JP2009034965A - Inkjet recording device and method of estimating the amount of residual ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device capable of exactly estimating the amount of residual ink without being affected by electric noises generated when the heater is driven and without reducing the durability of the recording head and a method of estimating the amount of residual ink. <P>SOLUTION: The method comprises the steps of driving the heater to turn on and off alternately by repeating "on" and "off" periods, obtaining the detected temperature of the recording head in the "off" period, and estimating the amount of residual ink according to the detected temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that uses a recording head that discharges ink using the thermal energy of a heater, and a method for estimating the remaining amount of ink in the ink jet recording apparatus.

  In recent years, as a recording apparatus such as a printer, a copying machine, and a facsimile, an ink jet recording apparatus (ink jet recording apparatus) capable of ejecting minute ink droplets based on a high driving frequency has become widespread. In particular, a thermal ink jet recording type recording apparatus that ejects ink from nozzles using bubbles of ink generated by the heat generated by a heater (electrothermal converter) can form nozzles with high density, High-definition images can be recorded.

  In an ink jet recording apparatus, a configuration in which an ink tank is replaced is generally used, and prior to recording, it is important to inform a user whether or not there is a possibility that ink will run out during the recording. In particular, in a device such as a facsimile machine in which recording data does not remain at the user's hand, it is necessary to reliably prevent a situation where ink runs out during recording, and it is required to estimate with high accuracy of the remaining amount of ink.

  In a thermal ink jet recording type recording apparatus, a method is known in which a change in the temperature of a recording head before and after driving a heater is detected to determine the remaining ink amount. This method uses a phenomenon in which the temperature of the recording head changes depending on the presence or absence of ink in the recording head. That is, when the heater is driven in a state where ink is sufficiently present in the recording head, the ink heated by the heater is foamed, and the ink is ejected from the nozzle by the foaming energy. Therefore, in this case, the heat energy of the heater is consumed, and heat is relatively not stored in the recording head. On the other hand, when the heater is driven in a state where there is no ink in the recording head, all the heat of the heater is stored in the recording head, so the temperature of the recording head becomes high.

  As a method of estimating the remaining amount of ink based on the temperature change of the recording head as described above, Patent Document 1 discloses an estimated value of the temperature of the recording head derived from the energy input to the recording head and a monitor of the temperature of the recording head. A method of comparing values with each other is described. That is, the presence or absence of ink is determined by comparing the difference between the estimated value and the monitor value with a predetermined threshold value.

  Such an estimation method of the remaining amount of ink based on the change in the temperature of the recording head also determines the ink ejection state, and therefore estimates the level immediately before the ink runs out with higher accuracy than other estimation methods. be able to. Other estimation methods include, for example, a method of calculating the amount of ink used by counting the number of ink ejections from when the ink tank is not used, and estimating the ink remaining amount from the calculated value, or the light of the ink tank For example, the remaining amount of ink is optically estimated by applying light to the transmission part.

Japanese Patent Laid-Open No. 06-336024

  In the method for estimating the remaining amount of ink based on the temperature change of the recording head, it is important to accurately acquire the temperature of the recording head. However, since a high frequency voltage is applied when the heater is driven, electrical noise is likely to occur. When noise is placed on a signal line that sends a detection signal for the temperature of the recording head, an accurate temperature can be obtained. There is a risk of it being impossible. If the heater is continuously driven a predetermined number of times and then the temperature of the recording head is detected to estimate the remaining ink amount, the number of times the heater is driven becomes important. If the number of times of driving is too small, the remaining amount of ink cannot be estimated because the temperature change of the recording head is small. On the other hand, if the number of times of driving is too large, the recording head becomes extremely high in the absence of ink, and there is a high possibility that the recording head will be damaged, leading to a decrease in durability. There is.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus and an ink remaining amount capable of accurately estimating the remaining amount of ink without being affected by electrical noise generated when the heater is driven and without impairing the durability of the recording head. It is to provide an estimation method.

  The inkjet recording apparatus of the present invention is an inkjet recording apparatus that performs recording on a recording medium using a recording head capable of ejecting ink supplied from an ink supply unit from an ejection port using thermal energy of a heater. Ink remaining amount for estimating the ink remaining amount of the ink supply unit based on temperature detection means for detecting the temperature of the head and the temperature detected by the temperature detection means when the heater is continuously driven a plurality of times The ink remaining amount estimating means has a driving pattern in which a driving period in which the heater is continuously driven a plurality of times and a non-driving period in which the heater is not driven thereafter are alternately repeated a plurality of times. Therefore, the heater is driven, the detected temperature of the temperature detecting means is acquired during the non-driving period, and the acquired detected temperature and a predetermined reference temperature are And estimating the amount of ink remaining in the ink supply section based on compare results.

  The method for estimating the remaining amount of ink according to the present invention is an inkjet recording apparatus that performs recording on a recording medium using a recording head capable of ejecting ink supplied from an ink supply unit from an ejection port using thermal energy of a heater. In order to estimate the remaining amount of ink in the ink supply unit, based on a temperature detection step of detecting the temperature of the recording head and the temperature detected by the temperature detection means when the heater is continuously driven a plurality of times An ink remaining amount estimating step for estimating the ink remaining amount, wherein the ink remaining amount estimating step includes a driving period in which the heater is continuously driven a plurality of times, and thereafter The heater is driven in accordance with a drive pattern that alternately repeats the non-drive period during which the heater is not driven, and the temperature detected by the temperature detecting means is set during the non-drive period. Obtained to, and estimates the amount of ink remaining in the ink supply unit based on a result of comparison between the detected temperature and a predetermined reference temperature and the acquired.

