic process such as an electrophotographic copying machine and a printer, and more particularly to a variable-magnification type image forming apparatus and an editing function. The present invention relates to an electrophotographic apparatus suitable for use in an image forming apparatus of the type.

(Prior Art) In a well-known image forming apparatus (electrophotographic apparatus) for transferring a transferable toner image formed on a surface of an image bearing member as a photoconductor onto a transfer material and fixing and fixing the transferable toner image, various images are printed from the same original. Magnification-changing types capable of obtaining a copy image having a size of 1 are widely used. Further, recently, there is a growing demand for an image forming apparatus having an editing function of erasing an arbitrary portion of a document and inserting another document.

In a variable-magnification type image forming apparatus, the size of the image carrier that forms the image of the original has a certain size so that it can receive the image of maximum magnification. Of course, an unnecessary portion (non-image area) for image formation occurs in a part of the image carrier.

Since the non-image area on the image carrier is not exposed at the time of image exposure, the electric charge is saved, so that the development is performed in the subsequent developing process, and the toner adheres to the non-image area and the toner is wasted. In addition to being consumed, the cleaner is burdened and the inside of the device is contaminated. Therefore, in order to prevent this, it is usual to irradiate the non-image area of the image carrier with light to eliminate the charge in the non-image area.

In addition, in an image forming apparatus having an editing function, it is necessary to erase an arbitrary portion of the electrostatic latent image formed on the image carrier as usual, and therefore, the light is still recorded on an arbitrary portion of the image carrier. To irradiate the area to eliminate static electricity.

Conventionally, as an illuminating device for removing unnecessary charges on the image carrier, as shown in FIG. 10, a suitable number of light emitting elements such as LEDs 32 are arranged so as to face the surface of the image carrier 31. In some cases, these are turned on as needed to eliminate the charge in the non-image area Y as shown in FIG. The LED 32 as a light emitting element includes, for example, a transparent cylindrical portion 33 and a convex lens-shaped light condensing portion 34 at the irradiation side tip.

(Problems to be Solved by the Invention) However, in such a conventional technique, the light emitted from the condensing unit 34 of the LED 32 effectively removes electricity,
A part of the light flux emitted from the cylindrical portion 33 (especially the light flux 35 in the case shown in the figure) enters the image area X, blurs the boundary between the image area X and the non-image area Y, and blurs the image near the boundary. This causes deterioration of image quality.

That is, as shown in FIG. 10, a part of the light flux emitted from the LED 32 enters the boundary portion 36 along the rotation direction on the image carrier 31, so that the image quality of this portion is deteriorated. Further, the light flux from the LED 32 is transmitted to the image carrier 31.
Since the circular area is illuminated above, the boundary between the non-image area Y and the image area X becomes a blurred wave at the boundary portion 37 in the axial direction of the image carrier 31. Note that if an attempt is made to edit with such a configuration, the static elimination portion Z in the image area X
At the boundary of, the same thing as above occurs.

As described above, in the conventional example, in the vicinity of the boundary between the non-image area or the area where the image should be erased and the image area, which is caused by scaling or editing, the image quality is deteriorated and a sharp edge of the image portion may be formed. There was a problem that I could not do it.

The present invention was made in order to solve the above problems of the above-mentioned conventional example, and its purpose is to define a boundary between an image area and a non-image area or a portion where an image should be erased.
It is an object of the present invention to provide an electrophotographic apparatus capable of cutting a light-eliminating beam into a sharp shape, eliminating deterioration of image quality near the boundary, and preventing wasteful consumption of toner.

