JPH02266379A - Copying machine with blank lamp - Google Patents

Abstract

PURPOSE:To correctly erase a picture only in the designated range by providing a blank lamp light quantity decreasing means decreasing the light quantity of a blank lamp when a photographing mode is set. CONSTITUTION:An electrifying charger electrifies the surface of the photosensitive body before an exposure process is driven by an electrifying charger driving part. A picture part to be erased and a part out of the picture range on the surface of the photosensitive body before a developing process are irradiated with light by the blank lamp and the blank lamp is driven by a blank lamp driving part. The discharging quantity of the electrifying charger is controlled by the electrifying charger driving part according to the presence or absence of a photographing mode data from a mode setting switch. The photographing data is also supplied to the blank lamp light quantity decreasing means, by which light quantity control data according to the presence or absence of the photographing mode data is outputted to the blank lamp driving part. The light quantity of the blank lamp is changed based on this light quantity control data. Thus, only the designated range of the picture can be correctly erased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Al Industrial Field of Application) The present invention relates to a copying machine using electrophotography, and more particularly to a copying machine equipped with a blanking lamp that exposes any part of the surface of a photoreceptor to light.

(b) Prior Art Conventionally, there is a copying machine that erases an arbitrary portion of an image on a photoreceptor and copies it onto a sheet of paper. A copying machine having such an image erasing function is equipped with a blank lamp that faces the surface of the photoreceptor between the charging process and the developing process. This blank lamp consists of multiple minute light sources.
By controlling the on/off timing of each of the plurality of minute light sources, charges on a given portion of the surface of the photoreceptor are erased, and developer is prevented from being adsorbed to this portion during the development process. - In general, a blank lamp has minute light sources arranged in a row in the direction of the rotation axis of the photoreceptor, and the range in which the image is erased can be set using the arrangement interval of the minute light sources as the minimum unit. Furthermore, when the document size is small, a blank lamp is irradiated outside the image area in order to reduce the amount of developer consumed.

Furthermore, when copying a photographic original, some devices are equipped with a surface potential lowering means that lowers the surface potential of the photoreceptor compared to when copying a normal image composed of characters or line drawings. In this manner, by lowering the surface potential of the photoreceptor in the photographic mode, the overall density level of the image is lowered, making it possible to faithfully reproduce the halftone portion of the photographic image.

(C) Problems to be Solved by the Invention However, as shown in FIG. 8, the photoreceptor surface 82 is not only irradiated with parallel light from the blank lamp 81; This flare, which includes a flare indicated by a two-dot chain line, has a lower light intensity than the parallel light beam in the center, and the surface potential of the photoreceptor surface 82 irradiated with light from the rank lamp 81 is indicated by a solid line 83 at the bottom of the figure. It changes like this.

When the potential of the photoreceptor surface 82 is relatively high in the normal copying mode, the portion that is not irradiated with light from the blank lamp 81 has a potential of
3 is maintained, and the surface potential of the portion irradiated with the parallel light beam of the blank lamp 81 decreases to 1. Further, the surface potential of the portion receiving the flare light gradually increases from the center to the outside. Therefore, in order to reliably erase the image on the original when the potential of the photoreceptor surface 82 is sufficiently high, the light from the blank lamp 8 is sufficient to lower the surface potential of the photoreceptor surface 82 from ■3 to Vl. It must have a sufficient amount of light.

However, when the surface potential of the photoreceptor surface 82 is lowered to ■2 in the photo mode, the blank lamp 81
When the photoreceptor surface 82 is irradiated with light, the potential of the photoreceptor surface 82 changes as shown by the broken line 84 in the lower part of FIG. Expands by d. This expansion of the range in which the surface potential decreases causes the problem that even portions of the image that should be left are erased. This also applies to the direction of the rotation axis of the photoreceptor.

The purpose of the present invention is to reduce the amount of light from a blank lamp when the surface potential of the photoreceptor is lowered in photo mode, thereby preventing the surface potential of the portion of the photographic original image that should be preserved from becoming too low. To provide a copying machine equipped with a blanking lamp capable of accurately erasing an image only in a designated range.

(d) Means for Solving the Problems It is an object of the present invention to have a potential lowering means for lowering the surface potential of a photoreceptor during a photo mode for copying a photographic original;
A copying machine equipped with a blank lamp for exposing an arbitrary part of the surface of a photoreceptor is characterized in that a blank lamp light amount reducing means is provided for reducing the light amount of the blank lamp during the photographic mode.

That is, as shown in FIG. 1, a charger that charges the surface of a photoreceptor before an exposure process is driven by a charger drive section. Further, a blank lamp that irradiates light onto an image portion to be erased and outside the image range on the surface of the photoreceptor before the development process is driven by a blank lamp drive section.

