JPH0331143A - Image forming device - Google Patents

Abstract

PURPOSE:To match the tip of a toner image on a light-sensitive drum and the tip of a fed recording medium regardless of the size of the recording medium by providing a control means driving the second sheet feed roller at the timing that the tip of the image of an image forming section and the tip of the recording medium match for each size of the recording medium. CONSTITUTION:The size of a recording medium P stored in a storing means 56 is detected by a detecting means 74. The recording medium P stored in the storing means 56 is rammed to the second sheet feed roller 58 by the first sheet feed roller 57. The second sheet feed roller 58 is driven at the timing that the tip of an image of an image forming section and the tip of the recording medium P match for each size of the recording sheet P detected by a controller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a storage means for storing a recording medium, and a first paper feeder that feeds out the recording medium of the storage means and abuts it against a second paper feed roller. The present invention relates to an image forming apparatus including a roller and a feeding means having a second paper feeding roller that feeds the abutted recording medium to an image forming section.

(Background of the Invention) Next, a conventional example will be explained using the drawings. FIG. 4 is a block diagram of an electrophotographic copying apparatus as an example of a conventional example.

In the figure, a transparent glass document tray 1 on which a document tray is placed is provided at the center of the upper part of the main body of the copying machine, and at the left end of the document tray 1, a placement position is specified depending on the size of the document tray. A scale plate 2 is provided. Furthermore, a document cover 3 is provided on the top of the document table 1 so as to be able to be folded forward to cover the document placed thereon. The document tray is placed on the document table 1 according to the scale designated by the scale plate 2, and is covered with the document cover 3 to restrict its movement.

A first mirror unit 6, which is provided with an exposure lamp 4 and a first mirror 5, is located below the original table 1 and inside the main body of the copying apparatus, and extends parallel to the document table 1 and in the left-right direction in FIG. It is installed so that it can be moved in a straight line, allowing it to scan the entire surface of the document tray. Further, the second mirror unit 9, which is constructed by integrating the second mirror 7 and the third mirror 8, is rotated at half the speed of the first mirror unit 6 in order to maintain a predetermined optical path length as shown in FIG. It is designed to be able to move linearly in the left-right direction and parallel to the original table 1. The main lens 10 allows the reflected light from the original on the original placing table 1 to pass through the first mirror 5. Second mirror 7 and third mirror 8
A lens that is reflected by and then enters the main lens 1
The light that exits the mirror 0 passes through the fourth mirror 11 and enters the photosensitive drum 12 as an image support via a slit 13.

The charging electrode 14 uniformly charges the photosensitive drum 12 with electric charge. Therefore, the photosensitive drum 1 rotates clockwise in FIG. 4 due to the incidence of light from the optical system.
2, electrostatic latent images are sequentially formed. The developing device 15 converts the electrostatic latent image on the photosensitive drum 12 into a visible toner image.

On the other hand, the paper feeding device that feeds the transfer paper includes a paper feed cassette 16 that accommodates the transfer paper (recording medium) P, and a paper feed cassette 1 that accommodates the transfer paper (recording medium) P.
The first paper feed roller 17 feeds out the transfer paper P one by one from 6.
, a second paper feed roller 18 that feeds this fed-out transfer paper P to the photosensitive drum 12 side, and the paper feed cassette 16.
and the second paper feed roller 18 and the second paper feed roller 18
and guide plates 19 and 20 disposed between the transfer pole and a transfer pole to be described later. During copying, the transfer paper P in the paper feed cassette 16 is fed out by the first paper feed roller 17, guided by the guide plate 19, and transferred to the second paper feed roller 18.
is confronted with. The second paper feed roller 18 is driven by a paper feed timing signal such that the leading edge of the toner image on the photosensitive drum 12 and the leading edge of the transfer paper P coincide with each other.

The transfer pole 21 transfers the toner image on the photoreceptor drum 12 to the transfer paper P.
The separation pole 22 is used to separate the transfer paper P from the photosensitive drum 12, and the separated transfer paper P is sent to the fixing device 24 via the transfer paper conveying means 23.
After being fused and fixed by a heat fixing roller and a pressure roller, the sheet is discharged onto a sheet discharge tray 26 by a sheet discharge roller 25. After the transfer process is completed, the photosensitive drum 12
The cleaning device 27 removes the toner remaining on the drum.
However, in order to facilitate this removal, a cleaning removal electrode 28 that performs alternating current corona discharge is provided in front of the cleaning removal electrode 28. Further, a charge erasing section 29 is disposed downstream of the charging electrode 14 and faces the photoreceptor drum 12 for erasing the charge in the non-image area with light to prevent toner from adhering to the non-image area. Note that 30 and 31 are exposed areas before charging, respectively.

This is the pre-transfer exposure area.

(Problems to be Solved by the Invention) In the conventional example with the above configuration, the second paper feed roller 18 is arranged at a paper feed timing such that the leading edge of the toner image on the photosensitive drum 12 and the leading edge of the transfer paper P coincide with each other. It is designed to be driven by a signal.

This timing signal is applied to the first
When the mirror unit 6 reaches a predetermined position, a timing sensor (not shown) emits a signal.