(Means for Solving the Problems) Therefore, in order to achieve the above-mentioned object, the present invention comprises a rotatable image bearing member and a linearly arranged axially opposite the image bearing member in the axial direction of the image bearing member. In an electrophotographic apparatus that has a plurality of LED elements and exposes the image carrier with light emitted from the LED elements, a rectangle that passes light provided corresponding to each of the plurality of LED elements. The light-shielding member having a shaped opening overlaps the light from the adjacent LED elements on the image carrier by reducing the spread angle of the light from the LED elements provided corresponding to each of the plurality of LED elements. And a convex lens that collects light,
The ED elements are arranged at regular intervals over the entire width in the axial direction of the image carrier, and the image carrier is controlled through the opening of the light shielding member and the lens by controlling the light emission timing of each of the plurality of LED elements. Is exposed to form a non-image portion for image editing.

(Example) Below, this invention is demonstrated based on the Example shown in figure. 8th
An image forming apparatus (electrophotographic apparatus) to which the present invention is applied is shown in the drawing.
2 is shown, and its configuration will be described below.
3 is an original, 4 is an original lamp for illuminating the original 3, 5
Is an image forming optical system including a plurality of mirrors and lenses combined together.

Reference numeral 6 denotes an image carrier as a photoconductor formed in a cylindrical shape, which is rotatably supported in the direction of arrow a in FIG. 8. Around the image carrier 6, a primary charger 7, A developing device 8, a transfer charger 9, and a cleaner 10 are provided. Lighting device 1
Is disposed around the image carrier 6 and between the primary charging device 7 and the developing device 8. Further, although a fixing device and the like are arranged around the image carrier 6, they are omitted for convenience of description.
In the figure, 11 is a transfer material.

The image forming apparatus 2 forms an image of the original 3 on the surface of the image carrier 6 that is uniformly charged by the primary charger 7 through the imaging optical system 5 to form an electrostatic latent image. Form. Then, this electrostatic latent image is visualized by the developing device 8, and the visible image on the image carrier 6 is transferred to the transfer material 11 by the transfer charger 9.
It is used as a fixed image in the fixing device.

Further, the image forming apparatus 2 is a so-called variable-magnification type image forming apparatus in which copies of different sizes can be obtained from an original 3 of the same size by adjusting the position of the lens of the imaging optical system 5. I'm running. The scaling may be performed stepwise or continuously.

In this case, as shown in FIG. 1 (a), A is the image area in the case of the effective image area width of the image carrier 6 depending on the copy magnification, and the image area A Areas B of the adjacent side edges are non-image areas.

The illuminating device 1 is arranged in a large number across the entire width in the axial direction so as to face the surface of the image carrier 6 and illuminates the entire surface of the image carrier 6 where the electrostatic latent image is developed. , To remove the charges in the non-image area B. This lighting device 1
As shown in FIGS. 1 to 3, the light emitting element 12 as an LED element, a light shielding member 13, and a lens member 14 as a convex lens are included, and a light emitting chip 15 is combined as the light emitting element 12. An LED embedded in a mold 16 made of resin or the like is used.

In the illustrated embodiment, the LEDs 12 are linearly arranged at regular intervals to form an LED array (not shown). Corresponding to this, the light blocking member 13 and the lens member 14 are also LEs.
The light-shielding member array 18 and the lens array 19 are arranged in a one-to-one correspondence with D12.

The light-shielding member array 18 is formed by linearly integrally arranging the light-shielding members 13 formed in a black frame shape so as to shield light with a synthetic resin or the like. Each light shielding member 13 is composed of a side wall portion 20 and an inward flange portion 21, and a rectangular opening 22 is formed at the tip of the light shielding member. The inward flange portion is not always necessary here, and the rectangular opening may be formed even in the shape shown in FIG. 1 (b).
The light blocking member array 18 is fixed to a substrate (not shown) of the LED array in a state where the LEDs 12 are housed at predetermined positions in each light blocking member 13.

