JP2002086694A - Ink jet recording device and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording device which can suppress the reduction of through-puts being more than necessary, and also, can suppress a discharge paper smear even when a recording medium is brought in a from a place of a high humidity, right before the printing. SOLUTION: The tone of a color material on a recording medium which discolors in response to a moisture state is detected by a sensor 22, and the moisture state of the recording medium is judged. Then, the printing is performed at a printing speed in response to the moisture level.

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 performing recording by discharging ink from a recording head to a recording medium based on image data, and a control method thereof.

[0002]

2. Description of the Related Art In an ink jet recording apparatus, when the next recording medium is ejected before the ink on the recording medium printed last time is dried, the recording surfaces of the previous recording medium are rubbed by mutual rubbing. There is a risk that not only will the paper be smudged, but also a paper discharge smear that will stain the printed back surface of the next discharged recording medium.

[0003] For this reason, it has been proposed to control the discharge smear by controlling the printing speed of the recording medium to be printed next according to the amount of ink per unit area of the recording medium on which the previous printing was performed. Have been.

[0004]

However, even when the printing speed is controlled in accordance with the amount of ink ejected per unit area of the recording medium on which the previous printing was performed as described above, the environment in which the printing is performed. When the ink is difficult to dry, such as in a place with high humidity, there are problems such as that printing takes longer than necessary depending on parameters (lower throughput) and that the suppression of paper discharge smear is not sufficient. .

[0005] In addition, it has been proposed to provide a humidity sensor in the recording apparatus to solve the above problem.
The above problem may not be solved, for example, when a recording medium is brought in from a place having a different environment (humidity) immediately before printing.

SUMMARY OF THE INVENTION The present invention provides an ink jet recording apparatus and a control method thereof, which can suppress a decrease in throughput more than necessary and can suppress a discharge smear even when a recording medium is brought in from a location with high humidity immediately before printing. The purpose is to do.

[0007]

An ink jet recording apparatus and a control method thereof according to the present invention are configured as follows.

(1) In an ink jet recording apparatus that performs printing on a recording medium by discharging ink from a recording head based on print data, the color tone of a color material on the recording medium that changes color in accordance with the humidity is detected. A detecting means and a changing means for changing a printing speed in accordance with a detection result by the detecting means are provided.

(2) In the ink jet recording apparatus of the above (1), the changing means includes a detection result obtained by the detecting means, an ink amount per unit area of the recording medium ejected by the previous printing on the recording medium, and the previous time. The printing speed is changed according to the elapsed time from printing.

(3) In the ink jet recording apparatus according to the above (1) or (2), the changing means reduces the printing speed as the humidity of the recording medium on which the previous printing was performed is increased.

(4) In the ink jet recording apparatus according to the above (2) or (3), the changing means lowers the printing speed as the amount of ink per unit area of the recording medium ejected by the previous printing is larger. .

(5) In any one of (2) to (4) above, the changing means increases the printing speed as the elapsed time from the previous printing is longer.

(6) In any one of the above-mentioned ink-jet recording apparatuses (1) to (5), the changing means includes a scanning speed of the carriage, a delay time between printing of each line by the recording head, a feeding speed of the recording medium, and recording. The printing speed is changed by changing at least one of the medium feeding intervals.

(7) In a control method of an ink jet recording apparatus for performing printing on a recording medium by discharging ink from a recording head based on print data, a color tone of a color material on the recording medium that changes color in accordance with humidity. Is detected, and the printing speed is changed according to the detection result.

(8) In the control method of the ink jet recording apparatus of the above (7), the detection result, the amount of ink per unit area of the recording medium ejected by the previous printing on the recording medium, and the progress since the previous printing Printing speed is changed according to time.

(9) In the method of controlling an ink jet recording apparatus according to the above (7) or (8), the printing speed is reduced as the humidity of the recording medium on which the previous printing was performed is increased.

(10) In the method of controlling an ink jet recording apparatus according to the above (8) or (9), the printing speed is reduced as the amount of ink per unit area of the recording medium ejected by the previous printing is increased.

(11) In any one of the control methods (8) to (10), the printing speed is increased as the elapsed time from the previous printing is longer.

(12) In the control method of any one of (7) to (11), the scanning speed of the carriage, the delay time between printing of each line by the recording head, the feeding speed of the recording medium, the recording medium The printing speed is changed by changing at least one of the feeding intervals of the printing.

