JPS59107362A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce a residual toner on a photosensitive body, to prevent waste of a developer, and to decrease the burden of cleaning by comparing an image size of a designated scale factor with a transfer material size, and controlling an image part by setting a small size as a limit. CONSTITUTION:A titled device is provided with a destaticizing part on which plural light emitting elements are provided in parallel along the axial direction of a photosensitive body, and it is constituted so that size of an image part can be controlled. When A4 is designated by a form size designating key 35 of an operation panel, and an image size of B5 is designated by a reduction designating key 13B, a CPU32 reads out a form and a variable power size from a memory 33 and transfers them to a comparing and selecting means 36. The means 36 decides B5<A4, transfers it to a destaticizing light source part 14, and destaticizes a non-picture part except B5 width. Therefore, even in case when the form is A4, a developer adheres only to B5 width, a residual toner on a photosensitive body is reduced, waste of the developer is prevented, and the burden of cleaning can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus that forms an image on a transfer medium by forming an electrophotographic image on an image carrier based on a specified magnification.

[Technical background of the invention and its problems]

This type of image forming apparatus includes, for example, one having a variable magnification function, and conventionally, the non-image area on the surface of an image carrier (electrophotographic photoreceptor) corresponding to the magnification is Electric charge was removed before development to prevent unnecessary adhesion of developer to non-image areas. This reduces the burden of cleaning the developer remaining on the surface of the image carrier after transfer, and the developer remains permanently on the surface of the image carrier (as shown in Figure 1, the burden of cleaning the developer remaining on the surface of the image carrier is reduced. This is to prevent the deterioration of the electrophotographic characteristics of the image bearing member caused by cleaning efficiency (as the amount of cleaning agent increases, the cleaning efficiency decreases). If it is small, the image area of the image carrier corresponding to the blank area of the transfer medium will not be neutralized, and this will cause uneven exposure (unevenness during image exposure due to light reflected from the original) in this area, resulting in poor image quality. There was a problem in that it caused a decline. In addition, when obtaining an enlarged image based on the variable magnification function, if this enlarged image is larger than the size of the transfer medium, a relatively large amount of developer that is not transferred to the transfer medium remains on the image carrier, resulting in cleaning. There was a problem in that the developing agent that could not be completely cleaned remained on the image bearing member permanently, causing deterioration of the electrophotographic characteristics. [Purpose of the present invention] The present invention has been made in view of the above-mentioned circumstances, and its purpose is to eliminate any relationship between the size of an image to be formed based on a specified magnification and the size of a transfer medium. However, by reducing the amount of developer remaining on the image carrier after transfer, waste of developer can be prevented, and the burden of cleaning the remaining developer can be reduced. An object of the present invention is to provide an image forming apparatus capable of preventing deterioration of electrophotographic characteristics and deterioration of image quality.

[Summary of the invention]

In order to achieve the above object, the present invention includes a comparison selection means for comparing the size of an image to be formed and the size of a transfer medium based on a specified magnification and selecting the smaller size. , limit the image size to the smaller size obtained by this comparison and selection means tltlJ
The image size regulating means and metal plate are provided to reduce the amount of developer remaining on the image carrier after transfer.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of a copying machine showing a first embodiment of the present invention. In the figure, reference numeral 1 denotes a housing of a copying machine having a variable magnification function, and a photoreceptor 2 made of an image carrier, such as a selenium drum, which is rotatable in the direction of the second arrow A in the figure, is provided approximately in the center of the housing. . A document table 6 is provided on the base of the housing 1 and is capable of carrying a document thereon and moving back and forth in the directions of the first arrows B and jJ'. An exposure rung 4 is provided for irradiating light onto a document placed on a document table 6, and light can be irradiated from one end of the document to the other by moving the document table B. Then, the reflected light from the original is transferred to the first
A, an exposure device @8 is provided which exposes the surface of the photoreceptor 2 by irradiating it with image light through a second mirror 5B, a sixth mirror 5C, a lens unit 6, and a fourth mirror 7.

The variable magnification function of the copying machine shown in FIG. The lens unit 6 is moved along the optical path to achieve a predetermined same magnification, enlargement,
This is performed by changing the size of the exposed image on the photoreceptor 2 by positioning it at a reduced position.

