JP2671623B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a laser printer or a copying machine for forming an image on a recording medium, and more particularly to an image forming apparatus having a plurality of paper feeding portions.

[0002]

2. Description of the Related Art A laser printer, which provides high print quality, is often used as a device for printing documents, diagrams, etc. created by an information processing device such as a word processor. Further, copying of a created document or the like is easily performed by a normal electrostatic copying machine.

In these laser printers and copying machines, a photosensitive drum, a photosensitive belt or the like is usually used, and an image is formed by transferring a toner image formed on the surface thereof to a recording paper. There is. Such an apparatus usually includes a plurality of paper feeding units, but in order to transfer the toner image on the photoconductor to an appropriate position on the recording paper, it is necessary to accurately control the timing of each transfer. . Therefore, for example, Japanese Patent Laid-Open No. 60-56751 proposes the following paper feeding device.

In this paper feeding device, a roll pair called an aligning roll (hereinafter referred to as a resist roll) is provided between a paper feed roll (hereinafter referred to as a carry roll) and a photosensitive drum, and the carry roll is provided. The recording paper conveyed by means of the above is applied to the resist roll to be temporarily stopped, and thereafter, the driving of the resist roll is restarted at a predetermined timing to convey the recording paper to the photosensitive drum. That is, the standby position of the leading edge of the recording paper is defined by the registration roll.

[0005]

As described above, in the conventional apparatus, the transfer timing of the toner image on the photoconductor drum onto the recording paper is adjusted by the resist roll for sticking the recording paper and making it stand by. Therefore, the existence of this resist roll has been a major obstacle to downsizing the apparatus.

Therefore, an object of the present invention is to provide an image forming apparatus which does not require a resist roll and can be easily downsized.

[0007]

The [Summary of invention of claim 1, wherein a photosensitive member rotationally moves in (b) constant speed, (b) Plant
One that is almost orthogonal to the moving direction of this photoconductor at a constant exposure position
The image decomposed linearly in the direction is exposed in synchronization with the rotational movement.
And develop the electrostatic latent image formed by this
Toner image that creates one sheet of toner image corresponding to recording paper
Creating means and (c) Toner for feeding recording paper from the paper feed section
At the transfer position on the photoconductor as the position to transfer the image to this
A recording paper transport path for transporting the recording paper toward (1) a paper feed roller for sending the recording paper from the paper feed section to the recording paper transport path;
(E) the transfer position and the exposure position of the recording sheet conveying path at a photoreceptor between the paper feed roller Karako conveys the recording paper fed by the paper feed roller to the transfer position
Of the toner image for one sheet formed on the photoconductor is arranged on the paper feed roller side from the transfer position by a distance longer than the distance that the recording paper is conveyed in the time required for the leading edge of the toner image to reach the transfer position. Pre-stores the time from the start of feeding by the transport roll and (f) paper feed roller until the leading edge of the recording paper reaches the position before the transfer distance from the transfer position by the distance that the recording paper is transported. and arrival time storage means for, (g)
A timer that measures the elapsed time from the time when the conveyance of the recording paper from the paper supply unit is started, and (h) a conveyance roll stop that stops the conveyance roll when this timer measures the time stored in the arrival time storage means. Means, and (i) stop the transport roll
Preparative rotation of the transport rolls is stopped by means of one sheet
The exposure scan of the image to create the
The image forming apparatus is provided with a conveyance roll driving unit for restarting the printing operation.

According to the first aspect of the invention, the recording is performed from the paper feeding unit.
The arrival time is stored in the arrival time storage means from the time when the paper conveyance is started.
When the time has elapsed, the
Rotate the transport roll by temporarily stopping the transport roll
The exposure scan of the image to create a toner image for one sheet is
It will be restarted when it starts . Further, the transport roll is arranged on the paper feed roller side of the position where the recording paper is temporarily stopped. Then, the resist position as a standby position of the leading edge of the recording sheet and to set only the timer control, and the so that it is possible to arrange the conveying rolls corresponding to the resist roll at any position, a small device It is to be made of.