[0020]

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

(Outline of Printer) FIG. 1 is a sectional view showing the structure of an ink jet recording apparatus (printer) according to the present invention, and shows a printing mechanism of the printer as viewed from the front. In FIG. 1, reference numeral 1 denotes an ink jet cartridge including an ink tank and an ink jet recording head;
Reference numeral 2 denotes a carriage guide shaft, and reference numeral 3 denotes a PF roller for feeding paper. Reference numeral 21 denotes a carriage for mounting the ink jet cartridge 1, and reference numeral 22 denotes a sensor (detection unit) for reading a color (color tone) of a color material that changes color according to a moisture level (moisture condition) applied to a predetermined area on a recording medium. It is.

FIG. 8 is a side view showing the structure of the ink jet recording apparatus (printer) according to the present invention, and shows the printing mechanism of the printer viewed from the side. In FIG. 8, reference numeral 21 denotes a carriage for mounting the ink jet cartridge 1, 4 denotes an automatic sheet feeder for feeding recording paper, 5 denotes a discharge spur for discharging a recording medium such as recording paper or a plastic thin plate, Reference numeral 9 denotes a paper end sensor for detecting the presence or absence of a recording medium.

FIG. 9 is a side view showing a state in which the printer discharges a recording medium. In this embodiment, when recording is performed up to 6 inches, the leading end of the recording medium 8 hangs down and is discharged first. A state in which the recording medium 7 contacts the recording medium 7 will be described.

FIG. 9A shows a state where the first page is discharged, the second page is printed, and the recording medium 8 is discharged by about 3 inches. FIG. 9B shows a state in which the printing is further advanced, the printing of the second page is advanced by about 6 inches, and the leading end of the recording medium 8 of the second page is in contact with the first recording medium 7. FIG. 9C shows a state when printing is further advanced and the paper end sensor 9 shown in FIG. 8 detects the trailing edge of the paper.

FIG. 10 is a diagram showing a recording medium used in this embodiment. In FIG. 10, reference numeral 24 denotes a printing range on a recording medium. Reference numeral 25 denotes a coloring material portion coated with a coloring material that changes color according to the humidity level of the recording medium. In this embodiment, cobalt chloride is used as the coloring material. Cobalt chloride is a color material that is blue in a dry state and changes color to red when it absorbs moisture. As shown in FIG. 11, the color tone of the color material portion 25 changes as the amount of absorbed moisture increases, that is, the color material portion As the 25 colors increase, the color gradually changes from blue to red.

In the present embodiment, as shown in FIG. 11, the moisture level of the color material section 25 is divided into five levels, and the color (color tone) is determined based on the information obtained from the sensor 22 shown in FIG.
Is detected to determine which of the following corresponds to the moisture level.

(Control) A description will now be given of the discharge smear suppression control in the ink jet recording apparatus (printer).

In the present embodiment, first, the time during which the paper discharge smear does not occur is set to 30 seconds for the portion where the printing ratio of 50% or more is determined, and the portion at the top of the page is determined according to the humidity of the color material portion 25 shown in FIG. The color (color tone) of the color material that changes color is read by the sensor 22, and in the case of this embodiment, as shown in FIG. 11, the humidity level is divided into five levels based on the humidity of the recording medium, and Sometimes -4 seconds, and +4 seconds in the most humid state (level), the fixing auxiliary time (se
c) Set “a”, and set a value obtained by adding the fixing auxiliary time (sec) to 30 seconds in the memory as an initial value.

At the same time, a subtraction timer counter (not shown) is started to perform subtraction every one second.
Also, data (here, 1 to 6) indicating the position of a divided recording medium portion (area) to be described later and data 1 indicating that the recording medium is currently being printed are set.

Next, the recording medium is a paper end sensor 9.
Is ejected when the sheet is detected, the size of the recording medium can be known at this time because the length of the sheet can be determined by the feed amount from the start of printing. If the recording apparatus sets, for example, 18 inches as the maximum, if the area is divided and managed for every 3 inches, as shown in FIG. (1) is the leading edge during recording, and area (6) is the trailing edge.)

If the recording medium is shorter than this, the above-mentioned data is re-managed by shifting the memory position to the last position. This is advantageous because it is possible to determine the discharge smear without worrying about the length of the paper.
That is, when the next recording medium is ejected, it is possible to control a state in which the recording medium is rubbed from a specific position on the basis of the rear end of the previously printed recording medium.

Next, printing of the next page (the second page) is started, and the same marking processing as that of the first page is performed and managed on the second page, and at the same time, the smear is determined. When the position of the paper discharge port and the paper discharge tray are distant from each other as in the printer of this embodiment, the leading end of the recording medium contacts the recording medium of the discharged first page at the beginning of printing. Therefore, printing can be started without smear determination.

The judgment is started when the end of each area is reached. At this time, the position of the recording medium on the first page with which the leading end of the recording medium comes into contact is an area (5) referred to as an area on the memory. Because, as described above, the contents of the memory are copied back to the last when the paper is ejected, the second area (5) from the rear is always touched.

At the end of each area, it is determined whether or not the paper discharge smear will occur due to rubbing from the remaining number of the fixing time count in the area. If the fixing is completed, the printing is performed as it is, and if the fixing is completed, the printing must be completed. For example, a delay print mode for lowering the print speed by inserting a wait time between the printing of each line is set and executed.

The delay print mode is held in the area, and is reset if the next area can be continuously printed when the next area is determined. Further printing proceeds, and when the second page has passed (passed) the paper end sensor 9, it is determined whether the paper can be finally discharged by checking the numerical value of the area (6) of the first page. judge. That is, since the area (6) is originally located on the rear end side of the area where the second page begins to rub, the area (6) comes into contact with the second page only when the sheet is finally discharged and stacked. Different from area.

FIG. 4 is an explanatory view showing the area numbers assigned to the sub-scanning direction of the recording medium according to the embodiment. The state of the assigned area number is shown. After the recording medium is fed, the paper feed amount is counted, and in the present embodiment, the area is divided every three inches and recognized. In the present embodiment where the maximum length of the recording medium is assumed to be within 18 inches based on the specifications of the printer, six areas on the memory are secured.

The recording medium A shown in FIG. 4 has a length of 15 inches and extends up to the area 5 by the integration of the paper feed amount from the time of paper feeding until the paper passes the paper end sensor 9. It can be determined that the recording medium B has a maximum recording medium length of 18 inches.

FIG. 5 is an explanatory view showing a marking state of each area on a continuously printed recording medium according to the embodiment. The recording medium having the same length as the recording medium A shown in FIG. 2 shows a state in which printing is continuously performed on two sheets in which a printing pattern having a high printing ratio and a printing pattern having a printing ratio as low as text are mixed.

FIG. 6 is a view showing a check box (window box) for detecting the print ratio according to one embodiment. In the present embodiment, in a print head having a 128 nozzle width, 63 m at 6.25 kHz for 10 msec.
(Equivalent to the dot width) is counted.
That is, the total number of dots in the check box is 128 × 6
3 = 8064 dots, and 8064 dots printed in the area of the check box are calculated as 100% printing ratio.

FIG. 7 is an explanatory diagram showing how the print ratio of one embodiment is actually detected. The error occurring between the check box and the actual print image will be described with reference to FIG. .

FIG. 7A shows a state in which the print patterns are exactly overlaid on the check boxes. FIG. 7B shows a case where the print pattern is shifted up and down in the main scanning direction of paper feed by 64 nozzles, and the read timing is shifted in the sub-scanning direction of the carrier by 5 msec. This is the maximum reading error in this embodiment.

Since reading errors do not occur if the image is larger than the check box, the check box is preferably smaller. If the size of this check box is small, a reading error will occur in a very small solid black area having relatively good fixability, so that there is little problem with the discharge smear.

However, if the check box is set too small, detection will be performed even on text. In this case, the detection results may be accumulated to determine that the duty of the area in which many detections have been performed is high.

FIG. 2 is a block diagram showing a control configuration of the printer according to one embodiment. In FIG. 2, reference numeral 10 denotes an interface, and 11 denotes a gate array. 12 is ROM, 1
3 is a DRAM and 14 is an MPU. Reference numeral 15 denotes a head driver, 16 denotes a paper feed motor driver, and 19 denotes a paper feed transport motor. 17 is a motor driver for a carriage motor, and 20 is a carriage motor.

When print data is sent from the host via the interface 10, the print data is temporarily stored in the DRAM 13 through the gate array 11. After that, the data in the DRAM 13 is converted from the raster data into a print image to be printed by the recording head 18 by the gate array 11 and stored in the DRAM 13 again.

The data is again sent to the recording head 18 by the gate array 11 via the head driver 15 and the ink is ejected from the corresponding nozzle to perform printing.
At this time, a counter for dots to be printed on the gate array 11 is configured so that the number of dots printed at high speed can be counted.

The carriage motor 20 is operated via the carriage motor driver 17 to move the recording head 18 in the main scanning direction in accordance with the recording speed of the recording head 18. The interrupt control is performed from the MPU 14 to the gate array 11 every 10 msec, and the integrated amount of the counter value of the number of print dots is read. By doing this,
It is possible to detect the printing ratio printed per unit area from the number of dots printed during the unit time.

More specifically, as shown in FIG.
Assuming that printing was performed at a print frequency of 6.25 kHz using the print head of the nozzle, if the resolution was the same in both the vertical and horizontal directions, the number of print dots was counted within the range of the speed at which the carriage advances by 63 dots for 10 msec. Can be counted. In this case, an error occurs in the case as shown in FIG. 7, but basically, the smaller the size of this window, the smaller the area where the error occurs, and the better. In the above configuration, the MPU 14 detects a color (color tone) based on the information obtained from the sensor 22 shown in FIG. 1 described above, and discharges the detection result and the previous (previous) printing by printing on the recording medium. A changing means for changing the printing speed in accordance with the amount of ink per unit area of the recording medium and the elapsed time from the previous printing is provided.

FIG. 7A shows a state in which a solid black print area having a print ratio of 100% is completely overlapped with the same size as the window box. In this case, the count value indicates a print ratio of 100%. However, in the case of FIG. 7B, the printing ratio is 25% even if the printing ratio is exactly the same. If the window size is relatively larger than this window size, an error is unlikely to occur. Therefore, it is very effective as a modification of the present embodiment to count in the direction of the nozzle row or to increase the interrupt interval.

Hereinafter, the above-described discharge smear suppression control operation of this embodiment will be described in detail with reference to the flowchart of FIG. FIG. 3 is a flowchart showing a discharge smear control operation according to one embodiment. This operation is executed in accordance with an instruction from the MPU 14 based on a program stored in the ROM 12.

When the power of the recording apparatus is turned on, first, the STE
After the print ratio count routine is reset at P1,
Start. The print ratio count routine is counted according to the format shown in FIGS. Actually, there is no data at the time of printing when the power is turned on. Therefore, even if the MPU 14 shown in FIG. 2 checks the integrated value of the dot count counter of the gate array 11 in the interrupt routine every 10 msec, Calculated as 0%.

Next, an area marking routine is started in STEP2. In this routine, after the print signal is received, the transport motor 19 for paper feed is rotated via the motor driver 16 shown in FIG. Then, an operation of assigning an area number every 3 inches is started.

Next, in STEP 3, in this embodiment, whether or not the current paper feed position is the top of the page is detected from the rotation amount of the paper feed transport motor 19. If it is the top of the page, in STEP 4 the color of the portion of the recording medium where the color material changes depending on the humidity on the recording medium is indicated by the sensor 2 shown in FIG.
2 to detect the humidity level of the recording medium,
In P5, the fixing auxiliary time (se
Perform the setting of c). If it is not the top of the page S
Proceed to TEP6.

Next, it is detected in STEP 6 whether or not the delay print mode is set. The delay print mode is a part for checking whether or not the delay print is set to be performed before a part where smear is assumed to occur. If the delay printing mode is set, the delay printing is performed in STEP 7 according to the contents set in STEP 22 described later. If it is not set, the process proceeds to STEP 8 to perform normal printing.

Next, in STEP 9, it is determined whether or not the paper end sensor 9 shown in FIG. 8 has detected the end of the recording medium. When the end is detected, the flow goes to STEP16, and the necessary processing is performed at the rear end. STE otherwise
Going to P10, it is determined whether or not it is the rear end of each area marked in the processing of STEP2. If it is at the rear end, the flow goes to STEP 19 to determine whether the smear suppression control is necessary by determining the fixing property.

In other cases, the process proceeds to STEP 11 and S
The printing ratio is read using a printing ratio counting routine started in TEP1, and it is determined every 10 msec whether or not the portion is likely to cause smear at a high printing ratio.
If the printing ratio is low, the process returns to STEP 3 and the above operation is repeated. Conversely, if it is determined that the printing ratio is high, the process proceeds to STEP 12, and the area marking routine started in STEP 2 is used to determine which area the portion is in.

The process proceeds to STEP 14 to perform a marking process of marking 2 indicating that the recording medium is currently being printed in a three-dimensional dimension as a marking process. Further, an area number and a fixing time necessary for preventing the discharge smear are marked. In this embodiment, the fixing required time is set to 30 seconds when the printing ratio exceeds 50%.
In step 5, a value "30 + a" seconds is set by adding the fixing auxiliary time (sec) "a" determined by the humidity level of the recording medium.

Next, the process proceeds to STEP 15, where a timer for subtracting the set required fixing time every second is reset and started. As an example, consider a case where two high print ratio portions exist in area 1 of the first page of the recording medium shown in FIG. First, when the first high printing ratio portion is detected in the window shown in FIG. 6 in STEP 11, the printing ratio of that portion is calculated and stored by the marking process in STEP 14.

Next, when another portion having a high printing ratio is detected in the same area, a marking process is similarly performed in STEP14. At this point, if there is a high printing ratio portion in the same area, in this embodiment, the one printed later in time has priority, and the marking data is overwritten.

As another example, in the case where a plurality of areas exist in the same area and the initial value of the required fixing time is changed according to the printing ratio, the time until the completion of the fixing of the previously marked portion at that time is considered. The remaining time may be checked, and the larger remaining time in the same area may be preferentially overwritten on the smaller remaining time.

The above state is repeated, and printing and feeding of the recording medium proceeds. If the paper end sensor 9 detects PE (page end) in STEP 9, ST
Proceed to EP16. Here, it is determined whether the recording medium on which printing is almost completed at the end can be discharged from the discharge port and stacked. Specifically, the remaining number of fixing times in the area of the area 6 of the recording medium that has been discharged first is checked, and if it is 0, the process proceeds to STEP 17 to permit the discharge.

If it is not 0, the loop of STEP 16 is turned on, and the discharge is waited until the count value of the remaining fixing time becomes 0 (the printing speed is reduced). STEP1
When the paper ejection is completed in step 7, "2" in the marking data indicating that the recording medium is being printed is rewritten to "1" indicating that the recording medium is ejected in step 18. At the same time, rewrite the memory location to the last.

This is because, assuming that the position at which the recording medium of the second page starts to rub is determined in the second area from the rear, if the recording medium length is changed and the length is changed to the rear reference, the recording medium length will be changed. This is because the position on the memory at which rubbing starts even if the value changes can be made constant.

When printing is performed continuously on a plurality of sheets, the next recording medium is fed, but the control is similarly continued.

Only when the end of each area is reached in STEP 10, the process proceeds to STEP 19. Immediately after turning on the power,
The first sheet after printing has not been performed for a while has no remaining fixing time because printing has not been performed before. Therefore, the delay printing is not performed, but the same is routinely applied to the first and second sheets.

In STEP 19, it is first determined whether or not the end of the area (1) has been reached. Because of Figure 9
As shown in FIG. 3A, when the recording medium 8 is ejected while being printed and the ejection length is short, if the height of the ejection opening is high to some extent, the leading end of the recording apparatus is already ejected. There is no rubbing with the recorded recording medium. For this reason, since it is not necessary to perform the delay printing in the area (1), the process immediately returns to the original routine to continue the printing.

If it is area (2), STEP 2
At 0, go to check the remaining number of fixing times at (1, 5, **). If the number of remaining fixing times in the area (5) remains in STEP21, in order to delay the printing,
Proceed to 22 to set the delay print mode. If there is no remaining fixing time, the process proceeds to STEP 23, in which the delay print mode is not set, but the delay print mode that was set before that is reset.

The above operation is repeated at the head of each area, and the printing is completed without rubbing the area having the remaining number of fixing times. Thereafter, when the paper end is similarly detected in STEP 9, the above-described operation is performed, and thereafter, the same operation is performed.

As described above, in the present embodiment, by detecting the humidity on the recording medium and increasing or decreasing the fixing time of the ink according to the humidity, an appropriate fixing time according to the humidity of the recording medium is set. Inkjet recording device that can print and print at a more appropriate speed, thereby suppressing paper discharge smear regardless of the humidity of the recording medium, such as printing on a recording medium brought in from a humid environment immediately before printing Can be provided.

In this embodiment, the wait time (delay time) between printing of each recording line by the recording head is described.
The printing speed is changed by changing the printing speed and changing the paper discharge weight (changing the feeding speed of the recording medium). However, the wait time between printing on each line, the feeding speed of the recording medium, and the scanning of the carriage are changed. The printing speed may be changed by changing at least two of the speed and the feeding interval of the recording medium.

[0071]

As described above, according to the present invention,
This has the effect of suppressing an unnecessarily lowering of the throughput and suppressing the discharge smear even when the recording medium is brought in from a location with high humidity immediately before printing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an inkjet recording apparatus according to the present invention.

FIG. 2 is a block diagram illustrating a control configuration according to an embodiment;

FIG. 3 is a flowchart illustrating a discharge smear suppression control operation according to an embodiment;

FIG. 4 is an explanatory diagram showing an area number assigned to a sub-scanning direction of a recording medium according to one embodiment.

FIG. 5 is an explanatory diagram showing a marking state of each area on a continuously printed recording medium according to one embodiment;

FIG. 6 is a diagram showing check boxes according to an embodiment;

FIG. 7 is an explanatory diagram illustrating an error generated between a check box and an actual print image according to one embodiment;

FIG. 8 is a cross-sectional view illustrating a configuration of an inkjet recording apparatus according to the present invention.

FIG. 9 is an explanatory diagram illustrating a state in which a recording sheet according to an embodiment is discharged.

FIG. 10 is a diagram showing a recording medium according to an embodiment.

FIG. 11 is a diagram illustrating a relationship between humidity on a recording medium and a corresponding moisture level according to an embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink-jet cartridge 12 ROM 14 MPU (change means) 21 Carriage 22 Sensor (detection means)

Claims (12)

[Claims] An ink jet recording apparatus that performs printing on a recording medium by ejecting ink from a recording head based on print data, and detects a color tone of a color material on the recording medium that changes color in accordance with humidity. An ink jet recording apparatus comprising: a detecting unit that performs printing; and a changing unit that changes a printing speed in accordance with a result of detection by the detecting unit. 2. The printing apparatus according to claim 1, wherein the changing unit changes the printing speed in accordance with a result of the detection by the detecting unit, an amount of ink discharged per unit area of the recording medium, and an elapsed time from the previous printing. 2. The ink jet recording apparatus according to claim 1, wherein the apparatus is changed. 3. The ink jet recording apparatus according to claim 1, wherein the changing means decreases the printing speed as the humidity of the recording medium on which printing was performed last time increases. 4. The ink jet recording apparatus according to claim 2, wherein the changing means reduces the printing speed as the amount of ink per unit area of the recording medium ejected by the previous printing increases. 5. The ink jet recording apparatus according to claim 2, wherein the changing means increases the printing speed as the elapsed time from the previous printing is longer. 6. The printing speed by changing at least one of a scanning speed of a carriage, a delay time between printing of each line by a printing head, a feeding speed of a printing medium, and a feeding interval of a printing medium. The inkjet recording apparatus according to any one of claims 1 to 5, wherein (i) is changed. 7. A control method for an ink jet recording apparatus for performing printing on a recording medium by discharging ink from a recording head based on print data, wherein the color material on the recording medium is changed in color in accordance with the humidity. A method for controlling an ink jet recording apparatus, comprising detecting a color tone and changing a printing speed according to a result of the detection. 8. The printing speed is changed according to a detection result, an ink amount per unit area of the recording medium ejected by the previous printing on the recording medium, and an elapsed time from the previous printing. A method for controlling an ink jet recording apparatus according to claim 7. 9. The method according to claim 7, wherein the printing speed is decreased as the humidity of the recording medium on which printing was performed last time is increased. 10. The control method according to claim 8, wherein the printing speed is reduced as the amount of ink per unit area of the recording medium ejected by the previous printing is increased. 11. The printing speed is increased as the elapsed time from the previous printing is longer.
11. The method for controlling an inkjet recording apparatus according to any one of claims 10 to 10. 12. The printing speed is changed by changing at least one of a scanning speed of a carriage, a delay time between printing of each line by a printing head, a feeding speed of a printing medium, and a feeding interval of a printing medium. The method for controlling an ink jet recording apparatus according to any one of claims 7 to 11, wherein: