JPH0497175A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce a difference between a set area on an original on the magnification of 50% and an actual erased area by providing an erasing means which is composed of the odd number of light emitting elements, installed between an electrifying means and a developing means so that the center of the light emitting means of the central part is opposed to the center of an image carrier and can carry out the irradiation of the arbitrary position of the image carrier. CONSTITUTION:The image carrier 10, an image forming means which is provided opposite to the image carrier 10, and at least has the electrifying means 11, an image exposing means 13, and a developing means 14, and the erasing means 12 which is composed of the odd number of the light emitting means 31 and where the center of the light emitting means 31a of the central part is opposed to the exposing center 10a of the image carrier 10, are installed between the electrifying means 11 and the developing means 14. Thus, the maximum difference between the actual erased area by the erasing means 12 when copying is carried out on the magnification of 50%, and a theoretical value, can be half-reduced, without almost influencing on the copying on a different magnification.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to an electrophotographic apparatus, etc., and particularly to an image forming apparatus having an erasing array that can partially erase unnecessary charges on a photoreceptor. Regarding.

(Prior Art) Due to the demand for diversification or higher performance of the devices, image forming devices such as copying machines have recently been equipped with erasing arrays for erasing part of the electrostatic charge on the photoreceptor for image editing. A device is being developed. That is, in this erasing array, a plurality of light emitting diodes are generally arranged in a line and facing a photoreceptor, and a portion of the charge applied to the photoreceptor during charging is erased by irradiation from any of the light emitting diodes.

It is generally said that a device having such an erasing array also has a magnification conversion function.

However, in a device having such a combined erasing array and magnification conversion function, as shown in FIG. It has a structure in which 62 pieces are arranged at equal pitches. Therefore, the center of the gap between the 31st and 32nd light emitting diodes 6a and 6b located at the center of the erasing array 5 is opposed to the exposure center 7a of the photoreceptor 7.

For this reason, when attempting to perform partial erasure symmetrically around the exposure center 7a of the photoreceptor 7 on the original paper using a reduction copy with a magnification of 50%, the area for partial erasure set on the original paper must be If the size is 60x 50[:awl, no problem will occur, but if the size is 50x 50[av], as in area A shown in Figure 8 (a), then 50[%] ]Erase area B during reduction copying
Theoretically, it should be 25×25 [vnl, but in reality, the width can be selected to be 25 [val] because the pitch width of the light emitting diode 6 is large.
As shown in Figure 8 (b), 30X25 [m+n] is 20
X25 becomes [aun]. This erasing area B is 60 x 50 [converted to the size of the original paper].
mml corresponds to 40×25, and the set width of area A on the document sheet causes a large error of 10 [ma+ko], which is equivalent to two light emitting diodes.

That is, when reducing at a magnification of 50%, if the setting value in the width direction of the area on the original sheet for partial erasure is Yi = 10.20.30 - [mm1, etc. from the exposure center 7a of the photoreceptor 7. , the actual erase area is the same as the theoretical value Yo-5°10,
15...[ll1m], whereas the setting value in the width direction of the area for partial erasure is the exposure center 7a of the photoreceptor 7.
Therefore, if Yi = 5.15.25-[mm1, etc., the theoretical value is 2.5゜7.5, 12.5... [Although it is III, the actual erase area is Yo-5 ,10,15
...[mil], and converting this to the original size,
There is an error of 5 mils from the theoretical value. In addition, if these are expressed in tables and graphs, [Table 1] and Figure 9 (
The result will be as shown in b).

Note that the dotted line a represents the theoretical value, and the solid line a represents the actual erasing area. Moreover, since this error occurs on both the left and right sides of the document tray, the total length of the document tray has a large error of 10[ll1m].
It also has a big impact on the image.

On the other hand, when the magnification is 50 [%], the maximum error in the entire length of the document is 10 [m], even though it is frequently used.
ml, which is much larger.

[Table 1] Error in the erased area during reduction copying using a conventional device. However, this kind of error is the same even when the magnification is 71 [%]. As shown in (b), an error occurs between the theoretical value C shown by the dotted line and the actual erasure area d shown by the solid line, and this error has a greater influence on the image as the reduction ratio increases.

