JP2001232780A - Ink jet type image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet type image forming apparatus capable of not only prolonging a lifetime of a print head but also shortening an output time. SOLUTION: A residue of an ink can be detected only when a temperature of the print head exceeds 60 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet type image forming apparatus for forming an image by discharging ink from a print head to a recording medium.

[0002]

2. Description of the Related Art As one of output devices of computers and workstations, there is known an ink jet type image forming apparatus which forms an image on a recording medium such as recording paper by discharging ink. The inkjet type image forming apparatus generally includes a print head having nozzles for discharging ink, a carriage mounted with the print head and reciprocating in the main scanning direction, and a carriage (sub-heading) orthogonal to the main scanning direction. A recording medium transport device that transports the recording medium in the scanning direction (the recording medium transport direction).

When an image is formed on a recording sheet, the recording sheet being conveyed by the recording medium conveying device is temporarily stopped, and the carriage is reciprocated in the main scanning direction. Ink is ejected from the nozzles to form an image for one band in a portion of the recording paper that is located in an image forming area facing the outlet (ink ejection port) of the nozzle. Thereafter, the paper is conveyed by the width of one band and stopped, and the ink is ejected from the nozzles based on the image signals while the carriage is reciprocated again in the main scanning direction. An image is formed on a newly located portion. By repeating such an operation, an image is formed on the recording paper.

A plurality of nozzles are formed in the above-described print head, and a heating element and a piezoelectric element are formed in each of the nozzles. When ejecting ink from the nozzles, an image signal (electric signal) is sent to a heating element or a piezoelectric element to drive them. In this case, if an electric signal is simultaneously sent to a large number of heating elements or piezoelectric elements to eject a large amount of ink at a time (high density printing is performed), the temperature of the print head may increase.

When a large amount of ink remains in the print head, the print head is cooled by the remaining ink, so that the print head does not become hot. However, when the remaining amount of ink in the print head is small, the print head may become hot, and the print head may be damaged. Further, when the ink is ejected in a state where the remaining amount of the ink in the print head is low, the ink may adhere to the ink ejection port of the nozzle, the heating element, the piezoelectric element, or the like, and may cause ejection failure.

Therefore, the number of dots during printing (the number of times of ink ejection) is counted, and based on the counted value, for example, when the value exceeds a predetermined value, the amount of ink remaining in the print head or ink tank is detected. In addition, damage to the print head and defective ejection are prevented.

[0007]

However, the process of counting the number of dots during printing takes a long time, and the time required for forming an image (output time) increases accordingly. Further, since the remaining amount of ink is detected based on the number of dots during printing, the remaining amount of ink is detected even if a large amount of ink remains. Therefore, extra time is required for that, and the output time becomes longer.

In view of the above circumstances, an object of the present invention is to provide an ink jet type image forming apparatus capable of shortening the output time.

[0009]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising:
In an ink jet type image forming apparatus for forming an image by ejecting ink from a print head storing ink to a recording medium, (1) a temperature measuring means for measuring a temperature of the print head; and (2) a temperature measuring means. And an ink remaining amount detecting means for detecting the remaining amount of ink stored in the print head only when the temperature measured by the printer exceeds a predetermined temperature.

According to a second aspect of the present invention, there is provided an inkjet image forming apparatus for forming an image by ejecting ink from a print head storing ink onto a recording medium. (3) temperature measurement means for measuring the temperature of the print head; and (4) printing which stops printing until the print head reaches a predetermined temperature or less when the print head finishes printing for the width thereof. Stopping means; and (5) an ink remaining amount detecting means for detecting a remaining amount of ink stored in the print head only when a time period during which printing is stopped by the printing stopping means exceeds a predetermined time. It is characterized by having.

Here, (6) the print head is capable of changing the amount of ink ejected at one time, and (7) the ink remaining amount detecting means is configured to detect the amount of ink ejected by the print head at one time. The predetermined time may be changed in accordance with the amount of the ink to detect the remaining amount of ink.

Further, in the above-mentioned ink jet type image forming apparatus, (8) when the ink remaining amount detecting means detects a remaining amount of ink equal to or less than a predetermined amount, control is performed so that ink is not ejected from the print head. Means may be provided.

Further, the above-mentioned ink jet type image forming apparatus may further comprise (9) a warning unit for giving a warning when the ink remaining amount detecting unit detects a remaining amount of ink equal to or less than a predetermined amount.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ink jet type image forming apparatus according to the present invention will be described with reference to the drawings.

Referring to FIG. 1, a plotter which is an example of the ink jet type image forming apparatus of the present invention will be described.

FIG. 1 is a perspective view showing a schematic configuration of the plotter.

The plotter 10 has a platen 14 on which the recording paper 12 conveyed in the direction of arrow A is placed. Above the platen 14, two scanning rails (guide rails) 16 are extended in parallel with the platen 14. The scanning rail 16 includes a motor (not shown)
The carriage 20 reciprocates in the directions of arrows B and C (in the direction perpendicular to the direction of arrow A) by means of the belt 18 and is mounted via a slide bearing (not shown).

The carriage 20 has four print heads 22K (black), 22C (cyan), 22M (magenta), and 22Y (yellow) having ink discharge ports (nozzle outlets, not shown) for discharging ink. ) Is installed. In front of the ink ejection port is an image forming area 23 where an image is formed. Ink is ejected from the ink ejection port to a portion of the recording paper 12 that is located in the image forming area 23, whereby an image is formed on this portion.

At a position on one side of the movable range of the carriage 20 away from the image forming area 23, ink is forcibly sucked from the nozzles to clean the ink supply paths and nozzles formed in the print head 22. A recovery device 30 is provided for setting the ink discharge state of the print head 22 to the initial discharge state.

In forming an image on the recording paper 12 such as roll paper, the recording paper 12 is placed on the platen 14 and a part of the outer peripheral surface is opened through an opening (not shown) formed in the platen 14. The recording paper 12 is rotated by a transport motor (not shown) while the recording paper 12 is pinched by a transport roller 24 exposing the recording paper 12 and a pinch roller 26 that presses both ends of the recording paper 12 from above. Transport. The carriage 20 is reciprocated in the directions of arrows B and C above the recording paper 12, and an image signal carrying image information transmitted from the head control unit 44 (see FIG. 2) to each of the print heads 22K, 22C, 22M and 22Y. The ink is ejected from the nozzles based on the above, and an image is formed on a portion of the recording paper 12 located in the image forming area 23. During the image forming operation, when it becomes necessary to suck ink from the nozzles in order to clean the nozzles and the like, the carriage 20 is moved above the recovery device 30. When the image formation is completed, the cutter (not shown) mounted on the carriage 20 is protruded to a predetermined position to cut the recording paper 12 into a predetermined size.

The recovery device 30 includes four print heads 22.
Four rubber caps 32K, 32 that removably cover the respective outlets of the nozzles K, 22C, 22M, 22Y.
C, 32M, and 32Y. Each cap 32K,
One end of a tube (not shown) is connected to 32C, 32M, and 32Y, and the other end of the tube is connected to a suction pump (not shown). Four caps 32
K, 32C, 32M, and 32Y are fixed to the cap base 32.

The control system of the plotter 10 will be described with reference to FIG.

FIG. 2 is a block diagram showing a part of the control system of the plotter.

The plotter 10 has a built-in general control unit 40 (an example of a control means according to the present invention and an example of a print stop means) for controlling various operations of the plotter 10. The general control unit 40 includes the recovery device 30 described above.
A recovery operation control unit 42 for controlling the movement of the operation (see FIG. 1);
And a head controller 44 for controlling the ink discharge state of each of the print heads 22K, 22C, 22M, and 22Y (see FIG. 1).

