Patent Application
20180354260
One disclosed aspect of the embodiments relates to a recording apparatus and a recording method.
Recording apparatuses which record images on recording mediums using a recording head including a plurality of discharge ports through which ink is discharged are known. In such a recording apparatus, ink is discharged from the recording head at predetermined timings while the recording head or recording medium is moved so that the ink is applied onto the recording medium.
In the above-described recording apparatuses, the discharge speed of ink from the recording head can decrease due to ink concentration, etc. If the discharge speed decreases, the effect of the movement speed of the recording head or recording medium becomes relatively large, so that the ink can land onto a position deviated from an ideal position onto which the ink is supposed to land. In response thereto, Japanese Patent Application Laid-Open No. 2007-144966 discusses a technique for adjusting the timing to discharge ink for each nozzle based on driving pause intervals in a case in which the discharge speed changes depending on the driving pause intervals.
Meanwhile, recording apparatuses including circulation channels such as those discussed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2014-531349 have been known in recent years. The vicinities of discharge ports are in communication with the outside through the circulation channels, and ink is circulated between the vicinities of the discharge ports and the outside thereof to prevent the discharge ports from being clogged.
When a recording apparatus including circulation channels is used, even if ink is concentrated in the vicinities of discharge ports as a result of moisture evaporation in ink, the concentrated ink is sent outside through the circulation channel, so that the discharged ink is able to maintain a relatively low concentration.
However, the ink sent outside continues to be circulated in the circulation channels to cause the ink to be gradually concentrated in the circulation channels. Consequently, the concentration of the ink in the circulation channels increases over time, which causes a gradual increase in the concentration of the ink supplied to the vicinities of the discharge ports. An increase in the ink concentration can lead to a change in the discharge speed. In such a case, the landing position of the ink gradually deviates from the originally-determined ideal position.
The technique discussed in Japanese Patent Application Laid-Open No. 2007-144966 uses the driving pause intervals as an index to correct deviations of the ink landing positions, but what is calculable from the driving pause intervals is only an amount of change in the concentration until a recovery from a pause in the driving. Specifically, the technique discussed in Japanese Patent Application Laid-Open No. 2007-144966 is not capable of acquiring the level of ink concentration in the circulation channels which is caused by the circulation described above. Thus, the technique discussed in Japanese Patent Application Laid-Open No. 2007-144966 is not capable of suitably correcting deviations of the landing positions of the ink which are caused by ink concentration in the circulation channels.
The disclosure is directed to a technique for suitably correcting deviations of landing positions of ink which are caused by ink concentration in circulation channels.
According to an aspect of the embodiments, a recording apparatus includes a recording head, a circulation channel, a concentration acquisition unit, an adjustment unit, and a control unit. The recording head includes a plurality of discharge ports through which ink is discharged and a pressure chamber being in communication with the plurality of discharge ports. The circulation channel is in communication with the pressure chamber to circulate the ink between the pressure chamber and an external portion thereof so that the ink is supplied to and collected from the pressure chamber. The concentration acquisition unit is configured to acquire concentration information about an ink concentration in the circulation channel. The adjustment unit is configured to adjust a timing to discharge the ink based on the concentration information. The control unit is configured to control a recording operation of recording by discharging the ink from the recording head such that the ink is discharged at the timing adjusted by the adjustment unit.
Further features of the disclosure will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
A first exemplary embodiment will be described below.
A recording medium P fed from a sheet feeding portion 101 is conveyed in a positive X-direction (sheet conveyance direction, intersection direction) at a predetermined speed while being sandwiched by a pair of sheet conveyance rollers 103 and 104, and then the recording medium P is ejected to a sheet ejection portion 102. Between the sheet conveyance roller 103 located on the upstream side and the sheet conveyance roller 104 located on the downstream side are aligned recording heads 105 to 108 along the sheet conveyance direction, and the recording heads 105 to 108 discharge ink in a positive Z-direction according to recording data. The recording heads 105, 106, 107, and 108 discharge cyan, magenta, yellow, and black inks, respectively.
In the present exemplary embodiment, the recording medium P can be a continuous sheet stored in a roll shape in the sheet feeding portion 101 or a cut sheet which is cut in advance into a standard size. In the case in which the recording medium P is a continuous sheet, the recording medium P is cut into a predetermined length by a cutter 109 after the end of a recording operation by the recording heads 105 to 108 and then sorted by size and ejected onto a sheet ejection tray by the sheet ejection portion 102.
