JP2001334644A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an ink image from being disturbed by a sheet discharge roller disposed on the downstream side of a print region without lowering throughput. SOLUTION: The ink jet recorder comprises an ink jet recording head 11 moving in the widthwise direction of a recording medium P to form an ink image, sheet feed rollers 8a, 8b disposed on the opposite sides of the moving region of the ink jet recording head 11 to feed the recording medium by an amount of one print pass while grasping the recording medium at least on the downstream side, means 25 for storing the just preceding sheet feed amount, and a print control means 21 for determining a moment of starting next sheet feed or a moment of starting widthwise movement of the recording head 11 based on the distance L between the downstream side position of an ink image of relevant print pass formed by a recording head 10 and the grasping region of the sheet feed rollers 8a, 8b, and the just preceding sheet feed amount stored in the sheet feed storage means 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for ejecting ink droplets by an ink jet recording head to print one printing pass at a time, and more particularly to a paper feeding technique for recording paper.

[0002]

2. Description of the Related Art An ink jet recording apparatus includes an ink jet recording head which reciprocates in the width direction of a recording medium to eject ink droplets, and a paper feed mechanism comprising rollers arranged upstream and downstream of a printing area. And the recording medium is fed by a recording head while the recording medium is fed by a predetermined width. Immediately after printing formed on the recording medium, the ink is in an undried state, for example, as seen in JP-A-2-245356, a predetermined time required for drying the ink after printing is completed The paper feed is stopped only after the paper feed is stopped and the ink is dried.

[0003]

However, in a recording apparatus having various printing modes such as a high-density image printing mode, a normal image printing mode, a high-quality text printing mode, and a draft printing mode, some recording modes are useless. There is a problem that a long waiting time occurs and the throughput decreases. The present invention has been made in view of such a problem, and an object of the present invention is to provide an ink jet recording apparatus capable of preventing a disturbance of an ink image of a recorded image without lowering a throughput. That is.

[0004]

According to the present invention, there is provided an ink jet recording head which forms an ink image by moving in the width direction of a recording medium, and a moving area of the ink jet recording head. It is arranged so as to sandwich it, and the recording medium is
A paper feed mechanism for feeding paper for a print pass, paper feed amount storage means for storing the immediately preceding paper feed amount by the paper feed mechanism, and a downstream side of an ink image of the print pass formed by the recording head. Based on the distance between the position and the gripping area on the downstream side of the paper feed mechanism, and the immediately preceding paper feed amount stored in the paper feed storage means, at the time of starting the next paper feed by the paper feed mechanism, or And control means for determining a point in time when the recording head starts moving in the width direction.

[0005]

The drying time suitable for the printing mode is determined from the paper feed amount, and the paper feeding is executed when the ink image is dried to the extent that the ink image is not disturbed regardless of the printing mode.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention. FIG. 1 shows an embodiment of an ink jet recording apparatus to which a recording method according to the present invention is applied, and shows a cut sheet feeder 1 for feeding cut sheets one by one, and a cut sheet 2 fed. Are provided.

The paper detecting means 6 and the paper feed roller pair 7 (7a, 7a)
b), 8 (8a, 8b), paper discharge roller pair 9 (9a, 9
b) is arranged, and an ink jet recording head 10 for ejecting ink droplets between the paper feed roller pairs 7 and 8 to form ink dots on a sheet is mounted on the carriage 11 and arranged. It is desirable that the discharge roller 8b facing the recording surface of the roller pair 8 disposed on the downstream side is formed as a star wheel.

[0008] Of the pair of paper feed rollers 8 and the pair of discharge rollers 9 on the downstream side, the rollers 8a, 9a that come into contact with the printing surface are:
It is configured as a star wheel to minimize the contact area with the ink. In addition to the sheet conveyance path, a second sheet insertion port 12 is provided at a rear portion 4a of the sheet guide 4 so that continuous sheets such as a tractor (not shown) can be fed.

FIG. 2 shows an embodiment of a control device for controlling the recording mechanism according to the present invention. The control device 20 comprises a print control means 21 for receiving a print signal from an external device such as a host;
A paper feed motor driving unit 22 for driving the paper feed driving motor 13, a recording head driving unit 23 for driving the recording head 10, a carriage motor driving unit 24 for driving the carriage motor 14, and updating the previous paper feeding amount Paper feed amount storage means 25 for storing the data while printing, and a flushing timer 26 for detecting a flushing cycle for the recording head 10.
It is composed of

The operation of the apparatus having the above-mentioned configuration will be described with reference to the flowchart shown in FIG. When a print command is input from the host computer (step b),
The cut sheet P sent from the cut sheet feeder 1 is guided by a sheet guide 3 and is fed by a paper feed motor 1.
The sheet is gripped by a sheet feed roller pair 7 driven by 3 and is held at a printing start position by being sandwiched by a sheet feed roller pair 8 on the downstream side. As a result, the printing area becomes flat, and an interval suitable for printing is set between the printing area and the inkjet recording head 10.