The general control unit 40 also controls a display unit 46 (an example of a warning unit according to the present invention) on which the operating status of the plotter 10 is displayed. Further, the plotter 10 has an ink detection sensor 48 for detecting the amount of ink remaining in the ink tank 52 (see FIG. 3) mounted on each of the print heads 22K, 22C, 22M, and 22Y (see FIG. 1).
Is built-in. A signal carrying the result detected by the ink detection sensor 48 is configured to be transmitted to the general control unit 40. When the detected ink amount is equal to or less than a predetermined amount, “replace the ink tank” or “ "No ink remaining" is displayed on the display unit 46. Note that “detecting the amount of ink remaining in the ink tank” means “detecting the remaining amount of ink stored in the print head”.

The print head 22 has a built-in head temperature sensor 50 (which is an example of a temperature measuring means according to the present invention) for measuring the internal temperature. A temperature signal carrying the temperature measured by the head temperature sensor 50 is sent to the general control unit 40. Based on this temperature signal, the integrated control unit 40 controls the ink detection sensor 4 as described later.
8, the head control unit 44, the display unit 46 and the like are controlled.

The structure of the carriage 20 and the print head 22 will be described with reference to FIG.

FIG. 3 is a schematic diagram showing a carriage on which a print head is mounted.

The print head 22 has a square hole 22a into which the boss 52a of the ink tank 52 is fitted, and a claw abutment 22b for fixing the ink tank 52. The ink tank 52 includes the ink tank 5.
An elastic claw 52b for fixing the print head 2 to the print head 22 is formed.

When the ink tank 52 is mounted on the print head 22, the boss 52 of the ink tank 52 is inserted into the square hole 22a.
a into the upper surface 52c of the ink tank 52 with the arrow A
Direction to engage the elastic claw 52b with the claw abutment 22b. Thus, the ink tank 52 is mounted on the print head 22.

When replacing the ink tank 52 mounted on the print head 22, the upper surface 52
c in the direction of arrow A (downward) to remove the boss 52a from the square hole 22a and to attach the elastic claw 52b to the claw abutting portion 22b.
To cancel. As a result, the ink tank 52 is removed from the print head 22.

The ink detection sensor 48 shown in FIG. The detection table 60 is disposed in a non-image forming area outside the image forming area 23. The ink tank 5 is located below the print head 22.
A hole (not shown) for detecting the remaining amount of ink in 2 is formed. When the carriage 20 passes by the side of the detection table 60, the amount of ink remaining in the ink tank 52 (the remaining amount of ink) can be optically detected by the ink detection sensor 48. However, the timing at which the ink detection sensor 48 detects the remaining amount of ink is determined based on the temperature of the print head 22. The timing of detecting the remaining amount of ink and the accompanying printing operation will be described with reference to FIG.

FIG. 4 is a flowchart showing a first example of the printing operation.

This flow starts when the print start button is pressed. When the print start button is pressed to start printing (S401), the temperature of the print head 22 starts to be measured by the head temperature sensor 50 (see FIG. 2). The general controller 40 determines whether or not the temperature measured by the head temperature sensor 50 has exceeded 60 ° C. (an example of the predetermined temperature according to the present invention) (S402). When it is determined that this temperature does not exceed 60 ° C. (when the temperature is 60 ° C. or less), it is determined whether or not printing has been completed (S).
406). If it is determined that the printing has not been completed, the printing operation is continued. On the other hand, when it is determined that the printing has been completed, this flow ends.

If it is determined that the temperature measured by the head temperature sensor 50 has exceeded 60 ° C., the ink tank 52
(See FIG. 3)
Is detected (ink residual detection operation) (S403), and the presence or absence of ink is determined (S404). When it is determined that the ink remains in the ink tank 52, the process proceeds to S406.

If it is determined in S404 that there is no ink in the ink tank 52 (no ink remains), the printing is forcibly stopped by the general controller 40 (S40).
5), this flow ends. Here, the continuation and stop of the printing operation are determined based on whether or not there is ink in the ink tank 52 based on whether or not there is ink in the ink tank 52. For example, an amount corresponding to 1%) may be set as the predetermined amount of ink.

As described above, the remaining amount of ink is detected only when the print head 22 exceeds a predetermined temperature (here, 60 ° C.). 22 is suppressed, the print head 2
When the temperature 2 is lower than the predetermined temperature, the remaining amount of the ink is not detected.
Therefore, since the number of times of detecting the remaining amount of ink can be reduced,
The time for forming an image (output time) can be shortened by the reduced time. In addition, when there is no ink remaining, printing is forcibly terminated, so that the life of the print head 22 can be extended without being damaged. Further, the image quality is improved because the print head 22 is not damaged.

A second example of the printing operation will be described with reference to FIG.

FIG. 5 is a flowchart showing a second example of the printing operation.

This flow starts when the print start button is pressed. When the print start button is pressed to start printing (S501), the temperature of the print head 22 starts to be measured by the head temperature sensor 50 (see FIG. 2). The general controller 40 determines whether or not the temperature measured by the head temperature sensor 50 has exceeded 45 ° C. (an example of the predetermined temperature according to the present invention) (S502). When it is determined that the temperature does not exceed 45 ° C. (when the temperature is 45 ° C. or less), it is determined whether or not printing has been completed (S
508). If it is determined that the printing has not been completed, the printing operation is continued. On the other hand, when it is determined that the printing has been completed, this flow ends.

When it is determined that the temperature measured by the head temperature sensor 50 has exceeded 45 ° C., printing is stopped and the time is started to be measured by the control of the general controller 40 (S503). Thereafter, it is determined whether the temperature of the print head 22 has fallen to 45 ° C. or less within 10 seconds (an example of the predetermined time according to the present invention) (S504).

When the temperature of the print head 22 becomes 45 ° C. or lower, printing is restarted (S509), and it is determined whether or not printing is completed (S510). If it is determined that the printing has not been completed, the printing operation is continued. On the other hand, when it is determined that the printing has been completed, this flow ends.

On the other hand, in S504, the temperature is set to 4 within 10 seconds.
If it is determined that the temperature does not fall below 5 ° C., the ink detection sensor 48 detects the remaining amount of ink in the ink tank 52 (see FIG. 3) (ink residual detection operation) (S505), and determines whether ink is present. Is performed (S506). Therefore, the remaining amount of ink is detected only when the time during which printing is stopped exceeds 10 seconds, and the presence or absence of ink is determined.

If it is determined that the ink remains in the ink tank 52, the process proceeds to S509. Ink tank 52
When it is determined that no ink remains in the printer, the printing is forcibly stopped by the general controller 40 (S50).
7), this flow ends.

As described above, the remaining amount of ink is detected only when the time during which the print head 22 exceeds the predetermined temperature (here, 45 ° C.) exceeds the predetermined time (here, 10 seconds). Otherwise, the remaining amount of ink is not detected.
Therefore, since the number of times of detecting the remaining amount of ink can be reduced,
The time for forming an image (output time) can be shortened by the reduced time. In addition, when there is no ink remaining, printing is forcibly terminated, so that the life of the print head 22 can be extended without being damaged. Further, the image quality is improved because the print head 22 is not damaged.

A third example of the printing operation will be described with reference to FIGS.

FIG. 6 is a flowchart showing a third example of the printing operation, and FIG. 7 is an enlarged view showing the nozzles of the print head used in the printing operation of the third example.

In the print head 122 used in the third example, two heating elements (heaters) 126 and 128 for discharging ink from the ink discharge ports 124 are formed. The heating element 126 generates less heat than the heating element 128, and the heating element 128 generates more heat than the heating element 126. Therefore, when comparing the amounts of ink ejected by the print head 122 at one time (one ejection),
When the heating element 128 generates heat, the amount of ink is larger than when the heating element 126 generates heat. Therefore, when it is desired to lower the image density, only the heating element 126 is heated to discharge ink. Conversely, when it is desired to increase the image density, the heating element 128 is heated to discharge ink.

As described above, the print head 122 used in the printing operation of the third example is formed with the two heat generating elements 126 and 128 having different heat values. Therefore, the amount of ink ejected by the print head 122 at one time differs depending on which of the two heating elements 126 and 128 generates heat. The flow shown in FIG. 6 is characterized in that a predetermined temperature serving as a trigger is changed and the remaining ink amount is detected in accordance with the amount of ink ejected from the print head 122 at one time.

The flow shown in FIG. 6 is started when the print start button is pressed. When the print start button is pressed to start printing (S601), the head temperature sensor 5
By 0 (see FIG. 2), the temperature of the print head 122 also starts to be measured. In the general control unit 40, the head temperature sensor 5
It is determined whether the temperature measured at 0 has exceeded 45 ° C. (an example of the predetermined temperature according to the present invention) (S60).
2). When it is determined that the temperature does not exceed 45 ° C. (when the temperature is 45 ° C. or less), it is determined whether or not the printing is completed (S609). If it is determined that the printing has not been completed, the printing operation is continued. On the other hand, when it is determined that the printing has been completed, this flow ends.

When it is determined that the temperature measured by the head temperature sensor 50 exceeds 45 ° C., it is determined whether or not the heating element 126 is generating heat (S603). When it is determined that the heating element 126 does not generate heat, the heating element 128 generates heat.

When it is determined that the heating element 126 is generating heat, the temperature measured by the head temperature sensor 50 becomes four.
It is determined whether the time exceeding 5 ° C. has continued for 10 seconds (exceeding 10 seconds) (S604). On the other hand, when it is determined that the heating element 128 is generating heat, the time when the temperature measured by the head temperature sensor 50 exceeds 45 ° C.
It is determined whether or not it has continued for two seconds (S605). The reason for determining which of the two heat generating elements 126 and 128 is generating heat is to change the predetermined time according to the amount of ink that the print head 122 discharges at one time.

If it is determined in S604 that the time when the head temperature exceeds 45 ° C. is shorter than 10 seconds, printing is restarted (S610), and it is determined whether or not printing is completed (S611). If it is determined that the printing has not been completed, the printing operation is continued. On the other hand, when it is determined that the printing has been completed, this flow ends.

On the other hand, in S604, the above time is 10
If it is determined that the time has exceeded the second,
(See FIG. 3)
Is detected (ink residual detection operation) (S606), and the presence or absence of ink is determined (S607). Therefore, the remaining amount of ink is detected only when the time during which printing is stopped exceeds 10 seconds, and the presence or absence of ink is determined.

If it is determined that the ink remains in the ink tank 52, the process proceeds to S610. Ink tank 52
If it is determined that no ink remains in the printer, the printing is forcibly stopped by the general controller 40 (S60).
8), this flow ends. If it is determined in step S603 that the heating element 128 is generating heat, the process proceeds to step S603.
Proceeding to 605, it is determined whether the time when the head temperature exceeded 45 ° C. exceeded 6 seconds. If it is determined that this time is equal to or shorter than 6 seconds, the process proceeds to S609. On the other hand, if it is determined that this time exceeds 6 seconds, the process proceeds to S606, proceeds to S607 in the same manner as described above, and proceeds to S608.

As described above, the temperature used as a trigger for detecting the remaining amount of ink is changed in accordance with the amount of ink ejected by the print head 122 at one time. Can be changed and output time can be further shortened. In addition, when there is no ink remaining, printing is forcibly terminated, so that the life of the print head 122 can be extended without being damaged. Further, the image quality is improved because the print head 122 is not damaged.

In the above example, the predetermined time serving as a trigger for detecting the remaining amount of ink is changed according to the amount of ink ejected by the print head 122 at one time. However, when the print head 122 ejects ink so as to form an image for one band in a plurality of times, the predetermined time may be changed according to the number of times.

[0058]

As described above, according to the first image forming apparatus of the present invention, the remaining amount of ink in the print head is detected only when the print head exceeds a predetermined temperature. When the temperature of the head is equal to or lower than the predetermined temperature, the remaining amount of ink in the print head is not detected. Accordingly, since the number of times of detecting the remaining amount of ink can be reduced, the time for forming an image (output time) can be shortened by the reduced time.

According to the second ink jet type image forming apparatus of the present invention, the remaining amount of ink in the print head is detected only when the print stop time exceeds a predetermined time. If the time is less than the time, the remaining amount of ink in the print head is not detected. Therefore, the number of times of detecting the remaining amount of ink can be reduced, and the time for forming an image (output time) can be shortened by the reduced time.

Here, the print head is capable of changing the amount of ink ejected at one time, and the ink remaining amount detecting means is adapted to change the amount of ink ejected at one time by the print head. If the predetermined time is changed to detect the remaining amount of ink, the above-described predetermined time can be changed according to the amount of ink ejected by the print head at one time. And the output time can be further shortened.

Further, when the ink remaining amount detecting means detects a remaining amount of ink equal to or less than a predetermined amount, if there is provided control means for controlling not to discharge ink from the printing head, damage to the printing head may be prevented. It can be prevented more reliably.

Furthermore, if the ink remaining amount detecting means is provided with a warning means for warning when the ink remaining amount is less than a predetermined amount, the ink can be replenished or the print head can be replaced in accordance with the warning. The print head can be more reliably prevented from being damaged.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a plotter which is an example of an inkjet type image forming apparatus of the present invention.

FIG. 2 is a block diagram showing a part of a control system of the plotter of FIG.

FIG. 3 is a schematic diagram showing a carriage on which the print head of the plotter of FIG. 1 is mounted.

FIG. 4 is a flowchart illustrating a first example of a printing operation.

FIG. 5 is a flowchart illustrating a second example of a printing operation.

FIG. 6 is a flowchart showing a third example of the printing operation.

FIG. 7 is an enlarged view showing nozzles of a print head used in the printing operation of the third example of FIG.

[Explanation of symbols]

 Reference Signs List 10 plotter 20 carriage 22K, 22C, 22M, 22Y print head 40 general control unit 44 head control unit 46 display unit 48 ink detection sensor 50 head temperature sensor 126, 128 heating element

Claims (5)

[Claims] 1. An ink jet type image forming apparatus for forming an image by ejecting ink from a print head storing ink to a recording medium, comprising: a temperature measuring means for measuring a temperature of the print head; An ink jet type image forming apparatus, comprising: an ink remaining amount detecting unit that detects a remaining amount of ink stored in the print head only when the measured temperature exceeds a predetermined temperature. 2. An ink jet image forming apparatus for forming an image by ejecting ink from a print head in which ink is stored to a recording medium, wherein a temperature measuring means for measuring a temperature of the print head; When the printing of the width is completed, the printing head stops printing until the temperature of the print head becomes equal to or lower than a predetermined temperature, and only when the time during which printing is stopped by the printing stop means exceeds a predetermined time, An ink-jet type image forming apparatus comprising: an ink remaining amount detecting unit for detecting a remaining amount of ink stored in the print head. 3. The print head is capable of changing the amount of ink ejected at one time, and the ink remaining amount detecting means is configured to change the predetermined amount according to the amount of ink ejected by the print head at one time. 3. The ink jet type image forming apparatus according to claim 2, wherein the remaining amount of ink is detected by changing a time. 4. A printing apparatus according to claim 1, further comprising control means for controlling not to eject ink from said print head when said ink remaining amount detecting means detects an ink remaining amount equal to or less than a predetermined amount. 4. An inkjet image forming apparatus according to claim 1, 2, or 3. 5. The apparatus according to claim 1, further comprising a warning unit that warns when the remaining ink amount detecting unit detects a remaining amount of ink equal to or less than a predetermined amount. The inkjet type image forming apparatus of the above.