JPH0538653U - Automatic charge eliminating device for non-image area of photoconductor of variable magnification copier - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the image covers the entire surface of the original, it is possible to reproduce the entire image without loss and to minimize even if a black band occurs, the non-photosensitive member image of the variable-magnification copying machine. Part automatic charge removal equipment is provided. In a copying machine capable of copying at an arbitrary magnification, a divided static elimination lamp capable of divided lighting, a document size detection means for detecting a document size, a copy magnification setting means for setting a copy magnification, and the same copy magnification setting Means and the original size detecting means, and the light emission pattern determining means for determining the light emission pattern of the divided static elimination lamps based on the same information, and each lamp of the divided static elimination lamps can be turned on independently. According to the light emission pattern determined by the light emission pattern determining means, it is possible to light up to a discharge lamp immediately before the image area of the photosensitive member. apparatus.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to static elimination of a non-image area of a photoconductor in a copying machine capable of copying at an arbitrary magnification.

[0002]

[Prior art]

 The surface of a photoconductor in a copying machine is formed of a thin film of a photoconductive material, which holds a charge in a dark place and dissipates an electric charge by reflected light of a document to form a latent image.

In the case of a variable-magnification copying machine, the relationship between a document, a photoconductor, and a copy sheet is schematically shown in FIG.

Reference numeral 01 is an original, 02 is a surface of a photoconductor, and 03 is a copy sheet. Now, it is assumed that the surface image of the original 01 is reduced, and the reflected light of the light projected on the original is reduced by the optical system to be exposed. When the body surface 02 is irradiated, the light-irradiated portion 02a forms an electrostatic latent image whose surface potential changes depending on the intensity of light, and the other portion 02b retains the electric charge as before. The surface potential is the highest.

Toner is attached according to the surface potential of the photoconductor and is transferred onto the paper 03. Therefore, the light-irradiated portion 02a on the surface of the photosensitive member needs to have an area equal to or wider than the paper 03.

If it is narrow, the part 02b which is not irradiated with light overlaps the end of the paper 03, and a large amount of toner is transferred at the same part, and a black band is formed on the edge of the paper. I will end up.

When the copying paper 03 is small and the width of the light radiated on the surface of the photoconductor is narrow, the area 02b which is not exposed to the light is large and the amount of toner adhered to the surface of the photoconductor 02 is large. This imposes a heavy burden on the copying machine and greatly affects the life and reliability of the copying machine itself.

Therefore, in order to remove excess charges on the surface of the photoconductor that is not exposed to light, static elimination lamps are arranged in the widthwise direction of the photoconductor, which is disclosed in Japanese Patent Application Laid-Open No. 58-184955 and Japanese Patent Application No. 58-9947. No. 0 (Japanese Utility Model Publication No. 54-125031) There is an example described in microfilm.

[0009] In both examples, the static elimination lamps are arranged in the width direction of the photoconductor to selectively turn on the light, thereby removing excess charges on both sides of the photoconductor and reducing the amount of extra toner adhering to the photoconductor. ing.

[0010]

[Problems to be solved]

 However, in the example described in the former publication, as can be seen from that example, the static elimination lamps are arranged according to the paper size, and the image size (paper size) of the latent image formed on the surface of the photoconductor by enlarging and reducing the size is set. Correspondingly, the charge of non-image parts other than that image is to be erased.

As described above, since the discharge lamp is selectively turned on according to the paper size, it is not subdivided to cope with any size, and the disassembly irradiation ability is poor.

[0012] Therefore, in order to completely eliminate static electricity in the non-image portion, the static electricity reducing lamp was subdivided so as to be able to independently light up in accordance with an arbitrary size of the paper, and it was attempted to eliminate the electricity by considerably entering the image portion. In the latter example, the lighting width of the static elimination lamp is set to be larger than the lighting width in the normal mode.

Therefore, there is a considerable amount of erasure in the image portion, and there is a possibility that even a necessary image may be erased if the image is displayed over the entire surface of the document and there is no margin.

[0014]

[Means and Actions for Solving the Problems]

 The present invention has been made in view of such a point, and an object thereof is to provide an automatic static eliminator capable of copying the entire image without missing even when the image covers the entire surface of the original document.

The configuration of the present invention will be described with reference to FIG. In a copying machine capable of copying at an arbitrary magnification, A is a document size detecting means for detecting a document size, and B is a copy magnification setting means for setting a copy magnification.

C is a divided static elimination lamp that can be turned on independently of each lamp.

Reference numeral D is a light emission pattern determining means for inputting information from the document size detecting means A and the copy magnification setting means B and determining the light emission pattern of the divided static elimination lamp C based on the same information. It is possible to turn on the static elimination lamp just before this one.