Further, the lens array 19 is formed by integrally arranging the lens members 14 which are convex lenses made of synthetic resin such as acrylic or glass, as shown in FIG. This lens array 19 includes each lens member 1
It is arranged on the front surface of the light blocking member array 18 so that the optical axis C of 4 passes through the center of the opening 22 of the light blocking member 13. At that time, of course, the LED chip 15 of the LED 12
Is located on the optical axis C. The lens member 14 condenses light so that the divergence angle θ of the light flux emitted from the opening 22 of the light shielding member 13 is reduced and the lights from the adjacent LED elements are overlapped on the image carrier to collect the image. 6 to illuminate the image carrier 6 and increase the illuminance of the light radiated on the image carrier 6 to L
The unevenness of the light amount in the arrangement direction of the ED elements is prevented, and the distance L ₇ between the lens member 14 and the image carrier 6 is increased so that toner or the like floating around the image carrier 6 adheres to the lens member 14. It is intended to prevent a decrease in light amount due to.

The size of the opening 22 of the light shielding member 13, the LED 12
It is necessary to set the dimensions of each part such as the optical path length from to the lens member 14 so that the image carrier 6 is illuminated under predetermined conditions. By the way, using the LED12 of wavelength 610nm,
When acrylic having a refractive index of about 1.5 is used as the material of the lens member 14, as an example of dimensions of each part, FIG. 4 and FIG.
As shown in the figure. Distance between each LED 12 L ₁ = 2.5m
m, the optical path length from the light emitting chip 15 of the LED 12 to the lens member 14 L ₂ = 2.0 mm, of which the part L of the mold 16
₃ = 1.5 mm, air portion L ₄ = 1.0 mm, size of opening 22 length L ₅ = 1.6 mm, width L ₆ = 1.4 mm, radius of curvature R = 2.3 mm of lens member 14, thickness T = 1.4 mm, the distance L ₇ between the lens member 14 and the image carrier 6 is 2.0 mm to 3.0 mm.

In the above configuration, in the electrophotographic apparatus according to the present invention,
The surface of the image carrier is illuminated as follows. That is, the light beam emitted from the light emitting chip 15 of the LED 12 is blocked by the light blocking member 13 and is irradiated in a rectangular shape only from the opening 22.
The divergence angle θ is narrowed down by means of 4, and the image carrier 6 is irradiated in a rectangular shape. Since the side wall portion 20 of the light shielding member 13 exists between the LED 12 and the LED 12,
The light from one LED 12 leaks to the adjacent light shielding member 13 side, and the lens member 1 corresponding to the adjacent LED 12 is provided.
It does not enter 4.

As described above, the light flux emitted from the LED 12 is shaped into a rectangular light flux by the light shielding member 13, and further, the divergence angle θ is narrowed down by the lens member 14 to reduce the spread angle θ.
It is irradiated in a rectangular shape with a high illuminance, and other light flux does not reach the image carrier 6 at all. Therefore, the surface of the image carrier 6 is illuminated in a rectangular shape similar to the opening 22 of the light blocking member 13, and the other portions are not illuminated with light.
Therefore, as shown in FIG. 6, the positions and shapes of the LEDs 12, the light shielding member 13, and the lens member 14 are set so that the areas D and E illuminated by the LEDs 12 partially overlap with each other on the surface of the image carrier 6. By doing so, as shown in FIG. 7, the light amount distribution on the surface of the image carrier 6 does not leak light to the image area A, and only the non-image area B can be sharply illuminated with high illuminance. The amount of light in the valley portion of the distribution is also higher than the level required to eliminate the charge on the image carrier 6, so that the non-image area B is uniformly eliminated.

In the illustrated invention, the case where the lens members 14 are integrally arranged linearly to form the lens array 19 has been described. In such a case, the lens members 14 can be easily manufactured in a state where a large number of the lens members 14 are arranged with high precision. If the lens members 14 are individually formed and arranged and there is an error in the arrangement accuracy of the lens members 14, the LEDs arranged in a straight line are formed.
As shown in FIG. 9, the problem that the light flux from the beam 12 does not illuminate linearly along the axial direction on the surface of the image carrier 6 due to variations in the direction orthogonal to the array can be solved. it can. Further, when the lens members 14 are formed in series as the lens array 19 as described above, a black partition may be provided at the boundary between the lens members 14 by a two-color molding method or the like, if necessary. In such a case, it is possible to more reliably prevent the light from the LED 12 from entering the adjacent lens member 14.