  According to the present invention, the heater is driven in accordance with a driving pattern in which the driving period in which the heater is continuously driven a plurality of times and the non-driving period in which the heater is not driven thereafter are alternately repeated a plurality of times. In addition, the detected temperature of the recording head is acquired. Therefore, it is possible to acquire the accurate detected temperature of the recording head without being affected by electrical noise generated when the heater is driven, and as a result, it is possible to accurately estimate the remaining amount of ink based on the detected temperature. it can. In addition, since the heater is driven in a plurality of drive periods, the durability of the recording head can be improved without causing the heater to generate excessive heat.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to the case of forming significant information such as characters and graphics, but may be significant. It also represents the case where images, patterns, patterns, etc. are widely formed on the recording medium, or the medium is processed, regardless of whether it is manifested so that it can be perceived by human eyes. And

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. Therefore, by being applied on the recording medium, formation of images, patterns, patterns, etc., processing of the recording medium, or ink processing (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium) Represents a liquid that can be subjected to

  Furthermore, “nozzle” (also referred to as “recording element” or “recording element”), unless otherwise specified, generates an ejection port, a fluid path communicating therewith, and energy used for ink ejection. The elements (heaters (electrothermal converters), etc.) to be used are collectively referred to.

(First embodiment)
1 to 14 are diagrams for explaining a first embodiment of the present invention.

  FIG. 1 is a diagram for explaining a configuration example of a recording apparatus to which the present invention is applicable.

  In FIG. 1, (a) is a perspective view of a main part of the recording apparatus, and (b) is a view taken along an arrow I in (a). Reference numerals 100 and 101 denote recording heads integrated with the ink tank. The recording head is not limited to the ink tank integrated recording head as in this example, and may be configured to be separable from the ink tank. The ink tank on the recording head 100 side stores black ink, light cyan ink, and light magenta ink, and the ink tank on the recording head 101 side stores cyan ink, magenta ink, and yellow ink. The recording heads 100 and 101 have the same configuration except for the ink to be stored. The recording heads 100 and 101 are formed with a plurality of ejection openings 102 corresponding to each color ink.

  Reference numeral 103 denotes a conveyance roller, and reference numeral 104 denotes an auxiliary roller. These cooperate with each other to rotate the recording medium P in the sub-scanning direction of the arrow Y by rotating in the direction of the arrow in the figure while suppressing the recording medium P. Transport to. Reference numeral 105 denotes a paper feed roller that feeds the recording medium P and plays the role of holding the recording medium P in between, like the transport roller 103 and the auxiliary roller 104. A carriage 106 on which the recording heads 100 and 101 can be mounted is reciprocated in the main scanning direction (X1 and X2 directions) along the arrow X. The carriage 106 moves to a home position h indicated by a dotted line in the drawing and stands by when recording is not being performed or when a recovery operation of the recording head is performed. In the recording apparatus of this example, the size of the maximum recordable recording medium is an A4 size version. A platen 107 serves to stably support the recording medium P at the recording position. Reference numeral 108 denotes a carriage belt for moving the carriage 106 in the main scanning direction.

  FIG. 2 is an explanatory diagram of the configuration of the recording head. Since the recording heads 100 and 101 have the same structure, the configuration of the recording head 101 will be described as a representative here. 2A is a perspective view of the recording head 101, FIG. 2B is a cross-sectional view of the recording head, FIG. 2C is a bottom view of the recording head viewed from the Z direction, and FIG. It is an enlarged view around an exit.

  In FIG. 2A, reference numeral 201 denotes a contact pad through which the recording head receives a recording signal from the recording apparatus main body and is supplied with electric power necessary for driving the recording head. A broken line in FIG. 2A indicates an inner wall of the recording head, and 10 g of cyan ink, magenta ink, and yellow ink are respectively injected into the ink tank chambers 202, 203, and 204 divided by the inner wall. Yes. The structure of these ink tank chambers is the same. FIG. 2B is a cross-sectional view of the ink tank chamber 202 for cyan ink. Reference numeral 205 denotes an ink absorber, 206 denotes an ink flow path, and 207 denotes a recording head chip. The ink absorbed and held by the ink absorber 205 is supplied to the recording head chip 207 through the ink flow path 206.

  In FIG. 2C, the print head chip 207 is provided with a diode sensor 208 for detecting the temperature of the print head substrate. Since it is difficult to directly detect the temperature of the ink, in general, the temperature of the recording head substrate (hereinafter referred to as “recording head temperature”) is detected and output to the recording apparatus main body as the ink temperature. Yes. As a configuration for detecting the print head temperature, for example, a metal thin film sensor or the like may be used in addition to the diode sensor. Reference numeral 209 denotes a row of discharge ports that discharge cyan ink (discharge port row), 210 denotes a row of discharge ports that discharge magenta ink (discharge port row), and 211 denotes a row of discharge ports that discharge yellow ink (discharge port row). It is. These discharge port arrays have the same structure.

  FIG. 2D is an enlarged view of the ejection port array 209 for ejecting cyan ink. A plurality of ejection ports 102 are arranged on the ejection port array 209, and bubbles are generated in the ink below each ejection port 102 (on the Z direction side) to eject the ink from the ejection ports 102. The heater 212 is provided. Thus, a plurality of discharge ports 102 are provided so as to form a discharge port array, and a plurality of heaters 212 are provided corresponding to each of the plurality of discharge ports 102.