According to the second aspect of the invention, (a) a constant speed
And the photoconductor that rotates and moves at (b)
Linearly decomposed in a direction almost orthogonal to the moving direction of the photoconductor
The scanned image is exposed and scanned in synchronism with the rotational movement, and
1 corresponding to recording paper by developing the electrostatic latent image formed
Toner image creating means for creating a toner image for one sheet, and (c)
Send the recording paper from the paper feed unit and transfer the toner image to it
To convey to the transfer position on the photoconductor as a position
A recording sheet conveying path, (d) from each of the paper feed unit and the paper feed roller for feeding the recording paper in these recording sheet conveying path, conveys the recording sheet fed by these feed roller (E) to the transfer position From the exposure position of the photoconductor to the photoconductor on the recording paper conveyance path between the transfer position and each paper feed roller.
A conveyance roll disposed on the paper feed roller side from the transfer position by a distance longer than the distance that the recording paper is conveyed in the time required for the leading edge of one sheet of toner image formed above to reach the transfer position. , (F) For each paper feed unit, from the start of feeding by the paper feed roller until the leading edge of the recording paper reaches a position before the transfer distance of the recording paper in the required time from the transfer position. and arrival time storage means for previously storing a time, (g) a timer for measuring an elapsed time from the conveyance is started in the recording paper from one paper-feeding unit, (h) fed the timer of recording paper a transport roll stop means for stopping the transport roll when the measured stored time to the arrival time storage means corresponding to the sheet feeding unit which, (i) conveying b
1 rotation of the transport roll stopped by the roll stop means
Image exposure scanning starts to create one sheet of toner image
The image forming apparatus is provided with a conveyance roll driving unit that restarts at the timing .

According to the second aspect of the invention, any one of the paper feeds is used.
From the time when the recording paper starts to be conveyed
When the corresponding time stored in the corrugation has elapsed, the transport roll
To temporarily stop the transport roll by the stop means
Then, the toner image for one sheet is created by rotating the transport roll.
The exposure scan of the image
I have decided. In addition, the position of the recording paper
A transport roll is placed on the side of the paper feed roller. Soshi
The registration position as the standby position at the leading edge of the recording paper.
I decided to set it only with the imager control, and register it at an arbitrary position.
A transport roll equivalent to a stroll can be placed
In this way, the device is downsized.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments. Overview of laser printer configuration

FIG. 1 shows a schematic configuration of a laser printer as an embodiment of an image forming apparatus. This figure shows the laser printer from the side, with the left side to the front.

This laser printer includes a laser scanning device 10
1 is provided. In the laser scanning device 101, a semiconductor laser (not shown) that modulates and outputs laser light according to an image signal is arranged. A laser beam (broken line in the figure) emitted from this semiconductor laser is incident on a polygon mirror (rotating polygon mirror) 102 that rotates at a constant speed, and is deflected according to this rotation. The deflected laser beam is fθ
After passing through the lens 103, the traveling direction is changed by the mirrors 104 and 105, and the laser scanning device 101 outputs the light.

On the extension of the laser beam output from the laser scanning device 101, a photosensitive drum 106 rotating in the direction of arrow A is arranged. The laser beam output from the laser scanning device 101 is transferred to the photosensitive drum 106.
The predetermined exposure position 107 is repeatedly scanned in the axial direction, that is, the main scanning direction. A charge corotron 108 is arranged so as to face the photoconductor drum 106 and slightly before the exposure position 107.
The surface of 6 is uniformly charged. By irradiating the charged photosensitive drum 106 with the laser beam 131, an electrostatic latent image corresponding to image information is formed on the drum surface. This electrostatic latent image is developed by the developing device 109 on the drum surface on the downstream side of the exposure position 107. In the developing device 109, a developing roll 1 for magnetically raising the toner to develop an electrostatic latent image.
10 and parts such as a toner supply mechanism 111 for supplying the toner in the cartridge to the developing roll 110 are arranged. A predetermined developing bias is applied to the developing roll 110.

The toner image formed by the development of the developing device 109 moves to a position facing the transfer corotron 112 by the rotation of the photosensitive drum 106, and is electrostatically transferred onto recording paper (plain paper) there. Will be. The charge corotron 108 and the transfer corotron 112 used in this embodiment have a structure in which a single wire corotron wire is stretched between the ground and the voltage application terminal.

Next, a recording paper conveyance path will be briefly described. This laser printer is provided with two paper feeding devices. The first paper feeding device 136 is a manual paper feeding device, and is capable of manually feeding various sizes of paper. The manually fed sheet is sent out onto the transport path 134 by a pair of transport rolls 137.

The second paper feeding device 113 is removably arranged at the bottom of the laser printer, and a cassette tray 132 on which recording papers are stacked is inserted from the front side. The recording paper 133 arranged on the uppermost layer of the cassette tray 132 is sent out onto the transport path 134 by a pair of transport rolls 115.

The recording paper sent from the first paper feeding device 136 is conveyed by the conveying roll 137 along the conveying path 134, and the conveying roll 137 is stopped when a predetermined time has elapsed from the start of the conveying. Stops its progress. After that, when image formation is started on the photoconductor drum 106, the rotation of the transport roll 137 is restarted in synchronization with the rotation position of the formed toner image, and the recording paper is stabilized at a constant speed. Transport is started.