In the illustrated embodiment, the case where the non-image area B is present only on one side of the image area A on the image carrier 6 has been described, but the non-image areas on both sides of the image area A on the image carrier are described. It is needless to say that the present embodiment can be applied even when there is a region.

Further, since the present embodiment illuminates in a rectangular shape, the light emitting elements are arranged along the entire axial length of the image carrier,
It can also be used in the case of irradiating the surface of the image bearing member corresponding to the front end portion and the rear end portion beyond the image area with light to erase charges.

Further, in the illustrated embodiment, the case where the present embodiment is used to eliminate the static electricity in the non-image area caused by the reduction ratio has been described, but the present invention is not limited to this, and the editing function of the present embodiment is not limited to this. It may be used in an image forming apparatus having the same, and in this case, by changing the light emission timing of the LED of the illumination device of this embodiment, any part of the image carrier such as a region where the image should be erased is discharged. You may do it.

(Effects of the Invention) The present invention has the above-described configuration and action. The light emitted from the LED element is blocked by a light shielding member so that the image carrier is proved in a rectangular shape. Since the light passing therethrough is irradiated onto the image carrier, it is possible to illuminate the image carrier in a rectangular shape in a sharp shape. Therefore, it is possible to surely prevent a light flux for performing charge removal from entering the image area, and it is possible to surely remove unnecessary charges on the image carrier, resulting in deterioration of image quality and waste of toner. Consumption can be prevented. In particular, by reducing the spread angle of light from the LED elements, the LEs adjacent to each other on the image carrier are
By providing a convex lens that collects the light so that the light from the D element overlaps, it is possible to prevent uneven light amount in the arrangement direction of the LED elements, and it is possible to obtain a white background without unevenness that is formed in one image. It can be anything.

[Brief description of drawings]

FIG. 1 (a) is a vertical cross-sectional view showing a usage state of the lighting device used in the present invention, and FIG. 1 (b) is a cross-sectional view showing another example of the light shielding member,
FIG. 2 is a plan view showing a state where the lens member of the illumination device is removed, FIG. 3 is a perspective view showing a lens array, FIG. 4 is a sectional view showing dimensions of each part of the illumination device, and FIG. FIG. 6 is a plan view, FIG. 6 is a perspective view showing a light irradiation state of the illuminating device, FIG. 7 is a flag showing a light amount distribution characteristic of the illuminating device, and FIG. FIG. 9 is a perspective view showing a change in the irradiation direction of light depending on the arrangement state of the illuminating device, and FIG. 10 is a schematic diagram showing a using state of the illuminating device used in the conventional electrophotographic apparatus. DESCRIPTION OF SYMBOLS 1 ... Lighting device 12 ... Light emitting element 13 ... Light blocking member 14 ... Lens member

Claims (1)

[Claims] 1. A rotatable image carrier, and a plurality of LEs which are opposed to the image carrier and are linearly arranged in the axial direction of the image carrier.
An electrophotographic apparatus that includes a D element and exposes the image bearing member with light emitted from the LED element, in which a rectangular opening is provided corresponding to each of the plurality of LED elements and through which light passes. And a light-shielding member having a portion, and the LED elements provided corresponding to each of the plurality of LED elements have a small divergence angle of light and are adjacent to each other on the image carrier.
And a convex lens that collects light so that light from the ED element is overlapped, the plurality of LED elements are arranged at a constant interval over the entire axial width of the image carrier, and each of the plurality of LED elements is arranged. The electrophotographic apparatus is characterized in that a non-image portion for image editing is formed by exposing an arbitrary region of the image carrier through the opening of the light shielding member and the lens by controlling the light emission timing of the.