  In this example, the number of ejection ports 102 arranged on the ejection port array 209 is 600, the interval between the ejection ports 102 is 1/600 inch, and the recording pixel density is 600 dpi. The ejection port 102 is configured to eject about 2 pl of ink droplets per droplet. The maximum ejection frequency (maximum driving frequency) of the heater 212 for ejecting the ink droplets is 20 kHz, but the maximum ejection frequency suitable for recording is 10 kHz. When ink droplets are landed at an interval of 1200 dpi in the main scanning direction, the moving speed in the main scanning direction of the carriage 106 on which the recording heads 100 and 101 are mounted is 8.33 inches / second (= 10000 (dots / second) ÷ 1200 ( Dot / inch)).

  FIG. 3 is a block diagram of the control system of the recording apparatus. Each component of the control system of this example can be broadly divided into software system control means and hardware system processing means.

  The software control means includes processing means such as an image input unit 303, an image signal processing unit 304, and a central control unit CPU 300 that access the main bus line 305. The hardware processing means includes processing means such as an operation unit 308, a recovery system control circuit 309, a head temperature control circuit 314, a head drive control circuit 316, a carriage drive control circuit 306, and a paper feed control circuit 307. The carriage drive control circuit 306 is a control circuit for driving the carriage 106 in the main scanning direction, and the paper feed control circuit 307 is a control circuit for transporting the recording medium P in the sub scanning direction. The CPU 300 includes a ROM 301 and a RAM 302, gives appropriate recording conditions to input information, and drives the ink ejection heater 212 in the recording heads 100 and 101.

  A program for executing a printhead recovery timing chart is stored in the RAM 302 in advance, and if necessary, recovery conditions such as preliminary ejection conditions are set in a recovery system control circuit 309, the printheads 100, 101, and the like. To give. The image input unit 303 receives image data, commands, status signals, and the like from an external device (host device) connected to the recording device. The recovery system motor 310 drives the recording heads 100 and 101, the cleaning blade 311, the cap 312, and the suction pump 313. The cleaning blade 311 and the cap 312 move relative to the recording heads 100 and 101. In order to estimate the ink remaining amount, when ink droplets are ejected from the recording head as described later, the ink droplets can be ejected into the cap 312. The head drive control circuit 316 receives a detection signal from the thermistor 315 that detects the ambient temperature of the printing apparatus and a detection signal from the diode sensor 208 that detects the print head temperature. Based on the output values of these detection signals, the head drive control circuit drives the heaters 212 of the recording heads 100 and 101 to perform ink ejection, ink preliminary ejection, and ink temperature adjustment for temperature control. .

  When the heater 212 is driven, a recording signal (DATA), a clock signal (CLK) for transferring the recording signal, a driving signal (HE) for driving the heater, and a recording signal are sent from the recording apparatus to the recording head. A latch signal (LT) for latching to the holding circuit is sent. FIG. 4A is a timing chart of those signals, and FIG. 4B is a drive block diagram of the heater 212. The recording signal (DATA) is input in synchronization with the clock signal (CLK), and then the latch signal (LT) is input to determine the recording signal (DATA_LTD). Thereafter, by inputting a drive signal (HE), a drive voltage is applied to the heater 212 selected by the driver, and ink is ejected from an ejection port corresponding to the heater 212. The latch signal (LT) and the drive signal (HE) are non-signal, that is, high level until the input of the recording signal (DATA) is completed. The recording signal (DATA) and the clock signal (CLK) are synchronized.

  When a recording head having 600 nozzles in the ejection port array (600 ejection ports) is driven at 10 kHz, the frequency of the clock signal (CLK) is 6 MHz (= 10 kHz × 600). As described above, since there are high-frequency signals such as the clock signal (CLK) and the recording signal (DATA), there is a possibility that electrical noise is generated in the recording heads 100 and 101. The electrical noise may adversely affect the output value of the diode sensor 208 output from the recording head to the recording apparatus.

  FIG. 5 shows the time change of the output value of the diode sensor 208 when the heater is driven so that 750 ink droplets are ejected from all the cyan ink ejection nozzles of the recording head 101 at a driving frequency of 15 kHz. It can be seen that during the heater drive time started at the time of 10 ms in the figure, noise is greatly on the output value of the diode sensor 208. The cause is as described above. In such a situation, it is difficult to obtain an accurate output value of the diode sensor 208.

  FIG. 6 is a flowchart for explaining a recording operation including estimation of the remaining amount of ink. This is because the control for the recording operation for both of the recording heads 100 and 101 is the same, and here, the cyan ink ejection control in the recording head 101 will be described as a representative.

  The printing apparatus determines whether or not there is a certain amount of ink remaining by receiving the printing data (step S601). The determination here does not require so high accuracy. For example, the ink consumption is calculated from the number of ink ejections so far, and it is determined whether or not the remaining amount of ink in the ink tank is less than 5 g. In this example, the remaining ink amount of 5 g is an amount obtained by adding a certain margin to the remaining ink amount sufficient for recording the next page regardless of the recording pattern. If the remaining ink amount is 5 g or more, the process proceeds to step S604 to record one page. When the remaining ink amount is less than 5 g, the process proceeds to step S602, and the remaining ink amount estimation control 1 is performed. The ink remaining amount estimation control 1 will be described in detail later.

  Next, based on the result of the ink remaining amount estimation control 1, it is determined whether there is an ink remaining amount that can be recorded for the next one page (step S603). If ink that can be recorded for the next one page remains, the process proceeds to step S604 to record one page. If there is no ink that can be recorded for the next one page, the process proceeds to step S605 to notify the user through the display of the host device that there is no ink remaining. Thereafter, the recording data from the current page on which recording has not yet been performed is stored in the RAM (step S606), and the recording ends.

  After recording for one page in step S604, the process proceeds to step S607 to determine whether there is recording data for the next page. If there is no next recording data, the recording is terminated. If there is such recording data, the ink remaining amount in the ink tank is calculated from the ink consumption corresponding to the number of ink ejections at the time of recording the previous page. Thereafter, the process proceeds to step S501, and it is determined again whether the remaining amount of ink is less than 5 g. Thereafter, the above-described processing is repeated.

  The ink remaining amount estimation control 1 in this example estimates the ink remaining amount based on the comparison result between the temperature of the recording head and the result of increasing the temperature of the recording head by ink ejection performed when ink is surely present.

  Prior to such ink remaining amount estimation control 1, when a new recording head is mounted on the carriage, acquisition control for acquiring the temperature characteristics of the recording head is performed. This acquisition control only needs to be performed in a state where there is sufficient ink to exceed the amount of ink consumed in the control, and is not specified only when a new recording head is mounted as in this example. For example, if the recording head has a storage area for storing information related to the remaining amount of ink and the remaining amount of ink can be recognized, the acquisition control can be performed when the remaining amount of ink is equal to or greater than a predetermined amount. .

  FIG. 7 is a flowchart of the acquisition control. First, in step S701, the counter value n for setting the number of repetitions is set to 1 (n = 1). In step S <b> 702, the heater is driven so that 600 inks are ejected from all the nozzles for ejecting cyan ink in the recording head 101 at a driving frequency of 10 kHz. As shown in FIG. 5, while the heater is being driven, there is a possibility that an accurate output value of the diode sensor 208 cannot be acquired due to the influence of noise. Therefore, after stopping the heater drive for 20 ms in step S703, the output value of the diode sensor 208 is acquired (step S704). That is, after waiting for 20 ms to eliminate the influence of noise, the print head temperature Tref_1 (n = 1) corresponding to the output value of the diode sensor 208 is acquired.

  Thereafter, the process proceeds to step S705, and it is determined whether or not the counter value n is 5 or more. In the initial stage, since n = 1, the process proceeds to step S706, and 1 is added to the counter value n to set n = 2. Thereafter, the process proceeds to step S702 again, the heater is driven so as to eject 600 ink droplets, and after waiting for 20 ms in step S703, the printhead temperature Tref_2 (n = 2) in step S704. To get.

  Such processing is repeated five times until the counter value n reaches 5, and the control is terminated after obtaining Tref_5 at the fifth time.

  FIG. 8 shows the temperature change of the recording head when the acquisition control of the temperature characteristic of the recording head is started from time T0.

  Each of the times T0 to T1, T2 to T3, T4 to T5, T6 to T7, and T8 to T9 is a time during which the heater is driven to eject 600 inks at a driving frequency of 10 kHz. Each of T1 to T2, T3 to T4, T5 to T6, T7 to T8, and T9 to T10 is a non-drive time for 20 ms when the heater is not driven. The temperature of the circled portion in the figure is the reference temperature Tref_n (n = 1 to 5) of the recording head acquired in step S704. Tref_n (n = 1 to 5) is stored in the RAM area as shown in FIG.

  Next, the remaining ink amount estimation control 1 for estimating the remaining ink amount will be described with reference to the flowchart of FIG. The driving of the heater is the same as the temperature characteristic acquisition control of the recording head in FIG.

  First, in step S1001, a counter value n for setting the number of repetitions is set to 1 (n = 1). Next, in step S1002, the heater is driven so that 600 ink droplets are ejected from all the nozzles for ejecting cyan ink of the recording head at a driving frequency of 10 kHz. After that, after waiting for 20 ms in step S1003 to eliminate the influence of noise, in step S1004, the printhead detection temperature T_1 (n = 1) corresponding to the output of the diode sensor 208 is acquired.

  In the next step S1005, the recording head reference temperature Tref_1 acquired in step S704 of FIG. 7 is subtracted from the detected temperature T_1, and whether or not the temperature after the subtraction is lower than 10 ° C. (specified temperature). to decide. In this example, even if the temperature detection error of the diode sensor 208 or the like is included, if there is a temperature change of 10 ° C. in the recording head, it can be determined that there is a clear state change in the recording head. Set to 10 ° C.

  If the post-subtraction temperature {(T_1)-(Tref_1)} is 10 ° C. or higher, it is determined in step S1006 that there is no ink amount (specified ink amount) sufficient to perform the recording of the next page. The remaining amount estimation control 1 ends. If the temperature {(T_1)-(Tref_1)} is less than 10 ° C., it is determined in step S1007 whether the counter value n is 5 or more. Since the counter value n is 1 in the initial stage, the process proceeds to step S1008, where 1 is added to the counter value n, so that n = 2. Thereafter, the process proceeds to step S1002 again, the heater is driven so as to eject 600 ink droplets, and after waiting for 20 ms in step S1003, the printhead temperature T_2 (n = 2) in step S1004. To get. Thereafter, in step S1005, it is determined whether or not the temperature {(T_2) − (Tref_2)} obtained by subtracting Tref_2 from T_2 is lower than 10 ° C. If the temperature is 10 ° C. or higher, it is determined in step S1006 that there is no ink.

  Such processing is repeated five times until the counter value n reaches 5. If the temperature {(T_5) − (Tref_5)} obtained by subtracting Tref_5 from T_5 acquired in the fifth time is also less than 10 ° C., it is determined that there is ink sufficient to perform the recording of the next page. The remaining amount estimation control 1 ends.

  FIG. 11 shows the temperature change of the print head when such ink remaining amount estimation control 1 is started from time T0.

