JPS62127869A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent exactly the formation of an unnecessary dark image without being influenced by an image forming magnification, an image forming form size, etc., by executing the charge dissipation of a prescribed width, or a non-electrification, based on the smaller size of either an electrostatic latent image size, or a copying paper size as a reference. CONSTITUTION:After being electrificated uniformly by an electrification charger 32, a charge non-existence area is formed by dissipating a charge existing in a prescribed area by an LED array 33, an electrostatic latent image corresponding to an original is formed by irradiating a reflected light from the original, to a charge existence area, converted to the developed image of a toner image by a developing device 34, and the toner image is transferred onto a transfer paper by a transfer charger 35. Subsequently, a transfer paper P is peeled off by a separation charger 36, and a residual toner is recovered by a cleaner 37.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an image forming apparatus, and more specifically,
For example, the present invention relates to an image forming apparatus that can remove substantially an image portion of a portion corresponding to the peripheral edge of a three-dimensional document.

<Prior Art> Conventionally, in electrophotographic apparatuses, in order to prevent a substantial image from being formed on the periphery of the obtained image and deteriorating the image quality, a plain white color is used for sheet-like originals. By using the Braden, it is possible to prevent the formation of a rough image on the back of the image or on the part that does not correspond to the document surface, and for three-dimensional documents such as bookcases, the periphery of the paper where the image is formed is prevented. There is provided an apparatus for causing a light emitting diode array to emit light corresponding to a predetermined width of the sheet, thereby dissipating the charge in the predetermined width portion and preventing the formation of a ++3 image on the peripheral edge of the sheet. (See Japanese Patent Application Laid-Open No. 59-88758).

<Problems to be Solved by the Invention> In the above-mentioned electrophotographic device, the wire erasing width can be freely set, but since the width must be set by external operation, the setting operation is difficult. This is troublesome, and if this setting operation is forgotten, the image area will be lost, especially in the case of reduced copying, resulting in a problem that the required copy will not be obtained.

In addition, since the method is designed to prevent the formation of a rough image on the periphery based only on the copy paper size, it is effective only when there is a correlation between the original and the copy paper, and is effective in other cases. The problem is that it is not valid. For example, if copy paper of a size larger than the size determined by the original size and copying magnification is used, an 1111 image will be formed at the periphery of the resulting copy image.

<Object of the invention> This invention was made in view of the above problems,
To provide an image forming apparatus that can reliably prevent the formation of a positive image at the periphery of an image actually obtained, regardless of the original size, paper size, and image forming magnification.

Means for Solving the Problems> To achieve the above object, an image forming apparatus of the present invention includes: a charge-free area forming means, a document size detecting/instructing means, an image forming magnification setting means, The paper size detection/instruction means and the control means are two different things.

The charge-free area forming means includes an antistatic member 1, a charge-dissipating light emitter, etc., and forms a charge-free area on the surface of the photoreceptor. The document size detection/instruction means detects/instructs the document size,
The above image forming magnification setting means is! The paper size detection/instruction means detects/instructs the size of the paper on which the image is formed, and the control stage 9 sets the magnification of the image to be printed on the original. , and the image formation size on the surface of the photoreceptor based on the image formation magnification, determine the size 130 relationship with the paper size, and from the periphery of the smaller size, calculate the size of the image formed on the surface of the photoreceptor based on the image formation magnification. The charge-free region forming means is driven so that an electrostatic latent image corresponding to the document exists only in the inner region.

Effect> With the image forming apparatus having the above configuration, when an image is exposed to light using a light source, an image of a selected predetermined magnification is formed on the surface of the photoreceptor, and the image is transferred onto paper, the image forming apparatus has an image size of 1 quintillion. The detection/instruction means detects/instructs the document size, and the paper size detection/instruction means detects/instructs the paper size.
The image forming magnification is set by the image forming magnification setting means.

Then, the control means calculates the size of the image formed on the surface of the photoreceptor based on the document size and the image forming magnification, determines the size relationship with the paper size, and transmits a control signal based on the determination result to the charge-free area. By supplying the electrostatic latent image to the forming means, an electrostatic latent image corresponding to the document can be made to exist only in the area inside the width t determined corresponding to the image forming ratio from the peripheral edge of the smaller size.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 6 is a schematic diagram showing the internal mechanism of the copying machine. Inside the copying machine main body (1), which has a document holder (11) on the top surface,
The optical system (2), copy processing section (3), and copy paper transport section (4) are shown on the right.

The optical system (2 is a light source (21), a mirror (22N23)
) (24), a lens (25), and a mirror (26), and a light source (21) and a mirror (22).
) is moved in the direction of the arrow at a predetermined speed, and the mirror (23H24) is moved in the same direction at half the speed mentioned above, thereby making it possible to sequentially expose the entire surface of the document. Further, (27) is a photoelectric switch for detecting the leading edge of the rough stone, and after detecting the leading edge of the Ii1 manuscript by the photoelectric switch (27), it detects the manuscript by counting the number of pulse signals corresponding to the manuscript size. The rear end of the frame can be detected.

The copying processing section (3) includes a photosensitive drum (31) rotating in the direction of arrow B, an electrostatic charger (32), and an 11mm D array (33) as a charge-free area forming means.
, a developing device (34), a transfer charger (35), a separating device (36), and a cleaner (31) are arranged in this order, and the charger (32) is uniformly charged. After being avoided, the LED array (33) prevents the charges existing in a predetermined area from disappearing to form a normally open non-existing area, and responds to the original by irradiating the charged area with reflected light from the original. An electrostatic latent image is formed and developed into a toner image by a developing device (34), and the toner image is transferred onto copy paper by a transfer charge tz (35).

The copy paper (P) is then peeled off by a separation charger (36), and the remaining toner is collected by a cleaner (37).

-F The copy paper conveyance section (4) includes a paper feed roller (41), a conveyance roller (42), a register 1 to 0-ra (43), a conveyance bell 1-(44), a fixing device (45), and One sheet of copy paper is loaded into the paper feed roller (41) from the paper feed cassette (12), which has an IJI output roller (4G) and is installed in a predetermined position on the copying machine body (1) so that it can be collected. The copy paper is conveyed one by one through the conveyance roller (42) to the registration roller (43) in synchronization with the timing of forming the leading edge of the electrostatic latent image, and is conveyed to the transfer section. Then, the copy paper separated from the photoreceptor drum (31) by the separation charge (tlf36) is transported to the fixing device (45) via the transport bell I- (44), where the 1-toner image is transferred. After being heated and fixed, the receiver is discharged onto the table (13) by a discharge roller (46). In addition, in the figure, paper feed force cera 1~
(12) is shown in only one row, but in reality there are three rows above and below.
It is installed in stages.

FIG. 5 is a perspective view showing the document size detection/instruction means, and shows the contact glass (14) on which the document ([)) is placed.
It has a length detection/indication part (51) and a width detection/indication part (52) on the periphery. The length detection/instruction section (51) has a movable part over the entire length of the contact glass (14), and is configured to work in conjunction with a variable terminal of a variable resistance (not shown). The above width detection/indication section (52)
The contactor 1 has a knob that is movable from either end to the center of the glass (14), and is configured to work in conjunction with a variable resistance force variable terminal (not shown). In this example, the document (D) is placed on a contact glass (1
4) Hit above.

Figure 4 is a plan view of the operation panel, from the right to keys 1 to 61 (61), clear key (62), and numeric keypad (6
3), a zoom key (64), an input end key (65), a copy key (66), a cassette selection key (G1), a display (68), and a density setting key (69). The display device (68) is composed of a fluorescent display tube, etc., and from the right, the paper feed cassette display section (68a), the number of sheets display section (68b), and the copy paper size display section (6aC).
, copy magnification display section (68d), and density display section (68d).
8e). A copy paper size display symbol (68r) is provided corresponding to the copy paper size display section (68c).
l is formed.

FIG. 1 is a block diagram showing the electrical configuration of the main parts.
A paper leading edge detection signal, a transport pulse signal, a setting magnification signal, and a copy paper size detection signal are supplied to a microcomputer (71) serving as a control means, and the length detection/instruction section (51) and width detection/ The detection signal from the instruction section (52) is converted into a digital signal by the A/D converter (12) and supplied to the microcomputer (71). A control signal from the microcomputer (71) is supplied to a driver (73) for driving the LEI array (33).

FIG. 2 is a flowchart explaining the operation. In step 2, the document size SO is input using the quality detection/instruction section (51) and the width detection instruction section (52), and in step 2, the cassette selection key is pressed. 67),
Copy paper tube size S stored in the selected paper cassette
Input D using the magnet 1- and reed switch, etc., and in step 2, operate the zoom key (64), then operate the numeric keypad (63), and then input end-1
The copy magnification M is set by operating =-(G5) or by operating the same-size copy key (66). Next, in step 2, the amount of electrostatic latent image size 3i = MXSO is set to D based on the original size and the copying magnification, and in step 2, W = MXWO is set to J3 (however, WO is set corresponding to the same size copying). The erasing width W of the peripheral edge of the copy paper) is calculated, and in step (2), the magnitude relationship between the electrostatic latent image size Si and the copy paper size So is determined.

If it is determined that the electrostatic latent image size S1 is less than or equal to the copy paper size So, in step (2) the page width to be left after charge erasure is calculated based on 3i-2W, and in step (2) LE in copy paper transport direction
Set the timing for the end of all lighting of the D array (33) (copy paper leading edge timing + W/K) and the timing for the start of all lighting (Sl-W)/K (where K is the transport pulse width) (see Fig. 3). (See A).