As illustrated in
As apparent from
In the discharge port array 22, a plurality of discharge ports for discharging the cyan ink is aligned in the Y-direction. In each discharge port of the discharge port array 22 is disposed a recording element (not illustrated). The recording elements are used to perform a discharge operation in which a driving pulse is applied to each of the recording elements to drive the recording elements so that the recording elements generate heat energy to cause the ink to foam and discharge the ink from the discharge ports. Hereinafter, a row of the recording elements in the respective discharge ports of the discharge port array 22 is also referred to as a recording element array.
Further, the sub-heater 23 is a member which heats the ink in the vicinities of the recording elements in the heater board HB0 to an extent that the ink is not discharged. Further, the temperature sensor 24 is a member which detects the temperature near the recording elements in the heater board HB0. In the present exemplary embodiment, the sub-heater 23 is driven with different driving intensities based on the temperature detected by the temperature sensor 24 during and before recording to adjust the ink temperature to a desired temperature. Details thereof will be described below.
While the heater board HB0 including therein one sub-heater 23 and one temperature sensor 24 is described above, the heater board HB0 can include therein a plurality of sub-heaters 23 and a plurality of temperature sensors 24.
As illustrated in
As illustrated in
In the front side of the discharge port forming member 18 are formed the discharge ports 12. Further, in the discharge port forming member 18 are formed the pressure chambers 13 in communication with the discharge ports 12.
On the front side (side closer to the discharge port forming member 18) of the substrate 19 are disposed the recording elements 11 described above, and a common ink supply path 16 and a common ink collection path 17 are formed in the substrate 19. Further, the ink supply openings 14 are formed to connect the common ink supply path 16 with the pressure chambers 13 in the discharge port forming member 18, and the ink collection openings 15 are formed to connect the common ink collection path 17 with the pressure chambers 13 in the discharge port forming member 18.
The common ink supply path 16 and the common ink collection path 17 are formed over the range in the Y-direction in which the discharge ports 12 are aligned. Further, control is performed to generate a negative pressure difference between the common ink supply path 16 and the common ink collection path 17 as described below. Thus, while the ink is discharged from some of the discharge ports 12 by a recording operation, the negative pressure difference causes the ink in the common ink supply path 16 to flow through the ink supply openings 14, the pressure chambers 13, and the ink collection openings 15 and then into the common ink collection path 17 (a dotted arrow in
Further, the support member 20 functions as a cover which constitutes a part of walls of the common ink supply path 16 and the common ink collection path 17 in the substrate 19.
The recording head 105 is fluidically connected with the first circulation pump (P2) 1001 on the high-pressure side, the second circulation pump (P3) 1002 on the low-pressure side, and the main tank (ink tank) 1003 which stores the ink. The main tank 1003 is capable of ejecting foam contained in the ink to the outside thereof through an air communication port (not illustrated) which communicates the inside and the outside of the main tank 1003 with each other. The ink in the main tank 1003 is consumed through image recording/recovery processing (including preliminary discharge, suction ejection, and pressure ejection), and when the main tank 1003 becomes empty, the main tank 1003 is removed from the recording apparatus and replaced.
As described above, each of the plurality of heater boards HB0 to HB14 in the recording head 105 includes the common ink supply path 16 and the common ink collection path 17, and the plurality of pressure chambers 13 are formed between the common ink supply path 16 and the common ink collection path 17 to be in communication with the common ink supply path 16 and the common ink collection path 17 through the ink supply opening 14 and the ink collection opening 15. While
The first circulation pump 1001 pumps the ink contained in the common ink supply path 16 and returns the ink to the main tank 1003 through a connection portion 111a of the negative pressure control unit 230 and an outlet 211b of the recording head 105. The second circulation pump 1002 pumps the ink contained in the common ink collection path 17 and returns the ink to the main tank 1003 through a connection portion 111b of the negative pressure control unit 230 and an outlet 212b of the recording head 105. The first circulation pump 1001 and the second circulation pump 1002 are desirably positive displacement pumps capable of transferring liquid quantitatively. Specific examples include tube pumps, gear pumps, diaphragm pumps, and syringe pumps. Alternatively, a commonly-used constant-flow valve or relief valve can be provided at an outlet of a pump to ensure a constant flow.
While the recording head 105 is driven, the first circulation pump 1001 and the second circulation pump 1002 respectively pass a constant amount of ink to the common ink supply path 16 and the common ink collection path 17 in the direction of an arrow A (supply direction) and the direction of an arrow B (collection direction) in
The negative pressure control unit 230 is disposed on the flow path between the third circulation pump (P1) 1004 and the recording head 105. The negative pressure control unit 230 has the function of maintaining the pressure of the ink on the recording head 105 side constant even when the ink flow rate in the ink circulation system is changed according to the concentration (discharge amount) of an image to be recorded. The negative pressure control unit 230 includes two pressure adjustment mechanisms 230a and 230b, and any mechanisms capable of controlling the pressure in the flow path located on the downstream side of the pressure adjustment mechanisms 230a and 230b within a predetermined range with a desired set pressure being the center can be used. For example, a mechanism similar to a vacuum regulator can be employed. In the case of using a vacuum regulator, desirably a pressure is applied to the inside of the flow path located on the upstream side of the negative pressure control unit 230 by the third circulation pump 1004 through an ink supply unit 220 as illustrated in
Respectively different control pressures are set to the two pressure adjustment mechanisms 230a and 230b of the negative pressure control unit 230. The pressure adjustment mechanism 230a which is set to a relatively high pressure is denoted by “H” in
The inlet 211a of the common ink supply path 16 is connected with the high-pressure-side pressure adjustment mechanism 230a, and the inlet 212a of the common ink collection path 17 is coupled with the low-pressure-side pressure adjustment mechanism 230b, so that a negative pressure difference occurs between the common ink supply path 16 and the common ink collection path 17. Thus, some of the ink flowing in the directions of the arrows A and B in the common ink supply path 16 and the common ink collection path 17 flows in the direction of an arrow C through the ink supply openings 14, the pressure chambers 13, and the ink collection openings 15.
As described above, the ink flows in the directions of the arrows A and B in the common ink supply paths 16 and the common ink collection paths 17 in the heater boards HB0 to HB14 in the recording head 105. Thus, heat generated in the heater boards HB0 to HB14 is ejected outside by the flow of the ink in the common ink supply path 16 and the common ink collection path 17. Further, the above-described structure makes it possible to prevent the ink from thickening in the discharge ports 12 and the pressure chambers 13 by causing the ink to flow also in the direction of the arrow C in the discharge ports 12 and the pressure chambers 13 from which no ink is discharged during the recording operation.
As illustrated in
Then, the controller 304 includes a recording data generation unit 305, a central processing unit (CPU) 306, a discharge timing generation unit 307, a temperature value storage memory 308, a heating table storage memory 314, and data transfer units 310 to 313.
The CPU 306 reads a program stored in the ROM 303 and executes the program to control entire operations of the recording apparatus, e.g., an operation of driving drivers such as motors. Further, the ROM 303 stores fixed data necessary for various operations of the recording apparatus as well as various control programs to be executed by the CPU 306. For example, the ROM 303 stores a program for executing recording control in the recording apparatus.
The DRAM 302 is needed for the CPU 306 to execute a program. The DRAM 302 is used as a work area of the CPU 306 or as a temporary storage area for various types of received data and stores various types of setting data. While only one DRAM 302 is illustrated in
The recording data generation unit 305 receives image data from a host (personal computer (PC)) outside the recording apparatus. The recording data generation unit 305 performs color conversion processing, quantization processing, etc. on the image data to generate recording data for use in discharging ink from the recording heads 105 to 108 and stores the recording data in the DRAM 302.
The discharge timing generation unit 307 receives position information indicating the relative positions of the respective recording heads 105 to 108 and the recording medium P which are detected by the encoder sensor 301. The discharge timing generation unit 307 generates discharge timing information indicating timings of discharges from the respective recording heads 105 to 108 based on the position information. Details of the generation of the discharge timing information will be described below.
The four data transfer units 310 to 313 read the recording data stored in the DRAM 302 in synchronization with the discharge timings generated by the discharge timing generation unit 307. Further, the data transfer units 310 to 313 generate heating information defining heating conditions of the respective heater boards HB0 to HB14 based on the temperature information about the respective heater boards HB0 to HB14 of the recording heads 105 to 108 which is stored in the temperature value storage memory 308 and a table stored in the heating table storage memory 314. Then, the data transfer units 310 to 313 transfer the recording data and the heating information to the respectively corresponding recording heads 105 to 108.
Then, while performing various heating operations based on the heating information, the recording heads 105 to 108 drive the recording elements based on the recording data to discharge the ink. At this time, temperatures detected by the temperature sensors 24 of the heater boards HB0 to HB14 in the recording heads 105 to 108 are output to a heating control unit 309 in the recording apparatus. Then, the heating control unit 309 stores temperature information about the newly-detected temperatures in the temperature value storage memory 308 and updates the temperature information. The updated temperature information is used at the next heating information generation timing.