  Each of the times T10 to T11, T12 to T13, T14 to T15, T16 to T17, and T18 to T20 is a time during which the heater is driven so as to eject 600 ink droplets at a driving frequency of 10 kHz (driving period). It is. Each of T11 to T12, T13 to T14, T15 to T16, T17 to T18, and T19 to T20 is 20 ms (non-driving period) in which the heater is not driven. Thus, in this example, a driving pattern is set in which the driving period and the non-driving period are alternately repeated five times. The temperature of the circled portion in the drawing is the print head temperature T_n (n = 1 to 5) acquired in step S1004. The solid line, broken line, and alternate long and short dash line in the figure are temperature changes when the remaining ink amount is 5 g, 3 g, and 1 g, respectively. When the remaining amount of ink is more than 3 g, the recording head 101 in this example can record one page of the A4 size plate without being faded as long as it is driven with an ejection frequency of 10 kHz regardless of the recording pattern. .

  FIG. 12 shows the printhead temperature T_n and the temperature difference {(T_n) − (Tref_n)} when the remaining amount of ink is 5 g, 3 g, and 1 g (n = 1 to 5). When the remaining amount of ink is 5 g, Tt_n and Tref_n are equal, and the difference {(T_n) − (Tref_n)} is always smaller than 10 ° C. in the entire range where n = 1 to 5, so at least the next page is recorded. It is determined that there is as much ink as possible. When the remaining amount of ink is 3 g, T_n and Tref_n are substantially equal from n = 1 to 3, but a difference starts to appear from n = 4. When n = 5, the difference {(T_n) − (Tref_n)} Becomes 10 ° C. When the ink remaining amount is 3 g or less, it cannot be guaranteed that the next page of the A4 size version will not be blurred, and therefore it is determined that there is no ink. When the ink remaining amount is 1 g, the temperature difference {(T_n) − (Tref_n)} becomes 10 ° C. or more at n = 3, and it is determined that there is no ink, so the processing after n = 4 is interrupted. The Thus, when it is determined that there is no ink, the heater is not driven thereafter.

  FIG. 13 shows, as a comparative example, the recording head 101 when the heater is continuously driven so that 3000 inks are ejected at a driving frequency of 10 kHz without setting a standby time of 20 ms as in this example. The temperature change of is shown. The dotted line, solid line, broken line, and alternate long and short dash line in the figure indicate the temperature change of the print head when the remaining ink amount is 10 g (when new), 5 g, 3 g, and 1 g, respectively. Since noise may enter the output of the diode sensor 208 while the heater is being driven, the recording head temperature acquisition timing is set to the timing when 20 ms has elapsed after the heater driving is completed, as in this embodiment. .

  FIG. 14 shows the temperature of the print head after the heater driving when the remaining amount of ink is 10 g, 5 g, 3 g, and 1 g in such a comparative example. Further, FIG. 14 shows the difference (temperature difference) between these temperatures and the temperature of the recording head when the ink remaining amount is 10 g. When the remaining amount of ink is 5 g, it can be determined that there is ink because the temperature difference is 10 ° C. or less as in the case of the present embodiment. When the ink remaining amount is 3 g, it can be determined that there is no ink because the temperature difference is 10 ° C. or more as in the case of the present embodiment. However, when the remaining amount of ink is 1 g, the temperature difference becomes 10 ° C. or more, but the recording head becomes as high as 110 ° C. When the temperature of the recording head becomes higher than 100 ° C., the constituent members of the recording head including the dissolution of the nozzle may be damaged, and the durability of the recording head may be impaired.

  In the present embodiment, the heater is driven a plurality of times by a predetermined number of times, and in order to accurately acquire the temperature of the recording head between those driving times, the heater is driven before the temperature of the recording head reaches a high temperature. Can be canceled. As a result, the durability of the recording head is improved.

  As described above, in this embodiment, there is an ink remaining amount necessary for the next recording without being affected by the electric noise generated when the heater is driven and without impairing the durability of the recording head. It is possible to accurately estimate whether or not it exists. The next recording unit is not limited to one page as in the present embodiment. The recording unit may be several scanning units or several page units of the recording head, and accordingly, the remaining amount of ink necessary for the next recording can be optimally set. It is not specified to 3g.

(Second Embodiment)
FIG. 15 shows the number of ejections of ink (number of ejections of ink droplets) and driving when it is estimated that cyan ink is continuously ejected from the recording head 101 and the remaining amount of ink is 3 g. It is explanatory drawing of the relationship with a frequency (ejection frequency of an ink droplet). The case of magenta ink and yellow ink is the same as that of cyan ink. The number of ink ejections necessary for detecting the remaining ink amount decreases as the drive frequency increases. Hereinafter, one of the main factors will be described.

  Ink used in the ink jet recording apparatus is normally held by a negative pressure generating member (such as an ink absorber) in the ink tank so that it does not spill out from the ejection port of the recording head when not ejecting. That is, pressure (hereinafter referred to as “negative pressure”) applied to the ink from the recording head to the ink tank side is applied. When the ink remaining amount in the ink tank decreases due to ink consumption due to recording, the negative pressure generating member in the ink tank does not change the force that holds the ink, and the amount of ink to be held is reduced. Shows a tendency to gradually increase. When the negative pressure becomes excessively large, the ink is strongly pulled from the recording head side to the ink tank side, and there is a possibility that ink cannot be supplied to the ejection port. As a result, the ink may not be ejected even though the ink remains in the ink tank. The negative pressure also varies depending on the ink ejection state in the recording head. That is, when a large amount of ink is ejected per unit time and the amount of ink consumed per unit time is large, the negative pressure dynamically changes in the direction of increasing, and the ink is pulled more strongly in the direction of the ink tank. . On the other hand, when a small amount of ink is ejected per unit time and the ink consumption per unit time is small, the dynamic negative pressure change of the ink tank is small.

