JPS60209760A - Side-unnecessary image erasing device of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To suppress variation in side-unnecessary image erasure range without increasing the cost of the device by adjusting the arrival range of irradiation light with a partition plate which is provided inside of the innermost light emitting diode in a light emitting diode group. CONSTITUTION:For examples, light emitting diodes L1-L61 are arrayed in a main scanning direction and in parallel, and a constant current source 22 which supplies constant currents individually and a drive controller 23 which controls their on-off states are provided. Further, the partition plate equipped with an adjusting screw 24 so as to adjust the interval l from the surface of a photosensitive drum 1 is provided between L2 and L3, L43 and L44, L49 and L50, and L59 and L60. When the specified size of the drive controller 23 is B4 in A4 size copying operation, light emitting diodes L1, L2, and L50-L61, i.e. 14 light emitting diodes are turned on to erase an unnecessary image in outline, but the quantity of image erasure is too large (small) owing to the quatities of light of the light emitting diodes L2 and L59 judging from the copy state of the 1st sheet, partition plates C2 and C49 are moved down to make an adjustment so that the inward diffusion of light is prevented (increased). Consequently, the selection condition of light emitting diodes in use need not be made severe, so an increase in the manufacture cost of the device is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a side unnecessary image erasing device for an electrophotographic copying machine, and more particularly to a side unnecessary image erasing device using a light emitting diode (LED).

[Prior art]

A typical electrophotographic copying machine is as shown in Figure 1.
As the photoreceptor drum 1 rotates, a charge is applied uniformly to the surface of the photoreceptor drum 1 by the charging corotron 2, and then the original 4 placed on the platen 3 is irradiated with light from the light source 5. Reflected light 6 at this time is reflected% 7 a, 7
The light is made incident on the photoreceptor drum through an optical system constituted by a condenser lens 8 and a condenser lens 8, and an electrostatic charge and image corresponding to the image information of the document is formed on the surface of the photoreceptor drum. Then, this electrostatic latent image is visualized by a developing device 9, and the resulting toner image is transferred to a charged paper 11 by a transfer corotron 10. After the transfer, the residual toner on the photoreceptor drum 1 itself and the surface of the photoreceptor drum is electrically neutralized by the static eliminating corotron 12, and the residual toner on the surface of the photoreceptor drum is removed by the cleaning device 13.
Remove by. Thereafter, the surface of the photoreceptor drum 1 is further irradiated with the charge eliminating lamp 14 to return the completely charge-eliminated photoreceptor drum 1 to its pre-charged state, making it possible to use the photoreceptor drum repeatedly. In this way,
The process returns to the first step, which is the charge application step using the charging corotron 2, and copying is continued repeatedly.

By the way, when an electrostatic latent image is formed on the surface of a photoreceptor drum by reflected light from an irradiated document, variations in the distribution of charges applied to the photoreceptor drum,
Or, due to errors in light collection during light irradiation,
Images may be formed on unnecessary parts such as the ends of the photoreceptor drum. This not only results in forming an unnecessary image on the recording paper, but also often causes problems in subsequent steps if the image remains on the photoreceptor drum without being transferred.

Therefore, a side unnecessary image erasing means is used for erasing the electrostatic latent image formed in the unnecessary portion with light from a light emitting diode before it is visualized by the developing device.

This is as shown in FIG. 2 (for example, Ll...L61
An inter-row and side unnecessary image erasing device 15 consisting of 61 light emitting diodes arranged in a row parallel to the main scanning direction.
Image Lamp Assembly - Below 15
A method has been used to erase unnecessary images on the side using an IL assembly (commonly referred to as an IL assembly).

For example, as shown in FIG. 3, on the surface of the photoreceptor drum 10,
When irradiating with 14 light emitting diodes Ll, L2 and "50...'" 61, and trying to irradiate and erase the electrostatic latent image in the unnecessary part on the side, from the inner edge of the light emitting diode that is lit, Distance to the inner edge of the erasable area of the image s4
．． s2 changes depending on the potential of the sensitive material on the photosensitive drum, the luminous efficiency, and the current If flowing through the light emitting diode. Therefore, the paper width W may be the side unnecessary image erasing range (f-image erasing amount)
, a4. The area excluding a2 becomes the clean area R. Here, since the potential of the sensitive material changes depending on the document, it cannot be controlled, but in order to keep the image area R constant, it is necessary to control the luminous efficiency of the light emitting diode and the current flowing through the light emitting diode. Of these, the current can be easily controlled by using a constant current power supply, but in order to keep the light emitting efficiency of the light emitting diode constant, parts must be selected strictly. However, there is a wide variation in the luminous efficiency of single light-emitting diodes currently on the market, and if parts are sorted, the yield may be as low as 5%.
A 15IL assembly using 61 light emitting diodes would be very expensive to manufacture.

Therefore, in order to reduce the variation in image area, usually
Instead of erasing the unnecessary images on both sides using light emitting diodes, a method is used in which one side is erased by another means. For example, in the case of the corner registration method, the image on one side is cut by tightening the width of the charged corotron on the fixed registration side.
Light emitting diodes are used only on one side. However, in this method, since one side of the charged corotron is cut off, there is a problem that the image becomes fainter about 1 cm from the edge.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to suppress variations in the unnecessary image erasing range on the side and to suppress high manufacturing costs of the device.

[Structure of the invention]

In order to achieve the above object, the side unnecessary erasing device of the present invention selects a predetermined number of light emitting diodes at both ends from light emitting diodes arranged in a row parallel to the main scanning direction according to the paper size to be used. In order to light up the 46 photodiodes and erase unnecessary electrostatic latent images prior to the current value, a movable partition plate is installed on the same side of the innermost light emitting diode of the group of light emitting diodes to be lit. The reach range of the irradiated light can be adjusted.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

This side unnecessary image erasing device has 61
15IL assembly 21 formed by arranging 61 light emitting diodes L1...''61 in a row parallel to the main scanning direction.
and a constant current power supply 2 for independently supplying constant current to these light emitting diodes L, . . . L6°.
2, and a drive control device 23 for controlling the blinking of these light emitting diodes L1...L61.

Furthermore, these light emitting diodes L,..."6
1, between L2 and L3, between L43 and L44, L4
9 and L5o, L5. and L6o, as shown in a partially enlarged sectional view in FIG. (not shown) C47, C5,
(not shown).

Next, a side unnecessary image erasing operation using this side unnecessary image erasing device will be explained.

First, when copying using B4 size paper, it is desired to erase all unnecessary images outside the image area R1 shown in FIG. 6(a). Therefore, if the size of the drive control device is specified as 4, the light emitting diode L11
L21 L601 L61 is turned on by a constant current power supply, and the unnecessary image is erased by receiving the light from the light emitting diode.At this time, the state of the first copy is observed, and if the amount of image erasure is too large, Move the partition plate C2'' 59 completely downward, that is, in the direction closer to the surface of the photoreceptor drum 1, to prevent light from diffusing inward.If the amount of image erasing is too small, move the partition plate upward. That is, it moves in a direction away from the surface of the photoreceptor drum 1 and guides the light further inward.In this way, the partition plate C2''5
After adjusting the distance between the photosensitive drum 9 and the photosensitive drum 1, copying is continued. Also, the light emitting diode L2 during copying. L6
Even if the amount of image erasing becomes small due to a decrease in the amount of light at 0, it can be adjusted to some extent by moving the partition plates c2 to c5.

In this way, when copying is continued, the distribution of the amount of image erasure (distance from the edge of the paper to the image area 1) has extremely small variation, as shown in FIG. For reference, FIG. 8 shows the distribution of the amount of image erasure in the case of fc using a conventional device Vik without using a partition plate. From the comparison between FIG. 7 and FIG.
It is clear that the variation in the amount of image erasure has been significantly improved.