In the case of using a recording apparatus including circulation channels as illustrated in
Thus, in the present exemplary embodiment, the ink concentrations in the circulation channels are estimated, and a correction value for use to correct deviations of ink landing positions is determined based on the estimated ink concentrations. In the present exemplary embodiment, information about the amounts of ink evaporation in the circulation channels, information about the amounts of ink consumption in the circulation channels, and information about the initial amounts of ink in the circulation channels are acquired (evaporation amount acquisition, consumption amount acquisition, initial amount acquisition), and the ink concentrations in the circulation channels are acquired (concentration acquisition) based on the acquired information.
The following processing is performed for each ink color. To simplify descriptions, only the processing for one ink color will be described below.
In the present exemplary embodiment, first, an evaporation amount Vx during recording operation and an evaporation amount Vy during a non-recording operation are calculated and then added up to obtain a total evaporation amount V (Vx+Vy). In the present exemplary embodiment, the processing of calculating the evaporation amounts Vx and Vy is performed to calculate the evaporation amount V before and after the processing of updating the ink concentrations in the circulation channels (N(x)→N(x+1)), which will be described below.
First, a non-discharge ratio Hx, an evaporation rate Zx, and a recording time Tx are calculated for each ink color to calculate the evaporation amounts Vx during recording operation with respect to the respective ink colors.
If recording start information is received, the process of calculating the evaporation amount Vx during recording is started. First, in step S1, a count (dot count) of the number of discharges of the inks of the respective colors in a page is performed based on the recording data for use in recording to calculate an ink dot count Dx.
Then, in step S2, the non-discharge ratio Hx is calculated for each ink color. The non-discharge ratio Hx corresponds to the ratio of pixels not discharging ink with respect to pixels capable of discharging ink. Specifically, a case in which each color is fully discharged is set as 1, and a value obtained by subtracting the dot count Dx from a dot count Da in the case of the full discharge and dividing the obtained value by the dot count Da in the case of the full discharge is determined as the non-discharge ratio Hx. In the present exemplary embodiment, the non-discharge ratio Hx is calculated for each ink color.
Next, in step S3, processing is performed to refer to the ink evaporation rate Zx. The evaporation amount per second is measured in advance, and the measured evaporation amount is stored as the evaporation rate Zx in the heating table storage memory 314. The values of the evaporation rate Zx are higher at higher temperatures because evaporation is more likely to occur at higher temperatures. Table 1 shows details of the evaporation rate Zx in the present exemplary embodiment. In the case in which the heater board temperature is lower than 25 degrees Celsius, the evaporation rate is expressed by Zx=μg/sec. In the case in which the heater board temperature is 25 degrees Celsius or higher and lower than 40 degrees Celsius, the evaporation rate is expressed by Zx=150 μg/sec. In the case in which the heater board temperature is 40 degrees Celsius or higher, the evaporation rate is expressed by Zx=420 μg/sec.
Next, in step S4, the recording time Tx necessary for recording one page is calculated. Specifically, the recording time Tx is calculated by dividing the length of one page by the sheet conveyance speed.
Then, in step S5, the evaporation amount Vx during recording operation is calculated. Specifically, the non-discharge ratio Hx, the evaporation rate Zx, and the recording time Tx are multiplied together to calculate an evaporation amount in one page. Then, similar processing is performed on each page to calculate the evaporation amount Vx during recording operation.
Next, an evaporation rate Zy and an elapsed time Ty of the non-recording operation are calculated to calculate for each ink color the evaporation amount Vy during the non-recording operation.
If the process of calculating the evaporation amount Vy during non-recording is started, then in step S11, processing is performed to refer to the evaporation rate Zy of each ink color. The evaporation rate Zy during non-recording per minute is measured in advance, and the measured evaporation amount is stored in the heating table storage memory 314. Further, the values of the evaporation rate Zy are higher at higher temperatures because evaporation is more likely to occur at higher temperatures.
During non-recording operation, the discharge ports 12 of the recording heads 105 to 108 are covered with a cap member, so that the evaporation rate per elapsed time is lower than that during recording operation. Table 2 shows details of the evaporation rate Zy in the present exemplary embodiment. In the case in which the heater board temperature is lower than 15 degrees Celsius, the evaporation rate is expressed by Zy=1 μg/min. In the case in which the heater board temperature is 15 degrees Celsius or higher and lower than 25 degrees Celsius, the evaporation rate is expressed by Zy=2 μg/min. In the case in which the heater board temperature is 25 degrees Celsius or higher, the evaporation rate is expressed by Zy=5 μg/min.
Next, in step S12, the elapsed time Ty during non-recording operation is calculated.
Then, in step 13, the evaporation amount Vy during the non-recording operation is calculated. Specifically, the evaporation rate Zy and the elapsed time Ty are multiplied to calculate the evaporation amount Vy during non-recording operation, and the process is ended.
The evaporation amount Vx during recording operation and the evaporation amount Vy during non-recording operation which are calculated as described above are added to calculate the total evaporation amount V.
Next, an ink consumption amount In during recording operation and during non-recording operation is calculated.
If the process of calculating the ink consumption amount is started, then in step S21, whether a recording instruction is given is determined. If no recording instruction is given (NO in step S21), the processing proceeds to step S24 described below. On the other hand, if a recording instruction is given (YES in step S21), the processing proceeds to step S22. In step S22, processing is performed to refer to an ink consumption amount which is acquired from a dot count, etc. and used during recording, and the ink consumption amount during recording is calculated. In step S23, after the calculation, the calculated consumption amount is added to the ink consumption amount In.
Then, in step S24, whether a recovery instruction is given is determined. If no recovery instruction is given (NO in step S24), the process of calculating the ink consumption amount In is ended. On the other hand, if a recovery instruction is given (YES in step S24), the processing proceeds to step S25. In step S25, processing is performed to refer to a recovery use amount stored in advance in the memory. Then in step S26, the recovery use amount is added to the ink consumption amount In. Thereafter, the process of calculating the ink consumption amount In is ended.
As described above, in the present exemplary embodiment, each time a recording instruction or a recovery instruction is given, the ink consumption amount or the recovery use amount is added to the ink consumption amount In to manage the ink consumption amount in the circulation channels.
In the present exemplary embodiment, the ink concentration in the circulation channels is calculated using the evaporation amount V and the ink consumption amount In which are calculated as described above.
If the process of calculating the concentration is started, then in step S31, whether a recording instruction is given is determined. If no recording instruction is given (NO in step S31), the process is ended. On the other hand, if a recording instruction is given (YES in step S31), the processing proceeds to step S32. In step S32, a concentration N(x) which is already calculated in the previous concentration calculation processing is read. The initial values Nref of the concentrations of the inks used in the present exemplary embodiment are as shown in Table 3.
Next, in step S33, whether the recording operation is ended is determined. If the recording operation is not ended (NO in step S33), the processing returns, and the determination of whether the recording operation is ended is repeated until the recording operation is ended. On the other hand, if the recording operation is ended (YES in step S33), the processing proceeds to step S34. In step S34, processing is performed to refer to the evaporation amount V, the ink consumption amount In during recording operation, and the ink consumption amount In during recovery operation which are calculated as described above, and the initial values J of the ink amounts in the circulation channels. The initial values J of the ink amounts in the circulation channels are values determined in advance according to the shape of the circulation channels, ink, etc. In the present exemplary embodiment, the initial values J of the ink amounts in the circulation channel are as shown in Table 4.
Then, in step S35, the concentrations N(x+1) after recording/recovery operation are calculated based on the evaporation amounts V before and after recording/recovery operation, the ink consumption amounts In during recording/recovery operation, the initial values J of the ink amounts in the circulation channels, and the concentrations N(x) before recording/recovery operation. The evaporation amount V and the ink consumption amount In each correspond to the amount from the time of calculation of the concentration N(x) before recording/recovery operation to the time of calculation of the concentration N (x+1) after recording/recovery operation.
A method for deriving the concentration N (x+1) will be described below. In the following description, the ink amount in the circulation channels before recording/recovery operation is denoted by J(x).
The amount of pigment existing in the circulation channels prior to recording/recovery operation is expressed as N(x)×J(x), where N(x) denotes the concentration and J(x) denotes the ink amount.
Further, after recording/recovery operation, the ink is lost by an amount In through recording/recovery operation and by an amount V through evaporation, compared to the ink before recording/recovery operation, so that the ink amount is expressed as J(x)−In−V. Further, the concentration after recording/recovery operation is expressed as N (x+1), so that the amount of pigment existing in the circulation channels after recording/recovery operation is expressed as N (x+1)×(J(x)−In −V).
Further, the pigment is also contained in the ink discharged during recording/recovery operation. This amount is expressed as N(x)×In, as the concentration is N(x) and the ink consumption amount is In.
Since the pigment does not evaporate, the ink amount V lost through evaporation does not contain the pigment.
Thus, the sum of the amount of pigment existing in the circulation channels after recording/recovery operation and the amount of pigment lost through discharges during recording/recovery operation is equal to the amount of pigment existing in the circulation channels before recording/recovery operation. Accordingly, formula 1 below is derived.
N(x+1)×(J(x)−In−V)+N(x)×In=N(x)×J(x) formula 1
From formula 1, the following formula 2 for calculating the concentration N (x+1) in the circulation channels after recording/recovery operation is obtained.
N(x+1)=N(x)×(J(x)−In)/(J(x)−In−V) formula 2
The value of J(x) is significantly larger than the values of In and V, so that the item J(x) can be approximated to the initial value J of the ink amount. Accordingly, formula 3 below is derived.
N(x+1)=N(x)×(J−In)/(J−In−V) formula 3
In the present exemplary embodiment, the concentration N (x+1) after recording/recovery operation is calculated based on formula 3 described above.
Thereafter, in step S36, the current concentration N(x) is updated to N (x+1), and the process is ended.
While the concentration N (x+1) is calculated using formula 3 in the present exemplary embodiment, the concentration N (x+1) can also be calculated using formula 2 in which J(x) is not approximated. In this case, although the ink amount J(x) in the circulation channels before recording/recovery operation needs to be calculated separately, since no approximation is involved, the concentration N (x+1) is calculated more accurately.
In the present exemplary embodiment, the ink discharge timings are adjusted based on the ink concentration in the circulation channels which is obtained as described above. In the present exemplary embodiment, even if the concentration of some of the ink is increased, the discharge timings are adjusted such that the inks of the respective colors land in ideal positions, and control is performed to cause the inks of the respective colors to land onto the same positions.
Further, while
To cause the ink to land in an ideal position 400 on the recording medium P in the X-direction, the recording head 105 discharges the ink with a positional relationship in that the recording head 105 is located in a position 402 deviated from the ideal position 400 in the positive X-direction. The discharge is performed at a timing before the timing at which the recording head 105 and the ideal position 400 have a positional relationship facing each other. An ink drop discharged from the recording head 105 is discharged in the direction of the vector sum of the discharge speed Ve and the movement speed Vm. The ink discharge timing corresponding to the position 402 is preset such that an ink drop discharged in the direction of such a vector sum lands in the ideal position 400.
In this case, if the ink is discharged in the positional relationship in that the recording head 105 is located above the position 402 as in
The reason is as follows. As a result of the decrease in the ink discharge speed Ve′, the direction of the vector sum of the discharge speed Ve′ and the movement speed Vm which is the direction in which the ink is discharged is changed. In the case in which the concentration is increased which is illustrated in
In the present exemplary embodiment, when the concentration in the circulation channels is increased, the ink discharge timing is adjusted to be earlier than that in the case in which the concentration is not increased. Details thereof will be described below.
In the present exemplary embodiment, in the case in which the concentration in the circulation channels is increased, the ink is discharged at an earlier timing than the timing at which the ink is discharged in the case in which the concentration is not increased (timing at which the recording head 105 corresponds to the position 402 on the recording medium P). Specifically, as illustrated in
As described above, even in the case in which the concentration in the circulation channels is increased, it is possible to reduce a deviation of the landing position of the ink by adjusting the ink discharge timing to an earlier timing than that in the case in which the concentration is not increased.
In view of the above-described points, the discharge timing adjustment is performed according to the concentration in the circulation channels in the present exemplary embodiment.
If the process of adjusting a discharge timing is started, then in step S41, information indicating the concentration N (x+1) calculated as described above is acquired.
Next, in step S42, the timing to discharge each ink is adjusted based on the concentration information. In the discharge timing adjustment in step S42, a table which defines the correspondence relationship between the concentrations and the discharge timings as illustrated in
Thereafter, the process of adjusting a discharge timing is ended.
In the present exemplary embodiment, a reference timing is stored for each ink in the memory. The reference timing is set such that each ink lands in an ideal position and the landing positions of the respective inks are aligned unless there is a change in the concentration, and a specific value of the timing is preset at the time of the manufacture of the recording apparatus, etc.
Furthermore, if the concentration N (x+1) calculated for each ink according to the flowchart in
On the other hand, in the case in which the concentration N (x+1) is not lower than the predetermined threshold value, the discharge timing adjustment value is set to “−1”, i.e., the discharge timing is adjusted to an earlier timing than the reference timing. The reason is as follows. As the concentration decreases, the discharge speed also decreases, and the ink is discharged at an earlier timing than the reference timing as illustrated in
In the present exemplary embodiment, various methods are applicable as a specific method of adjusting the ink discharge timing.
For example, the recording apparatus in the present exemplary embodiment applies the same driving pulse to the plurality of recording elements forming the recording element array to discharge the ink. In view of this point, the ink discharge timing can be adjusted to an earlier timing by performing control to temporally shift the timing to apply the driving pulse to an earlier timing.
Further, the recording apparatus in the present exemplary embodiment discharges the ink according to recording data which specifies that the ink is to be discharged or not to be discharged with respect to each pixel sectioned by each column (raster) extending in the X-direction and each row (column) extending in the Y-direction. In view of this point, it is possible to adjust the ink discharge timing to an earlier timing by performing control to offset the recording data in the negative X-direction.
As described above, the ink discharge timing is adjustable to an earlier timing by performing control to shift the timing to apply the driving pulse or control to offset the recording data in the present exemplary embodiment.
As illustrated in
The reference timing is adjusted such that no deviation of the ink landing position occurs if the ink has the original concentration and is discharged at the reference timing. Thus, not the absolute value of the concentration but the amount of change in the concentration from the original concentration needs to be used to determine the level of a decrease in the discharge speed caused by an increase in the concentration. Since the original concentration of the black ink is higher than those of the other inks, when the inks are compared when they reach the same concentration, the amount of change in the concentration of the black ink is smaller than those of the other inks. Thus, the predetermined threshold value for the black ink is set greater than those for the other inks to cancel the effect of the original concentration which is high.
While whether to perform the discharge timing adjustment is determined using the absolute value of the concentration in the present exemplary embodiment, the amount of change from the original concentration can be calculated to perform the discharge timing adjustment using the calculated amount of change.
As described above, the present exemplary embodiment makes it possible to prevent a deviation of the ink landing position by adjusting the ink discharge timing according to the concentration in the circulation channels even in the case in which the concentration increases in the circulation channels and a deviation of the ink landing position can occur.
A second exemplary embodiment will be described below. In the first exemplary embodiment described above, an example in which the ink discharge timing is adjusted to prevent a deviation of the ink landing position which is caused by an increase in the ink concentration in the circulation channels is described.
In the present exemplary embodiment, on the other hand, the form will be described below in which the distance between the recording head and the recording medium (hereinafter, also referred to as “head-to-medium distance”) is adjusted to prevent a deviation of the ink landing position which is caused by an increase in the ink concentration in the circulation channels. Specifically, control is performed such that the head-to-medium distance is adjusted to enable the inks of the respective colors to land in ideal positions even when the concentrations of some of the inks are increased so that the inks of the respective colors land onto the same position.
Description of those that are similar to those in the first exemplary embodiment described above is omitted.
In the present exemplary embodiment, the recording heads 105 to 108 are attached to the recording apparatus such that each of the recording heads 105 to 108 is individually movable in the Z-direction.
At this time, the recording head 105 is positioned at a position 404 in the Z-direction. The reason is that an ink drop discharged at the position 404 can land in the ideal position 400 if the ink is discharged in the direction of the vector sum of the discharge speed Ve and the movement speed Vm.
In this case, if the ink is discharged from the recording head 105 in the position 404 the same as that in
In the present exemplary embodiment, when the concentration in the circulation channels is increased, the head-to-medium distance is adjusted to lower the position of the recording head 105 in the Z-direction (move the position of the recording head 105 in the positive Z-direction) such that the head-to-medium distance becomes shorter than that in the case in which the concentration is not increased.
In the present exemplary embodiment, as illustrated in
As described above, even in the case in which the concentration in the circulation channels is increased, a deviation of the ink landing position can be also reduced by reducing the head-to-medium distance to a shorter distance than that in the case in which the concentration is not increased.
In view of the above-described aspects, the head-to-medium distance is adjusted according to the concentration in the circulation channels in the present exemplary embodiment.
If the process of adjusting the head-to-medium distance is started, then in step S51, information indicating the concentration N (x+1) calculated as described above is acquired.
Next, in step S52, the head-to-medium distance of each of the recording heads corresponding to the respective inks is adjusted based on the concentration information. In the head-to-medium distance adjustment in step S52, a table which defines the correspondence relationship between the concentrations and the head-to-medium distances as illustrated in
Thereafter, the process of adjusting the head-to-medium distance is ended.
In the present exemplary embodiment, a reference head-to-medium distance is stored for each ink in the memory. The reference head-to-medium distance is such a distance that each ink lands in an ideal position and the landing positions of the respective inks are aligned unless there is a change in the concentration, and a specific value of the head-to-medium distance is preset at the time of the manufacture of the recording apparatus.