  For example, when the remaining amount of ink is 10 g, the negative pressure is the minimum necessary for holding ink. Therefore, even if ink is continuously ejected at a high driving frequency of 10 kHz, the negative pressure only slightly changes in the increasing direction, and the ink is sufficiently supplied to the nozzles. Further, when the ink remaining amount is 3 g, the negative pressure increases because the amount of ink to be held decreases, and therefore the negative pressure further increases when ink is ejected continuously at a driving frequency of 10 kHz. For this reason, the ink is gradually not supplied to the nozzles, and some of the nozzles may be driven without being supplied with the ink, and may not discharge ink (color discharge state). In this case, the temperature of the recording head rises rapidly. However, when the ink remaining amount is 3 g, when ink is continuously ejected at a low driving frequency such as 1 kHz, the dynamic change in the negative pressure is small, and the ink is sufficiently supplied to the nozzles.

  As described above, the timing at which the nozzles are in the color ejection state, that is, the timing at which the temperature of the recording head suddenly rises and the estimation of the remaining amount of ink can be estimated differs depending on the drive frequency. Therefore, as shown in FIG. 15, the number of ink ejections necessary for estimating the remaining ink amount varies depending on the drive frequency.

  In the first embodiment described above, the remaining amount of ink is estimated after waiting for 20 ms after the heater is driven at a driving frequency of 10 kHz so as to eject 600 ink droplets each time. Therefore, the substantial drive frequency in the period including the standby time of 20 ms is equivalent to 7.5 kHz lower than 10 kHz {(600 shots / (60 ms + 20 ms)}. In the second embodiment, it is described above. By using the relationship as shown in FIG. 15, the amount of ink consumed at the time of estimation of the remaining amount of ink is reduced compared to the case of the first embodiment.

  FIG. 16 is a flowchart for explaining a recording operation including estimation of the remaining ink amount. Except for the remaining ink amount estimation control 2 in step S1602, the process is the same as that in FIG. 6 of the first embodiment described above, and steps S1601, S1603 to S1607 in FIG. 16 correspond to steps S601 and S603 to S607 in FIG. Therefore, those descriptions are omitted.

  The ink remaining amount estimation control 2 in this example estimates the ink remaining amount based on the temperature change of the recording head before and after ink ejection. FIG. 17 is a flowchart of the remaining ink amount estimation control 2 in this example.

  In the remaining ink amount estimation control 2, first, in step S1701, the print head temperature Tb before the heater driving is acquired. Next, in step S1702, the counter value n for setting the number of repetitions is set to 1 (n = 1), and then the process proceeds to step S1703 to determine whether or not the counter value n is 1. Since n = 1 at the initial stage, the process proceeds to step S1704, and the heater is driven so that 2000 ink droplets are ejected from all the cyan ink ejection nozzles in the recording head 101 at a driving frequency of 10 kHz. In the case of this example, even if the heater is driven so that 2000 ink droplets are ejected when the ink remaining amount is 0 g, the temperature of the recording head leads to damage to the constituent members of the recording head including the dissolution of the nozzles. It does not reach a high temperature of 100 ° C. In this way, 2000 shots means the maximum number of times of driving in a range where the recording head does not reach a high temperature of 100 ° C. which causes damage.

  As described above, the output value of the diode sensor 208 cannot be obtained accurately during the driving of the heater due to the influence of noise. Therefore, after waiting for 20 ms in step S1705 and eliminating the influence of noise, the print head temperature Ta_1 (n = 1) corresponding to the output value of the diode sensor 208 is acquired in step S1706. Next, in step S1707, the temperature Tb acquired in the previous step S1701 is subtracted from the temperature Ta_1, and it is determined whether or not the temperature difference {(Ta_1) − (Tb)} is lower than 45 ° C.

  The reason why the comparison reference temperature is 45 ° C. is as follows. First, when the remaining amount of ink is more than 3 g, the recording head 101 in this example can print one page of the A4 size version as long as the recording head is driven with a driving frequency of 10 kHz for any recording pattern. This is because recording can be performed without fading. Second, when the heater is driven when the ink remaining amount is 3 g, the temperature change of the recording head of this example is 35 ° C. Third, when estimating a change in the state of the recording head in this example (in this case, a change in the remaining amount of ink), even if a temperature detection error of the diode sensor 208 is included, the temperature change of 10 ° C. may occur in the recording head. This is because it can be clearly determined that the state has changed. Therefore, in the case of this example, it is possible to reliably determine that the remaining amount of ink is 3 g or less when the temperature change of 45 ° C. or more occurs in the recording head.

  When the temperature difference {(Ta_1) − (Tb)} is 45 ° C. or more, it is determined in step S1708 that there is no ink necessary for recording the next page, and the remaining ink amount estimation control 2 is terminated. If the temperature difference {(Ta_1) − (Tb)} is less than 45 ° C., it is determined in step S1709 whether the counter value is 2 or more. Since n = 1 initially, the process proceeds to step S1710, 1 is added to the counter value n to set n = 2, and then the process proceeds to step S1703 again. Since n = 2 this time, the process proceeds to step S1711 and the heater is driven so that 500 ink droplets are ejected. In this example, even if the heater is driven to discharge 500 ink droplets when the temperature change generated in the print head when n = 1 is less than 35 ° C., the temperature of the print head is It does not reach 100 ° C. Therefore, the 500 shots means the maximum number of times of driving in a range where the temperature of the recording head does not reach 100 ° C. even if color discharge is performed.