Similarly, the recording paper 133 sent out from the cassette tray 132 of the second paper feeding device 113 is conveyed by the conveying roll 115 along the conveying path 134,
When a predetermined time has elapsed from the start of conveyance, the conveyance roll 11
When 5 stops, its progress stops. After this,
When image formation is started on the photosensitive drum 106, the transport roll 1 is synchronized with the rotational position of the formed toner image.
The rotation of 15 is restarted, and the recording paper is stably conveyed at a constant speed.

In this way, the recording paper is transferred onto the photosensitive drum 106 and the transfer corotron 11 at a desired timing.
Pass between two. Only at the time of this passage, the transfer corotron 112 discharges, whereby the toner image on the photoconductor drum 106 is electrostatically attracted toward the transfer corotron 112, and the toner image is transferred onto the recording paper. .

The transferred recording paper is de-charged from its back surface by a de-charging needle (not shown) arranged on the downstream side of the transfer corotron 112, and is peeled off from the surface of the photosensitive drum 106. The peeled recording paper is carried on a carrying path of a predetermined length to release the tension, and then carried to a fixing device 118 composed of a pair of a heat roll 116 and a pressure roll 117.

In the fixing device 118, the heat roll 116 and the pressure roll 11 in which the recording paper is nipped with a predetermined width.
Pass between 7. At this time, the side of the recording paper on which the toner image is transferred becomes the heat roll 116 side, and the pressure roll 117 presses the recording paper against the heat roll 116 to enable efficient heat transfer. Heat roll 11
6 is controlled to a constant temperature of high temperature. In this state,
The toner image on the recording paper is thermally fixed on the paper surface.

The exit roll 1 is provided on the exit side of the fixing device 118.
19 is prepared so that the recording paper is ejected to the upper part of the laser printer. The recording paper is ejected with the recording surface facing down because it passes through such a path, and it is possible to bind the sheets printed one page at a time in a stapler in the ejected order.

By the way, the toner image not transferred onto the recording paper is removed from the drum surface by the cleaning device 120 arranged further downstream of the transfer corotron 112. The cleaning device 120 is provided with a blade or the like for removing toner from the drum surface.

In this laser printer, the photosensitive drum 1
06, cleaning device 120, charge corotron 1
08, and the developing device 109 is the process cartridge 1
21 is integrally configured. Also, the front cover 12
3 is designed to open and close around the hinge 122,
User can clear the jam of recording paper, process cartridge 1
21 and the transfer corotron 112 can be replaced and the fixing device 118 can be attached and detached very easily.

A low-voltage power source (not shown) and a high-voltage power source 124 are arranged behind the laser scanning device 101 to supply necessary electric power to each constituent block. A control device 125 is arranged behind the high-voltage power supply 124 to electrically control the entire laser printer. The image information processing device 1 is provided above the high voltage power supply 124 and the control device 125.
26 is arranged to convert the image information sent from the host computer or the like into a laser beam modulation signal of the laser printer and send it to the control device 125.

FIG. 2 shows a main part of the control device 125. This device is provided with a central processing unit (hereinafter referred to as CPU) 141 for controlling the operation of the entire control device, and a timer 142, a first memory 143, a second memory 144, and an input unit via a bus 156. It is connected to the output interface 157.

The first and second memories 143 and 144 respectively have first and second sheet feeding devices 136 and 11 respectively.
3 is stored, and the timer 142 is stored.
Is designed to measure the time corresponding to these timing data.

Further, to the CPU 141, a paper feed start signal 145 and an image output start signal 146 are input from the image information processing device 126 (FIG. 1) via the input / output interface 157 and the bus 156, while the first and The roll driving signal 14 is sent to the second sheet feeding devices 136 and 113.
7, 148 or roll stop signals 149, 150 are output respectively.

Next, the paper feeding operation will be described with reference to FIG. Upon receiving the paper feed start signal 145 from the image information processing device 126 (step S101), the CPU 141 determines whether this is for the first or second paper feed device (step S102).

When this is for the first paper feeding device 136 (Y), the timing data stored in advance in the first memory 143 is read out and the timer 142 is read.
And the roll drive signal 147 is output to the first sheet feeding device 136 (step S104). As shown in FIG. 4, since the timing data indicates that the leading edge of the recording paper 151 is indicated by a broken line after the conveyance roll 137 of the first paper feeding device 136 starts to convey the recording paper 151, the virtual registration position 153 is shown. Is the time it takes to reach. The virtual registration position 153 corresponds to the standby position of the recording paper, which is conventionally defined by the registration roll. That is, the time required for the recording sheet to be conveyed from the virtual registration position 153 to the transfer position 152 and the time until the leading edge of the image exposed at the exposure point 107 on the photosensitive drum 106 reaches the transfer position 152. It is preset so that and become equal.