In this state, when print data is output from the host computer, the print control means 21 moves the recording head 10 in the width direction of the sheet by the carriage motor 14 and executes printing for one print pass ( Steps
B). When printing for one print pass is completed, the apparatus waits for the input of a paper feed command (step C).

The print control means 21 determines the paper feed amount N1 designated by the paper feed command (step S1).
D) When the number of steps N1 of the paper feed amount is larger than 439, that is, when the distance between the downstream line of the ink image of one printing pass just recorded and the holding area of the paper discharge roller pair 9 is longer than L. Moves the recording head 10 to the capping position and executes capping (step E).

This capping operation is performed when the paper feed amount is 43
When the number of steps is about nine, the recording head 10 is left in a state where the ink droplets are not ejected, so that the ejection failure of the ink droplets, that is, the flying of the ink droplets is prevented. Therefore, when the print characteristics of the recording head 11 do not change even if the printing head 11 is left for a long time depending on the type of the ink or the environment, the capping step is unnecessary.

When the printing of one print pass is completed and the paper feed is performed, the print control means 21 stores the paper feed amount for the immediately preceding print pass stored in the paper feed storage means 25. Is read, and the current print mode is determined based on the paper feed amount (steps F and H).

In this embodiment, the paper feed amount N1 (the number of paper feed steps) is set to 6 according to the print mode as follows.
Are classified into stages. 1 19 ≧ N1 (image printing by interlace method) 2 19 <N1 ≦ 50 (image printing) 3 50 <N1 ≦ 94 (high quality character printing) 4 94 <N1 ≦ 288 (draft printing) 5 288 <N1 ≦ 439 (High-speed printing with print head width) 6 439 <N1 (Line feed operation)

Based on the result of this determination, a reference waiting time TW set for each print mode is determined. The waiting time TW will be described. When paper feeding is performed after printing of one print pass, the ink image formed by the printing enters the gripping area of the paper discharge roller pair 9 and the roller 8b comes into contact with the undried ink image to disturb the ink image. In order to prevent such inconvenience, the roller 8b is contaminated with ink. Since the drying speed of the ink is related to the printing mode, that is, the ink density of the ink image, it is set individually for each printing mode.

The distance between the downstream position of the ink image of the printing pass formed by the recording head and the grip area on the downstream side of the paper feed mechanism is L (mm), and the recording paper is set to the length N1.
(Mm) is the time required to send by TN (seconds), and the time required to print one print pass in the main scanning direction is TC
(Second), and the paper feed interval during printing is TPF (second). When a paper feed is performed such that the ink image formed by the recording head reaches the gripping area on the downstream side of the paper feed mechanism by the next paper feed (in this embodiment, when the paper feed for 439 steps is executed) ) The time required for the downstream side of this ink image to reach the gripping area on the downstream side of the paper feed mechanism from the time when printing of one print pass is completed is TN0 (second).
Then, when TN0 ≧ TW, it is possible to avoid the above-described inconveniences such as ink displacement and contamination. When this condition cannot be satisfied, that is, when (TN0 <TW), (TW−T
N0) A waiting time of more than seconds is required.

Since TW is determined by the print mode and the type of recording paper, it is constant during the printing period.
N0 changes according to the paper feed speed during printing. In the present embodiment, TN0 is not about 0.3 to 0.5 second, which is a time which particularly affects the degree of drying of the ink, while TW = 35 seconds. Therefore, it is considered that the minimum value TW−TN0 = TW1. And treat it as a fixed value.

When the waiting time TW1 has elapsed (step T), the paper feed for N1 steps is executed (step nu), and the value N1 is stored in the paper feed storage means 25. Then, returning to step (a), the same process is repeated again.

