Patent Grant
8882235
This application claims priority from Japanese Patent Application No. 2012-105792 filed on May 7, 2012, which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an image recording apparatus in which a liquid is discharged from a discharge port onto a recording medium.
2. Description of Related Art
In known printers which have been developed to reduce ink bleed of dots formed on a sheet, a pretreatment liquid is applied to target areas in advance of application of ink to agglomerate or precipitate pigments contained in the ink.
In such known printers, when an image forming region is jammed with sheets, the pretreatment liquid applied onto the sheets increasingly adheres to a side surface of an ink discharging head, and the adhered pretreatment liquid transfers to a discharge surface and contacts the ink. In addition, even when sheet jams did not occur, a surface of a sheet onto which the pretreatment liquid has been applied contacts the discharge surface, which brings the pretreatment liquid into contact with ink on the discharge surface. In such a case, agglomerated or precipitated pigments of the ink partially or entirely close the discharge port, which significantly reduces ink discharge properties. Similarly in printers having a plurality of heads for discharging different color inks, an ink applied onto a sheet in advance adheres to a side surface or discharge surface of a head for discharging a different color ink causing a reduction in the quality of images due to color mixture.
It is an object of the present invention to provide an image recording apparatus which is configured to perform a head recovery operation.
According to an embodiment of the present invention, an image recording apparatus comprising: a liquid applying mechanism configured to apply a first liquid onto a recording medium; a liquid discharge head comprising a liquid discharge surface and configured to discharge a second liquid from a liquid discharge port formed in the liquid discharge surface onto the recording medium, wherein the liquid discharge head is disposed downstream from the liquid applying mechanism in a transport direction of the recording medium; a wiper configured to wipe the liquid discharge surface of the liquid discharge head: a recording medium sensor disposed downstream from the liquid discharged head in the transport direction and configured to detect a presence of the recording medium: a processor; and a computer readable medium storing computer readable instructions. The computer readable instructions, when executed by the processor, cause the image recording apparatus to perform: determining a jam of a recording medium onto which the first liquid has been applied by the liquid applying mechanism based on a detection of the recording medium sensor; counting a number of jams determined; determining a passage of a recording medium through a region facing the liquid discharge head; counting a number of passages determined; incrementing the number of jams when the number of passages is equal to or greater than a first threshold value; and performing a head recovery operation in which the liquid discharge head discharges the second liquid through the liquid discharge port and the wiper wipes the discharge surface when a jam of a recording medium is determined and when the number of jams is incremented.
Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings.
For a more complete understanding of the present invention, needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawings.
Example embodiments are described in detail herein with reference to the accompanying drawings, like reference numerals being used for like corresponding parts in the various drawings.
Referring to
The space A may hold the two heads 10, a transport unit 21 for transporting sheet P, a guide unit for guiding the sheet P, a humidifying mechanism 50, which may perform a humidifying process, e.g.,
Based on the image dada sent from an external device, the controller 1p may control a transport operation of the sheet P by the components of the printer 1, an ink discharge operation in conjunction with the transport of the sheet P, and a maintenance operation for recovering and maintaining ink discharge function. The maintenance operation may include a flushing process, a purging process, a wiping process, and a humidifying process. The flushing process may include a discharge of ink from all or part of discharge ports 14a formed in discharge surfaces 10a of the heads 10 when actuators corresponding to the appropriate discharge ports 14a are driven. Ink droplets may be discharged from the discharge ports 14a in a predetermined number based on flushing data, e.g., data different from image data. The purging process may include a discharge of ink from all of the discharge ports 14a when a purging pump 69, e.g.,
The transport unit 21 may comprise a platen 9 and two pairs of transport nip rollers 5 and 6. The two pairs of transport nip rollers 5 and 6 may be disposed at the two sides in a transport direction, respectively, with the platen 9 disposed therebetween. Each pair of the transport nip roller 5 and 6 may comprise two rollers and may transport the sheet P in the transport direction while the sheet P is vertically pinched. The pair of transport nip rollers 5 may transport the sheet P onto the upper surface of the platen 9. The pair of transport nip rollers 6 may transport the sheet P from the upper surface of the platen 9 to the sheet discharge portion 31.
The platen 9 may be disposed so as to face the discharge surfaces 10a at a predetermined distance during printing and may constitute a portion of the paper transport path. Referring to
Each of the heads 10 may be a line scan head with a substantially rectangular shape extending in a main scanning direction. The lower surface of each head 10 may function as the discharge surface 10a, e.g., liquid discharge surface, having the multiple discharge ports 14a, e.g.,
The pre-coating liquid may comprise cationic polymers and multivalent metal salts, e.g., magnesium salt, and may react with colorants of ink to generate insoluble or poorly soluble metal complexes. The pre-coating liquid may react with a pigment ink to agglomerate a pigment. The pre-coating liquid may react with a dye ink to precipitate a dye. Hence, ink bleed may be prevented. In addition, ink may be less likely to permeate the sheet P, which may increase the fixability of the ink to a surface of the sheet P. The quality of images can be thus enhanced.
Each of the two heads 10 may be held by the housing 1a via a head holder 3. Each discharge surface 10a may face the platen 9 or the glass table 8 with a gap interposed therebetween at a predetermined distance. The head holder 3 may comprise an annular cap 40 and a pair of joints 51 for each head 10. The term “sub-scanning direction” herein may refer to a direction parallel to a direction in which the sheet P is transported by the transport unit 21, and the term “main scanning direction” herein may refer to a direction parallel to a horizontal plane and orthogonal to the sub-scanning direction.
The head holder 3 may be moved up and down by a holder lift mechanism having a holder lift motor 68, e.g.,
The guide unit may be provided in parallel with the paper transfer path and may have two sections with the transport unit 21 interposed therebetween. An upstream-side guide section may comprise two guides 27a and 27b and a pair of feed rollers 26. The upstream-side guide section may connect a sheet feed unit 1b to the transport unit 21. A downstream-side guide section may comprise two guides 29a and 29b and two pairs of feed rollers 28. The downstream-side guide section may connect the transport unit 21 to the sheet discharge portion 31.
The space B may hold the sheet feed unit 1b. The sheet feed unit 1b may include a tray 23 and a roller 25, and the tray 23 may be detachable from the housing 1a. The tray 23 may have a box shape and may open upward. The tray 23 may accommodate the sheet P of various sizes. The roller 25 may feed the topmost sheet P in the tray 23 and transport the sheet P to the upstream-side guide section.
The sheet transport path may be provided in the spaces A and B so as to extend from the sheet feed unit 1b to the sheet discharge portion 31 through the transport unit 21. In response to a printing command input from an external device, the controller 1p may drive a sheet feed motor for the roller 25, feed motors for the feed rollers of the guide sections, and a transport motor. The sheet P fed from the tray 23 may be transported to the transport unit 21 by the feed rollers 26. The pre-coating liquid and ink may be discharged in sequence while the sheet P passes immediately below the heads 10 in the sub-scanning direction, so that images may be formed on the sheet P. Then, the sheet P may be transported upward by the two pairs of feed rollers 28. The sheet P may subsequently be discharged from an opening 30 formed at the top of the housing 1a onto the sheet discharge portion 31.
The space C may hold an ink unit 1c provided so as to be detachable from the housing 1a. The ink unit 1c may include a cartridge tray 35, two cartridges 39 disposed alongside in the cartridge tray 35, and a water tank 54, e.g.,
Referring to
The channel unit 12 may have a layered structure of nine metallic plates 12a to 12i provided in sequence, as illustrated in
The actuator units 17 may be disposed in a staggered pattern of two rows so as not to overlap the openings 12y. The actuator units 17 may have unimorph-type actuators for the corresponding discharge ports 14a so as to cover the corresponding pressure chambers 16. Each unimorph-type actuator may include multiple stacked piezoelectric layers, an electrode provided on the outermost surface of the actuator and facing the pressure chamber 16, and a common electrode with the outermost layer interposed between the electrode and the common electrode.
The reservoir unit 11 may have an internal ink channel including a reservoir. The reservoir temporarily may hold ink supplied from the cartridges 39. The reservoir unit 11 may have an uneven lower surface with a protrusion and a hollow. In the protrusion, one end of the ink channel may open and be in communication with the opening 12y of the channel unit 12. The hollow may form a gap with the upper surface 12x. The actuator units 17 may be provided in this gap such that a small space may be formed between the hollow and each actuator unit 17.
In the circuit board, a variety of driving signals sent from the controller 1p may be processed and then output to the actuators via the driver IC. The output of the driving signals may enable the actuators to change the volumes of the corresponding pressure chambers 16, so that liquid droplets may be discharged from the corresponding discharge ports 14a.
Referring to
The pair of joints 51 may be closely provided at the two ends of the head 10 in the main scanning direction. In the humidifying process, as illustrated in
Each cap 40 may include an elastic body 41 and a movable portion 42 which may move up and down. The elastic body 41 may be formed from an elastic material, such as rubber, and may include four parts, e.g., base part 41x, protruding part 41a, fixing part 41c, and connecting part 41d, as illustrated in
The fixing part 41c may have a T-shaped cross-sectional structure. The flat upper surface of the fixing part 41c may be bonded to the head holder 3 to surround the entire head 10, e.g., discharge surface 10a. The fixing part 41c is partially pinched by the head holder 3 and the joint 51, e.g., base portion 51x, in the vicinity of the through-hole 3a. The connecting part 41d may connect the fixing part 41c positioned at the inner side to the base part 41x positioned at the outer side. The connecting part 41d may extend therebetween while curving. The curve of the connecting part 41d may enable the base part 41x to be moved up and down by the movable portion 42. The protruding part (lip) 41a may project from the lower surface of the base part 41x in a tapered manner and may have a triangular cross-sectional surface. The base part 41x may have a recess 41b formed in the upper surface thereof, and the recess 41b may couple to the lower end of the movable portion 42.
The movable portion 42 may have an annular metallic component and may be moved in a vertical direction relative to the head holder 3. The movable portion 42 may connected to a lip lift motor 44, e.g.,
Referring to
One end of the tube 55, e.g., end of the branched portion 55b, may be attached to one of the joints 51, e.g., left side in
The tank 54 may hold water in its lower space and humidified air in its upper space. The tube 56 may be connected to the tank 54 at a level lower than the surface of water held in the tank 54, e.g., lower space, and the tube 57 may be connected to the tank 54 at a level higher than the surface of water held in the tank 54, e.g., upper space. The tube 56 may have a check valve which may enable air to flow only in a direction indicated by arrows as shown in
Referring to
As illustrated in
The controller 1p may include a central processing unit (CPU), e.g., a processor, a nonvolatile memory, e.g., a computer readable medium, which may store a program executed by the CPU and data used in the program in a rewritable manner, and a random access memory (RAM) which may temporarily store data at the execution of the program. In each functional section of the controller 1p, such hardware and the software stored in the nonvolatile memory may be in cooperation with each other. Referring to
The actuator units 17 may be controlled by the head control unit 71 in an image forming process and the flushing process. In the image forming process, droplets of each liquid, e.g., ink droplets and pre-coating liquid droplets, may be discharged based on image data. The discharge of liquid droplets may be performed in conjunction with transport of the sheet P at a predetermined moment determined by signals output from a sheet sensor (tip detection signal). In the flushing process, droplets of each liquid may be discharged based on flushing data.
The jam detector 73 may receive detection signals output from the multiple jam detection sensors 81, e.g., a recording medium sensor, provided along the sheet transport path. Two jam detection sensors 81 may be provided at positions immediately upstream and downstream of the two heads 10 in the sheet transport path, respectively. Each jam detection sensor 81 may detect the tip of the transported sheet P and then outputs the detection signal to the jam detector 73 of the controller 1p. When the jam detector 73 does not receive the signal at a predetermined time interval depending on a relationship of the distance between the two sensors 81 with a transport speed of the sheet P, the jam detector 73 may determine that a sheet jam has occurred between the start of discharge of the pre-coating liquid to the sheet P and the passage of this sheet P through a region facing the head 10(K). In this case, the sheet jam may cause the pre-coating liquid to adhere to a side surface of the head 10(K). The jam detection sensor 81 positioned on the upstream side of the sheet transport path also may function as a sheet sensor, and a timing for the discharge of liquid droplets may be determined based on signals output from the sheet sensor, which may detect the tip of a sheet.
The jam counter 74 may count the number of times of sheet jams when the jam detector 73 detects a problematic sheet jam. When a jam purging procedure is performed, the jam counter 74 may reset the cumulative number of times of sheet jams to zero.
The passage counter 75 may count the number of sheets P which have passed below the head 10(K) after completion of the latest recovery operation. The number to be counted may be referred to as “sheet passage”.
The application amount counter 76 may count the total amount of the pre-coating liquid applied, e.g., discharged, to the sheets P which have passed below the head 10(K) after completion of the latest recovery operation.
The elapsed time counter 77 may count time from detection of a sheet jam by the jam detector 73 to removal of a sheet P concerning the sheet jam from the sheet transport path. The elapsed time counter 77 may determine that the sheet P concerning the sheet jam has been removed from the sheet transport path when closing of a maintenance cover is detected after jam detection sensor 81 detects no sheet P.
When the jam detector 73 detects a sheet jam and then a sheet P concerning the sheet jam is removed from the sheet transport path, the elapsed time corrector 78 may correct elapsed time based on results of detection by a humidity detection sensor 82 provided in the vicinity of the heads 10 and the elapsed time measured by the elapsed time counter 77. If detected humidity is larger than reference humidity, the elapsed time corrector 78 may perform the correction such that the elapsed time may be decreased in proportion to an increase in a difference between the detected humidity and the reference humidity. If detected humidity is smaller than reference humidity, the elapsed time corrector 78 may perform the correction such that the elapsed time may be increased in proportion to an increase in a difference between the detected humidity and the reference humidity. The correction performed in this manner may enhance a correlation of an increase in the viscosity of a liquid adhering to the heads 10 with the elapsed time. The detected humidity may be the average of results of the humidity detection per unit time.
In particular, the correction of elapsed time may be performed as follows: six threshold values may be determined to define five humidity regions (0 to 20%, 21 to 40%, 41 to 60%, 61 to 80%, and 81 to 100%); if detected humidity is larger than humidity of a reference region to which reference humidity belongs, e.g., 21 to 40%, elapsed time may be corrected such that the elapsed time may be decreased in proportion to an increase in a difference in the humidity between the reference region and a detection region to which the detected humidity belongs; and if detected humidity is smaller than humidity of the reference region, elapsed time may be corrected such that the elapsed time may be increased in proportion to an increase in a difference in the humidity between the reference region and a detection region. Such correction of elapsed time based on the humidity regions may enable easy correction of elapsed time. Each humidity region may have the same humidity range, or at least two humidity regions may have different humidity ranges. The number of the humidity regions may be arbitrarily determined as long as at least two humidity regions are provided.
The jam count corrector 79 may perform correction to increase the number of times of sheet jams counted by the jam counter 74 every time the sheet passage counted by the passage counter 75 exceeds a predetermined threshold value, e.g., first threshold value: 100 sheets in the present embodiment. Furthermore, the jam count corrector 79 may perform correction to increase the number of times of sheet jams counted by the jam counter 74 every time the total application amount of ink counted by the application amount counter 76 exceeds a predetermined threshold value, e.g., third threshold value: 100 ml.
The maintenance control unit 72 may be configured to control the holder lift motor 68, the heads 10 via the head control unit 71, the purge pump 69, the wiper moving motor 63, the lip lift motor 44, the pump 53 of the humidifying mechanism 50, and the reversal mechanism 7 to carry out the flushing process, purging process, wiping process, and humidifying process included in the maintenance operation.
The flushing process may be performed immediately before the start of printing and at a regular time interval after the start of the printing. In the flushing process, the actuator units 17 of the heads 10 may be driven by the maintenance control unit 72 to force liquid droplets to be discharged from the discharge ports 14a. The liquid droplets may be discharged onto the glass table 8 or the sheet P during a printing process. In the latter case, the liquid droplets may be discharged in the minimum amount, e.g., 4 pl, so as to avoid image pixels in view of the quality of an image.
The purging process may be performed after a sheet P, which has caused a sheet jam, is removed from the sheet transport path or immediately before the start of printing. At the start of the purging process, the holder lift motor 68 may be controlled by the maintenance control unit 72 to move the heads 10 to a safe position, and then the reversal mechanism 7 may be controlled by the maintenance control unit 72 to introduce the glass table 8 to a position facing the discharge surfaces 10a. The purge pump 69 may subsequently be controlled by the maintenance control unit 72 to pump a liquid, e.g., ink or pre-coating liquid, to the heads 10. The liquid may be forced to be discharged from the discharge ports 14a. The waste liquid may be retrieved to a waste fluid tank via the glass table 8.
The wiping process may be performed after the flushing process or the purging process. As illustrated in
When the sheet transport path is jammed with the sheet P, e.g., when the jam detector 73 detects a sheet jam caused by the sheet P, the maintenance control unit 72 may perform a recovery operation including a sequence of the purging process and wiping process after the sheet P is removed by users. A combination and frequencies of the purging process and wiping process in the recovery operation may be determined, as illustrated in
After removal of a sheet which has caused a sheet jam, the normal purging procedure may generally be employed as the recovery operation. In the purging process, a liquid of approximately 2 ml may be forced to be discharged from all discharge ports 14a. The jam purging procedure may be performed when a jam count corrected by the jam count corrector 79 reaches a predetermined threshold value, e.g., second threshold value: three times; two combinations of the purging process and the wiping process may be performed in addition to the normal purging procedure. In the second and third purging processes, an amount of a liquid to be discharged may be smaller than that in the first purging process, e.g., approximately 1 ml. Furthermore, in proportion to the decrease in the amount of the liquid forced to be discharged, the speed of the wiping by the wiper 61, e.g., movement speed of the wiper 61, may be decreased in the second and third wiping processes relative to that in the first wiping process. An increase in the frequency of the purging process may correspond to a decrease in the speed of wiping.
When a jam count corrected by the jam count corrector 79 reaches three, the frequencies of the purging process and wiping process may be increased in the recovery operation as compared with the other case.
When the elapsed time corrected by the elapsed time corrector 78 is less than a predetermined threshold value, e.g., fourth threshold value: four hours, the maintenance control unit 72 may perform the recovery operation without the humidifying process; when the elapsed time corrected by the elapsed time corrector 78 is not less than four hours, the maintenance control unit 72 may perform the recovery operation after the humidifying process.
If the sheet P, to which the pre-coating liquid has been applied, causes a sheet jam before the sheet P completely passes across the head 10(K), the pre-coating liquid may adhere to the upstream-side surface of the head 10(K). If the sheet jam occurs several times, accumulation of an adhering pre-coating liquid and spread of such a pre-coating liquid to the discharge surface 10a may cause defective discharge. The jam purging procedure may be performed once every three times of removal of sheets, which have caused sheet jams. Thus, problems caused by the spread of the pre-coating liquid may be prevented.
The humidifying process may include humidification of the discharge space S1 being in a capped state, e.g., sealed state, and may start after completion of printing or removal of a sheet which has caused a sheet jam. During the humidifying process, the heads 10 may be located at the printing position. In addition, the glass table 8 may be positioned so as to face the discharge surfaces 10a by the reversal mechanism 7.
At the beginning of the humidifying process, the maintenance control unit 72 may move the movable portion 42 down with the rotation of the gears 43. Then, the protruding part 41a may be moved from the separation position for printing, e.g.,
The pump 53 may be driven by the maintenance control unit 72 to circulate the humidified air. Once the pump 53 is driven, air may be retrieved from the opening 51a, and humidified air may be supplied from the opening 51b to the discharge space S1. The retrieved air may travel to the lower space inside the tank 54 through the tubes 55 and 56. The retrieved air may be humidified with water stored in the lower space and then held in the upper space of the tank 54. The humidified air held in the upper space may have a humidity of approximately 100%. The humidified air in the upper space may be output to the opening 51b through the tube 57. The pump 53 may be stopped by the maintenance control unit 72 in a predetermined time period. The humidified air may be supplied to humidify ink inside the caps 40, which may prevent an increase in the viscosity of ink in the discharge ports 14a. Furthermore, agglomerate generated on the discharge surfaces 10a may also be humidified, which may enable easy removal thereof through the wiping process.
In
Referring to
The jam detector 73 may determine whether the sheet P has caused a sheet jam at S106. When the jam detector 73 determines that a sheet jam occurs, e.g., YES at S106, the maintenance control unit 72 may wait until the sheet P which has caused the sheet jam is removed by users, e.g., NO at S107, after the jam counter 74 increases the jam count by one. The elapsed time counter 77 may start to count elapsed time from detection of the sheet jam. The elapsed time may continued to be counted until removal of the sheet concerning the sheet jam. During this step, the elapsed time corrector 78 may sample an output from the humidity detection sensor 82 for every unit time and calculate average humidity, e.g., detected humidity. After removal of the sheet which has caused the sheet jam, e.g., YES at S107, when the detected humidity is larger than reference humidity, the elapsed time corrector 78 may perform correction such that the elapsed time may be decreased in proportion to an increase in a difference between the detected humidity and the reference humidity; or when the detected humidity is less than the reference humidity, the elapsed time corrector 78 may perform the correction such that the elapsed time may be increased in proportion to an increase in a difference between the detected humidity and the reference humidity at S108. Then, the maintenance control unit 72 may determine whether the elapsed time is greater than or equal to four hours at S109.
When the maintenance control unit 72 determines that the elapsed time is greater than or equal to four hours, e.g., YES at S109, the humidifying process may be performed at S110, and then the jam purging procedure, as illustrated in
When the jam detector 73 determines that the sheet P does not cause a sheet jam, e.g., NO at S106, the maintenance control unit 72 may determine whether a jam count has been corrected to an extent exceeding the unit number of times depending on the passage of sheet P and the amount of ink applied to the sheet P at S116. When the degree of the correction, e.g., total increased number, is greater than or equal to the unit number of times, e.g., one, the procedure may go to S111; and when the degree of the correction is less than the unit number of times, the procedure may return to S101. After S111 and S101, the procedure may advance as described above.
In the printer 1, the recovery operation may be performed in view of both direct adhesion of the pre-coating liquid to the discharge surface 10a of the head 10(K) due to sheet jams and accumulation of the pre-coating liquid on a side surface of the head 10(K) due to the passage of the sheet P. This may enable efficient elimination of a reaction of the pre-coating liquid with ink in the vicinity of the discharge ports 14a, so that a decrease in discharge properties due to such a reaction may be efficiently prevented.
When a jam count corrected by the jam count corrector 79 is greater than or equal to three, the jam purging procedure may be performed in the recovery operation; thus, the frequencies of the purging process and wiping process to be carried out may be greater than those in the normal purging procedure, which may enable further steady removal of the pre-coating liquid remaining on the head 10(P) and products derived from the pre-coating liquid.
In the jam purging procedure, the amount of liquid to be discharged from all discharge ports 14a may be gradually decreased as the sequence of the purging processes advances, which may prevent an increase in the amount of the liquid used in the purging process. In addition, the discharge surfaces 10a may be wet due to the purging process before the wiping process, which may prevent damage of the discharge surfaces 10a through the wiping process.
In the second and third wiping processes in the jam purging procedure, the wiper 61 may move at a speed less than that in the first wiping process, so that the discharge surfaces 10a may be efficiently wiped while damage of the discharge surfaces 10a may be prevented.
Because a jam count is corrected based on the total application amount of the pre-coating liquid, the recovery operation may be performed at an appropriate moment depending on the frequency of discharge of the pre-coating liquid.
When elapsed time corrected by the elapsed time corrector 78 is less than four hours, only the recovery operation may be performed without the humidifying process; and when the elapsed time corrected by the elapsed time corrector 78 is greater than or equal to four hours, the recovery operation may be performed after the humidifying process. Because the elapsed time corrector 78 corrects elapsed time based on detected humidity, the recovery operation may be adequately performed depending on the elapsed time from the occurrence of a sheet jam.
In this case, the average results of the humidity detection may be employed as the detected humidity, which may enable easy control for the correction of elapsed time.
Each cap 40 may cover the discharge surface 10a and part of a side surface of the head 10, so that the pre-coating liquid remaining on a side surface of the head 10(K) may be prevented from drying and then adhering thereto.
In this case, the humidifying process may steadily prevent the pre-coating liquid remaining on a side surface of the head 10(K) from drying and then adhering thereto.
The upper surface of the wiper 61 may be tilted such that an end on the upstream side in the sheet transport direction may have the greater height in a direction orthogonal to the discharge surface 10a during the wiping process. The pre-coating liquid on a passing sheet P may likely accumulate on the upstream side surface of the head 10(K); thus, the pre-coating liquid spreading to the discharge surface 10a may be efficiently removed.
Each cap 40 may cover the entire discharge surface 10a of the corresponding one of the heads 10. In another embodiment, as shown in
In addition to accumulation of the pre-coating liquid on a side surface of the head 10(K) due to sheet jams and sheet passage, ink transferred through the wiping process in each purging procedure may accumulate on the side surface of the head 10(K). In this case, an increase in the viscosity of the ink and drying of a product generated by a reaction of the ink with the pre-coating liquid may quickly advance. Agglomerate generated on the side surface due to sheet jams may be therefore less likely to spread onto the discharge surface 100a. For example, S111 in
In a structure for the humidifying process, an inlet and outlet of humidified air may be provided to the cap 240 or may be provide to the head 10.
The recovery operation may be performed in view of both the amount of the pre-coating liquid adhering to a side surface of the head 10(K) due to sheet jams and the amount of the pre-coating liquid adhering to the head 10(K) due to the passage of the sheet P; thus, the pre-coating liquid may be efficiently prevented from transferring to the vicinity of the discharge ports 14a by, for instance, a sheet jam caused later.
Because the cap 240 covers a part of the discharge surface 10a, a size of the capping mechanism may be reduced.
In the jam purging procedure of the recovery operation, the purging process and the wiping process may be performed in the same number of times. In another embodiment, the number of times of the wiping process may be greater than that of the purging process. As illustrated in
The jam purging procedure may be performed when a jam count reaches three. In another embodiment, the jam purging procedure may be performed in response to another jam count. The jam count may be reset to zero every time after the jam purging procedure. In another embodiment, the jam count may not be reset to zero. In this case, multiple threshold values may be defined to determine whether the jam purging procedure should be carried out. In such multiple threshold values, the minimum value may be at least two, and a difference between one threshold value and the next threshold value may be at least two.
A combination of the purging process and the wiping process may be performed several times. In another embodiment, at least part of the second and subsequent purging processes may not be performed in the jam purging procedure.
A discharge amount of a liquid may be gradually decreased as the sequence of purging processes advances. In another embodiment, the liquid may be discharged in an arbitrary amount in the purging processes of the jam purging procedure. The amount of a liquid may be sequentially increased as the sequence of purging processes advances.
The moving speed of the wiper 61 in the second and third wiping processes may be less than that in the first wiping process. In another embodiment, the wiper 61 may move at various speeds in each wiping process in the jam purging procedure. The moving speed of the wiper 61 may be kept at a certain level as the sequence of wiping processes advances.
The average of results of humidity detection may be employed as the detected humidity. In another embodiment, the result of humidity detection immediately after removal of a sheet which has caused a sheet jam may be directly employed.
The upper surface of the wiper 61 may be tilted such that an end on the upstream side in the sheet transport direction has a greater height in a direction orthogonal to the discharge surface 10a during the wiping process. In another embodiment, the upper surface of the wiper may be, for instance, parallel to the discharge surfaces 10a.
The printer 1 of the first embodiment may have the two heads 10. In another embodiment, the printer may have three or more heads 10.
The head 10 which discharges the pre-coating liquid may be positioned on the most upstream side in the sheet transfer direction. In another embodiment, the head 10 disposed at such a position may discharge ink droplets, or the pre-coating liquid may be applied with, for instance, a roller.
While the invention has been described in connection with various exemplary structures and illustrative embodiments, it will be understood by those skilled in the art that other variations and modifications of the structures, configurations, and embodiments disclosed above may be made without departing from the scope of the invention. For example, this application comprises possible combinations of the various elements and features disclosed herein, and the particular elements and features presented in the claims and disclosed above may be combined with each other in other ways within the scope of the application, such that the application should be recognized as also directed to other embodiments comprising other possible combinations. Other structures, configurations, and embodiments consistent with the scope of the claimed invention will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples are illustrative with the true scope of the invention being defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-105792 | May 2012 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 8104868 | Taira | Jan 2012 | B2 |
| 20090289985 | Sumida et al. | Nov 2009 | A1 |
| 20120127231 | Nukui | May 2012 | A1 |
| 20130076826 | Nukui | Mar 2013 | A1 |
| Number | Date | Country |
|---|---|---|
| 2003-165230 | Jun 2003 | JP |
| 2009-279777 | Dec 2009 | JP |
| 2011-178053 | Sep 2011 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20130293622 A1 | Nov 2013 | US |