The magnification can be specified using the enlargement specification key 16A on the operation panel provided on the front side of the housing 1 (for example, the enlargement rate is displayed according to the paper size, such as B5 → A4), and the reduction specification key (for example, A4 → 16B (in which the reduction ratio is displayed according to the paper size such as B5).

In the vicinity of the photoreceptor 2, there is a charge eliminating lamp 10 that uniformly removes charge from the surface of the photoreceptor 20 along the rotational direction of the photoreceptor 2.
and a charger 11 that uniformly charges the surface of the neutralized YC conductor 2 are attached, and further ahead of the charger 11 there is a photoconductor 2.
A static elimination light source section 14 is provided in which a plurality of light emitting elements are arranged in parallel along the axial direction. The static eliminating light source unit 14 selectively turns on the built-in light emitting elements to lower the surface potential of the originally irradiated portion of the photoreceptor 2 to a bias potential level or less. , the enlargement designation key 16. Comparison and selection means (details will be described later) that compares the size of the image to be formed and the size of the transfer medium and selects the smaller size based on the magnification specified by the A or reduction specification key 13B. This is an example of an image size regulating means that regulates the image size to a limit of the smaller size obtained by. In addition, the light source section 14 for static elimination
It is desirable that the wavelength of the light from the light emitting element built into the photoconductor 2 is in a range that does not cause optical fatigue to the photoconductor 2. For example, for the St photoconductor, a blue source is suitable;
EL, tungsten rungs combined with filters or I? L or the like can be used as a light emitting element.

Further, the surface of the charged photoreceptor 2 is subjected to image exposure by the exposure device 8, so that an electrostatic latent image is formed. A developing device 12 for making the electrostatic latent image visible using a developer (hereinafter also referred to as toner) is provided ahead of the static elimination light source section 14.
A paper feeding device 20 for feeding a transfer medium (hereinafter simply referred to as paper) below the photoreceptor 2 is provided on the side of the housing at the front of the photoreceptor 2 . This paper feeding device 20 includes a first paper feeding cassette 21/f (for example, A4 size paper is stored) that stores a plurality of sheets of a predetermined size, and a second
A paper feed cassette 21B (for example, storing B5 size paper) is removably provided on the side of the housing 1.
By selectively driving the first paper feed roller 22A and the second paper feed roller 22B disposed above each paper feed force sensor 2M and 21B, the paper is sent out from the desired paper feed cassette and sent out. The timing for transporting the paper is determined by an aligning row 226 provided at the end of the paper transport path. Note that the paper sizes that can be accommodated in each of the paper feed cassettes 2M and 21B are fixed.
Different protrusions 21α and 21b are attached to the tip of the valley paper cassette in accordance with the paper size that can be accommodated in each paper feed power center, and a paper size detector 254 that can be engaged with each protrusion 21α and 21b , 25.6 are installed in the housing 1, and the paper size in both paper feeders 2M and 21B is detected by paper size detection signals from the paper detectors 25α and 25b. It has become.

Further, a transfer charger 27 transfers the developed image on the photoreceptor 2 to the paper that is transported again at the timing of the transport by the aligning roller 26, and peels the paper to which the developed image has been transferred from the photoreceptor 2. A peel charger 28 is provided within the housing.

The transferred paper is then sent to a fixing device 29, the developer on the paper is fixed, and the paper is discharged onto a discharge paper V-30. In addition, what is shown by 31 in FIG. 2 is a cleaning section that collects the developer remaining on the surface of the photoreceptor 20 after the transfer.

Next, the drive control system of the static elimination light source section 14 will be explained with reference to FIG. 6. This drive control system first includes ('/
'U32 and memory 66 are connected and provided.

This memory 66 is A4. Various paper size data corresponding to paper sizes such as B5 and the enlargement designation key 13. (, # The maximum size of the image to be formed based on the magnification specified with the small specification key 16B (for example, A4 size if the magnification is specified with the enlargement specification keys such as 13Il+ and 44) Corresponding scaling size data is stored.The CI"U32 is
By inputting the paper size detection signal from the paper size detectors 25/2, 251), the paper size stored in both the paper feed power sets 2M and 21B is recognized, and the Paper size specification key 6
5 makes it possible to accept the specification of paper of that size, and Lfc paper size data corresponding to the paper size specification signal of the paper size specification key 65 is read out from the memory 63. Further, this CPU 62 is configured to read out variable size data corresponding to the specified magnification signal from the memory 66 by inputting the specified magnification signal specified by the enlargement specification key 16A2 and the reduction specification key 16B. The comparison and selection means 36 compares the paper size data read out by the CPU 62 with the variable size data and selects the data corresponding to the smaller size.
It is connected to the PU 32 and controls the lighting drive of the light emitting elements built in the static elimination light source section 14 in accordance with the size data selected by the comparison and selection means 36.

Next, the main operations of the apparatus of the above embodiment will be explained with reference to FIGS. 4 and 5. For example, paper size specification key 6
Assume that the A4 size is specified in 5 and the reduction ratio from A4 to B5 is specified in the reduction specification key 13B. Then the CPU
52 reads paper size data (data corresponding to the size of A4CA4 size paper) from the memory 63, and
The variable size data B5 (data indicating that the maximum image size to be reduced and formed is B, which corresponds to the size of the size paper) is read out and transferred to the comparison and selection means 66. The comparison and selection means 36 determines variable size data B5◇paper size data A4, and transfers the variable size data Bs', which is data of a smaller size, to the static elimination light source unit 14. The static elimination light source unit 14 that received the transfer. As shown in FIG. (outside the range indicated by width W5). As a result, the surface potential of the non-image area of the photoreceptor 2 is lower than the bias potential level, so that no wasteful developer is attached to the non-image area, and the A4 paper fed from the first paper feed cassette 21A is A for size paper
4 size paper @W4 instead of Es size paper width W
Since the developer is transferred only in step 5, it is possible to prevent waste of developer and reduce the burden of cleaning the developer remaining on the surface of the photoconductor, which in turn allows the developer to remain permanently on the surface of the photoconductor. It becomes possible to prevent deterioration of the electrophotographic characteristics of the photoreceptor and deterioration of image quality caused by the deposition.

Next, a second embodiment will be described. The same members as those shown in FIGS. 2 to 5 are given the same reference numerals, and detailed explanation thereof will be omitted. FIG. 6 is a sectional view showing another embodiment, and the difference is that it is located between the charger 11 and the photoreceptor 2, and restricts the charging area of the surface of the photoreceptor 2 by the charger 11. The charging area regulating section 40 constitutes an image size regulating means.

The charging area regulating section 40 is configured as shown in FIG. 7, for example. That is, an antistatic surface 41. A first slow-closing member 41 is formed with a double gear 41B on the other end thereof, and an antistatic surface 4 is formed on one end thereof. A and a rack gear 42B are formed at the other end of the second MIM member 42, which is disposed so as to be movable in the longitudinal direction of the electrical appliance 11 (in the axial direction of the photoreceptor 2). A stepping motor 44 having a binion gear 43 that meshes with both rack gears 41B and 42B is provided, and rotation of the stepping motor 44 causes the first and second slow closing members 41 and 42 to move in opposite directions. 1
The charging width F formed by the space between the corrosion-preventing surfaces 41A and 42A can be freely adjusted.

Note that when both the shield L members 41 and 42 are made of metal, it is desirable that the binion gear 46 be made of resin as a noise countermeasure. Further, an initial position detector 45 is provided which detects the initial position of both light shielding members 41 and 42 by coming into contact with the end of the second light shielding portion 4A42.

The drive control system of the stepping motor 44 is shown in FIG. 8, and the difference from that shown in FIG. 6 is as follows.
A charging width W formed by both the shielding members 41 and 42
The rotation angle data (based on the initial position shown in FIG. 7) of the stepping motor 44 that should be driven in order to make the width dimension of each paper size (for example, A4 size, B5 size) correspond to the paper size data. The rotation angle memory 48 is connected to the CPU 32, and the rotation angle memory 48 stores the rotation angle data corresponding to the smaller size data selected by the comparison and selection means 66.
The rotational drive amount of the stabilizing motor 440 is controlled by reading the information from the rotational speed.

Next, the main operations of the apparatus of the above embodiment will be explained with reference to FIG. For example, use the paper size specification key 65 to select A4
Specify the size and use the reduction specification key 16B to change from A4 to B
Assume that a reduction ratio of 5 is specified. Then, the CPU 62 reads the paper size data (data corresponding to the size of A4CAa size paper) from the memory 66, and also reads out the variable size data BS (data that corresponds to the size of the B6 size paper). data indicating that it is compatible)
is read out and transferred to the comparison and selection means 6. The comparison selection means 66 calculates that variable size data Bs<paper size data A.
4, the variable size data B5, which is small size data, is sent to the rotation angle memory 48, and the corresponding rotation angle data is transferred to the stepping motor driver 49. The transferred driver 49 rotates the stepping motor 44 by a predetermined amount so that the charging width formed by both the shielding parts U21 and 22 becomes the width of the B5 size paper. After that, when the charger 11 is activated, the charging width on the surface of the photoreceptor is regulated by both slow-closing members, so that the surface potential of the non-image area of the photoreceptor 2 (a range other than the paper width of the size CBs) is at the bias potential. The level state is maintained. As a result, the same effects as in the first embodiment can be obtained.

It should be noted that the above embodiment is just an example, and it goes without saying that each member can be replaced with another member having a similar function. For example, the specification of the magnification is not limited to specifications such as A4 → B5 (it is also possible to specify it arbitrarily by combining various paper sizes. is not limited to the case where it is achieved by a combination of a rack gear and a binion gear, but it is also possible to apply a wired drive that combines a pulley and a wire.In addition, the light source for weight removal is connected from the charger to the developing device. It can be provided at any position up to that point.

〔Effect of the invention〕

As is clear from the above description, in the image forming apparatus of the present invention, regardless of the relationship between the size of the image to be formed based on the designated magnification and the size of the transfer medium, at least During development, the surface potential of the non-image area of the image carrier can be brought to the bias potential level, so the amount of developer remaining on the image carrier after transfer can be reduced, and the amount of developer remaining on the image carrier can be reduced. In addition to preventing wastage, it is possible to reduce the burden of cleaning residual developer, and in turn, it is possible to reduce the burden of cleaning the remaining developer.
Aq! It has excellent effects such as being able to prevent deterioration of image quality and deterioration of image quality.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the amount of developer remaining on the surface of the photoreceptor and cleaning efficiency, and FIG.
FIG. 6 is a block diagram showing the drive control system of the light source for weight removal; FIGS. 4 and 5 are explanatory views of the operation of the first embodiment; FIG. FIG. 6 is a sectional view of a copying machine showing a second embodiment of the present invention. FIG. 7 is a detailed explanatory diagram of the charging area control WiIJ section. FIG. 9 is an explanatory diagram of the operation of the second embodiment device. 2... Image carrier, 11... Charger, 14.
・・Image size standard ft1lJ means (light source section for static elimination),
36... Comparison selection means, 40... Image size regulating means (charged area regulating section), 41... First slow closing member,
42...Second slow closing member. Figure 1

Claims (4)

[Claims] (1) In a device that forms an image on a transfer medium by forming an exposed image on an image carrier based on a specified magnification, the size of the image to be formed based on the specified magnification and the A comparison selection means for selecting a smaller size by comparing the size of the transfer medium with the size of the transfer medium, and an image size regulation means for regulating the image size up to the smaller size obtained by the comparison and selection means are provided. An image forming apparatus characterized by: (2) The image forming apparatus according to claim 1, wherein the image size regulating means includes a charger that charges the surface of the image carrier, and a charging area regulating section that regulates the charging area by the charger. . (3) The charging area regulating section includes first and second blocking members that are disposed between the image carrier and the charger and are movable in opposite directions along the longitudinal direction of the image carrier. An image forming apparatus according to claim 2. (4) The image forming apparatus according to claim 1, wherein the image size regulating means is a charge eliminating light source section that irradiates the charged image carrier with a variable exposure range.