In addition, by using such a partition plate, it is possible to compensate for some variation in the amount of light emitted by the light emitting diodes, so the selection conditions for the light emitting diodes to be used do not have to be very strict, which makes it easier to manufacture the device. High costs can be avoided.

In the embodiment, a B4 size copy was described, but when A4 size paper is used, the copying process is as follows. That is, as shown in FIG. 6(b),
Light-emitting diodes L, L2゜L50'' L61, that is, 14 light-emitting diodes are turned on, and after copying one sheet, the state of this copy is observed, and the partitions are set depending on the amount of image erasing. plates C2 and C4
Just adjust the position of 9. In this case as well, the variation in the amount of image erasing can be kept small, and therefore the variation in the image area is also small.

In addition, when using B5 size paper, the light emitting diodes L1, L2, L44...L as shown in FIG.
6. is lit, but in this case as well, the partition plate C
By adjusting 2 and C43, it is possible to suppress variations in the amount of image erasure and to reduce fluctuations in the image area R3.

〔Effect of the invention〕

As described above, according to the present invention, from among the light emitting diodes arranged in a row parallel to the main scanning direction, a predetermined number of light emitting diodes at both ends are turned on depending on the paper size to be used. , unnecessary stillage prior to development! li
When erasing the foil image, a movable partition plate is provided inside the innermost light emitting diode of the group of light emitting diodes to be lit, so that the reach range of the irradiated light can be adjusted. Although a normal light emitting diode is used, variations in the side unnecessary image erasing range can be suppressed, and the manufacturing cost of the device can also be prevented from increasing.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the structure of a general electrophotographic copying machine, Fig. 2 is a diagram showing a normal side unnecessary image erasing device, and Fig. 3 is a diagram showing the erasing range of side unnecessary images by the device shown in Fig. 2. 4 is a diagram showing a side unnecessary image erasing device according to an embodiment of the present invention, FIG. 5 is a partially enlarged sectional view of the same device, and FIGS. 6(a) to 6(c) are the same. FIG. 7 is a diagram showing the mechanism of unnecessary image erasing by the apparatus, FIG. 7 is a diagram showing the distribution of the amount of image erasure by the same apparatus, and FIG. 8 is a diagram showing the distribution of the amount of image erasure by the conventional apparatus. 1... Photosensitive drum, 2... Charged corotron, 3...
...Platen, 4...Document, 5...Light source, 6...
Reflected light, 7a, 7b... Reflecting mirror, 8... Condensing lens, 9... Developing device, 10... Transfer corotron, 11
... Paper, 12 ... Static elimination corotron, 13 ... Cleaning device, 14 ... Static elimination lamp, 15 ... Side unnecessary image erasing device, 21 ... 15IL assembly,
22... constant current power supply, 23... drive control device, L,
...R6, ...light-emitting diode, R* R1, R2
* Rs "'Image area, al + IL2...'Unnecessary image erasure range (image erasure amount), C2r Ca5 * Ca
q aC59...Partition p board. Figure 1 Figure 2 Figure 1 et al Figure 4 Figure 5 Figure 6 ((1) Figure 6 (C) Figure 6 (b) Figure 7 2.0 3.0 4.0 (mm) 5A Power Figure 8 May Power i

Claims (1)

[Claims] It is equipped with light emitting diodes arranged in a row parallel to the main scanning direction, and depending on the paper size used, a predetermined number of light emitting diode groups at both ends are lit to create an electrostatic latent image. In a side unnecessary image erasing device that erases unnecessary side images on a supported photoreceptor drum prior to development, one of the light emitting diodes to be turned on is A side unnecessary image erasing device for an electrophotographic copying machine, characterized in that a movable partition plate is provided inside the innermost light emitting diode.