Moreover, when the magnification is 71%, as shown in [Table 2], the maximum error in the entire length of the original is t3.34 [a+a]. Error in the erase area and if this error is large, it will have a big impact on the image, causing problems such as parts that need to be kept being erased when copying, or parts that you want to erase remaining. Furthermore, while the set area is square, the actual erased area is rectangular, creating an unnatural viewing angle.

However, the above error can be solved by arranging small light emitting diodes at narrow intervals, but this requires an increase in the number of light emitting diodes, which significantly increases the cost and also increases the number of ICs that drive and control the light emitting diodes. This has led to an economical problem in that it is not suitable for low-cost equipment, as the cost for this is also increased.

(Problem to be Solved by the Invention) Conventionally, due to economic considerations, although light-emitting diodes with a relatively large pitch width are used, an even number of light-emitting diodes are arranged in the erasing array, and the number of light-emitting diodes in the center is Since the center of the gap between the light emitting diodes faces the exposure center of the photoconductor, when reducing the copy at a magnification of 50 [%], depending on the size of the area set on the original, the area on the original may differ from the set area on the original. There was a problem in that a large error occurred between the actual erased area and the image was adversely affected.

Therefore, the present invention eliminates the above-mentioned problems, and maintains economic efficiency without particularly reducing the pitch width of the light emitting diode, and has a high reduction ratio and a magnification of 50[
The present invention aims to provide an image forming apparatus capable of reducing the error between a set area on a document and an actual erased area (1) and improving image quality.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention comprises an image bearing member, and at least a charging means, an image exposure means, and a developing means provided opposite to the image bearing member. and an odd number of light emitting means, and is installed between the charging means and the developing means so that the center of the light emitting means in the center faces the center of the image carrier, and irradiates any position on the image carrier. A possible erasing means is provided.

Furthermore, in order to solve the above problems, the present invention provides an image carrier;
An image forming means provided opposite to the image carrier and having at least a charging means, an image exposure means, and a transfer means, and an odd number of light emitting means, such that the center of the light emitting means in the central portion faces the center of the image carrier. An erasing means capable of irradiating any position on the band carrier is provided.

Furthermore, in order to solve the above problem, the present invention provides the light emitting means with an odd number of light emitting diodes having the same size and arranged at equal intervals.

(Function) By the above means, the present invention can achieve a magnification of 5 while being inexpensive.
This is intended to reduce the error between the set area on the document and the actual erased area at 0[%], thereby improving the image quality during editing.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. FIG. 1 is a schematic explanatory diagram of an image forming apparatus, and 1 in the figure indicates charging, partial erasure, exposure, development, transfer, cleaning,
This is a main body of the apparatus that incorporates an image forming process means 2 that performs static elimination, fixing, and the like. and image forming process means 2
As shown in FIG. 2, a charging device 11 as a charging means, an erasing array 12 as an erasing means, and an exposure device 1 as an image exposure means are arranged around the photoreceptor 10 in order along the direction of rotation thereof.
3, the developing device 14 as a developing means, the transfer charger 15a as a transfer means, and the peeling charger 1
A transfer peeling charger 15, a cleaning device 16, and a static eliminator 17 are provided. Furthermore, the device body 1
On the right side, a first cassette 18a and a second cassette 18b1 for storing paper P and a manual paper feed table 18c are provided. In addition, each cassette 18a is provided in the main body 1 of the apparatus.
, 18b, and first to third pickup rollers 20a that take out the paper P from the manual paper feed table 18c,
20b and 20c are provided, and the paper P taken out by the pickup rollers 20a to 20c is transferred to the photoreceptor 10.
A conveyance path 22 is formed which leads to a paper discharge tray 21 provided on the left side of the apparatus main body 1 through the conveyance path 22 .

Further, first and second separation rollers 23a, 23b and registration rollers 24 are arranged on the upstream side of the photoconductor 10 in the conveyance path 22, and a conveyance belt 26, a fixing device 27, and a paper ejection roller 28 are arranged on the downstream side. It is located. In addition, 30 is
This is an original table on the upper surface of the apparatus main body 1 on which a document tray is placed, and a scale (not shown) is provided around it for indicating an area on the document tray.

In the erase array 12, inside the cover 12a,
63 light emitting diodes 31, which are light emitting means and have a size of 4 x 2 [mm], are arranged in a 5 [mm] pinch, and the center of the 32nd light emitting diode 31a in the center is the exposure center LOa of the photoreceptor 10. , and are symmetrical with respect to the exposure center 10a of the photoreceptor 1°.

Reference numeral 32 denotes an operation panel provided on the top surface of the apparatus main body 1, which includes operation keys 33 such as a copy key 33a, a numeric keypad 33b, a paper size key 33c, and an erase key 33d, and display sections such as a display panel 34a and a message panel 34b. 3
It consists of 4.

Furthermore, the exposure device 13 has a magnification conversion function, and from the document table 30, a first mirror 13b, a second mirror 13c,
The first optical path length from the lens L3e to the lens 13e via the third mirror 13d, the fourth mirror 13f, and the fifth optical path length from the lens L3e to the lens L3e.
photoreceptor 1 via the mirror 13g and the sixth mirror 13h.
The ratio of the second optical path length to the zero exposure section 13a is changed by a drive device (not shown).

Next, we will discuss the effect. To start copying,
When setting a document on the document table 30, and then inputting copy conditions such as the number of copies, copy magnification, tip amount, paper size, etc. using the operation keys 33 on the operation panel 32 of the apparatus main body 1, and also performing partial erasing. , operate the erase key 33d, read the coordinates of the four corners that display the areas on the document to be irradiated by the erase array 12 on the scale around the document table 30, enter them from the numeric keypad 33b, and then press the copy key 33a. Turn on. For example, if the copy magnification is 5
0 [%], and furthermore, as an area for partial erasure,
When an area C of 45 x 45 [mm] is set on the document paper symmetrically with respect to the exposure center 10a of the photoreceptor 10, the exposure device 13 starts the [first optical path length
: [The lens 13 is adjusted so that the second optical path length is 2:1.
After the fourth and fifth mirrors 13f and 13g are moved, driving of the photoreceptor 10 is started.

As the photoreceptor 10 rotates, it is uniformly charged by the charging device 11 and partially erased by the erasing array 12, after which the electrostatic latent image corresponding to the original image is removed by 50% in the exposure section 13a. Formed at a reduced rate.

Next, as the photoreceptor 10 rotates, it is developed and visualized in a developing device 14, and reaches a transfer peeling charger 15. Meanwhile, in synchronization with this, paper P is fed from one of the cassettes 18a and 18b designated on the operation panel 32, and this paper P is transferred to the separation rollers 23a and 23b.
Then, at the timing when the leading edge aligns with the electrostatic latent image on the photoreceptor 10 via the registration roller 24, the transfer peeling charger 15 is activated.
sent to. Then, the toner image is transferred to the photoreceptor 1.
The paper P peeled off from the paper P is conveyed to the fixing device 27 side and fixed thereon, and then transferred to the paper ejection tray 21 by the paper ejection roller 28.
Paper is ejected on top.

On the other hand, after the transfer is completed, the photoreceptor 10 is moved to the cleaning device 1.
The residual toner is removed by step 6, and the charge is removed by charge eliminator 17, making it possible to make the next copy.

Copying is then repeated until the set number of copies is obtained.

However, here, the erase array 12 actually performs the process shown in FIG.
The erasing area D of 25×25[+1101] shown in b) will be erased. This is the theoretical value of 22.5X when area C set on the manuscript is reduced by 50%.
Compared to 22.5 [m+n], when converted to original size,
Although there is an error of 5 [+ nm] in the total length, it is better than the conventional 1
Compared to 0[m+nl, it is reduced by half.

In this example, the magnification is 50% and the magnification is 71%.
The error between the theoretical value of the area set on each document and the actual erase area when ) as shown in
At a magnification of 50%, where the actual erasing area is shown by the solid line f with respect to the theoretical value shown by the dotted line e, the error is halved compared to the conventional one, but the actual erase area is smaller than the theoretical value shown by the dotted line g. At a magnification of 71%, which is indicated by the solid line in the erased area, the error is maintained at approximately the same level as the conventional one.

(Margins below) [Table 3] Error in erase area during 50-hour reduction copying according to this embodiment [Table 4] Error unit of erasure area during 7 consecutive reduction copying according to this embodiment [Dragon] Like this If configured, the light emitting diode 31 can be added to the conventional device.
Just by adding one more, you can achieve a large reduction rate of 50%.
Also, when the erasing area D is converted to the document size, the maximum error from the theoretical value is 5 [mm], which can be halved compared to the conventional method. Therefore, even when performing partial erasure and obtaining a reduced image with a magnification of 50%, images that should be kept are not erased or images that should be erased remain, as was the case in the past, and the image quality is improved. It becomes possible to achieve significant improvements. Moreover, there is no adverse effect such as an increase in the error from the theoretical value at other reduction ratios smaller than 50 [1%].

