JPH0154704B2 - - Google Patents

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 camera is as shown in FIG. 1. As the photoreceptor drum 1 rotates, a charging corotron 2 first applies electric charges uniformly to the surface of the photoreceptor drum 1, and then A document 4 placed on a platen 3 is irradiated with light from a light source 5, and the reflected light 6 is reflected by mirrors 7a, 7b and a condenser lens 8.
The electrostatic latent image is made incident on the photoreceptor drum through an optical system constituted by the above, and an electrostatic latent image corresponding to the image information of the document is formed on the surface of the photoreceptor drum. This electrostatic latent image is visualized by the developing device 9, and the resulting toner image is transferred to the corotron 1.
The image is transferred onto the paper 11 charged with 0. After the transfer, the photoreceptor drum 1 itself and the residual toner on the surface of the photoreceptor drum are electrically neutralized by the neutralizing corotron 12, and the residual toner on the surface of the photoreceptor drum is removed by the cleaning device 13. . After this, the surface of the photoreceptor drum 1 is further irradiated by the static elimination lamp 14 to return the completely neutralized photoreceptor drum 1 to its pre-charged state, making it possible to use the photoreceptor drum repeatedly. be. 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, an image 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 an unnecessary portion with light from a light emitting diode before it is visualized by the developing device.

For example, as shown in FIG. 2, L ₁ ...L ₆₁
The inter and side unnecessary image erasing device 15 consists of 61 light emitting diodes arranged in a row parallel to the main scanning direction.
Side Image Lamp Assembly (hereinafter referred to as ISIL assembly) was used to erase unnecessary side images.

For example, as shown in FIG. 3, the surface of the photoreceptor drum 1 is illuminated with 14 light emitting diodes L ₁ , L ₂ , L ₅₀ ...L ₆₁ , and the electrostatic latent image in the unnecessary part on the side is
When attempting to erase, the distances S ₁ and S ₂ from the inner edge of the lit light-emitting diode to the inner edge of the erasable area of the image are determined by the potential of the sensitive material on the photosensitive drum, the luminous efficiency, and the light-emitting diode. It changes depending on the current I _f flowing through. Therefore, the image area R is the area obtained by subtracting the side unnecessary image erasing ranges (image erasing amounts) a ₁ and a ₂ from the paper width W. Here, since the potential of the sensitive material changes depending on the document, it cannot be controlled, but various measures have been taken to control the amount of light from the light emitting diode in order to keep the image area R constant. For example, normal copying is performed by using methods such as controlling the current flowing through the light emitting diode using a constant current power supply, or strictly selecting parts to keep the light emitting efficiency of the light emitting diode constant. In this case, the amount of image erasing is adjusted to be constant and the image area R is adjusted.

By the way, when using an automatic document feeder, skew feeding or misalignment of side registration is an unavoidable problem, but side images can be erased for normal copying (when the automatic document feeder is not used). When adjusting the amount, there was an inconvenience that black streaks appeared at the edges of the copy when the document was shifted diagonally due to automatic feeding. vice versa,
If the side erase amount was adjusted to be large for automatic document feeding, there was a problem in that the erase amount was too large during normal copying.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and
In both automatic document feed mode and normal copy feed mode, adjust the image erasure amount to an appropriate value to obtain beautiful copies without black streaks at the edges. It is an object of the present invention to provide a side unnecessary image erasing device that can eliminate unnecessary images.

[Structure of the invention]

In order to achieve the above object, the side unnecessary image erasing device of the present invention recognizes in advance the relationship between the appropriate image erasing amount in automatic feed mode and the appropriate image erasing amount in normal copying feeding mode. and, depending on the relationship, when the automatic document feeding mode is selected as the mode is changed, a switching adjustment means is provided for switching so as to expand the reachable range of the light irradiated by the light emitting diode. This switching adjustment means changes the amount of current applied to the light emitting diode.The amount of current applied to the light emitting diode is kept constant, and the light reach range is adjusted by adjusting the height of the shielding plate, that is, the distance from the photoreceptor. It is possible to easily obtain beautiful copies by using the same light emitting diode and adjusting the intensity of the light or adjusting the range of light with a shielding plate.

〔Example〕

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

As shown in FIG. 4, this side unnecessary image erasing device includes an ISIL assembly 21 in which 61 light emitting diodes _L1 ... _L61 are arranged in a row parallel to the main scanning direction, and these light emitting diodes. A constant current power supply 22 for independently supplying constant current to L ₁ ...L ₆₁ , and these light emitting diodes L ₁ ...L ₆₁
and a drive control device 23 for controlling the blinking of the light.

Furthermore, this drive control device 23 operates while an operation signal is input from the automatic document feed mechanism 24.
Operating current value I _f in normal case (when the automatic document feed mechanism does not operate and the operator sets the document)
is multiplied by a predetermined value,
The feed mode switching adjustment device 25 is equipped with a built-in microcomputer that controls the feed mode to increase the feed rate.

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

First, when copying using B4 size paper, as shown in Figure 5, image area R ₁
I want to delete all the images outside of. If the size specification of the drive control device is B4, the light emitting diode L ₁ ,
A constant current is supplied to L ₂ , L ₆₀ , and L ₆₁ , and when the document feeding mode is set to manual at this time, the operation signal from the automatic document feeding mechanism 24 is
OFF, and the feed mode switching adjustment device 25
controls the current flowing through the constant current power supply 22 by controlling the current in the manual feed mode.

In addition, the document is transported by the automatic document feed mechanism 24.
When the document is sent, an activation signal from the automatic document feed mechanism 24 is input to the feed mode switching adjustment device 25. The feed mode switching adjustment device 25 performs current control in the automatic feed mode, and the operating currents of the light emitting diodes L ₁ , L ₂ , L ₆₀ , and L ₆₁ are controlled.

In this way, the light emitting diode is lit
The side unnecessary images are erased by the irradiation lights L ₁ , L ₂ , L ₆₀ , and L ₆₁ . At this time, the image erasure amounts a ₁ , a ₂ (distance from the edge of the paper to the image area) in the normal feeding mode are a ₁ , a ₂ = 2 mm as shown in Figure 6a, and in the automatic feeding mode, As shown in Figure 6b, a ₁ ,
a ₂ =5mm. Even in the automatic feed mode, beautiful copies can be obtained without black streaks occurring at the edges of the copies. Furthermore, in the case of normal feed mode, it is possible to widen the image area.

For comparison, an example is shown in which the automatic feed and normal feed are operated with the same current as in the past.The amount of image erased is 3.5 mm.
When automatic feeding was used, black lines sometimes appeared at the edges of copies.

In the embodiment, a method has been described in which the operating current value I _f is switched and controlled depending on the mode, but the method is not necessarily limited to this, and as shown in FIG. A movable partition plate C is provided inside the light-emitting diodes arranged on the innermost side of the screen, and by moving this partition plate closer to or away from the photoreceptor drum, the reach range of the irradiated light from the light-emitting diodes can be adjusted. Adjustment methods are also effective.

As described above, according to the present invention, without reducing the arrangement pitch of the light emitting diodes, by adjusting the amount of current applied to the light emitting diodes or moving the shield plate to adjust the distance from the photoreceptor,
It is possible to make fine adjustments to the light reach range extremely easily.

〔Effect of the invention〕

As explained above, according to the present invention,
Depending on the paper size used, select one of the light emitting diodes arranged in a row parallel to the main scanning direction.
When a predetermined number of light-emitting diodes at both ends are turned on to erase unnecessary electrostatic latent images prior to development, when the document is being fed automatically, the light irradiated by the light-emitting diodes is directed toward the inside of the document compared to when the document is being fed normally. Because it is adjusted to reach up to It becomes possible to widen the area.

[Brief explanation of drawings]

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 shows the erasing range of side unnecessary images by the device in Fig. 2. FIG. 4 is a diagram showing a side unnecessary image erasing device according to an embodiment of the present invention, FIG. 5 is an explanatory diagram showing the mechanism of image erasing by the same device, and FIGS. Figure 6c is a diagram showing the amount of image erasure when copying is performed using the same device in the same mode and automatic feed mode, Figure 6c is a diagram showing the amount of image erasure when copying is performed using the conventional equipment, and Figure 7 is a diagram showing the amount of image erasure when copying is performed using the conventional equipment. It is a part of explanatory drawing which shows another Example. 1... Photosensitive drum, 2... Charged corotron, 3...
Platen, 4... Original, 5... Light source, 6... Reflected light, 7
a, 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, 2
1...ISIL assembly, 22...constant current power supply, 23
... Drive control device, 24 ... Automatic document feed mechanism, 25
...Feed mode switching adjustment device, L ₁ ...L ₆₁ ...Light emitting diode, R, R ₁ ...Image area, a ₁ , a ₂ ...Unwanted image erasure amount.

Claims (1)

[Claims] 1. Consisting of light emitting diodes arranged in a line along the main scanning direction, an electrostatic latent image is carried by lighting up a predetermined number of light emitting diodes at both ends depending on the paper size used. In a side unnecessary image erasing device for erasing an unnecessary image on the surface of a photoreceptor prior to development, the light emitting diodes on the surface of the photoreceptor are removed without changing the predetermined number of light emitting diodes determined according to the paper size used. a switching adjustment means for switching the reachable range of the light emitted from the light emitting diode; A side unnecessary image erasing device for an electrophotographic copying machine, characterized in that the apparatus further comprises a control means for switching the switching adjustment means so as to enlarge the image inward. 2. The electronic device according to claim 1, wherein the switching means is a light amount switching means for expanding the range of light from the light emitting diode on the surface of the photoreceptor by increasing the light amount of the light emitting diode. Side unnecessary image erasing device for photocopying machines. 3. The light-emitting diode is provided with a height-adjustable shielding plate on the inside, and the switching means adjusts the height of the shielding plate located further inside of the innermost one of the light-emitting diodes. , the side of the electrophotographic copying machine according to claim 1, further comprising a shielding plate switching means for expanding the range of light from the light emitting diode on the surface of the photoconductor by increasing the distance from the photoconductor. Unwanted image erasing device.