However, during feeding by the second paper feed roller, if the size of the transfer paper P differs, the frictional resistance load caused by the first paper feed roller 17 and the guide plate 19 will differ.

Therefore, depending on the size of the recording paper P, the photosensitive drum 12
There is a problem that the leading edge of the upper toner image and the leading edge of the transfer paper P do not match.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to create an image in which the leading edge of the toner image on the photosensitive drum and the leading edge of the fed recording medium match, regardless of the size of the recording medium. An object of the present invention is to provide a forming device.

(Means for Solving the Problems) The present invention for solving the above problems includes a storage means for storing a recording medium, and a first paper feed roller that feeds out the recording medium of the storage means and abuts it against a second paper feed roller. , a feeding device having a second sheet feeding roller that feeds the abutted recording medium to an image forming section; detection for detecting the size of the recording medium accommodated in the accommodation device; means and
A control means is provided for driving the second paper feed roller at a timing when the leading edge of the image in the image forming section and the leading edge of the recording medium coincide with each other for each size of the recording medium.

(Function) In the image forming apparatus of the present invention, first, the size of the recording medium accommodated in the accommodation means is detected by the detection means.

Next, the recording medium accommodated in the storage means is brought into contact with the second paper feed roller by the first paper feed roller. The control unit drives the second paper feed roller at a timing when the leading edge of the image in the image forming unit and the leading edge of the recording medium coincide with each other for each detected recording paper size.

(Embodiment) Next, an embodiment in which the present invention is applied to a copying machine will be described with reference to the drawings. FIG. 1 is a circuit block diagram showing the main parts of an embodiment of the present invention, FIG. 2 is a configuration diagram showing the mechanical configuration in FIG. 1, and FIG. 3 is the configuration of the transfer paper size detection device in FIG. 1. It is a diagram.

First, the mechanical configuration of this embodiment will be explained using FIG. 2. In the figure, in the center of the upper part of the main body of the copying machine, a transparent glass document tray 41 on which a document tray is placed is provided, and at the left end of the document tray 41, a placement position is specified depending on the size of the document tray. A scale plate 42 is provided. Furthermore,
A document cover 43 that covers the placed document is provided on the top of the document placement table 41 so that it can be folded forward. The document tray is placed on the document table 41 according to the scale designated by the scale plate 42, and is covered with a document cover 43 to restrict its movement.

A first mirror unit 46, which is provided with an exposure lamp 44 and a first mirror 45, is located below the original table 41 and inside the main body of the copying apparatus.
It is installed so that it can be moved linearly in the left and right directions of the figure, allowing it to scan the entire surface of the document. Also, the second mirror 4
7 and a third mirror 48, the second mirror unit 49 rotates in the left-right direction in FIG. 2 at half the speed of the first mirror unit 46 so as to maintain a predetermined optical path length. It is designed to be able to move linearly in parallel to the original table 41. The main lens 50 is connected to the document mounting table 4
The reflected light from the original plate on the first mirror 45. Second
This is a lens that is reflected by the mirror 47 and the third mirror 48 and then enters the lens, and the light that exits the main lens 50 passes through the fourth mirror 51- and enters the photosensitive drum 52 as an image support via the slit 53. It is supposed to be done.

The charging electrode 54 uniformly charges the photoreceptor drum 52. Therefore, the photosensitive drum 5 rotates clockwise in FIG. 2 due to the incidence of light from the optical system.
2, electrostatic latent images are sequentially formed. The developing device 55 converts the electrostatic latent image on the photosensitive drum 52 into a visible toner image.

On the other hand, the paper feeding device that feeds the transfer paper P includes a paper feed cassette 56 that accommodates the transfer paper (recording medium) P, and a first paper feed roller 5 that feeds out the transfer paper P one by one from the paper feed cassette 56.
7, a second paper feed roller 58 that feeds the fed-out transfer paper P to the photosensitive drum 52 side, and the paper feed cassette 5.
6 and the second paper feed roller 58 and the second paper feed roller 5
8 and guide plates 59 and 60 disposed between the transfer pole and transfer poles to be described later. During copying, the transfer paper P in the paper feed cassette 56 is fed out by the first paper feed roller 57, guided by the guide plate 59, and transferred to the second paper feed roller 5.
I am hit by 8. The second paper feed roller 58 is driven by a paper feed timing signal (described later) such that the leading edge of the toner image on the photosensitive drum 52 and the leading edge of the transfer paper P coincide.

The transfer pole 61 transfers the toner image on the photoreceptor drum 52 to the transfer paper P.
The separation pole 62 is used to separate the transfer paper P from the photosensitive drum 52, and the separated transfer paper P is sent to the fixing device 64 via the transfer paper conveying means 63.
After being fused and fixed by a heat fixing roller and a pressure roller, the sheet is discharged onto a sheet discharge tray 66 by a sheet discharge roller 65. After the transfer process is completed, the photosensitive drum 42
The cleaning device 67 removes the toner remaining on the drum.
However, in order to facilitate this removal, a cleaning removal electrode 68 that performs alternating current corona discharge is provided in front of the cleaning removal electrode 68. Further, a charge erasing section 69 is disposed downstream of the charging electrode 54 and faces the photoreceptor drum 52 for erasing the charge in the non-image area with light to prevent toner from adhering to the non-image area. In addition, 70 and 71 are the exposed areas before charging, respectively.

This is the pre-transfer exposure area.

Furthermore, 72 is a timing sensor that responds when the first mirror unit 46 comes to a predetermined position, and 73 is a solenoid-driven clutch that transmits or cuts off the driving force to the second paper feed roll 58.

Further, 74 is a transfer paper size detection device that detects the size of the transfer paper P accommodated in the paper feed cassette 56.

Here, the transfer paper size detection device 74 will be explained using FIG. In the figure, a maximum of four protrusions 56a are attached to the front end surface of the paper feed cassette 56 in this embodiment, corresponding to the size of the transfer paper P. On the other hand, four microswitches 75 are provided on the apparatus side, and when the paper feed cassette 56 is set in the apparatus, the protrusion 56a presses the microswitches 75. The size of the transfer paper P is detected depending on the type of the pressed microswitch 75.

Next, the circuit configuration of the main part of this embodiment will be explained using FIG. In the figure, 76 is a control section of the copying apparatus.

The control unit 76 includes a non-volatile RAM 77 in which drive timing data of the second paper feed roller 58 for each size of transfer paper P determined in advance is written, and a non-volatile RAM 7
Read the data written to timer IC7.
9 is provided with a CPU 78 for setting the data.

80 is a drive circuit that drives the solenoid of the clutch 73.

Next, the operation of the above configuration will be explained. The difference in operation between this embodiment and the conventional example is when paper is fed from the second paper feed roller 58 to the photosensitive drum 52. Since the other operations are the same as those of the conventional example, they will be omitted.

During assembly or maintenance, the non-volatile RAM 77 takes into account the frictional resistance load of the guide plates 59, 60, etc., and stores the leading edge of the toner image on the photoreceptor drum 52 and the transferred transfer paper for each size of the transfer paper P. Predetermined data that matches the leading edge of the paper P is written.

First, the control device 76 takes in the size information of the transfer paper P stored in the paper feed cassette 56 from the transfer paper size detection device 74. Next, the CPU 78 selects data corresponding to the size of the transfer paper P from the nonvolatile RAM 77, and sets the timer I.
Set it to C79.

When the first mirror unit 46 starts scanning and reaches a predetermined position, the timing sensor 72 responds and provides a timing signal to the timer IC 79. The timer IC 79 supplied with the timing signal operates the drive circuit 80 based on the set data. When the drive circuit 80 operates, the solenoid of the clutch 73 operates, and the second paper feed roller 58 feeds the transfer paper P to the photosensitive drum 52.
to be sent to.

According to the above configuration, the transfer paper P can be fed to the photosensitive drum 52 at the same timing regardless of the size of the transfer paper P.

Note that the present invention is not limited to the above embodiments. Although the present embodiment has been described with reference to a single paper feed cassette, the present invention can also be applied to an image forming apparatus in which a plurality of paper feed cassettes can be set. In this case, non-volatile RAM77
The controller 76 records data equal to the number of paper cassette stages x the size of the transfer paper P, and the control unit 76 takes in the position information of the selected paper cassette 56 and the size information of the transfer paper P and takes appropriate action. The selected data is selected from the non-volatile RAM 77.

Furthermore, it goes without saying that the present invention is not limited to copying apparatuses, but can also be applied to other image forming apparatuses, such as laser beam printers.

(Effects of the Invention) As described above, according to the present invention, the detection means detects the size of the recording medium accommodated in the accommodation means, and the tip of the image in the image forming section and the recording medium are By providing a control means for driving the second paper feed roller at a timing when the leading edge of the toner image coincides with the leading edge of the toner image on the photoreceptor drum, the leading edge of the toner image on the photosensitive drum and the fed recording medium are aligned, regardless of the size of the recording medium. It is possible to realize an image forming device in which the leading edge of

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing the main parts of an embodiment of the present invention, FIG. 2 is a configuration diagram showing the mechanical configuration in FIG. 1, and FIG. 3 is the configuration of the transfer paper size detection device in FIG. 1. figure,
FIG. 4 is a block diagram of an electrophotographic copying apparatus as an example of a conventional example. In these figures, P... Transfer paper (recording medium) 16.56... Paper feed cassette (accommodating means) 17.57
...First paper feed roller 1.8.58...Second paper feed roller 72...Timing sensor 73...Clutch 74
...Transfer paper size detection means 76...Control section 77...Nonvolatile RA
M78...CPU 80...Drive circuit

Claims (1)

[Scope of Claims] A storage means for storing a recording medium, a first paper feed roller that feeds out the recording medium in the storage means and abuts it against a second paper feed roller, and transfers the abutted recording medium to an image forming section. an image forming apparatus comprising: a feeding means having a second paper feeding roller for feeding the paper to the storage means; a detection means for detecting the size of the recording medium accommodated in the accommodation means; An image forming apparatus comprising: a control means for driving the second paper feed roller at a timing when the leading edge of the image in the section coincides with the leading edge of the recording medium.