With the above-described structure, the present invention can selectively turn on the static elimination lamps that are subdivided according to the light emission pattern determined by the light emission pattern determination means D, and can selectively light one of the image areas of the photoconductor. Even before the static elimination lamp is turned on, static electricity can be prevented from entering the image portion formed on the photoconductor to eliminate static electricity, and even if a black band occurs, it can be minimized.

Therefore, even when the image covers the entire surface of the original, the entire image can be reproduced without missing.

[0020]

【Example】

 Embodiments according to the present invention illustrated in FIG. 3 and subsequent drawings will be described below.

FIG. 3 is a schematic diagram of the internal construction of a variable power copying machine according to this embodiment.

In the figure, a platen glass 3 as an original placing table is stretched on a top surface of a casing 2 of a dry electrophotographic copying machine 1, and a platen cover 4 is pivotably attached to the copying machine casing 2 above the platen glass 3 so as to be freely opened and closed. The platen cover 4 presses and fixes the original 5 placed on the platen glass 3 from above.

An exposure lamp 6, a reflector 7 and a first mirror 8 are installed directly below the platen glass 3, a lens 12 is located on the right side of the first mirror 8, and a second mirror 9 and its side are located on the right side of the lens 12. The third mirror 10 is disposed below, the fourth mirror 11 is disposed to the left of the third mirror 10, and the drum-shaped photoconductor 13 is disposed below the fourth mirror 11.

Around the drum-shaped photoconductor 13, in order of its rotation direction (clockwise in FIG. 3), a charging device 14, a dividing static elimination lamp 15, a developing device 16, a transfer device 17, a peeling device 18, and a cleaning device 19 are sequentially installed. It is arranged.

The copy paper 20 is supplied from the paper cassette 21, received by the transfer device 17 to transfer the toner, fixed by the fixing device 22 and discharged to the discharge tray 23.

Under the above-described structure, first, when the slit-shaped light projected from the exposure lamp 6 illuminates the surface of the original 5 through the platen glass 3 and scans to the right, the reflected light is reflected. Is redirected by the first mirror 8, passes through the lens 12, is reflected by the second, third, and fourth mirrors 9, 10, 11 and reaches the surface of the drum-shaped photoconductor 13 to form an image, thereby forming an electrostatic latent image. To form.

Then, after the excess charge on the surface of the photoconductor is removed by the division charge-eliminating lamp 15, the toner is attached by the developing device 16, and the transfer device 17 transfers the toner image to the copy paper 20 sent from the paper cassette 21. The copy paper 20 is peeled off from the drum-shaped photoconductor 13 by the peeling device 18, the toner remaining on the surface of the photoconductor is scraped off by the cleaning device 19, and the surface of the photoconductor is charged again by the charging device 14. And is used to form a latent image by exposure.

A magnification setting button 30 for setting a copying magnification is provided on the top surface of the copying machine casing 2.

Further, a carriage that supports the exposure lamp 6 and the like and moves to the left and right is equipped with five document detection sensors 31 using light-receiving photodiodes, and as shown in FIG. One document detection sensor 31 is arranged on the carriage at a position of 105 mm to 105 mm, and then four document detection sensors 31 are arranged at intervals of 10 mm.

In the copying machine according to the present embodiment, the original placement method is center registration, and the original detection sensors 31 are arranged as described above to make the standard paper size B5 to A3. be able to.

The surface of the platen glass 3 side of the platen cover 4 that presses the original 5 placed on the platen glass 3 is not pure white but has a reflection density of 0.3 to 0.5 and is slightly blackened. It has a reflection density different from that of the white background of the document and can be identified by the document detection sensor 31.

The original 5 placed by center registration on the platen glass 3 can be detected in the vertical direction (vertical direction in FIG. 4) by the detection state of the original detection sensor 31, and the exposure lamp 6 can be detected. The size of the document in the horizontal direction (horizontal direction in FIG. 4) can be detected by the document detection time of the document detection sensor 31 which moves together.

Further, the divided static elimination lamps 15 are arranged in the axial direction of the drum-shaped photoconductor 13 so that the divided static elimination lamps 15 can be lit in 30 divisions only on one side, and the disassembly irradiation ability is 3 mm.

The charge of the non-image portion on the surface of the drum-shaped photoconductor 13 is removed by controlling the light emission pattern of the divided charge-elimination lamp 15, and the original 5, the surface of the drum-shaped photoconductor 13, and the divided charge-elimination are performed. The relationship between the lamp 15 and the copy paper 20 is schematically shown in FIG.

The surface of the drum-shaped photoconductor 13 is a part (image part) 13a where an electrostatic latent image is formed by the irradiation of light on the surface of the drum-shaped photoconductor 13 by an optical system based on the set copy magnification. Portion (non-image portion) 13b, and the charge-eliminating lamp corresponding to the non-image portion 13b is turned on in order to remove the electric charge of the non-image portion 13b.