Furthermore, the number of additional light emitting diodes 31 is 1 compared to the conventional device.
Since there are only 1 pieces, the cost of the erase array 12 itself does not increase much, and there is no need to add an IC to control the erase array 12, which conventionally used 2 pieces, and the cost of increasing the number of ICs increases. It is also possible to prevent build-up, and it can also be applied to low-cost equipment.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways. For example, the erasing means may not only erase a part of the original, but may also be used when only a part of the original is desired to be left, or when it is desired to erase only a part of the original. It can be used to erase excess charge, and the main body of the apparatus may be optional, such as a color copying device or an automatic document feeder as an option. Further, the main body stage of the apparatus may be either a development transfer type or a latent image transfer type. Furthermore, the erasing area on the document may be specified by providing a slide switch on the scale around the document table instead of using the numeric keypad, and moving this slide switch to a predetermined position.

[Effects of the Invention] As explained above, according to the present invention, the pitch of the light emitting means forming the erasing means is not reduced, and while maintaining almost the same pitch as before, copying at other magnifications is possible. The actual erased area by the erasing means when copying at a magnification of 50% without affecting the
The maximum error from the theoretical value can be halved compared to the conventional method, and it is possible to improve the image quality of edited images such as masking and trimming at a magnification of 5° [%] compared to the conventional method. Moreover, the number of light emitting means is increased by one compared to the conventional one, and furthermore, the number of light emitting means is increased by one compared to the conventional one.
Since there is no need to increase C, there is almost no increase in cost compared to the conventional method, and application to low-cost equipment is fully possible.

[Brief explanation of drawings]

1 to 6 show one embodiment of the present invention, FIG. 1 is a schematic explanatory diagram of an image forming apparatus, FIG. 2 is an explanatory diagram of image forming process means around the photoconductor, and FIG. 3 is a diagram showing the photoconductor. 4 is a top view of the operation panel,
Figure 5 (a) is an explanatory diagram of area C set on the manuscript paper;
Figure 5 (b) is an explanatory diagram of the actual erased area D for area C at a magnification of 50 [%], and Figure 6 is an explanatory diagram of the actual erased area D at a magnification of 50 [%].
], and a graph showing the error between the actual erasing area and the theoretical value at a magnification of 71%; FIGS. 7 to 9 show the conventional device; FIG. Figure 8 (a) is an explanatory diagram of area A set on the manuscript,
Figure 8 (b) is an explanatory diagram of the actual erased area B for area A at a magnification of 50%, and Figure 9 is an illustration of the actual erased area B at a magnification of 50%.
], and a graph showing the error between the actual erase area and the theoretical value at a magnification of 71%. 1... Device main body, 1o... Photoreceptor, 10a...
...Exposure center, 12...Erasing array, 13...
Exposure device, 31...Light emitting diode, Agent: Patent Attorney Nori Ogo Figure (A) ＾ 〉-5%-/ Figure (B) qF ζN Figure (A) /-78 Figure (B) )

Claims (3)

[Claims] (1) In an image forming apparatus having a magnification conversion means with a magnification of at least 50%, an image bearing member, at least a charging means, an image exposure means, provided opposite to the image bearing member,
The image forming means includes an image forming means having a developing means, and an odd number of light emitting means, and is installed between the charging means and the developing means so that the center of the light emitting means in the center faces the exposure center of the image carrier. An image forming apparatus comprising an erasing means capable of irradiating an arbitrary position on an image carrier. (2) In an image forming apparatus having a magnification conversion means with a magnification of at least 50%, an image bearing member, at least a charging means, an image exposure means, provided opposite to the image bearing member,
The image forming means includes an image forming means having a transfer means, and an odd number of light emitting means, and is installed between the charging means and the transfer means so that the center of the light emitting means in the center faces the exposure center of the image carrier. An image forming apparatus comprising an erasing means capable of irradiating an arbitrary position on an image carrier. (3) The image forming apparatus according to any one of item 1 and item 2, wherein the odd number of light emitting means are comprised of an odd number of light emitting diodes having the same size and arranged at equal intervals. .