  Then, after waiting for 20 ms in step S1705, the print head temperature Ta_2 (n = 2) is acquired in step S1706. In step S1707, it is determined whether or not the temperature difference {(Ta_2) − (Tb)} is less than 45 ° C. If the temperature difference is 45 ° C. or more, it is determined in step S1708 that there is no remaining ink. . If the temperature difference is less than 45 ° C., it is determined in step S1709 whether or not the counter value n is 2 or more. Since n = 2 this time, the process shifts to step S1712 to determine that there is an ink remaining amount necessary for recording the next page, and the ink remaining amount estimation control 2 is ended.

  FIG. 18 shows a temperature change of the recording head 101 when the remaining ink amount estimation control 2 is started at time T10. Times T10 to T11 are times when the heater is driven to eject 2000 ink droplets at a driving frequency of 10 kHz, and T12 to T13 are heaters so as to eject 500 ink droplets at a driving frequency of 10 kHz. Is driving time. Each of T11 to T12 and T13 to T14 is a standby time (non-driving time) of 20 ms during which the heater is not driven. The circles in the figure are the print head temperature Ta_n (n = 1, 2) acquired in step S1706. The solid line, broken line, and alternate long and short dash line in the figure indicate temperature changes when the remaining ink amount is 5 g, 3 g, and 1 g, respectively.

  FIG. 19 shows the printhead temperatures Ta_n, Tb, {(Ta_n) −Tb} when the remaining amount of ink is 5 g, 3 g, and 1 g (n = 1, 2). When the remaining amount of ink is 5 g, the temperature difference {(Ta_n) −Tb} is always smaller than 45 ° C. when n = 1 or 2, so that there is a recordable amount of ink for the next page. It is judged. When the remaining amount of ink is 3 g, the temperature difference {(Ta_n) −Tb} is 45 ° C. when n = 2. That is, when the remaining amount of ink is 3 g or less, it cannot be guaranteed that the next page of the A4 size plate will not be blurred, and therefore it is determined that there is no ink. When the ink remaining amount is 1 g, when n = 1, the temperature difference {(Ta_n) −Tb} is 45 ° C. or more, and it is determined that there is no ink. In this case, processing after n = 2 is interrupted.

  As described above, in the present embodiment, similarly to the above-described embodiment, the heater is driven a plurality of times by a predetermined number of times, and the temperature of the print head is accurately obtained between the drive times. Before the temperature reaches a high temperature, the driving of the heater can be stopped. As a result, the durability of the recording head is improved.

  Further, in the present embodiment, the first ink droplet ejection number does not reach a high temperature (100 ° C. in this example) that leads to damage to the recording head even when the remaining amount of ink is 0 g. In the range, the maximum number of discharges (2000 in this example) was set. Therefore, the waiting time for acquiring the temperature of the recording head can be reduced as compared with the case of the first embodiment described above. As a result, the substantial drive frequency within the period including the first and second ink ejection times (200 ms, 20 ms) and the first and second standby times (20 ms, 20 ms) is the same as that of the first embodiment. Higher than the case. That is, the substantial drive frequency in this embodiment is 8.62 kHz (= 2500 shots / (200 ms + 20 ms + 50 ms + 20 ms)). As a result, the remaining amount of ink can be estimated from the number of ink ejections of 2500, which is 500 fewer than that of the first embodiment, and the ink consumption can be suppressed correspondingly.

(Other embodiments)
INDUSTRIAL APPLICABILITY The present invention can be widely applied to an ink jet recording apparatus that records on a recording medium using a recording head capable of ejecting ink supplied from an ink supply unit from an ejection port using thermal energy of a heater. . The ink supply unit can include an ink tank that is integral with or separate from the recording head, and / or an ink storage space inside the recording head. The ink remaining amount of the ink supply unit is estimated based on the detected temperature of the recording head when the heater is continuously driven a plurality of times. At this time, the driving pattern for driving the heater may be a driving pattern in which a driving period in which the heater is continuously driven a plurality of times and a non-driving period in which the heater is not driven thereafter are alternately repeated a plurality of times. It is not specified only for the drive pattern of the embodiment. It is only necessary that the detected temperature of the recording head is acquired during the non-driving period, and the ink remaining amount can be estimated based on a comparison result between the detected temperature and a predetermined reference temperature. When the ink remaining amount is estimated, it is desirable not to drive the heater according to the subsequent drive pattern.

  In addition, the reference temperature can be set to a different temperature for each of the plurality of non-drive periods, and the temperature in the later non-drive period can be set higher than the temperature in the previous non-drive period. It is not specified only in the above-described embodiment. Further, when the difference between the detected temperature and the reference temperature is equal to or higher than the specified temperature, it can be estimated that the remaining amount of ink is equal to or lower than the specified ink amount corresponding to the reference temperature. In this case, the reference temperature and the specified ink amount are It is not specified only in the above-described embodiment.

  The recording apparatus to which the present invention can be applied is not limited to the serial scan type inkjet recording apparatus as described above, and is widely applied to various recording apparatuses using an inkjet recording head capable of ejecting ink by the heat generated by a heater. be able to. For example, the present invention can also be applied to a so-called full-line type ink jet recording apparatus that uses a long recording head extending over the entire width direction of the recording area of the recording medium.