When the image represented on the original document covers the entire surface of the original document and there is no blank area, and when it is desired to obtain a copied image for the entire area, one image is placed in the image portion 13a of the drum-shaped photoreceptor 13. By turning on the lamp up to the front, the width of the black band appearing at both ends of the image on the surface of the photoconductor can be suppressed to 3 mm or less.

Further, the division charge-eliminating lamp 15 turns on all of the division charge-eliminating lamps 15 just before the latent image on the photoconductor of the black edge at the rear end of the copy paper 20 has finished passing through the division charge-eliminating lamps 15. Occurrence can be prevented.

FIG. 6 shows a schematic block diagram of a control system for controlling the light emission pattern of the divided static elimination lamp 15 with timing in this way.

The control is performed by the microcomputer 32, and the copy magnification information input by the magnification setting button 30 and the document size information from the document detection sensor 31 are input to occupy the surface of the drum-shaped photoconductor 13. The range of the image portion 13a is calculated, the light emission pattern of which lamp of the divided charge elimination lamp 15 is to be turned on and off is determined, and the divided charge elimination lamp 15 is drive-controlled based on the light emission pattern. ..

For example, when a reduction ratio of 86% is set for an A4 size document, the microcomputer 32 calculates B5 as the copy image size, and the range of the non-image part 13b other than the image part 13a is calculated. Corresponding, and the lamps from the end up to the one before entering the image portion 13a are determined as the lamps to be lit.

As described above, in this embodiment, the non-image portion on the surface of the photoconductor is determined from the copy magnification and the document size, and the charge is removed to prevent a problem due to the adhesion of excess toner. The entire image area can be reproduced, and the black bands on both ends can be reduced to a maximum of about 3 mm.

Moreover, since this black band is a duplicated portion of the document pressing surface where the reflection density of the platen cover 4 is 0.5 or less, it is extremely thin and causes almost no problem.

When the original has a blank space, the lamp corresponding to the end of the image portion 13a can be turned on to completely prevent the generation of the black band, and the erasure at both ends can be suppressed to 3 mm or less.

[0044]

[Effect of the device]

 In the present invention, the light emission pattern of the split static elimination lamp is determined from the copy magnification and the original size, and the excess charges on the surface of the photoconductor are automatically removed. The static elimination in front of the image area of the photoconductor is eliminated. Even if the lamp is turned on, it is possible to avoid eliminating static electricity by entering the image part formed on the photoconductor, and even if the image covers the entire surface of the original, it is possible to reproduce the entire image without causing any black spots. Can be minimized.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention.

FIG. 2 is a schematic diagram showing the relationship between a document, the surface of a photoconductor, and a copy sheet.

FIG. 3 is an internal schematic view of a copying machine according to an embodiment of the present invention.

FIG. 4 is a diagram showing an arrangement state of a document detection sensor in the present embodiment.

FIG. 5 is a schematic diagram showing a relationship among a document, a surface of a photoconductor, a divided static elimination lamp, and a copy sheet in the present embodiment.

FIG. 6 is a block diagram of a control system of this embodiment.

[Simple explanation of symbols]

1 ... Dry electrophotographic copying machine, 2 ... Copier casing, 3 ...
Platen glass, 4 ... Platen cover, 5 ... Original, 6 ...
Exposure lamp, 7 ... Reflector, 8 ... First mirror, 9 ... Second mirror, 10 ... Third mirror, 11 ... Fourth mirror, 12 ... Lens, 13 ... Drum-shaped photoreceptor, 14 ... Charger, 15 ... Split Static elimination lamp, 16 ... Developing device, 17 ... Transfer device, 18 ... Peeling device, 19 ... Cleaning device, 20 ... Copy paper, 21 ... Paper cassette, 22 ... Fixing device, 23 ... Discharge tray, 30 ... Magnification setting button, 31 … Original detection sensor, 32… Microcomputer.

Claims (1)

[Scope of utility model registration request] 1. A copying machine capable of copying at an arbitrary magnification, a divided static elimination lamp capable of divided lighting, a document size detecting means for detecting a document size, a copy magnification setting means for setting a copy magnification, and the same copying. And a light emission pattern determining means for inputting information from the magnification setting means and the document size detecting means and determining the light emission pattern of the divided static elimination lamps based on the same information. It is possible to turn on the light, and according to the light emission pattern determined by the light emission pattern determining means, it is possible to light up to the discharge lamp immediately before the image area of the photoconductor, and the non-photoconductor portion of the variable magnification type copying machine. Automatic static eliminator.