JPH03172252A - Picture forming device - Google Patents

Abstract

PURPOSE:To accurately convey paper forms by a resist roller with an adequate deflection amount given to the paper form even when assumed that its characteristic of rigidity or the like is changed by changing humidity, by providing a control part in which the deflection amount of the paper form by a paper conveying roller is controlled based on a detection result of a humidity sensor. CONSTITUTION:By a paper conveying roller in a paper conveying part 33, paper forms are brought into contact with a resist roller 21 and with a predetermined amount of deflection given. Now based on a detection result by a humidity sensor 24 arranged in the vicinity of the paper conveying part 33, the deflection amount of the paper form is controlled by a control part 30. As a result, even when assumed humidity is changed, the corresponding adequate deflection amount is given to the paper form, and it is brought into contact with the resist roller 21 in a proper attitude. Next the paper form in contact with the resist roller 21 is supplied to a picture forming part 9 in the predetermined timing by the resist roller 21. A picture is formed in the supplied paper form by the picture forming part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus, and particularly to an image forming apparatus for forming an image on paper.

[Conventional technology]

A conventional image forming apparatus, such as a copying machine, consists of an exposure section that obtains image information by scanning a document, an image forming section that includes a photoreceptor drum, etc. that receives information from the exposure section and forms a toner image; and a paper transport section for transporting the paper to the image forming section. The paper transport section is generally
Registration rollers supply paper to the image forming section at a predetermined timing, and the paper is brought into contact with the registration rollers at a predetermined time! It is equipped with paper conveyance rollers for bending the paper.

In this type of copying machine, sheets are conveyed one by one from a paper feed cassette or the like to a registration roller side by a sheet conveying roller of a sheet conveying section. The leading edge of the paper that has been conveyed contacts the registration rollers, and is further bent by a predetermined amount.
The paper is supplied to the image forming section at a predetermined timing by the registration rollers. As a result, the leading edge of the image on the image forming unit and the leading edge of the paper are aligned, and the image is copied at the correct position on the paper.

[Problem to be solved by the invention]

Paper stored in a paper cassette case or the like is relatively easily affected by humidity. When the humidity is low, paper becomes relatively hard and stiff.

On the other hand, as humidity increases, paper becomes softer and less stiff. However, in the conventional configuration, the amount of deflection of the paper by the paper transport roller is set regardless of changes in stiffness due to changes in humidity. For this reason, in the conventional configuration, it is not possible to always set the flexure period of the paper to an optimal state, and there are cases where the paper cannot be brought into contact with the registration rollers in the correct posture. In such a case, as a result, the paper cannot be conveyed accurately by the registration rollers, and the image on the image forming section and the paper will not match accurately.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can provide paper with an appropriate deflection in response to changes in humidity and can accurately supply paper to an image forming section.

[Means to solve the problem]

An image forming apparatus according to the present invention is an apparatus for forming an image on paper.

This device includes an image forming section for forming an image on supplied paper, a paper transport section for transporting the paper to the image forming section, a humidity sensor disposed near the paper transport section, and a paper transport section for transporting the paper to the image forming section. and a control section that controls the amount of deflection of the paper by the conveyance roller. The paper transport section includes a registration roller for supplying paper to the image forming section at a predetermined timing;
It has a paper conveyance roller for bringing the paper into contact with the registration row and deflecting it by a predetermined amount. Further, the control section controls the amount of deflection of the paper based on the detection result by the humidity sensor.

[Effect]

In the image forming apparatus according to the present invention, the paper is brought into contact with the registration row and deflected by a predetermined amount by the paper transport roller of the paper transport section.

At this time, the amount of deflection of the paper is controlled based on the detection result from a humidity sensor placed near the paper transport section. As a result, even if the humidity changes, the paper is given an appropriate amount of deflection in response to the change, and the paper can come into contact with the registration rollers in the correct posture.

The paper that has come into contact with the registration rollers is supplied to the image forming section at a predetermined timing by the registration rollers. An image is formed on the supplied paper by the image forming section.

〔Example〕

FIG. 1 is a schematic vertical cross-sectional view of an embodiment of the present invention.

In the figure, a document mounting table 2 is fixed to the upper surface of a main body 1 of a copying machine. Twenty-one document pressers 3 are mounted above the document table 2 so as to be openable and closable. On the other hand, on the right side of the copying machine main body 1, from the top, there is a bypass table 4, a paper feed cassette 5, and a paper feed cassette 5.
．． 6 is installed.

Further, on the left side of the machine, there is installed a paper ejector for ejecting copied paper.

Inside the copying machine main body 1, an optical system 8 for reading originals is provided at the top.

This optical system 8 is composed of a light source, a mirror, and the like.

Further, a photoreceptor drum 9 on which an electrostatic latent image is formed on the surface of the photoreceptor drum 9 is disposed at a substantially medium position of the main body 1 of the apparatus. Around the photoreceptor drum 9, there is a main charging corona discharger 10 that charges the photoreceptor drum 9 to a predetermined charge, a developing device 11 that develops the electrostatic latent image on the photoreceptor drum 9, and a toner on the paper. A transfer corona discharger 12 for transferring an image, a separation corona discharger 1 for separating paper from the photoreceptor drum 9
3, and a cleaning device Z'14 for removing residual toner and the like on the photosensitive drum 9.

A paper feeding device 17 is provided between the image forming section composed of the photosensitive drum 9 and the like, the bypass table 4, and the paper feeding cassettes 5 and 6. Above the tip of the paper feed cassette 5.6 is a paper feed roller 16a.
, 16b are provided. Furthermore, a registration roller 21 consisting of a pair of rollers is provided at the end of the paper feeder 17 on the side of the image forming section. A paper feed sensor 22 is arranged upstream of the registration rollers 21 to detect when a sheet of paper approaches the registration rollers 21 .

Upstream of the paper feed sensor 22, the conveyance path of the paper feed device 17 branches, and an intermediate conveyance I+-ra 23 is disposed on the upwardly branched conveyance path. Further, a humidity sensor 24 is arranged on the inner wall surface of the copying machine main body 1 between the bypass table 4 and the paper feed cassette 5.

A conveyance device 18 is provided downstream of the image forming section. A fixing device 20 is provided between the conveyance device 18 and a discharge roller 19 provided on the paper discharge tray 7 side for fixing the transferred image on the conveyed paper.

Furthermore, the copying machine according to this embodiment has a control section 30 as shown in FIG. The control unit 30 includes a CPU, R
It includes a microcomputer consisting of AM, ROM, etc. In addition to the control program, the ROM contains a table (based on experimentally obtained data) showing the relationship between the detection results by the humidity sensor 24 and the control of the paper transport roller (corresponding to the paper feed roller 16b and intermediate transport roller 23). A table) and a table (a table including experimentally obtained data) showing the relationship between the detection results by the paper type sensor and the control of the paper conveyance roller, which will be described later, are stored. The control unit 30 also includes a key panel 31 including a print key for instructing to start copying, and the humidity sensor 24.
The paper feed sensor 22, the paper type sensor 32, and other input sections are connected. Here, the paper type sensor 32 is a sensor for detecting the size, thickness, and material of the supplied paper. This paper type sensor 32 is of a magnetic type, for example, in which the paper type is expressed by the arrangement of a plurality of magnets provided in the paper feed cassette 5.6. Furthermore, the control unit 30 also controls the paper feed rollers 16a and 1.
6b and an intermediate conveyance roller 23;
The registration roller 21 and other output parts are connected
There is.

This copying machine is controlled by the control section 30 as will be described later.

Next, the operation of the above embodiment will be explained with reference to the control flowchart shown in FIG.

If you turn on the main switch (not shown), step St.
Initial settings such as setting the number of copies to 1 and setting paper in six paper feed cassettes are performed.

In step S2, it is determined whether the print key on the key panel 31 has been pressed. If the print key is not pressed, the process moves to step S3 and other processing is performed. It also includes paper feed route change processing. When the process in step S3 is completed, the process returns to step S2.

Here, if the print key is pressed, the program moves from step S2 to step S4. In step S4, based on the input signal from the humidity sensor 24,
Next, in step S5, paper type detection is performed based on the input signal from the paper type sensor 32. Through the processing in steps S4 and S5,
Control parameters are determined for determining the amount of deflection that must be applied to the paper before the registration [I-ra 21]. Next, in step S6, based on those control parameters, R of the control section 30 is
The paper feeding time is calculated by referring to the table stored in the OM.

Next, in step S7, the paper conveyance rollers are driven. If the use of paper cassette 6 is specified,
The paper feed roller 16b is driven, and the topmost sheet of paper is conveyed to the registration roller 21 side. On the other hand, if the use of the paper feed cassette 5 is specified, the paper feed roller 16a
and the intermediate conveyance roller 23 are driven, and the registration roller 2
Paper is conveyed to the first side. The same applies to the bypass stand 4. As the paper is conveyed through the paper feeder 17, the leading edge of the paper is eventually detected by the paper feed sensor 22. When paper is detected by the paper feed sensor 22, the determination in step S8 becomes Yes, and the process moves to step S9. In step S9, it is determined based on a timer (not shown) whether the sending time calculated in step S6 has elapsed. Before the feeding time elapses, the paper is fed to the registration roller 21 side by the paper feed roller 16b or the intermediate conveyance roller 23. If it is determined that the feeding time has elapsed, the process proceeds from step S9 to step SIO. transition,
The paper feed roller 16b or the intermediate conveyance roller 23 is stopped. As a result, the transported paper is given an amount of deflection that is appropriate for the humidity and paper type.

Next, the process moves to step Sll, where the optical system 8 performs an exposure operation, the photosensitive drum 9 performs image formation, and the fixing device 7i20
The remaining copying operations, such as the fixing operation, are performed. In step S12, it is further determined whether or not to perform 1 pixel on the next sheet. : If the number of copies per copy does not reach the specified number of copies, the operations from step S7 onwards are performed again. When the copying operation has been completed for the specified number of copies, the process proceeds from step S12 to step S2.
Return to

In this way, in the above-described embodiment, the amount of deflection of the paper supplied to the registration rollers 21 is appropriately set based on the humidity and paper type, so even if the humidity or paper type changes, the registration rollers can be moved in the correct orientation. The paper can be placed in contact with the paper. As a result, the timing and posture of conveying the paper by the registration rollers 21 become accurate, and the image is formed at the correct position.

Note that in the above-described embodiment, the present invention can be implemented in the same manner even if the paper type sensor 32 is omitted.

〔Effect of the invention〕

The image forming apparatus according to the present invention includes a humidity sensor and a system that performs control based on the detection result of the humidity sensor. It is equipped with a 7U section. Therefore, according to the present invention, even if the paper stiffness and other characteristics change due to changes in humidity, it is possible to give the paper an appropriate amount of deflection, and the paper conveyance by the registration rollers can be adjusted to a positive value. You will be able to do this.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of one embodiment of the present invention, FIG. 2 is a schematic block diagram of the control section thereof, and FIG. 3 is a control flowchart thereof. 8...Optical system, 9...Photoreceptor 1' ram, 16b...
・Paper feed 11-ra, 17...Paper feed device, 20...Fixing device, 21...L/register, 23...Intermediate conveyance roller, 24...Humidity sensor, 30... ...Control unit.

Claims (1)

[Claims] (1) An image forming apparatus for forming an image on paper, comprising an image forming section for forming an image on the supplied paper, and an image forming section for supplying the paper to the image forming section at a predetermined timing. a paper transport unit for transporting the paper to the image forming unit, the paper transport unit having a registration roller and a paper transport roller for bringing the paper into contact with the registration roller and deflecting the paper by a predetermined amount; and near the paper transport unit. An image forming apparatus comprising: a humidity sensor; and a control unit that controls an amount of deflection of paper by the paper transport roller based on a detection result by the humidity sensor.