(A) is a schematic perspective view of the principal part of the inkjet recording device in the 1st Embodiment of this invention, (b) is an I arrow directional view of the carriage part in (a). (A) is a perspective view of the recording head, (b) is a schematic sectional view of the recording head, (c) is a bottom view of the recording head, and (d) is an enlarged view of a nozzle portion of the recording head. FIG. 2 is a block configuration diagram of a control system of the ink jet recording apparatus of FIG. 1. (A) is a time chart of an input signal of the recording head, and (b) is a block diagram of a heater driving circuit in the recording head. It is explanatory drawing of the detected temperature at the time of detecting the temperature of a recording head based on the output value of the diode sensor at the time of heater drive. 5 is a flowchart for explaining recording control in the first embodiment of the present invention. 6 is a flowchart for explaining temperature head acquisition characteristics control of a recording head according to the first embodiment of the present invention. FIG. 8 is an explanatory diagram of a temperature change of the recording head during the acquisition control of FIG. 7. It is explanatory drawing of the temperature characteristic of the recording head acquired by the acquisition control of FIG. 7 is a flowchart for explaining ink remaining amount estimation control 1 in FIG. 6. It is explanatory drawing of the temperature change of the recording head in the ink remaining amount estimation control 1 of FIG. FIG. 12 is an explanatory diagram of the relationship between the temperature characteristics of the recording head of FIG. 7 and the temperature change of the recording head of FIG. 11. As a comparative example, it is an explanatory diagram of a temperature change of a recording head when a heater is driven so that 3000 ink droplets are continuously ejected at a driving frequency of 10 kHz. FIG. 14 is an explanatory diagram of a relationship between the temperature of the recording head and the remaining amount of ink in the comparative example of FIG. 13. It is explanatory drawing of the relationship between the frequency | count of continuous discharge of an ink required in order to estimate that it is the ink residual amount 3g, and a drive frequency. It is a flowchart for demonstrating the recording control in the 2nd Embodiment of this invention. It is a flowchart for demonstrating the ink residual amount estimation control 2 in FIG. FIG. 18 is an explanatory diagram of a temperature change of the print head in the ink remaining amount estimation control 2 of FIG. 17. FIG. 19 is an explanatory diagram of a relationship between a change in the temperature of the print head in FIG. 18 and the temperature of the print head before the heater is driven.

Explanation of symbols

100, 101 Print head 102 Discharge port 106 Carriage 207 Print head chip 208 Diode sensor 209, 210, 211 Discharge port array 212 Heater 300 CPU
301 ROM
302 RAM
P Recording medium

Claims (10)

In an ink jet recording apparatus that performs recording on a recording medium using a recording head capable of discharging ink supplied from an ink supply unit from a discharge port using thermal energy of a heater,
Temperature detecting means for detecting the temperature of the recording head;
Ink remaining amount estimating means for estimating the ink remaining amount of the ink supply unit based on the temperature detected by the temperature detecting means when the heater is continuously driven a plurality of times;
With
The ink remaining amount estimating means drives the heater according to a driving pattern in which a driving period in which the heater is continuously driven a plurality of times and a non-driving period in which the heater is not driven thereafter are alternately repeated a plurality of times, Acquiring the detected temperature of the temperature detecting means during the non-driving period, and estimating the ink remaining amount of the ink supply unit based on a comparison result between the acquired detected temperature and a predetermined reference temperature. Inkjet recording apparatus.   2. The ink jet recording apparatus according to claim 1, wherein when the ink remaining amount is estimated, the ink remaining amount estimating unit does not drive the heater according to the drive pattern thereafter. The reference temperature is set to a different temperature for each of the plurality of non-driving periods, and the temperature in the later non-driving period is set higher than the temperature in the previous non-driving period,
The remaining ink amount estimation means estimates that the remaining ink amount is equal to or less than a specified ink amount corresponding to the reference temperature when a difference between the detected temperature and the reference temperature is equal to or higher than a specified temperature. The ink jet recording apparatus according to claim 1.   The inkjet recording apparatus according to claim 3, wherein the reference temperature is set according to a temperature characteristic of the recording head.   The inkjet recording apparatus according to claim 1, wherein the number of times the heater is driven is equal for each of the plurality of driving periods.   5. The inkjet recording apparatus according to claim 1, wherein the number of times the heater is driven is different for each of the plurality of driving periods.   The inkjet recording apparatus according to claim 6, wherein in the plurality of driving periods, the number of times the heater is driven during a previous driving period is greater than the number of times the heater is driven during a subsequent driving period.   In the plurality of driving periods, the number of times the heater is driven during the first driving period is not higher than a temperature at which the recording head is damaged even if the recording head is driven when the remaining amount of ink is zero. The inkjet recording apparatus according to claim 7, wherein the number of times of driving is within a range that does not reach. A plurality of the discharge ports are provided so as to form a discharge port array,
A plurality of the heaters are provided corresponding to each of the plurality of discharge ports,
The ink jet recording apparatus according to claim 1, wherein the remaining ink amount estimation unit drives the plurality of heaters in the driving period. In an ink jet recording apparatus that records on a recording medium using a recording head capable of ejecting ink supplied from an ink supply unit from a discharge port using thermal energy of a heater, the ink remaining amount of the ink supply unit is estimated In order to do so, a temperature detection step for detecting the temperature of the recording head, and an ink remaining amount estimation for estimating the ink remaining amount based on the detected temperature of the temperature detecting means when the heater is continuously driven a plurality of times A method for estimating the remaining amount of ink including:
The ink remaining amount estimating step includes:
The heater is driven according to a drive pattern in which the heater is continuously driven a plurality of times and a non-drive period in which the heater is not driven is alternately repeated a plurality of times, and the temperature during the non-drive period A method for estimating a remaining amount of ink, comprising: obtaining a detected temperature of a detecting unit and estimating an ink remaining amount of the ink supply unit based on a comparison result between the obtained detected temperature and a predetermined reference temperature.

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