On the other hand, if it is determined that the electrostatic latent image size 3i is larger than the copy paper size Sp, the width to be left after the charge is erased is calculated in step (2) based on 5p-2W, and in step [phase] L in the copy paper transport direction
The timing of the end of all lighting of the ED array (33) (copy paper leading edge timing + W/K) and the timing of the full lighting start (copy paper trailing edge timing - W/K) are set (see FIG. 3B).

Then, after performing the processing in step (2) or step [phase] above, in step (2), the LED array (33
) is turned off, the charge corresponding to S.1 on the peripheral edge is erased, and a copy with almost no image can be obtained.

To summarize the above, the electrostatic latent image size calculated from the original size and copying magnification, and the smaller of the copy paper size are used as a reference, and a charge of a predetermined width determined corresponding to the copying magnification starts from the periphery. By performing erasing, it is possible to obtain a copy that is substantially free of unnecessary images, regardless of the copy magnification and copy paper size. In particular, even if you use a three-dimensional original like the original IJtfl and make an enlarged copy to 84 size, and use A3 size copy paper, you can use the three-dimensional original as the original IJtfl. Development, transfer, etc. in the case where the copy is reduced to the original size and A4 size copy paper is used, and the charge in a predetermined width part from the peripheral edge of the image corresponding to the b1 original has disappeared. Therefore, unnecessary approximate images are not formed, and the quality of the resulting copies can be maintained at a high level.

In addition, to input the document size, J3 sets the document (D) on the contact glass (14) and operates the quality detection/indication section (51) and the width detection/indication section (52). This makes it easy and reliable to input not only standard document sizes, but also irregular document sizes, such as wooden bags, which are inevitably shorter in length than the standard size when set. can be done.

7 to 9 do not show other embodiments of the charge-free area forming means. A shutter (32a) for shielding the opening on the photosensitive drum side is slidably attached.

More specifically, a charged charge r (32) with a charger wire stretched is stored in a frame (32b) formed at a predetermined position of the copying machine main body, and is placed on the IFi 1 port side of the frame (32b). A pair of sliding shutters (32a
) 1 (), the racks formed on the - side of each V vine (32a) are engaged with the binions (32c), respectively. The rotational force from the drive source (32dl) is transmitted as rotational force in opposite directions by gear coupling or wire coupling.

In the case of this embodiment, the above embodiment is replaced by an LED array (3
3) by controlling the lighting of the photoreceptor drum (31).
) to form a charge-free area by dissipating the charge on the surface of the photoreceptor drum (31), the charge 11 wire is removed from the photoreceptor drum (31) by sliding the JP ivy (32a) in the opposite direction to H. Changing the exposure quality and preliminarily limiting the charged area on the surface of the photoreceptor drum (31),
Even if parts other than the charged area are irradiated with reflected light from the source 1n, no electrostatic latent image is formed.

Therefore, in the case of this embodiment, the electrostatic charge iM to be applied to b1Kigori1q is defined as an area where no charge exists over a predetermined width from the periphery of the smaller of the J size and the copy paper size. 19, it is possible to reliably prevent the formation of a substantial image on the copied material.

<Effects of the Invention> As described above, the present invention achieves charge dissipation in a predetermined width based on the smaller of the electrostatic latent image size or the copy paper rise.
Or, since it is designed to perform non-charging, it is not affected by image forming magnification, image forming paper size, etc.
Reliably prevents the formation of unnecessary images and produces high quality images.
It has the unique effect of being able to do q.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the main parts of an embodiment of the image forming apparatus of the present invention, Fig. 2 is a flowchart explaining the operation, Fig. 3 is a diagram showing the charge dissipation area, and Fig. 4 is a plane view of the operation panel. FIG. 6 is a schematic diagram showing the internal mechanism of the copying machine. FIGS. 7 to 9 are other embodiments of the charge-free area forming means. Figure 1 showing
゜(21)...Light source, (31)...Photoreceptor drum, (
32a)... ShiT/ as a charge-free region forming means
Ivy, (33)...LED as charge-free region forming means
array, (51)...'Length detection/instruction section 1 constituting FA document output/instruction means, (52)...width detection/indication section constituting document size detection/indication means; (71)...Microcomputer, (D)...Manuscript, Patent 9 applicant: Sanda Kogyo Co., Ltd.

Claims (1)

[Claims] 1. Expose the original with a light source to see what is selected. forming an image with a predetermined magnification on the surface of the photoreceptor; In an image forming device that transfers onto paper, Forms an area where there is no charge on the photoreceptor surface. charge-free region forming means, and a document Document size detection to detect/instruct size /instruction means, image formation magnification setting means, Detects the size of the paper on which the image will be formed/ a paper size detection/indication means for instructing; For the above document size and image formation magnification Based on the image size formed on the photoreceptor surface Calculate the size relationship with the paper size. Determine, and from the periphery of the smaller size, Only the width determined according to the image formation magnification, Electrostatic latent that corresponds to the original only in the inner area In order to make the image exist, the above-mentioned charge-free region and control means for driving the forming means. An image forming apparatus characterized by: