JP3180994B2 - Inkjet printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer having an ink drying prevention device.

[0002]

2. Description of the Related Art In FIG.
The (head 2, ink tank 3) is mounted on a carrier (not shown) and has a carrier moving mechanism (carrier motor 4).
M, a sprocket 4 and a timing belt 5) reciprocate in the longitudinal direction of the platen 6. Reference numeral 6M denotes a paper feed motor, which directly rotates the platen 6.

In such an ink jet printer, an ink drying prevention device for preventing nozzle clogging is provided. This ink drying prevention device includes a cap 7 disposed at a fixed position and intermittent ejection control means.

That is, the power switch is turned off (see FIG. 7).
(YES in ST40), the head 2 is moved to the cap 7 (ST41, 42) and covered with the cap 7.
Then, the power lamp is turned off (ST43). Then, the intermittent ejection control means operates to intermittently eject a predetermined average amount of ink ejected from each nozzle of the head 2 per unit time to wet the inside of the cap 7. This is to prevent evaporation and drying of the ink attached to the nozzle.

That is, the intermittent discharge control means discharges a predetermined discharge amount (for example, seven pulses are supplied for one nozzle) every time a preset time Ts1 elapses (ST44, 45). Power switch O
N (YES in ST46), and the next print processing (ST4
Until step 7), intermittent ejection is performed as shown in FIG. 8 (S
T44-46).

Thus, the average time per unit time (set time T
By ejecting ink by a constant ejection amount (for 7 dots) every s1), the next printing can be performed with high quality without missing dots. The set time Ts1 and the ejection amount are appropriately selected based on the form and sealing properties of the head 2 and the cap 7. If the ejection amount per average unit time is too large, the ink overflows, and if the ejection amount is too small, the ink is dried.

[0007]

However, no matter how carefully the average amount of ink ejected per unit time is selected, missing dots may occur during the next printing process. In particular, a large amount of information is printed over a long period of time, such as image data,
It is likely to occur during the next printing process performed after the power is once turned off.

[0008] This is because if the printing time is long, the time for which the cap 7 is exposed to the air in the open state becomes longer, so that the inside of the cap 7 may dry abnormally. Therefore, even if a predetermined amount of ink is ejected per predetermined average unit time, the inside of the cap 7 cannot be sufficiently wetted. Although the temperature of the head 2 and the ink tank 3 rises with the printing operation for a long time, there is no problem during printing because the ink is cooled by the ink flow. However, the ink flow stops as soon as the power is turned off. Then, since the cooling is not performed, the temperature further rises, and as the subsequent print stop time becomes longer, the air is naturally cooled to generate bubbles. Therefore, missing dots occur during the next printing. It is estimated to be.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink-jet printer capable of performing high-quality and stable printing without missing dots regardless of the amount of the previous printing.

[0010]

According to a first aspect of the present invention, there is provided an ink jet printer, comprising: a cap for covering an ink jet head after printing; and an ink ejection amount per unit time on an ink jet head covered with the cap. in the inkjet printer equipped but the intermittent ejection control means for intermittently ink ejection operation to be constant, the ink dryness prevention unit consisting of the inkjet
A second intermittent discharge control means for performing an intermittent ink discharge operation per average unit time with an ink discharge amount larger than an average ink discharge amount per unit time by the intermittent discharge control means in a state where the head is covered with a cap ; A control operation time setting means for setting a control operation time of the second intermittent discharge control means, and a switching control means for switching from the second intermittent discharge control means to the intermittent discharge control means after a lapse of the set control operation time. , Are provided.

According to a second aspect of the present invention, there is provided an ink jet printer, comprising: a cap for covering the ink jet head after printing; and a predetermined average amount of ink ejected per unit time to the ink jet head covered with the cap. In an ink jet printer having an ink drying prevention device including an intermittent ejection control unit for performing only an intermittent ink ejection operation, a printing amount detection unit for detecting a printing amount, and an ink ejection per unit time for each printing amount and printing amount. A corresponding discharge amount data storage unit for storing corresponding discharge amount data corresponding to the amount, and an average unit corresponding to a print amount detected from the corresponding discharge amount data stored by searching the corresponding discharge amount data storage unit An ink ejection amount selection means for selecting an ink ejection amount per time, and the intermittent ejection control means The ink discharge amount per average unit time-option has been characterized by being intermittent ink discharge operatively formed.

[0012]

According to the first aspect of the present invention, when the head is covered with the cap, the second intermittent ejection control means intermittently ejects the ink within the time zone set by the control operation time setting means. When the setting control operation time elapses, the switching control means switches from the second intermittent discharge control means to the intermittent discharge control means. Here, since the average amount of ink ejected per unit time by the second intermittent ejection control means is larger than the amount of ink ejection per average unit time by the intermittent ejection control means, the opening time of the cap becomes longer. Even if there is enough moisture can be given. Further, even if the head temperature at the time of stoppage is high, the rise in temperature after stoppage can be suppressed and the generation of bubbles can be prevented. Therefore, the next printing can be performed with high image quality without missing dots.

According to the second aspect of the present invention, the ink ejection amount selection means searches the corresponding ejection amount data storage means and outputs the ink ejection amount per unit time average corresponding to the printing amount detected by the printing amount detection means. Automatically select the amount. Then, the intermittent ejection control means performs intermittent ejection by the selected average amount of ink ejected per unit time. Therefore, if the necessary and sufficient average amount of ink discharged per unit time, such as the intermittent discharge interval and the ink discharge amount for each time, are set in advance in the corresponding discharge amount data storage means, the dot size can be reduced. The next printing can be performed with high image quality without omission.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) The basic configuration of this ink jet printer is the same as that of a conventional example (FIG. 6), and as shown in FIG. 1, a second intermittent ejection control means (11, 12) and a control operation time setting. Means (14S) and switching control means (11, 12)
Immediately after the head 2 is covered with the cap 7,
After the set control operation time Ts2 has elapsed, the normal intermittent discharge control means (1) is activated.
1, 12).

In FIG. 1, a control unit 10 for driving and controlling the entire ink jet printer includes a CPU 11, a ROM 1
2, a RAM 13, an operation panel 14, a clock circuit 15, an interface (I / F) 16, an input / output port 17, and the like. Character generator 12G
Is formed with a partial storage area of the ROM 12, and the input / output port 17 is connected to a power switch 9S, a power lamp 9L, a driver 4D (carrier motor 4M), and a driver 6D (paper feed motor 6M). Driver 1D (inkjet head 1) and encoding circuit 8C
The (encoder 8E) is connected to the CPU 11 via a bus.

That is, the power switch 9S is turned on (NO in ST10 of FIG. 2 or YES in ST17, ST2).
When a print command is issued by performing a print command (ST21), the head 2 is detached from the cap 7 and moved in the longitudinal direction of the platen 6 to perform a printing process (ST21). The printing timing is determined by a printing timing signal C. output from the encoding circuit 8C generated based on the detection signals φA and φB from the encoder 8E for detecting the amount of displacement of the carrier. PLS can be done.
That is, the print timing signal C. Each time PLS is generated, ink is ejected from a nozzle corresponding to the print character.

Here, the intermittent ejection control means is formed of the CPU 11 and the ROM 12 and executed in ST10 to ST13, ST18 and ST19 in FIG. 2, as in the case of the conventional example (FIGS. 7 and 8). That is, the ink discharge amount per average unit time is determined, for example, as a discharge interval (ts1) shown on the right side of FIG. 3B and a discharge amount for each time (7 pulses are supplied to each nozzle). The average unit time is predetermined to an appropriate value, for example, 1 hour or 30 minutes.

The second intermittent discharge control means controls the ink discharge amount per unit time (Ts1, 7 pulses) controlled by the intermittent discharge control means (11, 12).
Control means for intermittently discharging an ink discharge amount having an average discharge amount per unit time larger than that of the CPU 1 and the ROM 12
This is executed in ST14 and ST15 in FIG.

The second intermittent discharge control means (11, 1
In the case of the first embodiment, the ink ejection amount per unit time according to 2) is equal to the ejection interval ts2 as shown on the left side of FIG.
It is set as 0 pulse energization. The discharge interval ts2 may be set to ts2 ≧ ts1 or ts2 <ts1.

However, as shown in FIG. 3 (C), the ink ejection amount is the same as one ejection amount (7 pulse energization) by the intermittent ejection control means (11, 12), and the ejection interval tsi is set to the ejection interval. Discharge intervals ts1, ts22, ts that are shorter and gradually longer than ts1
23 and ts24. That is, by setting an arbitrary combination of the discharge interval tsi and one discharge amount (Ni pulse energization), the average unit time (for example, 1 unit) can be set as compared with the case of the intermittent discharge control means (11, 12).
What is necessary is just to set so that the ink discharge amount per time) may be large.

Incidentally, the discharge interval ts1 of the intermittent discharge control means (11, 12), the ink discharge amount (7 pulses)
Also, the discharge interval ts2 (ts21, ts22, ts23, ts) of the second intermittent discharge control means (11, 12)
24), the ink discharge amount (100 pulses) is also set and stored in the RAM 23, and each value can be written by operating the keys on the operation panel 14.

Next, the control operation time setting means sets the control operation time Ts2 shown in FIGS. 2 and 3 (ST16) for controlling the second intermittent discharge control means (11, 12). Setting key 14 on operation panel 14 in FIG.
S is formed. Set control operation time Ts2
Are stored in the work area of the RAM 13. Note that the control operation time setting means may be configured to write and store the setting in the ROM 12 in advance.

Further, the switching control means automatically switches from the second intermittent discharge control means (11, 12) which has been operated until the set control operation time Ts2 has elapsed to the normal intermittent discharge control means (11, 12). The switching means is formed of the CPU 11 and the ROM 12, and is executed in ST16 of FIG. The actual control operation time Ti is determined as follows.
From the time when the movement is completed (YES in ST12 of FIG. 2),
The CPU 11 counts with reference to the clock circuit 15.

Next, the operation of the first embodiment will be described.
Turn off the power switch 9S (Y in ST10 of FIG. 2).
ES), the CPU 11 sends a signal to the driver 4D to move the head 2 to the cap 7 (ST11, ST12).
YES). Then, the power lamp 9L is turned off (S
T13). Here, since the head 2 is covered with the cap 7, the CPU 11 refers to the clock circuit 15 and
i, Ti are counted.

Here, the second intermittent discharge control means (11,
In 12), a signal is sent to the driver 1D at each ejection interval ts2 shown in FIG. 3B (YES in ST14), and 100 pulses are supplied to each nozzle. Intermittent discharge control is repeatedly performed within the set control operation time Ts2 (ST
15, 16, ST17 YES). Therefore, when the cap 7 dries due to a large print amount in the previous print processing (ST21), or when the head 2 or the ink tank 3
Even if the temperature is high, the inside of the cap 7 can be sufficiently moistened or cooled so that the temperature does not rise any more. Therefore, the next printing process (ST21) can be performed with high image quality without missing dots.

When the setting control operation time Ts2 has elapsed (NO in ST16), the switching control means (11, 12)
Automatically switches to the normal intermittent discharge control means (11, 12). Therefore, until the power switch 9S is turned on (YES in ST20), the intermittent ejection control means (11,
12) is operated (ST18 to ST20). 7 pulses are supplied at each discharge interval ts1 shown in FIG.

The power switch 9S is turned on even before the set control operation time Ts2 has elapsed (YE in ST17).
S) and immediately enter the printing process (ST21).

According to the first embodiment, however, the second
Intermittent ejection control means (11, 12) and the control operation time setting means (14S) and switching control means (11, 12) is provided and, like the ink-jet head 1 is covered by a cap 7
State is first second intermittent discharge control means is large ink discharge amount per average unit of time (11, 12) a setting control operation time T
Since it is configured to operate within s2 and switch to the normal intermittent ejection control means (11, 12) having a small average amount of ink ejection per unit time after the elapse of the set control operation time Ts2, the printing amount by the previous printing process Even if the cap 7 is very dry and the cap 7 is very dry or the temperature of the head 2 and the ink tank 3 is increased due to excessively large amount, the cap 7 is sufficiently wetted or stopped. Since the subsequent temperature rise can be suppressed, the next printing process can be performed with high image quality without missing dots.

The second intermittent discharge control means (11, 1
2) discharge interval ts2 (ts21, ts2
2, ts23, ts24) and the ink discharge amount per operation (100 pulses) can be changed by key operation on the operation panel 14, and the control operation time Ts2 is also changed by the control operation time setting means (14S). Since it is possible, the most suitable operation for the printing mode can be performed, and the applicability is expanded.

(Second Embodiment) In the second embodiment, the control unit 10 is the same as that in the first embodiment (FIG. 1), and the printing amount detecting means (11, 12) and the corresponding ejection amount data A storage unit (13C) and an ink ejection amount selection unit (11, 12) are provided, and the average ink ejection amount per unit time of the intermittent ejection control unit (11, 12) is determined by the printing amount Q in the previous printing process.
It is formed so that increase / decrease is automatically selected by i.

That is, whether or not a dot is missing in the next printing process depends on whether or not the ink is prevented from being sufficiently and sufficiently dried by the ink drying prevention device (7). Means (11, 1
If the uniform ink ejection amount per unit time is fixedly determined in 2), inconvenience occurs depending on the print amount Qi in the previous print processing. Thus, in the second embodiment, the ink ejection amount is formed so as to be able to be automatically increased or decreased using the degree of the printing amount Qi as an index.

The print amount detecting means (11, 12) outputs the print amount (for example, the print amount during the previous print processing (ST38 in FIG. 4)).
The automatic detection of the total number of the dots ejected by the ink) is performed.
Executed in Specifically, the dot drive signal output to the driver 1D of the inkjet head 1 is counted.

The corresponding ejection amount data storage means 13C stores corresponding ejection amount data in which the printing amount Qi and the ink ejection amount per unit character time (Ni pulse energization) for each printing amount Qi are associated. As shown by a two-dot chain line in FIG. 1, the RAM 23 has a partial storage area (13C).

The corresponding ejection amount data is, for example, as shown in FIG.
As shown in (1) and (B2), when the ejection interval ts2 is fixed and the printing amount Q1 is larger than the average printing amount Q (Q1> Q), the ejection amount per one time within a predetermined time Ts3. Is energized for 100 pulses per nozzle, and energized for 10 pulses after the elapse of time Ts3. When the print amount (Q2) is a print amount Q2 that is much larger than the print amount Q1 (Q2> Q1), the time is longer than the time Ts3. Long time Ts4
In each case, the ejection amount (number of pulse energizations) Ni and the time T required for intermittent ink ejection with 200 pulse energization and 10 pulse energization after the elapse of time Ts4.
This is data in which si and each ejection interval tsi correspond to each print amount Qi.

Alternatively, without introducing the concept of time (Ts3, Ts4), for example, as shown in FIGS. 5 (C1) and (C2), the discharge intervals are set to ts21, ts21, ts
, Ts22,..., Ts26, ts26 are repeated twice, so that the ejection interval gradually becomes longer (for example, ts21 <Ts22), and the ink amount of each ink ejection is larger than the print amount Q3 (for example, ts21 <Ts22). When Q3> Q2), 100 pulses are applied, and a larger print amount Q4 (> Q
In the case of 3), the data may be set so that 200 pulses are applied.

Next, the ink discharge amount selecting means searches the corresponding discharge amount data storage means 13C and selects an ink discharge amount corresponding to the detected (read) print amount.
ST34 and 35 in FIG. 4 comprising PU11 and ROM12.
Executed in

According to the second embodiment having such a configuration, during the printing process (ST38 in FIG. 4), the printing amount detecting means (11, 1) is used.
2) detects the print amount Q1, and the CPU 11
3 is stored in the work area (ST39).

When the power switch 9S is turned off (YES in ST30), the head 2 is moved to the cap 7 (ST31). Then, the ink discharge amount selecting means (11, 12) operates to read the detected print amount Q1 (ST34) and to store the corresponding discharge amount data storage means 13C.
And the corresponding discharge amount data corresponding to the print amount Q1 [discharge interval ts2 in FIG. 5 (B1), discharge amount per one time (100 pulse application, 10 pulse application), time T
S3] is selected (SYT35).

Thus, the intermittent discharge control means (11, 1
In 2), ink ejection is controlled based on the automatically selected corresponding ejection amount data (ST36). That is, FIG.
As shown in (1), before the elapse of the time Ts3, 100 pulses are applied to each nozzle at each ejection interval ts2, and after that, the ejection amount is switched to 10 pulses while maintaining the same ejection interval ts2.

However, also in the case of the second embodiment, the first
In addition to the same operation and effect as in the embodiment, the ink ejection amount per average unit time is automatically selected according to the amount of printing Qi performed immediately before. Can be discharged efficiently.

[0041]

According to the first aspect of the present invention, the second intermittent ejection control means, the control operation time setting means, and the switching control means are provided, and the ink jet head is covered with the cap.
In first average unit time per ink ejection amount is larger second intermittent discharge control means set the control operation time in a worked and the average per unit time of the ink ejection amount is small normal intermittent discharge control after a set control operation time Means, the cap may be very dry or the head and ink tank may have risen in temperature due to an excessively long printing time due to the excessive printing amount in the previous printing process. Even if the cap is sufficiently moistened or the rise in temperature after stopping is suppressed, the next printing process can be performed with high image quality without missing dots.

According to the second aspect of the present invention, a print amount detecting means, a corresponding discharge amount data storage means, and an ink discharge amount selecting means are provided, and the average ink discharge amount per unit time of the intermittent discharge control means is determined first. Claims 1 and 2 are configured to be automatically selected to increase or decrease according to the amount of printing in the printing process.
In addition to the effects of the present invention, since the ink ejection amount per average unit time is automatically selected depending on the amount of printing performed immediately before, ink with no excess or shortage can be efficiently ejected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation.

FIG. 3 is a diagram for explaining an ink ejection operation.

FIG. 4 is a flowchart for explaining the operation of the second embodiment.

FIG. 5 is a view for explaining an ink ejection operation.

FIG. 6 is a diagram for explaining a conventional example.

FIG. 7 is a flowchart for explaining a conventional operation.

FIG. 8 is a diagram for explaining a conventional ink discharging operation.

[Explanation of symbols]

Reference Signs List 1 inkjet head 2 head 3 ink tank 4 sprocket 5 timing belt 6 platen 7 cap 9S power switch 10 control unit 11 CPU (intermittent discharge control means, second intermittent discharge control means, switching control means, print amount detection means, ink discharge 12 ROM (intermittent ejection control means, second intermittent ejection control means, switching control means, print quantity detection means, ink ejection quantity selection means) 13 RAM 13C corresponding ejection quantity data storage means 14 operation panel 14S setting key (Control operation time setting means) 15 Clock circuit

Claims (2)

(57) [Claims] 1. A cap for covering an inkjet head after printing, and an intermittent ejection control means for performing an intermittent ink ejection operation on the inkjet head covered with the cap so that an average amount of ink ejected per unit time is constant. In the ink jet printer provided with an ink drying prevention device comprising: an ink discharge amount larger than an average ink discharge amount per unit time by the intermittent discharge control means in a state where the ink jet head is covered with a cap. A second intermittent discharge control means for performing an intermittent ink discharge operation per hit, a control operation time setting means for setting a control operation time of the second intermittent discharge control means, and the second intermittent discharge control means after a lapse of the set control operation time. Switching control means for switching from the intermittent discharge control means to the intermittent discharge control means. Inkjet printer. 2. A cap for covering the inkjet head after printing, an intermittent ejection control means for intermittently ejecting an ink by a predetermined average amount of ink per unit time on the inkjet head covered with the cap. An ink jet printer equipped with an ink drying prevention device comprising: a print amount detecting means for detecting a print amount; and corresponding discharge amount data in which a print amount and an ink discharge amount per average unit time for each print amount are corresponded. Corresponding ejection amount data storage means for storing, and ink ejection for selecting an ink ejection amount per average unit time corresponding to a printing amount detected from the corresponding ejection amount data stored by searching the corresponding ejection amount data storage means. And an intermittent ejection control means for intermittently controlling the selected intermittent ejection amount per unit time. Jet printer, characterized in that the discharge operatively formed.