JPS62175359A - Recording sheet conveying device - Google Patents

Abstract

PURPOSE:To maintain the paper feed of recording sheets at a predetermined intervals, by stopping a paper feed means when the space between the trailing end of the preceding recording sheet and the leading end of the following recording sheet is smaller than a predetermined value, which is measured just before a registering roller. CONSTITUTION:A registration sensor 126 arranged just before a registering roller 111, for detecting a fed recording sheet measures the space between the trailing end of the preceding recording sheet and the leading of following recording sheet. If the measured space is shorter than a stop and delay time corresponding to the inertia of the registering roller 111, a paper feed means (separating and conveying rollers 109, 110, 123) is stopped, and therefore, the space is made to be longer than the aforementioned stop and delay time. As a result, non-uniformity in the spaces of fed recording sheets is restrained, thereby the feed intervals of recording sheets are maintained to be uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a recording paper conveying device for conveying a sheet of recording paper in a so-called page printer such as a laser printer or a copying machine.

[Prior Art] In a so-called page printer such as a laser printer or a liquid crystal shutter printer, a linear recording image is formed using a laser beam or a liquid crystal shutter, and this is exposed to a photoreceptor to record the image through an image forming process similar to that of a copying machine. Images (hard copies) are formed one by one. Also,
Copying machines also form copied images on each sheet of recording paper.

As described above, in a recording apparatus that uses sheet-shaped recording paper, it is necessary to appropriately separate the recording papers stacked in a paper feed cassette or paper feed tray one by one and send them to an image forming station.

Paper feeding mechanisms that separate and feed the recording paper one by one include those that use corner claws, friction pads, or two friction rollers that rotate in the same direction. . Among these, there are many types of recording paper that can be applied to those using friction rollers, so they have been widely adopted in recent years, and an example is shown in Figure 5 (a).
).

In the figure, a pickup roller 2 is in contact with the top of the recording paper stacked in a paper feed cassette 1 while applying a predetermined pressure, and this pickup roller 2 is moved by a paper feed solenoid (not shown) to the top of the recording paper. be separated from

A feed roller 3 is arranged at a predetermined distance from the pickup roller 2, and a torque limiter 4 set to a predetermined torque is attached to the drive shaft of the feed roller 3. A reversing roller 5, to which a driving force in the same direction as the feed roller 3 is transmitted, is in contact with the feed roller 3.

Therefore, when the recording paper is not located in the area where the field roller 3 and the reversing roller 5 are in contact (hereinafter referred to as the nip), and when one recording paper is inserted into the nip, the torque limiter 4 slips, so the reversing roller 5 rotates along with the feed roller 3. Also, when two or more sheets of recording paper are fed into the nip, the torque of the torque limiter 4 overcomes the frictional force between the recording sheets, causing the reversing roller 5 to rotate. The lower recording paper is pushed back into the recording paper cassette 1 by rotating it in the driving direction.

In this way, the recording paper is separated one by one and sent to the image forming station.

Now, in the image forming station, an inverted recorded image formed by developing an electrostatic latent image formed by exposure from a recorded image generating mechanism (for example, a laser writing device) not shown on the photoreceptor 8 with toner is carried on the photoreceptor 8. The recording paper separated and sent out by the feed roller 3 and the reversing roller 5 is sent out by the registration roller 9 at the timing when the leading edge of the inverted recorded image formed on the photoreceptor 8 and the leading edge of the recording paper coincide with each other, and the recording paper is sent out to the transfer charger. Photoreceptor 8 by 1o
The image is transferred to the fixing roller (
The image is fixed and output by a path shown in the figure.

Note that the registration sensor 11 detects the recording paper.

Now, if this illustrated device is part of a laser printer, the host device that uses this laser printer (
A print start signal (see Figure 6 (a)) to start recording an image from a computer (for example, a minicomputer, etc.)
is applied, at that timing the pickup roller 2) the feed roller 3, the reversing roller 5 and the register 1-
The paper feed motor (path shown) that drives the roller 9 is activated (
(see FIG. 6(b)), and at the same time the paper feed clutch (path shown) for transmitting the driving force of the paper feed motor to the pickup roller 2) feed roller 3 and reversing roller 5 is turned on (see FIG. 6(c)). )reference).

As a result, the uppermost recording paper is conveyed by the pickup roller 2 in the direction of the feed roller 3 and the reversing roller 5, and the time point when a sufficient period TI has elapsed for the recording paper to be fed into the nip between the feed roller 3 and the reversing roller 5. The paper feed solenoid (path shown) is turned on (Fig. 6(d)).
), the pickup roller 2 is separated from the surface of the recording paper, and the conveyance of the recording paper by the pickup roller 2 is stopped.

At this time, the above-mentioned feed roller 3. The recording paper is separated into one sheet by the action of the torque limiter 4 and the reversing roller 5, and when the leading edge of the recording paper is detected by the registration sensor 11 (see FIG. 6(e)), from that point on, the leading edge of the recording paper is separated. When a period T2 has elapsed during which the recording paper contacts the registration roller 9 and is given an appropriate deflection, the paper feed clutch is turned off to stop the recording paper at that position and make the recording paper standby.

On the other hand, when the registration sensor 11 is turned on, the laser printer responds to the host device with a recording preparation completion signal indicating that preparation for data recording is completed. In response, the host device notifies that the recording data will be transferred, and when the recording data is transferred, the data recording process is started in synchronization with the transfer of the recording data, and the data is supplied to the registration roller 9. A registration clutch (path shown) that transmits the driving force of the paper motor is turned on, and the recording paper is sent to the photoreceptor 8 to record an image corresponding to the recording data.

In this way, when an image is recorded on the first sheet of recording paper, the laser printer prints the image of the next page when the time corresponding to the size of the recording paper has elapsed after turning on the registration clutch. A next page standby signal is sent to the host device to indicate that the next page can be recorded. On the other hand, in the host device.

When the recording data for the next page is complete, a print start signal corresponding to the second page is output to the laser printer, and from then on, the same processing as for the first page is performed to correspond to the recording data for the second page. The image is recorded on the second sheet of recording paper.

The above-described processes are sequentially performed on the recording data of subsequent pages, and images corresponding to the recording data of successive pages are recorded on recording paper and sequentially output.

By the way, as described above, when the recording paper is separated one by one by the feed roller 3 and the reversing roller 5, the recording paper following the separated recording paper is pushed back by the reversing roller 5 and stops. The position of the tip is any position on the path from the pickup roller 2 to the feed roller 3. That is, the position of the leading edge of the recording paper at the time when conveyance is started is on the path from the pickup roller 2 to the feed roller 3, but varies.

Therefore, the distance between the trailing edge of the preceding recording paper and the leading edge of the following recording paper varies depending on the dispersion of the position of the recording paper at the time when the conveyance starts.

For example, if the interval between the first and second recording paper is time T3,
The interval between the second and third recording sheets is time T4.

On the other hand, the registration roller 9 stops after a delay time Td determined by its inertia has elapsed since the registration clutch was turned off. for that.

If the interval between recording sheets is shorter than this delay time Td,
When the registration rollers are turned off in synchronization with the timing at which the trailing edge of the preceding recording paper passes through the registration rollers 9, the leading edge of the following recording paper may be caught in the registration rollers 9 rotating due to inertia.

For example, in the case shown in FIG. 6, the interval T4 between the second and third sheets is shorter than the delay time Td, so the leading edge of the third recording sheet is fed into the registration roller 9. At this time,
When the leading edge of the third sheet of recording paper is detected by the registration sensor 11 and the registration sensor 11 is turned on, a recording ready signal is sent to the host device as described above, so immediately after the registration sensor 11 is turned on. The host device starts transferring recording data.

Further, the copying process is started in synchronization with the transfer of the recording data, and therefore the leading edge position of the third recording sheet is shifted by the amount fed into the registration rollers 9.

As a result, the leading edge of the recording paper no longer matches the leading edge of the inverted recorded image formed on the photoreceptor 8, resulting in the inconvenience that the image is not transferred properly and the trailing edge of the image is cut off.

Such inconveniences are particularly noticeable in high-speed recording apparatuses that have a high recording speed. In other words, in such a high-speed recording apparatus, since the recording paper interval at the time of design is very short, it is easily affected by even slight variations in the paper feeding interval. Note that if you set the paper feed interval large in advance,
Although the above-mentioned inconveniences can be avoided, in that case it becomes difficult to realize a high-speed recording device.

[Objective] The present invention has been made in order to solve the above-mentioned disadvantages of the conventional technology, and an object of the present invention is to provide a recording paper conveyance device that can suppress variations in the feeding interval of recording paper.

[Configuration] In order to achieve this object, the present invention measures the distance between the trailing edge of the preceding recording paper and the leading edge of the following recording paper immediately before the registration roller, and stops the recording paper so that the distance corresponds to the inertia of the registration roller. If it is shorter than the delay time, the paper feeding means is stopped so that the interval becomes longer than the stop delay time.

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

FIG. 1 shows a laser printer according to an embodiment of the present invention. In addition to the two paper feed cassettes, this laser printer is equipped with a large paper feed unit that can store about 1000 sheets of zero recording paper.

In the figure, a laser printer 100 includes a laser beam generating section 101 that generates a laser beam modulated with an image signal corresponding to a recorded image, a drum-shaped photoreceptor 102 . A charger 10 that uniformly charges the surface of the photoreceptor 102
3. A developing device 104 that develops an electrostatic latent image formed by exposing the charged surface with a laser beam output from the laser beam generating section 101 toner; a paper feed cassette 105 in which recording paper is stacked; 106, Recording paper cassette 1
Pickup rollers 107 and 108 that feed the recording paper from 05 and 106, this pickup roller 107 and 10
Separation and conveyance rollers 109, 110, which are composed of a feed roller, a reversing roller, and a torque limiter that separate and convey the recording paper sent out by 8 one by one. The recording paper conveyed by the separation conveyance rollers 109 and 110 is transferred to the photoreceptor 10 at the timing when the leading edge of the recording paper coincides with the leading edge of the toner image.
2) A transfer charger 112 that brings the recording paper sent out by the registration roller 111 into close contact with the photoreceptor 102 and transfers the toner image formed on the photoreceptor 102.) A record to which the toner image has been transferred. Separation charger 11 that separates paper from photoreceptor 102
3. It is composed of a fixing device 114 that fixes the toner image on the recording paper, a discharge roller 115 that discharges the recording paper on which the image has been fixed by the fixing device 114, and a stacker 116 that stacks the discharged recording paper.

Further, the conveyor belt 117 conveys the recording paper separated by the separation charger 113 to the fixing device 114, the cleaner 118 removes residual toner on the surface of the photoreceptor 102, and the static elimination lamp 11.9 Photoreceptor 1
This is to remove residual charges on the surface of 02.

A mass paper feed unit 120, which also serves as a dedicated stand for the laser printer 100, includes a recording paper tray 121 that can store a large amount of recording paper. A pickup roller 122 that feeds the recording paper from the recording paper tray 121. A separating conveying roller 1231 consists of a feed roller, a reversing roller, and a torque limiter, which separates and conveys the recording paper sent out by the pickup roller 122 one by one.The recording paper conveyed by the separating conveying roller 123 is transferred to the laser printer
The recording paper sent out by this transport roller 124 is conveyed to the guide plate 1.
25 to the registration rollers 111.

In addition, a register 1 is provided at a position immediately before the registration roller 111.
- A registration sensor 126 is provided to detect the recording paper being fed into the roller 111. The registration sensor 126 is located at the separation conveyance roller 109.
．． 110, 123, when the corresponding paper feed clutch (described later) is turned off, the recording paper coasted due to the inertia of the 5-separation conveyance rollers 109, 110, 123 is prevented from contacting the registration roller 111. It is set.

In addition, paper feed cassettes 105 and 106 and paper feed tray 1
21 and a laser printer 100 facing each
The main body and the mass paper feed unit 120 are each equipped with a mechanism for detecting the size of the recording paper stored therein. For example, marks are formed to indicate the sizes of the recording paper stored in the paper feed cassettes 105 and 106 and the paper feed tray 121, and detectors for detecting these marks are installed in the main body of the laser printer 100 and the large-volume paper feed unit 120. It is formed.

FIG. 2 shows an example of a control system of the laser printer 100.

In the figure, the control unit 130 controls the laser printer 1.
It controls each part of 00 and exchanges data with the host device via the input/output circuit 131. The control unit 130 also has a system memory that forms its work area and stores recording data transmitted from the host device and bit data of an image corresponding to this recording data, and a system memory that stores the recording data transmitted from the host device. is provided with a font memory for generating characters, graphics, etc. corresponding to the code when the code is code data.

The image generating section 132 includes the laser beam generating section 101. The laser printer consists of a data conversion section that converts the Z data corresponding to the recorded image transferred from the control section 130 into raster data, a recording signal generation section that converts the raster data into a recording signal given to the laser beam generation section 101, etc. 1
00, the part that generates the image to be recorded is shown in the image forming section 134.

Photoreceptor 102. The image forming system of the laser printer 100, which includes a developer 104 and the like, is shown. In addition, the paper feed force
-105, 106 and the size information of the recording paper stored in the paper feed tray 121 are also output to the control unit 130.

The operation display section 134 includes various operation keys for operating the laser printer 100 and the laser printer 1.
It is comprised of various indicators for displaying the operating status of 00, etc., and its operation data is applied to the control unit 130, and display data is applied from the control unit 130.

The paper feed motor 140 is connected to the pickup rollers 108, 109 and separation conveyance rollers 109, 1 of the laser printer 100.
10 and registration rollers 111, the paper feed clutch 141 transmits the driving force of the paper feed motor 140 to the pickup roller 107 and the separation conveyance roller 109, and the paper feed clutch 142 drives the pickup roller 108. The driving force of the paper feed motor 140 is transmitted to the separation conveyance roller 110, and the paper feed solenoids 143 and 144 are connected to the pickup roller 107°1.
08 away from the surface of the recording paper.

The paper feed motor 145 drives the pickup roller 1221, the separation conveyance roller 123, and the conveyance roller 124 of the large quantity paper feed unit 120, and also drives the paper feed clutch 14.
Reference numeral 6 transmits the driving force of the paper feed motor 145 to the pickup roller 122 and the separation conveyance roller 123, and the paper feed solenoid 147
2 away from the surface of the recording paper.

Further, the registration clutch 148 transmits the driving force of the paper feed motor 140 to the registration roller 111.

These paper feed motors 140, 145, paper feed clutch 14
1°142.146, paper feed solenoid 143, 144,
The operations of the resist clutch 147 and the resist clutch 148 are controlled by a control section. In addition, the control unit 130 includes:
A detection signal from the registration sensor 126 is added.

Note that detailed explanations of the laser printer 100 that are not directly related to the present invention will be omitted.

With the above configuration, the process executed by the control unit 130 when conveying the recording paper will be described with reference to the flowchart in FIG. 3. Further, the operating states of each part when executing this process are shown in FIGS. 4(a) to 4(g).

The control unit 130 monitors whether a print start signal is output from the host device in a judgment 201, and when the result of this judgment 201 becomes Y[ES, it turns on the paper feed motor and the paper feed clutch (process 202). ). As a result, the uppermost recording paper is sent out to the separation conveyance roller by the pickup roller.

Note that information such as the size of the recording paper to be recorded is added to the print start signal and transferred, so the control unit 13
0 selects the paper feed cassettes 105, 106 or the paper feed tray 121 that stores recording paper of the notified size.

That is, in process 202, when selecting the paper feed cassette 105, the paper feed motor 140 and the paper feed clutch 1
41, and when selecting the paper feed cassette 106, the paper feed motor 140 and the paper feed clutch 142 are turned on.
When selecting the paper feed tray 121, the paper feed motor 140
．． 145 and paper feed clutch 146 are turned on.

Next, a sufficient period T1 is waited for the recording paper to come into contact with the separating and conveying roller using a judgment 203, and when the result of this judgment 203 is YES, the paper feed solenoid 204 is turned on to separate the pickup roller from the surface of the recording paper. . Note that in this process 204, when the paper feed cassette 105 is selected, the paper feed solenoid 143 is switched to the paper feed cassette 106.
is selected, the paper feed solenoid 144 is selected, and when the paper feed tray 121 is selected, the paper feed solenoid 1 is
47 respectively.

As a result, the recording paper is separated by the action of the separation conveyance roller.
The sheets are separated and conveyed in the direction of registration rollers 111.

When the registration sensor 126 detects the leading edge of the recording paper (the result of judgment 205 is YES), it is determined whether the registration sensor 126 has been turned off for more than the delay time Td at that time.

That is, it is determined whether the recording paper feeding interval is longer than the delay time Td (determination 206). Note that, as described above, this delay time Td is the time required from when the registration clutch 148 is turned off until the registration roller 111 actually stops.

Now, if we consider the case where the first sheet of recording paper is conveyed, the result of judgment 206 is '/ES, and therefore judgment 2
07, the process waits for the period T2 to elapse after the registration sensor 126 is turned on (determination 207). This period T2
A time is set in which the leading edge of the recording paper hits the registration roller 111 and the recording paper has an appropriate deflection.

If the result of this judgment 207 is YES, the paper feed clutch is turned off to stop the recording paper (process 208). Note that in process 208, the paper feed clutch 141 is activated when the paper feed cassette 105 is selected, the paper feed clutch 142 is activated when the paper feed cassette 106 is selected, and the paper feed clutch 142 is activated when the paper feed cassette 105 is selected.
21, the paper feed clutch 146 is selected.

In this way, the recording paper is placed on standby in a state where it is abutted against the registration rollers 111.

Further, the control unit 130 responds to the host device with a recording preparation completion signal to the host device when the registration sensor 126 detects the leading edge of the recording paper, informing the host device that the preparation for recording data is completed. In response, when the host device notifies that the recording data will be transferred and the recording data is transferred, the control unit 130 starts the data recording process in synchronization with the transfer of the recording data, and also registers the recording data. The clutch 148 is turned on, thereby recording an image corresponding to the recording data on the recording paper and ejecting it to the stacker 116.

In this way, when an image is recorded on the first sheet of recording paper, the control unit 130
sends a next page standby signal to the host device indicating that the image of the next page can be recorded. On the other hand, the host device outputs a print start signal corresponding to the second page to the laser printer when the recording data for the first page is complete, and the result of judgment 1 201 becomes YES, and the control unit Step 130 executes the steps 202 and subsequent steps on the second sheet of recording paper. This process is executed for each sheet of recording paper.

Now, when the second sheet of recording paper is conveyed, as shown in Fig. 4 (a)
) to (g), the recording paper interval time T3 is greater than the delay time Td, so the result of judgment 206 is YE.
S, and as a result, the second recording paper is sent out to the registration roller 111 after being subjected to the same processing as the first recording paper.

Then, in the same manner as the first recording paper, an image corresponding to the recording data of the second page is recorded on the second recording paper.

Here, when the third recording paper is conveyed, the recording paper interval time T4 becomes shorter than the delay time Td, so judgment 20
6 is NO, and at that point, that is, when the leading edge of the third recording paper is detected by the registration sensor 126, the control unit 130 turns off the paper feed clutch and stops the recording paper (process 209). ). As a result, the registration roller 11
Since the recording paper stops before hitting the registration roller 111, the recording paper is prevented from being caught by the coasting registration rollers 111.

Then, judgment 209 monitors whether the delay time Td has elapsed since the registration sensor 126 was turned off.
If the result of step 09 is YES, since the registration rollers 111 have completely stopped at that point, the paper feed clutch is turned on to restart conveyance of the recording paper (process 211). Then, when five periods T2 have elapsed (the result of judgment 212 is YES), the process moves to process 208, the paper feed clutch is turned off, and the recording paper is placed on standby in a state in which it abuts against the registration rollers 111.

Note that in processes 209 and 211, the paper feed cassette 10
5 is selected, the paper feed clutch 141 is selected, and when the paper feed cassette 106 is selected, the paper feed clutch 1 is selected.
42, and when paper feed 1 to ray 121 are selected, paper feed clutch 146 is selected.

In this way, the recording paper is prevented from being caught by the coasting registration rollers 111, so the photoreceptor 10
The position of the leading edge of the recording paper when it is sent out in step 2 remains constant, and as a result, images are always properly recorded on the recording paper and output.

Note that the processing shown in FIG. 3 is a part of the processing executed by the control unit 130, and the control unit 130 executes a plurality of other processes in parallel. Also, laser printer 1
In the recording paper conveyance path inside the 00.

Multiple sheets of recording paper may be located at the same time, and the control unit 1
30 executes a similar series of processing for each recording paper.

Further, in the above-described embodiments, the present invention is applied to a laser printer, but the present invention may also be applied to other recording devices equipped with a similar paper feeding mechanism, such as a copying machine, a liquid crystal shutter printer, etc. I can do it.

Furthermore, the present invention can be applied to the case where recording paper is discharged to a post-processing machine such as a paper collating device, a folding machine, or a stamper. Further, in this case, since the interval between recording sheets discharged to the post-processing machine is constant, there is also an effect that the possibility of paper jams or the like occurring in the post-processing machine is reduced.

[Effects] As explained above, according to the present invention, the distance between the trailing edge of the preceding recording paper and the leading edge of the following recording paper is measured just before the registration roller, and the distance is determined by the inertia corresponding to the inertia of the registration roller. If it is shorter than the running time, the paper feeding means is stopped so that the interval is longer than the coasting time, so the paper feeding interval of the recording paper can be kept constant. Appropriate images can be recorded.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a laser printer according to an embodiment of the present invention, FIG. 2 is a block diagram illustrating the control system of the laser printer, and FIG. 3 is an example of the processing executed by the control unit when feeding paper. FIG. 4 is a waveform diagram showing an example of the operation of each part during paper feeding, FIGS. FIG. 3 is a waveform diagram showing an example of the operation of a conventional device. 100... Laser printer, 102... Photoreceptor, 1
12... Transfer charger, 105, 106... Paper feed cassette. 107.108,122...Pickup roller. 109.110,123...Separation conveyance roller, 111
...Registration roller, 126...Registration sensor,
130... Control unit, 140.145... Paper feed motor, 141, 142, 146... Paper feed clutch, 143
, 144, 147... paper feed solenoid, 148...
resist clutch. -'＼ Agent Patent Attorney Crest 1) Makoto '1゛・ノFigure 2 Figure 3 Figure 4 Figure 5 (a) Tart with print,
.

Claims (2)

[Claims] (1) A large number of stacked sheets of recording paper are separated and fed one by one from the topmost one by a paper feeding means, and the recording paper is placed at the leading edge of the inverted recorded image formed on the record carrier. A recording paper conveyance device that feeds the recording paper to the recording carrier using a registration roller at a timing when the leading edge of the recording paper coincides with the recording paper detecting means for detecting the recording paper, and a recording paper detecting means that detects the recording paper and detecting the recording paper after the trailing edge of the preceding recording paper has passed. control means for stopping the paper feeding means for a period of time obtained by subtracting the off period from the predetermined value when an off period of the output of the recording paper detecting means until the leading edge of the recording paper passes is smaller than a predetermined value; A recording paper conveyance device characterized by: (2) In claim 1, the paper feeding means includes a pickup roller that sends out the uppermost recording paper, a conveyance roller disposed apart from the pickup roller by a predetermined distance, and a conveyance roller that A recording paper transport device comprising a reversing roller that is rotated with a predetermined torque in the same direction as the transport roller while in contact with the reversing roller.