JPH10221907A - Image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of recorded sheets per unit time by narrowing a gap between papers without imposing unnatural load on the paper. SOLUTION: This image recorder 1 is provided with a paper feeding part 2 carrying the paper P from a tray T in specified timing and a paper matching part 3 allowing the paper P carried from the paper feeding part 2 to temporarily stand by on this side of the recording part 4 and then feeding the paper P to a recording part 4. In carrying after allowing the paper P to temporarily stand by, the matching part 3 controls so that carrying speed until the paper P reaches the recording part 4 from the standby position is made higher than recording speed at the recording part 4, and the carrying speed when the paper P reaches the recording part 4 is adjusted to the recording speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image recording apparatus which conveys a sheet at a predetermined conveying speed to perform recording.

[0002]

2. Description of the Related Art In a conventional image recording apparatus of a copying machine or the like, after a sheet is fed from a tray, when the leading end thereof reaches a registration roller, the sheet abuts against a nip of a gate or a registration roller to temporarily wait. The paper is conveyed again from the registration rollers in accordance with the recording timing of the image recording section.

At this time, the rotation of the registration roller is accelerated T time after the gate or the opening timing of the registration roller, and the rear end of the sheet is passed earlier than usual, so that
The leading edge of the next sheet can be quickly pushed into the registration roller to improve the number of recording sheets per unit time (see JP-A-6-255838).

FIG. 4 is a view for explaining the timing of paper transport in a conventional image recording apparatus. That is, first
The conveyance of the first sheet is started, and when the leading end reaches the registration roller position, the sheet is temporarily made to stand by for a time ts. Thereafter, the conveyance is started again, and after a lapse of a predetermined time, the rotation of the registration roller is accelerated within the passage time tb of the trailing end of the sheet, so that the time required for the trailing end of the sheet to reach the registration roller position is advanced by tx from the standard.

Thus, the time required for the leading edge of the second sheet to reach the position of the registration roller can be shortened, and the transport pitch tp of the first sheet and the second sheet can be shortened as a whole.

[0006]

However, such an image recording apparatus has the following problems. That is, when the sheet is temporarily made to stand by at the registration roller position and then conveyed again, the rotation of the registration roller is accelerated after a certain period of time to increase the conveyance speed at the rear end of the sheet. The transport speed of the trailing end of the sheet is faster than the speed, and a force is applied to push the sheet toward the recording unit by the registration rollers. Due to this force, the paper is displaced, and uneven density and banding occur at the time of image recording, thereby causing a problem that image quality is remarkably deteriorated.

[0007]

SUMMARY OF THE INVENTION The present invention is an image recording apparatus made to solve such a problem. That is, the image recording apparatus according to the present invention includes a sheet feeding unit that conveys a sheet from a storage position at a predetermined timing, and a sheet that is conveyed from the sheet feeding unit is temporarily stopped in front of a recording unit before the recording unit. And a sheet aligning means for feeding the sheet to the recording section. Then, control is performed so that the transport speed when the paper reaches the recording unit is adjusted to the recording speed.

Further, in the image recording apparatus of the present invention, the paper feeding means controls the transport speed from sending out the paper to the paper aligning means faster than the recording speed in the recording unit.
A speed control means for controlling the paper transport speed faster than the recording speed in the recording unit is provided between the paper feeding means and the paper aligning means, or the paper aligning means is provided with a paper transport speed according to the size or type of the paper. Is also to adjust.

Further, in the image recording apparatus according to the present invention, the sheet aligning means adjusts the transport speed of the sheet in accordance with the recording speed in the recording section, and the detecting means provided between the sheet aligning means and the recording section. It also adjusts the transport speed of the paper based on the information from the printer, or adjusts the timing at which the transport speed is reduced.

In the present invention, the sheet aligning means controls the transport speed from the standby position of the sheet to the recording section faster than the recording speed in the recording section in the transport after temporarily suspending the sheet. Therefore, the time required for the paper to pass through the paper alignment means can be shortened as compared with the case where the paper transport speed is made equal to the recording speed. Further, since the transport speed when the paper reaches the recording unit is adjusted to the recording speed, the paper can be transported without imposing an excessive load.