The charger drive unit controls the amount of discharge of the charger depending on the presence or absence of photographic mode data from the mode setting switch. Also, the photo mode data is blank lamp light f
The light is also supplied to the f1M reduction means, and the blank lamp light IE reduction means outputs light amount control data to the blank lamp drive section depending on the presence or absence of photographic mode data. The blank lamp driving section changes the light intensity of the blank lamp based on this advance control data.

(e) Function In the present invention, the amount of light irradiated from the blank lamp to the photoreceptor is increased or decreased along with the amount of charge by the charger depending on whether the photo mode is set or not. That is, in a normal document mode consisting of characters or line drawings, the surface potential of the photoreceptor is made sufficiently high, and a sufficient amount of light is irradiated from the blank lamp. On the other hand, in a photo mode for copying a photo original, the surface potential of the photoreceptor is lowered, and the amount of light emitted from the blank lamp is accordingly reduced. As a result, the range in which the potential decreases due to irradiation with the blank lamp becomes substantially constant regardless of the type of document.

(f) Embodiment FIG. 2 is a schematic front view showing the configuration of a copying machine equipped with a blank lamp, which is an embodiment of the present invention.

A photosensitive drum 22 is provided in the center of the copying machine main body 21 so as to be rotatable in the direction of arrow A, and a charging charger 23, a developing device 24, a transfer charger 25, and a peeling charger 26 are provided on the outer periphery of the photosensitive drum 22. , cleaner 27, and static elimination lamp 28 constitute a copying process section 29. In this copying process section 29, a blank lamp 1 is provided between the charging charger 23 and the developing device 24 so as to face the surface of the photosensitive drum 22.

A document table 31 made of hard transparent glass is provided on the top surface of the copying machine main body 21. A copy lamp 32, mirrors 33 to 36 and a lens 3 are provided on the lower surface of the document table 31.
An optical system device 38 with 7 is provided. Copy lamp 32 and mirrors 33 to 35 of optical system device 38
indicates the lower surface of the document table 31 during the copying process with arrows B and C.
Move back and forth in the direction. Further, a mode switch 2 is provided on the top surface of the copying machine main body 21. This mode switch 2 is a switch that is operated to set a photo mode when copying a halftone original such as a photo original.

A paper manual feed tray 4 is provided on one side of the copying machine main body 21.
1 and paper rollers 42 and 43 are attached, and together with paper feed rollers 44 to 46 constitute a paper feed section 47. Further, a paper output tray 5 is provided on the other side of the copying machine main body 21.
2 is attached, and together with the internal fixing roller 51 constitutes a paper ejection section 53. A timing roller 54 and a conveyance belt 55 are provided between the paper feed section 47, the copy process section 29, and the paper discharge section 53, forming a paper conveyance path 56.

During the copying process, the photosensitive drum 22 rotates in the direction of arrow A, and the optical system device 38 moves forward in the direction of arrow B. The surface of the photoreceptor drum 22 is charged by the charger 23 and then exposed to light reflected from the copy lamp 32 from the original, and ra1! A latent image is formed. A developer is supplied from the developing device 24 to this electrostatic latent image to visualize it. Paper is fed one by one from the paper feed section 47 to the photosensitive drum 22, and the transfer charger 25
A developer image is transferred from the surface of the photosensitive drum 22 onto the paper at the position . The paper onto which the developer image has been transferred is heated and pressurized by a fixing roller 51 to fix the image thereon, and then is discharged to a paper discharge tray 52 .

FIGS. 3(A) and 3(B) are diagrams showing the main parts of the copying machine, FIG. 3(A) is a diagram showing the arrangement of the blank lamp and the photosensitive drum, and FIG. It is a figure which shows a part of blank lamp.

The blank lamp 1 has minute light sources arranged in a line over substantially the entire radius of the photosensitive drum 22 in the direction of the rotation axis. The blank lamp 1 is divided into a plurality of frames by a side wall 4, and each frame includes LEDs 3a to 3C, which are minute light sources.
...is provided.

FIG. 4 is a block diagram of the control section of the copying machine.

Drivers 65 to 69 are connected to the CPU 61 via an I10 interface 64. This driver 65~
69 respectively include a main motor 71, a developing device 24,
A charger 23, a copy lamp 32 and a blank lamp 1 are connected. The CPU 61 executes the drivers 65 to 69 according to the program written in the ROM 62 in advance.
Outputs control data to. Drivers 65 to 69 drive each device according to this control data. When outputting this control data, a predetermined memory area of the RAM 63 is used as a working area. Also, the CPU 61 has an I
On/off data of the mode switch 2 is inputted via the 10 interface 64. The memory area MAI of the RAM 63 is assigned to a flag that stores the on/off data state of the mode switch 2, and the CPtJ61
sets this flag when ON data is input from mode switch 2.

FIG. 5 is a flowchart showing the processing procedure of the control section of the copying machine.

When the copying machine main body 21 is powered on, the CPU 61 starts warming up (nl).

Once this warm-up is complete, the print switch will
7), and when the print switch is operated, the main motor 71 is driven (n3) - Furthermore, the flag F1 assigned to the memory area MAI is activated.
If the flag F1 is set, a predetermined low voltage is applied to the charger 23, and if it is reset, a high voltage is applied (n4 to n4).
116). As mentioned above, flag F1 is mode switch 2
When the mode switch 2 is turned on and the photo mode is set, the output of the charger 23 is lowered to lower the surface potential of the photoreceptor drum 22. Along with this, other charger 25.2
6 is also driven to apply a developing bias to the developing device 24 (nl).

Thereafter, the paper is fed at a predetermined timing n8), the copy lamp 32 is turned on, and the optical system device is moved forward in the direction of arrow B shown in FIG. 2 (n9, n10). If flag F1 is set, reduce the on-duty of blank lamp 1,
If it is reset, it will drive at the normal duty ratio (
nll-n13). The processing of nil to n13 is the processing of the blank lamp light amount reducing means shown in FIG. 1, and when the photo mode is set, the on-duty of the blank lamp 23 is reduced and its light amount is lowered.

In this state, the copying operation is executed, and when the optical system device 38 reaches the end of the document, it is moved forward in the direction of arrow C (n14).
, turn off the copy lamp 32 (n15), above 08~
After executing the process of n15 for the set number of sheets, the developing device 2
4. Charger 2325.26 and main motor 71
Stop driving (n l 6 → n 17 to n 19)
.

As described above, according to this embodiment, when the photo mode is set, the light amount of the blank lamp 1 is adjusted according to the line 1b in FIG.
become that way. In this way, when the light intensity of the blank lamp 1 changes from line 1a to line 1b depending on the photo mode setting, the surface potential of the photoreceptor drum 22 that receives the light from blank lamp 1 changes from line IC to line 1d. . Therefore, as shown in FIG. 7, when the surface potential of the photoreceptor drum 22 is charged to the potential ■3 by the charger 23 in the normal original mode, the light amount of the blank lamp 1 is set as shown in FIG. As a result, the surface potential of the portion of the surface of the photoreceptor drum 220 that receives the parallel light from the blank lamp 1 is set to the lowest potential Vl at which the developer does not adhere. 23 is lowered and the surface potential of the photoreceptor drum 22 is lowered to the potential v2 shown in FIG.
The light intensity of the blank lamp 1 is reduced to about the line 1b in FIG. By doing this, the amount of potential reduction due to the light irradiation of the blank lamp 1 is reduced in accordance with the decrease in the surface potential of the photoreceptor drum 22 (V3-V2), as shown by the solid line in the lower part of FIG. Only the area receiving the parallel light from the blank lamp 1 can be set to the lowest potential (1).

(Effect of the Great Invention According to this invention, when the charged potential of the photoreceptor is changed between the copying mode of a normal original consisting of characters and line drawings and the copying mode of a photographic original, the photoreceptor The light intensity of the blank lamp can be reduced in response to the decrease in the charging potential of the blank lamp, and the image erasing range of each minute light source that makes up the blank lamp can be kept constant regardless of the type of document. The image will not be erased beyond the specified range.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of the present invention, Fig. 2 is a schematic diagram showing the configuration of a copying machine equipped with a blank lamp according to an embodiment of the invention, and Fig. 3 (A) is a blank lamp in the copying machine. 3(B) is a diagram showing the main parts of the blank lamp provided in the copying machine, FIG. 4 is a block diagram of the control section of the copying machine, and FIG. 5 6 is a flowchart showing the processing procedure of the control unit of the same copying machine, FIG. 6 is a diagram showing the relationship between the light amount of the blank lamp and the surface potential of the photoreceptor in the same copying machine, and FIG. FIG. 3 is a diagram showing the state of surface potential. Further, FIG. 8 is a diagram showing the state of the surface potential of a photoreceptor in a conventional copying machine. 1-blank lamp, 2-mode switch, 21-copying machine main body, 22-photosensitive drum, 31-document stand.

Claims (1)

[Claims] (1) In a copying machine equipped with a potential lowering means for lowering the surface potential of a photoreceptor during a photo mode for copying a photo original, and a blank lamp for exposing an arbitrary part of the photoreceptor surface, the blank lamp is turned off during the photo mode. A copying machine equipped with a blank lamp, characterized in that a blank lamp light amount reducing means is provided to reduce the amount of light.