JPS59142572A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a toner from adhering to a non-copy part of a photosensitive body and to prevent useless toner consumption in any mode by applying each separate toner adhesion preventing means with respect to each mode of positive - positive and negative - positive. CONSTITUTION:When forming a positive picture from a positive original, the side end part of a photosensitive body 4 and the front and rear parts of a latent image forming part are brought to a blank exposure by a lamp 1 in order to prevent a toner from adhering to a non-copy part on the photosensitive body. Also, when forming a positive picture from a negative original, a light shielding member 2 having a notch corresponding to size of the original or a transfer paper is placed so as to cause no exposure leakage to the non-copy part. When one mode of positive - positive or negative - positive is selected, either the blank exposure or the light shielding is operated. A destaticizing device can be used instead of the blank exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus that forms images corresponding to seventh and second originals.

Generally, when performing positive copying from a positive original, depending on the charge on the photoreceptor, the effective width and length of the exposure range, there may be an image pattern on the non-copied part of the paper, or a black part when the optical system returns. If there are dark areas, excess toner will adhere to these areas. This toner is not transferred to the paper and is removed in the next cleaning step, resulting in a disadvantage that the toner is wasted. Conventionally,
In order to overcome this drawback, the size of the original is detected and blank exposure is performed in accordance with the size of the original to prevent excess toner from adhering to the non-copied portion.

On the other hand, when performing positive copying from a negative original, if there is an image pattern in the non-copied part or a part that reflects a lot of light when the optical system returns, excess toner will adhere, and this toner will not be transferred to the paper. It had the disadvantage that it was wasted without much effort.

Conventionally, in this case, it has been proposed to detect the document size and provide a light shielding means in the non-copied part.

Then, in a copying machine having a negative/positive switching means, a blank exposure means and a light shielding member are arranged near the exposed image on the photoreceptor, and the negative original is shielded from light, and the positive original is subjected to blank exposure to remove excess toner. I tried to remove -.

However, blank exposure and light shielding are mutually contradictory functions, and depending on the placement positions of the blank exposure means and light shielding means with respect to the optical image and the related control devices, the functions of blank exposure or light shielding may not be fully achieved. It had the disadvantage of being blocked.

The present invention has been proposed to solve the above-mentioned drawbacks, and an object of the present invention is to provide an image forming apparatus that can use both negative and positive originals without wasting toner. do.

The present invention includes a first toner adhesion prevention means that operates when a negative original is used, and a second toner adhesion prevention means that operates when a positive original is used.
The toner adhesion prevention means includes a toner adhesion prevention means, and a control means for disabling the other when one of the first and second toner adhesion prevention means is used.

In general, methods for forming areas to which toner is not attached (referred to as non-image areas) include: 1. Making the area other than the original area into a non-image area depending on the document size; 2. Image areas to be formed (reduction, enlargement, same size). Create a non-image area depending on the paper size ■ Create a non-image area depending on the document-paper usage mode (reduction, enlargement, same size) K There are things etc. In the present invention, this forming method is referred to as "means for forming a non-image area on a photoreceptor in response to a predetermined signal."

In addition, as a non-image area forming means, ■ a charger that charges the toner with the same polarity; and ■ a charge neutralizer using light or a static eliminator to prevent toner from adhering as in the present embodiment. (2) As in the present embodiment, there is a method in which toner adhesion is prevented by using a light shielding member to maintain the charge on the surface of the photoreceptor.

In addition, there are light sources that use part of the direct light from a light source for document illumination, light sources that use reflected light when the light source illuminates a white area, and light sources for static elimination that are separate from the document light source. There is one in which seven or more blank light sources (in this example) are divided and arranged in series.

In the present invention, these means are referred to as "first and second toner adhesion prevention means used depending on the type of document".

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments with reference to the drawings.

An example of an image forming apparatus, particularly a copying machine, will be described. FIG. 1 is an explanatory diagram of the configuration of blank exposure means constituting an embodiment of the present invention.

The blank exposure means is a known means applied to copying machines that perform positive copying from positive originals, and is activated by detecting the width and length of the original to be copied, as shown in Figure 3. It is something to do.

Blank exposure means// is a blank exposure lamp//.

/, 2. /3. /llt, /S, /6 Composed of craftsmen. For example, when the width of the transfer paper is B size, the blank exposure lamp // only' is lit. For this reason, positive 1
Because toner often adheres to the white part of the original, the photoconductor q
No toner adheres to the area exposed by the blank exposure lamp // above. Blank exposure lamp/2 is a blank exposure lamp// for use with small-sized copy paper.
By lighting up , / and 2 at the same time, wasteful adhesion of toner in the width direction of the copy paper can be avoided. Furthermore, by lighting the blank exposure rung/B at this time, toner does not adhere to the lower width portion of the separation bell of the 9B size copy paper. Furthermore, in the longitudinal direction of the copy paper, the blank exposure lamps are used until a light image corresponding to the leading edge is projected on the transfer paper. /3. /G,
/! By turning on all of /B, the entire surface of the photoconductor is exposed to blank light, and when the light image corresponding to the tip is projected, the light goes out. The projection of the optical image corresponding to the rear end ends.
and full exposure lamp //, /, 2. '/3. /<17
．． /3. /Otsu lights up again. FIG. 3 is an explanatory diagram of the structure of a light shielding means constituting an embodiment of the present invention.

This light shielding means 2 is applied to a copying machine that performs positive copying from a negative original. This light shielding means β is a shutter β steam L2.
,2. ．． 2s, , 26.

For example, when the width of the copy paper is B size, the shutter 27 is activated as shown in FIG. For this reason, in the case of a negative original, toner does not adhere to the light-shielded areas, so toner does not adhere to the dark areas on the photoconductor that are light-shielded by the shutter and 2/.

The shank shown in FIG. 3 corresponds to the width of a smaller size copy paper. In the longitudinal direction of the transfer paper, a shutter 23 is operated to prevent toner from adhering to the copy paper except when the light image on the copy paper is being exposed. The case where positive copying is performed from a positive original or a negative original has been described above.

The present invention is applied to a copying apparatus having a positive/negative switching means. In this copying machine, it is necessary to provide a blank exposure means and a light shielding means and control the copying machine according to the document size. If the blank exposure means and the light shielding means are controlled in accordance with the document size, an inconvenience will occur in the arrangement relationship between the two. For example, in the embodiments shown in FIGS. controlled in the same way. In the first embodiment shown in FIG. 5, the blank exposure means is blocked by light shielding means. In this case, the light shielding means 2 for negative originals functions satisfactorily, but when switching to positive originals, the light shielding means 2 operates in accordance with the size of the original, which prevents blank exposure. Therefore, at least in the case of a positive original in which the blank exposure means is activated, the light shielding means 2 must be in an open state and the blank exposure means 2 must be controlled as shown in FIG. The third embodiment shown in FIG. 6 is a case in which the blank exposure means is placed in a position that blocks the light shielding means. In the case of a positive original, the blank exposure means/ functions fully, but in the case of a negative original, the operation of the light shielding means 2 is blocked by the blank exposure means. In this case, however, the light shielding means must be controlled at least in the state shown in FIG. g, in which all the blank exposure means are turned off.

That is, when the blank exposure means / is arranged so as to be blocked by the light shielding means 2 as in the embodiment shown in FIG. 5, the operation timing of each means is as follows.

In the case where the light shielding means is blocked by the blank exposure means as in the embodiment shown in FIG. 6, the operation timing of each means is as follows.

In the above-described embodiments of the present invention, positive copying is performed from a negative original and a positive original.
This also applies to changing the operational relationship when performing negative copying from a positive original.

The present invention 7 can also be used when providing margins at the leading edge of a separation belt or paper or other necessary margins (before and after images, between images in continuous copying, etc.).
is applicable. The present invention is still applicable to a dedicated copying machine that performs positive copying from a negative original as well as a dedicated copying machine that performs positive copying from a positive original. FIG. 2 shows a state diagram in which the third embodiment of the present invention is exposed to light, and FIG. State diagram where light is blocked against
FIG. 1 is a state diagram in which blank exposure is performed on the non-copied portion in the positive original copying process of the embodiment shown in FIG.

In still another embodiment of FIGS. 6 and 2, a light emitting member such as a light emitting diode or an electroluminescent sensor is disposed as a blank exposure means on the side of the light shielding means facing the photoreceptor. Good too.

In the embodiment of FIG. 5(A), for example, the blank shutter and blank exposure are controlled as shown in FIG. S(B) by the flow trigger and positive signal of FIG. S(B).

As explained above, in this embodiment, the blank exposure and light shielding functions are sufficiently achieved in an image forming apparatus having a negative/positive switching means, unnecessary consumption of toner is prevented, and copy paper can be transferred to a negative/positive original. This has the effect that a margin can be provided regardless of the situation, and that it is possible to easily switch between a negative original and a positive original.

In the above embodiments of the present invention, toner N is applied to photoreceptor areas of other widths mainly depending on the width size of the document or recording sort.
Although the means for preventing toner adhesion has been described as a toner adhesion prevention means, the present invention includes a method for preventing toner adhesion to an area before and/or after a formed image area.1. It includes a method that prevents toner from adhering to the area between images that occurs during continuous copy mode, a method that forms only a predetermined region as a non-image area, or a combination of these. , these are collectively referred to as toner adhesion prevention means.

The present invention is also applicable to obtaining a negative image from a negative original and a negative image from a positive original. In particular, in the negative original mode, the light shielding means for preventing light from being irradiated onto the photoreceptor is
In the positive original mode, a static eliminating means that lowers the potential of the photoreceptor is suitable.

As described above, the present invention has the effect of reliably preventing wasteful consumption of toner.

[Brief explanation of drawings]

1 is an explanatory diagram of the configuration of a blank exposure means constituting an embodiment of the present invention, FIG. 2 is an explanatory diagram of a blank exposure state by the blank exposure means of FIG. 1, and FIG. 3 is an explanatory diagram of the blank exposure state of the blank exposure means of FIG. FIG. 9 is an explanatory diagram of the structure of the light shielding means constituting one embodiment, and FIG. 5 (A) is an explanatory diagram of the light shielding state by the light shielding means of FIG. 3.
1 is a block diagram of the first embodiment of the present invention in which the blank exposure means is arranged so as to be blocked by the light shielding means, and FIG. S (B) is a flowchart of the operation of the embodiment of FIG. 1,
FIG. 6 is a block diagram of a second embodiment of the present invention in which the light shielding means is arranged so as to be blocked by the exposure means, and FIG.
FIG. S is an explanatory diagram showing the light shielding means of the embodiment in an open state, FIG. 5 is an explanatory diagram showing the blank exposure means of the embodiment in FIG. The configuration diagram of the embodiment shown in FIG.
The figure is an explanatory diagram of the blank exposure state of the embodiment shown in FIG.
/...Blank exposure means 1,? , Light shielding means 1 G... Photoreceptor. Fig. 1 1 Fig. 2 Fig. 3 MSt, Fig. 6 Fig. 11i3 Fig. 8 Fig. 10 Fig. 1 1 Fig. 11

Claims (1)

[Scope of Claims] In an image forming apparatus capable of forming images on both positive originals and negative originals, there is provided a first toner cooking prevention means used in the positive original use mode and - mode, and a first toner cooking prevention means used in the negative original use mode. a second toner adhesion prevention means, and a control means for disabling the other when one of the first and second toner adhesion prevention means is used, and a control means for placing a desired non-image area on the photoreceptor. An image forming apparatus characterized by forming an image.