Further, in the paper feeding means, the transport speed from sending out the paper to the paper aligning means is controlled to be higher than the recording speed, or a speed control means is provided between the paper feeding means and the paper aligning means. By adjusting the paper transport speed according to the size or type of the paper by the paper alignment means, the interval between the papers can be shortened as a whole of the paper transport.

Further, the sheet aligning means adjusts the sheet conveying speed in accordance with the recording speed in the recording section, or conveys the sheet based on information from a detecting means provided between the sheet aligning means and the recording section. By adjusting the speed or the deceleration timing of the transport speed, it is possible to accurately control the timing when the paper is temporarily re-conveyed and the re-transport and the transport speed of the sheet.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image recording apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating the image recording apparatus of the present embodiment. That is, the image recording apparatus 1 is mainly composed of a copying machine, and is configured such that a roller R is
1, a sheet feeding unit 2 for sending out the sheet P, a sheet aligning unit 3 for temporarily suspending the sheet P sent out from the sheet feeding unit 2, and setting a timing. A recording unit 4 for transferring the toner image on the belt B to the started sheet P.

In the image recording apparatus 1 according to the present embodiment,
The pre-registration roller R2 of the sheet aligning unit 3 is rotated by the motor M1, and the registration roller R3 is rotated by the motor M2. The timing of re-conveying the temporarily waiting sheet P is controlled and continuously conveyed. It is characterized in that the interval between the sheets of paper P is shortened to increase the number of recording sheets per unit time, and that the image quality is improved by accurate registration.

In the sheet aligning section 3, first, the leading edge of the sheet P conveyed from the tray T passes through the pre-registration point, and then reaches a position near the pre-registration roller R2 to a sensor S1 provided on the downstream side. The time is detected, and the transport speed is controlled based on a comparison between the time and a preset ideal arrival time.

Here, the correction of the transport speed by the pre-registration roller R2 is as follows. Ti is the ideal time of arrival of the sheet at the sensor S1, t is the detection time of arrival of the sheet at the sensor S1, L is the distance from the sensor S1 to the sensor S2, Vi is the ideal speed at the time of sheet conveyance, and calculation correction at the time of sheet conveyance. Assuming that the velocity is v and the correction value is vc, v = L / ((L / Vi) -Ti + t) vc = v · f (x) where vc = 1.2 · Vi when vc> 1.2 · Vi・ V
i, when vc <0.8 · Vi, vc = 0.8Vi Note that the detection of the sensor, the timer value, and the calculation accuracy are 1 ms.
ec, the speed change rate is up to ± 20% with respect to the ideal value, and the correction value over ± 20% is ± 20%. Further, f (x) is a gain control value.

When the leading end of the paper P reaches the position of the sensor S2 just before the registration roller R3, the paper alignment unit 3 temporarily suspends the paper P at the position of the registration roller R3, and conveys the paper P again at a predetermined timing. Have started. At this time, the rotation speed of the registration roller R3 is controlled to adjust the time until the sheet P reaches the recording unit 4.

FIG. 2 is a timing chart at a time TA from the start of sheet feeding to the registration ON reference in sheet conveyance. First, at the same time as the start of sheet feeding, the drive motor of the roller R1 is rotated to feed the sheet at a predetermined transport speed v0. Next, after a lapse of time t1 from the start of the sheet feeding, the rotation of the motor M1 of the pre-registration roller is started to convey the sheet at the conveying speed v0.

After the paper is conveyed by the pre-registration roller R2, a calculation time sw elapses from the time when the leading edge of the paper is detected by the sensor S1, and the rotation speed of the motor M1 of the pre-registration roller R2 is adjusted. The paper is conveyed at the corrected conveyance speed vc described above.

The adjustment based on the transport speed vc is performed until a time t2 before the leading edge of the sheet is detected by the sensor S2. When the leading end of the sheet is detected by the sensor S2, the sheet conveying speed is set to v0. Next, a time t3 after the leading edge of the sheet is detected by the sensor S2.
Thereafter, the rotation of the motor M1 of the pre-registration roller R1 is stopped. After a lapse of time t4 from the time when the leading end of the sheet is detected by the sensor S2, the conveyance of the sheet by the registration roller R3 is started.