When the roll drive signal 147 is received, the transport roll 137 of the first paper feeding device 136 starts transporting the recording paper 151.

Now, when the timer 142 measures the set time (step S105; Y), it outputs a time-up signal to the CPU 141. CPU 141 which received this
Indicates a roll stop signal 149 to the first sheet feeding device 136.
Is output (step S106). As a result, as shown in FIG. 4, the leading edge of the recording paper 151 is located at the virtual registration position 153.
Will stop at.

When the image output start signal 146 is input from the image information processing device 126 (step S107;
Y), the CPU 141 outputs the roll drive signal 147 again to the first sheet feeding device 136 (step S10).
8), so that the recording paper 151 by the transport roll 137
Is restarted.

After that, the recording paper 151 is transferred onto the photosensitive drum 106 and the transfer corotron 112 at a predetermined timing.
The toner image is transferred to an accurate position on the recording paper after passing through the space.

On the other hand, in step S102, when the paper feed start signal 145 is for the second paper feeder 113 (N), the timing data stored in advance in the second memory 144 is read out and the timer is read. 142 and the second sheet feeding device 113.
A roll drive signal 148 is output in response to (FIG. 1) (step S110).

As shown in FIG. 5, the timing data shows that the leading edge of the recording paper 133 is a virtual line indicated by a broken line after the conveyance roll 115 of the second paper feeding device 113 starts to convey the recording paper 133. This is the time required to reach the registration position 153. The virtual registration position 153 is the same position as that shown in FIG. Therefore, as described above, from the virtual registration position 153 to the transfer position 15
The time required for the recording paper to be conveyed up to 2 is equal to the time required for the head of the image exposed at the exposure point 107 on the photoconductor drum 106 to reach the transfer position 152.

When the roll drive signal 148 is received, the transport roll 115 of the second sheet feeding device 113 starts to transport the recording paper 133.

When the timer 142 measures the set time (step S111; Y), it outputs a time-up signal to the CPU 141. Receiving this, the CPU 141 receives the second
The roll stop signal 150 is output to the sheet feeding device 113 (step S112). As a result, as shown in FIG. 5, the leading edge of the recording paper 133 stops at the virtual registration position 153.

When the image output start signal 146 is input from the image information processing device 126 (step S113;
Y), the CPU 141 outputs the roll drive signal 148 to the second sheet feeding device 113 again (step S11).
4), so that the recording paper 133 by the transport roll 115
Is restarted.

After that, the recording paper 133 is transferred onto the photosensitive drum 106 and the transfer corotron 112 at a predetermined timing.
The toner image is transferred to an accurate position on the recording paper 133 after passing through the space.

In the present embodiment, the timer 142 starts the timing from the driving start of the transport roll 115 or the transport roll 137. However, a sensor for detecting the recording paper is provided before the virtual registration position 153, and the recording by this sensor is performed. The timer 142 may be started from the time when the leading edge of the paper is detected. In this case, the transport rolls 115, 1
It is possible to absorb a conveyance error due to a slip of 37, etc., and it becomes possible to adjust the registration position more accurately.
Further, in the present embodiment, the virtual registration position 153 is set to the position as shown in FIGS.
The recording sheet setting position 154 (FIG. 4) in the sheet feeding device 136 may be set as the virtual registration position. In this case, the time required for the leading edge of the recording paper 151 to reach the photosensitive drum 106 from the recording paper setting position 154 and the image exposed at the exposure point 107 on the photosensitive drum 106 reach the transfer position 152. The respective units are arranged so that the time until
The driving of the transport roll 137 may be started at the timing of the image output start signal 146 from. this is,
This is possible by setting the timing data set in the first memory 143 (FIG. 2) to “0”.

Further, in the present embodiment, the case where the number of sheet feeding devices is two has been described, but even in the case of more than two sheet feeding devices, the corresponding predetermined timing data is set in the memory and the same control is performed to facilitate the operation. Of course we can respond. It goes without saying that the configuration for setting the registration position as in this embodiment can be applied to a normal copying machine.

As described above, according to the first aspect of the present invention, whether the recording paper is started to be conveyed from the paper feeding unit.
When the time stored in the arrival time storage means has elapsed, the transport roll is temporarily stopped to set the registration position,
The transport roll is arranged on the paper feed roller side of the position where the recording paper is temporarily stopped . These makes no need to place the resist roll registration position, there is an effect that it is possible to easily reduce the size of the apparatus.

According to the second aspect of the invention, the photosensitive
1 formed on the photoconductor from the exposure position of the body
The registration position setting data corresponding to the time required for the leading ends of the toner images of the sheets to reach the transfer position is held for each paper feeding unit, and Timing is controlled by setting data in the timer . Therefore, it is possible to set the registration position of the recording paper fed from the plurality of paper feeding units by simply adding a simple circuit .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a laser printer as an embodiment of the present invention.

FIG. 2 is a block diagram showing in detail a control device in this laser printer.

FIG. 3 is a flowchart for explaining the operation of this control device.

FIG. 4 is an explanatory diagram for explaining a recording paper conveyance operation from the first paper supply device of the laser printer.

FIG. 5 is an explanatory diagram for explaining a recording paper feeding operation from a second paper feeding device of the laser printer.

[Explanation of symbols]

 106 Photoreceptor Drum 113 Second Paper Feeding Device 115 Conveying Roll 125 Control Device 131 Laser Beam 134 Conveying Path 136 First Paper Feeding Device 137 Conveying Roll 141 CPU 142 Timer 143 First Memory 144 Second Memory

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 21/00 370 G03G 21/00 370

Claims (2)

(57) [Claims] 1. A photosensitive member that rotates and moves at a constant speed and is substantially orthogonal to the moving direction of the photosensitive member at a predetermined exposure position.
Exposure of a linearly decomposed image synchronized with the rotational movement
Scanning and developing the electrostatic latent image formed thereby
Toner that creates a single toner image corresponding to the recording paper
The image forming means and the recording paper are sent out from the paper feeding section and the toner image is transferred to this
To convey to the transfer position on the photoconductor as a position
A recording sheet conveying path, a paper feed roller for feeding the recording sheet to the recording sheet conveying path from the paper feed unit, conveys the recording sheet fed by the paper feed roller to the transfer position and the transfer position paper From the exposure position of the photoconductor on the recording paper conveyance path between the paper rollers
The recording paper to the required time of the tip of the formed on the photosensitive member of the one sheet toner image to reach the transfer position a sheet only from the transfer position a distance greater than the distance to be fed transportable <br/> A conveyance roll arranged on the side of the paper roller, and the leading edge of the recording paper reaches a position before the transfer distance of the recording paper from the transfer position after the start of feeding by the paper feeding roller. Arrival time storage means for pre-storing the time until the start, a timer for measuring the elapsed time from the time when the conveyance of the recording paper from the paper feed section is started, and the time when this timer is stored in the arrival time storage means Of the image for forming the toner image for the one sheet by rotating the transport roll stopped by the transport roll stop means for stopping the transport roll when the
An image forming apparatus comprising: a conveyance roll driving unit that restarts the exposure scanning at a timing when the exposure scanning starts . 2. A photosensitive member that rotates and moves at a constant speed and is substantially orthogonal to the moving direction of the photosensitive member at a predetermined exposure position.
Exposure of a linearly decomposed image synchronized with the rotational movement
Scanning and developing the electrostatic latent image formed thereby
Toner that creates a single toner image corresponding to the recording paper
The image forming means and the recording paper are sent out from the paper feeding section and the toner image is transferred to this
To convey to the transfer position on the photoconductor as a position
A recording sheet conveying path, a paper feed roller for feeding the recording paper in these recording sheet conveying path from the paper feed unit, and the transfer position conveys the recording sheet fed by these feed roller to the transfer position each The exposure position of the photoconductor on the recording paper conveyance path between the paper feed roller and
Placed et the paper feed roller side from just the transfer position a distance greater than the distance to the recording sheet the required time is transported to the tip of the toner image of the photosensitive wherein one formed on the support content reaches the transfer position For each feeding unit, the leading edge of the recording paper is moved forward from the transfer position by the distance that the recording paper is conveyed during the required time. Arrival time storage means that stores in advance the time to reach the position, a timer that measures the elapsed time from the time when the conveyance of the recording paper is started from one of the paper feed units, and this timer wherein the conveying roll stop means for stopping the conveyor rolls when the stored time was measured in the arrival time storage means, said conveying roll which is stopped by the transport roll stop means of times that the sent corresponds to the sheet feeding portion of The image to create a toner image of the one sheet
An image forming apparatus comprising: a conveyance roll driving unit that restarts the exposure scanning at a timing when the exposure scanning starts .