On the other hand, the printing of one print pass is completed, and the next paper feed does not reach the gripping area of the paper feed mechanism, but printing and paper feed of several print passes (L / N1 print passes) are executed thereafter. In such a case, the time required for one print pass to reach the gripping area of the paper feed mechanism is (L / N1) × TPF-TC (seconds). Therefore, this time (L / N1) × TPF−
If TC is longer than the time TW required for drying, there is no problem. However, if TC is short, the above disadvantage occurs. Therefore, it is necessary to provide a waiting time longer than TW-{(L / N1) × TPF-TC} (second). is there. If the waiting time can be divided and provided for each paper feed of one print pass, it is set in proportion to the paper feed amount of that print pass.
That is, the waiting time for each printing pass is {(TW + TC) × N1 / L} (second), and the time required without waiting time is TPF (second), that is, the paper feed interval during normal printing. {(TW + TC) × N1 / L−TPF} (seconds).

In the present embodiment, a maximum value TC is used for printing one print pass in the main scanning direction for simplification of control, and TW + TC = TW2 is treated as a fixed value. Also, the paper feed interval TPF during printing is actually the sum of TC and TN plus play time, but since the print mode is determined, TN is determined to be a fixed value and the print width is determined. , Ie, a difference from the printing time that changes in accordance with the above, that is, the movement time TC in the main scanning direction. That is,
Assuming that the waiting time from the printing start time is the time α for determining which paper feeding is to be executed, TW2 × N1 / L−α (second).

When the waiting time (TW2 × N1 / L1-α) elapses (step S1), the paper feed for N1 steps is executed (step N), and the value N1 is stored in the paper feed storage means 25. Then, returning to step (a), the same process is repeated again.

In the above embodiment, the waiting time is determined only in accordance with the printing mode. However, the drying speed (drying time) of the ink image formed by printing depends on the type of recording paper and the printing time. Since it depends on the density and the ambient temperature,
Determine the type of paper, or input it as an external signal, or attach a sensor for environmental detection such as a temperature sensor or humidity sensor to capture the temperature or humidity of the print area as a parameter and adjust the length of waiting time. Can also be easily implemented.

With this arrangement, an optimum waiting time is provided in response to changes in recording paper, printing density, and environment to prevent disturbance of an ink image and contamination of a recording apparatus, and to reduce throughput caused by unnecessary waiting time. Can reliably be prevented from decreasing.

In the above embodiment, the paper is fed after the set waiting time has elapsed.
If the paper feed amount L after printing of one print pass is less than 439 steps, that is, if the paper feed mechanism does not reach the gripping area of the paper feed mechanism, the required amount is required as shown in steps (e) to (f) of FIG. After executing the paper feed of the number N1 of steps (step e), the apparatus waits for the input of a print command (step w).
The print mode is determined (step f) and the waiting time TW2
Waiting for the elapse of × N1 / L-α (Step Y) has the same effect.

In the above-described embodiment, the printing of cut sheets has been described. However, it is clear that the same operation can be performed when printing on continuous paper to prevent ink displacement.

[0027]

As described above, according to the present invention, the ink jet recording head which moves in the width direction of the recording medium to form an ink image, and the ink jet recording head are arranged so as to sandwich the moving area of the ink jet recording head, and at least the downstream side. A paper feed mechanism that grips the recording medium on the side and feeds the paper for one print pass, paper feed amount storage means that stores the immediately preceding paper feed amount by the paper feed mechanism, and the print path formed by the print head The next paper feed by the paper feed mechanism is started based on the distance between the downstream position of the ink image and the grip area on the downstream side of the paper feed mechanism and the immediately preceding paper feed amount stored in the paper feed storage means. Or the control means for determining the point in time when the recording head 11 starts to move in the width direction. Therefore, the drying time suitable for the printing mode is determined from the paper feed amount, and an unnecessary waiting time is generated. A reduction in printing throughput by executing the paper feed can be prevented without.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a printing mechanism and a paper feeding mechanism according to an embodiment of an inkjet recording apparatus of the present invention.

FIG. 2 is a block diagram showing a control device of the recording apparatus.

FIG. 3 is a flowchart showing an operation of the recording apparatus.

FIG. 4 is a flowchart showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cut sheet feeder 6, 7 Paper feed roller pair 10 Inkjet recording head 11 Carriage 20 Control device

Claims (10)

[Claims] An ink jet recording head that moves in the width direction of a recording medium to form an ink image; and is disposed so as to sandwich a moving area of the ink jet recording head, and holds the recording medium at least on the downstream side to hold the recording medium. A paper feed mechanism for feeding paper for a print pass; a paper feed amount storage unit for storing a paper feed amount immediately before the paper feed mechanism; and a downstream side of an ink image of the print pass formed by the recording head. Based on the distance between the position and the gripping area on the downstream side of the paper feed mechanism, and the immediately preceding paper feed amount stored in the paper feed storage means, at the time of starting the next paper feed by the paper feed mechanism, or An ink jet recording apparatus comprising: a control unit that determines a point in time when the recording head starts moving in the width direction. 2. The method according to claim 1, wherein the control unit is configured to control a time required from a time when the printing of the ink image of the print formed by the printing head is started to a time when the next paper feeding by the paper feeding mechanism is started, and Based on the distance between the downstream position of the ink image of the print formed by the head and the gripping area on the downstream side of the paper feed mechanism, the time when the next paper feed by the paper feed mechanism starts, or the recording 2. The ink jet recording apparatus according to claim 1, wherein a time point at which the head starts moving in the width direction is determined. 3. When the ink image formed one print pass before by the recording head has not reached the grip area on the downstream side of the paper feed mechanism, it is necessary to dry the ink image one print pass before. 2. The ink jet recording apparatus according to claim 1, wherein a time point at which the next paper feed by the paper feed mechanism is started or a time point at which the recording head starts moving in the width direction is determined in consideration of time. 4. An ink jet recording head which moves in the width direction of a recording medium to form an ink image, and is arranged so as to sandwich a moving area of the ink jet recording head, and holds the recording medium at least on the downstream side to at least hold the recording medium. A paper feed mechanism for feeding paper for the print path, a distance between a downstream position of an ink image of the print path formed by the recording head and a gripping area on the downstream side of the paper feed mechanism, and a print mode. An ink jet recording apparatus comprising: control means for determining a point in time when the next paper feed by the paper feed mechanism starts or a point in time when the recording head starts moving in the width direction based on the information. 5. The ink jet recording apparatus according to claim 4, wherein the print mode information includes information indicating a property of the recording medium. 6. The ink jet recording apparatus according to claim 4, wherein the information on the print mode includes information indicating an ink density of the ink image. 7. The printing apparatus according to claim 1, wherein the control unit determines a time required from a time when printing of the ink image of the print formed by the printing head is completed to a time when the next paper feeding by the paper feeding mechanism is started, and The distance between the downstream position of the ink image of the print path formed by the above and the gripping area on the downstream side of the paper feed mechanism, and the temperature or humidity information of the print area, the next paper feed by the paper feed mechanism 5. The ink jet recording apparatus according to claim 4, wherein a start point or a point in time when the recording head starts moving in the width direction is determined. 8. A time required for feeding the paper from the end of printing of the ink image to the grip area on the downstream side of the ink image is TN0, a drying time TW such that the ink image is not disturbed by contact with the grip area, When the control unit determines that the ink image formed by the recording head reaches the gripping area of the paper feeding mechanism by the next paper feeding and that TW> TN0, the printing pass 8. The ink jet recording apparatus according to claim 7, wherein the paper feed after printing is provided with a waiting time of TW-TN0 or more. 9. A time TN0 for a time required for paper feeding from the end of printing of the ink image to the grip area on the downstream side of the ink image, and a time TW for drying the ink image so as not to be disturbed by contact with the grip area. The time required to execute the paper feed amount N1 is TN, the time required to form an ink image by the recording head in the main scanning direction is TC, the paper feeding cycle during printing is TPF, and the time formed by the recording head is TPF. Assuming that the distance between the downstream position of the ink image in the print path and the gripping area on the downstream side of the paper feed mechanism is L, the control unit determines that the ink image formed by the recording head is moved by the next paper feed. If it is determined that (L / N1) × TPF-TC <TW is not reached in the gripping area of the paper feed mechanism, the paper feed after the printing of the print pass is performed by TW − ｛(L / N1). ) × T The inkjet recording apparatus according to claim 7, wherein a waiting time equal to or longer than PF-TCＴ is provided. 10. The time required for feeding the paper from the end of printing of the ink image to the grip area on the downstream side of the ink image is TN0, and the drying time is such that the ink image is not disturbed by contact with the grip area by TW. The time required to execute the paper feed amount N1 is TN, the time required to form an ink image by the recording head in the main scanning direction is TC, the paper feeding cycle during printing is TPF, and the time formed by the recording head is TPF. Assuming that the distance between the downstream position of the ink image in the print path and the gripping area on the downstream side of the paper feed mechanism is L, the control unit determines that the ink image formed by the recording head is moved by the next paper feed. If it is determined that TPF <(TW + TC) × N1 / L has not reached the gripping area of the paper feed mechanism, and Ｆ (TW
8. The ink jet recording apparatus according to claim 7, wherein a waiting time equal to or longer than (+ TC) × N1 / L｝ -TPF is provided.