Based on the foregoing, if the concentration N (x+1) calculated for each ink according to the flowchart in
On the other hand, in the case in which the concentration N (x+1) is equal to or greater than the predetermined threshold value, the head-to-medium distance is set to h2 (<h1). Specifically, the recording head is moved in the positive Z-direction such that the head-to-medium distance becomes shorter than the reference head-to-medium distance. When the concentration is decreased, the discharge speed is decreased, so that the ink is discharged from the short head-to-medium distance as illustrated in
The predetermined threshold value (8%) for the black ink is higher than those (7.5%) for the other inks also in
As described above, the present exemplary embodiment is capable of preventing a deviation of the ink landing position by adjusting the head-to-medium distance according to the concentration in the circulation channels even in the case in which the concentration increases in the circulation channels and a deviation of the ink landing position can occur.
While the form in which the cyan, magenta, yellow, and black inks are discharged from the different recording heads 105 to 108 is described in the above-described exemplary embodiments, any other forms can also be adopted. The cyan, magenta, yellow, and black inks can be discharged from a single recording head. Further, discharge port arrays for respectively discharging the cyan, magenta, yellow, and black inks can be disposed in the same heater board.
Further, while the exemplary embodiments describe the forms in which the discharge timing or the head-to-medium distance is adjusted such that the ink landing position is the ideal position in a case where the concentration increases, the adjustment does not necessarily have to be performed to adjust the ink landing position to be the ideal position. For example, even in a case where the landing position is deviated from the ideal position, the image quality is not likely to deteriorate significantly if the ink landing positions for each ink color are aligned. For example, if it is found that the landing positions of the cyan, magenta, and yellow inks are deviated from the ideal positions by a similar amount and the landing position of the black ink is the ideal position as a result of calculation of concentrations, the landing position of the black ink which is the ideal position is adjusted to the landing positions of the cyan, magenta, and yellow inks. An exemplary embodiment is applicable to various adjustments of the landing position according to the concentration as described above, such as adjustment to an ideal position or adjustment between colors.
Further, while the first exemplary embodiment describes the form in which the ink discharge timing is adjusted to correct the ink landing position and the second exemplary embodiment describes the form in which the head-to-medium distance is adjusted to correct the ink landing position, the forms can be executed in combination. Specifically, in the case in which the concentration is increased, even if the ink discharge timing is adjusted to an earlier timing while the head-to-medium distance is reduced, an advantage similar to that produced by the exemplary embodiments can be produced if the head-to-medium distance and the discharge timing are each adjusted such that the inks land in the ideal positions.
Further, while the form in which the recording heads 105 to 108 are individually movable in the Z-direction is described in the second exemplary embodiment, the recording heads 105 to 108 can be movable integrally. In this case, if the concentrations of only some of the inks are increased, it is not possible to adjust the head-to-medium distances with respect to only the recording heads of the inks. For example, in the case in which the concentrations of the cyan, magenta, and yellow inks are not increased and the cyan, magenta, and yellow inks can land in the ideal positions from the reference head-to-medium distances while the concentration of the black ink is increased and the ink landing position is deviated, it is not possible to move only the recording head 108 of the black ink. Further, if the recording heads 105 to 108 are integrally moved to uniformly reduce the head-to-medium distances so that a deviation of the landing position of the black ink is prevented, the landing position of the black ink is no longer deviated. However, the landing positions of the cyan, magenta, and yellow ink, which are not deviated in the case of the reference head-to-medium distances, will deviate. However, even in this case, since the discharge speeds (Ve) of the cyan, magenta, and yellow inks are higher than the discharge speed (Ve′) of the black ink, the level of the landing position deviations as a result of reducing the head-to-medium distances is smaller than the level of the deviation of the landing position of the black ink in the case of the reference head-to-medium distance. Thus, even in the form in which the recording heads 105 to 108 are integrally moved, if the concentration of any of the inks is increased, the influence of the landing position deviation is reduced to some extent by uniformly reducing the head-to-medium distances. Further, the landing position deviations of the cyan, magenta, and yellow inks occurring as a result of reducing the head-to-medium distances can be prevented by adjusting the ink discharge timings as in the first exemplary embodiment.
Further, while the forms in which the recording heads which are longer than the width of a recording medium are used, and recording is performed while the recording medium is conveyed is described in the above exemplary embodiments, any other forms are also adoptable. For example, a recording operation in which ink is discharged while the recording heads scan in the direction that intersects with the array direction in which the discharge ports are aligned, and a conveyance operation in which the recording medium is conveyed in the array direction during a scan may be repeatedly performed to complete recording on the recording medium through a plurality of times of scanning (movements).
The recording apparatuses according to exemplary embodiments are capable of suitably correcting deviations of ink landing positions which are caused by ink concentration in circulation channels.
While the disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2017-115989, filed Jun. 13, 2017, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-115989 | Jun 2017 | JP | national |