Hereinafter, a specific paper transport timing will be described with reference to FIG. In the following description, FIG.
Symbols not shown in FIG. 1 refer to FIG. First,
The conveyance of the first sheet is started, and when the leading end reaches the registration roller position, the sheet is temporarily made to stand by for a time ts.

Thereafter, conveyance is started again and the registration rollers R
From 3, the paper is fed in the direction of the recording unit 4. At this time, the rotation of the registration roller R3 is controlled so that the conveyance speed is higher than the recording speed in the recording unit 4. This fast transport speed is a time t slightly shorter than the time required for the leading edge of the paper to reach the recording unit 4.
a will be maintained. As a result, the entire sheet is conveyed at a speed higher than the recording speed.

After the elapse of the time ta, the rotation speed of the registration roller R3 is reduced so that the paper conveyance speed matches the recording speed of the recording unit 4. By adjusting the paper conveyance speed to the recording speed in this way, when the paper enters the recording unit, the paper is brought into a state of matching the recording speed, so that an unnecessary load due to the rotation of the registration roller R3 is not applied to the paper.

The second sheet is sent out from the tray T at such a timing that the leading end of the first sheet reaches the registration roller R3 immediately after the trailing end of the first sheet has passed the registration roller R3 of the sheet aligning section 3.

In the present embodiment, during the time ta described above, the paper transport speed is higher than the recording speed of the recording unit 4, so that the paper transport speed of the first sheet is smaller than when the recording speed and the transport speed are the same. The timing at which the rear end passes the position of the registration roller R3 can be advanced by the time tx. As a result, the timing at which the leading edge of the second sheet reaches the position of the registration roller R3 can be earlier.

When the paper reaches the recording unit 4, the transport speed and the recording speed match, so that the recording unit 4
When the image formed on the belt B is transferred to the sheet P, the positional deviation between the sheet P and the image due to the conveying force of the sheet P and the uneven conveyance of the belt B, especially in the case of color recording, the color shift is less likely to occur. And stable image quality can be obtained.

In this embodiment, in addition to the control of the paper transport speed by the paper alignment unit 3 as described above, the transport speed when the paper is fed out by the paper supply unit 2 is also controlled as needed.
That is, control is performed to increase or decrease the transport speed of the sheet sent from the tray T by rotating the roller R1 in accordance with the timing at which the transport speed of the sheet is increased or decreased by the sheet aligning unit 3.

If necessary, a pre-registration roller R2
By controlling the motor M1, the transport speed of the sheet passing through the pre-registration roller R2 may be adjusted. That is, the rotation speed of the pre-registration roller R2 is controlled by the motor M1 in accordance with the timing at which the conveyance speed of the paper is increased or decreased by the registration roller R3 described above, and the conveyance speed of the paper passing through the pre-registration roller R2 is increased. , To reduce.

As described above, by controlling the transport speed of the paper sent from the paper feed unit 2 and the transport speed of the paper at the pre-registration roller R2 in accordance with the rotation of the registration roller R3,
The conveyance interval of a plurality of sheets conveyed continuously as a whole as the image recording apparatus 1 can be narrowed, and unified speed control can be performed for control.

Further, in the present embodiment, the control of the sheet conveying speed by the registration roller R3 is adjusted according to the size and type of the sheet or the recording speed of the recording unit 4 as necessary. Is also good.

For example, when an image is recorded on a sheet thicker than the standard, the recording speed of the recording section 4 needs to be reduced. In the present embodiment, the sheet transport by the registration rollers 3 is performed based on the type of the sheet. The rate of increase or decrease of the speed is changed, or the rate of increase or decrease of the sheet conveyance speed at the registration roller 4 is changed according to the recording speed of the recording unit 4 that changes based on the type of sheet.

The size and type of paper are detected based on, for example, an input from a user interface, or detected by a size switch or a paper feed sensor interlocked with a side guide of a tray T storing paper different from the standard. The paper conveyance speed is adjusted in conjunction with the detection. As a result, it is possible to set an accurate sheet conveyance speed according to the size and type of the sheet and the recording speed of the recording unit 4.

Further, in the image recording apparatus 1 of this embodiment, a sensor S3 is provided between the registration roller R3 of the sheet aligning section 3 and the recording section 4, and the timing of the leading edge of the sheet passing through the registration roller R3 is determined by the sensor S3. And the degree of increase or decrease of the sheet conveyance speed by the registration roller R3 may be adjusted based on the detection.

That is, the sheet temporarily waits at the position of the registration roller R3, and then starts to be conveyed again at a predetermined timing, and the rotation of the registration roller R3 increases or decreases the predetermined conveyance speed described above. However, depending on the variation in the rotation of the registration roller R3 and the frictional state with the sheet, the desired conveyance speed may not be obtained in some cases.

Therefore, a sensor S3 is provided below the registration roller R3 in the conveyance direction, and the time required for the leading edge of the sheet to reach the position of the sensor S3 from the position of the registration roller R3 is measured to determine whether a desired conveyance speed is obtained. to decide.

The paper aligning section 3 obtains the actual transport speed of the paper based on the measured time, and finely adjusts the transport speed accordingly, or finely adjusts the deceleration time (timing) of the transport speed. The control is performed so that the recording timing in Step 4 and the conveyance of the sheet are accurately matched. As a result, highly accurate image transfer can be performed in the recording unit 4.

In this embodiment, a copying machine has been described as an example of an image recording apparatus. However, the present invention is not limited to this, and can be applied to any apparatus that forms an image on paper such as a printer or a facsimile. is there.

[0038]

As described above, according to the image recording apparatus of the present invention, the following effects can be obtained. That is, in the present invention, by increasing the transport speed of the entire sheet when the sheet passes through the sheet aligning means, the timing at which the next sheet reaches the sheet aligning means can be advanced, and the transport interval between the sheets can be reduced. Thus, the number of recordings per unit time can be increased. In addition, when the paper reaches the recording section, the recording speed and the transport speed are the same, so that image recording can be performed at an accurate position, and high-quality recording without density unevenness and banding can be achieved. It is possible to do.

Further, by increasing the transport speed of the sheet passing through the sheet aligning means, it is possible to absorb a variation in timing when the next sheet is transported, to secure time, and to make the transport interval between the sheets accurate. It becomes possible to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image recording apparatus according to an embodiment.

FIG. 2 is a timing chart of sheet conveyance.

FIG. 3 is a diagram illustrating a sheet conveyance timing.

FIG. 4 is a diagram illustrating a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image recording device 2 Paper supply part 3 Paper alignment part 4 Recording part B belt P paper R2 pre-registration roller R3 registration roller T tray

Claims (6)

[Claims] 1. A sheet feeding means for conveying a sheet from a storage position at a predetermined timing, and a sheet aligning means for temporarily stopping a sheet conveyed from the sheet feeding means before a recording section and then feeding the sheet to the recording section. Means, the sheet aligning means, in the transport after temporarily waiting the paper, the transport speed from the standby position of the paper to reach the recording unit, the recording unit An image recording apparatus, wherein the recording speed is made faster than the recording speed in the above, and the transport speed when the sheet reaches the recording section is controlled to match the recording speed. 2. The image recording apparatus according to claim 1, wherein said sheet feeding means controls a conveying speed from sending out said sheet to reaching said sheet aligning means faster than a recording speed in said recording section. apparatus. 3. A printing apparatus according to claim 1, further comprising a speed control unit for controlling a speed of conveying the sheet higher than a recording speed in the recording unit, between the sheet feeding unit and the sheet aligning unit. The image recording apparatus as described in the above. 4. The image recording apparatus according to claim 1, wherein said sheet aligning means adjusts the conveying speed of the sheet according to the size or type of the sheet. 5. The image recording apparatus according to claim 1, wherein said sheet aligning means adjusts a sheet conveying speed according to a recording speed in said recording section. 6. The paper aligning means adjusts a transport speed of the paper based on information from a detecting means provided between the paper aligning means and the recording unit, or adjusts a timing at which the transport speed is reduced. The image recording apparatus according to claim 1, wherein: