JP2013215951A - Liquid discharging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharging device having a plurality of discharge element substrates using inks having different usable temperature ranges, the liquid discharging device being capable of performing appropriate temperature-increase suppressing control and maintaining good printing quality while suppressing printing throughput reduction.SOLUTION: A liquid discharging device has first and second discharge element substrates disposed on a supporting member. Based on temperatures T1 and T2 of the first and second discharge element substrates, a temperature T1a at a position of the first discharge element substrate close to the second discharge element substrate is estimated. If either of the temperatures T1 and T1a is equal to or higher than a threshold temperature Tth1, the device performs temperature-increase suppressing control before a recording operation is performed using the first discharge element substrate. If the temperature T2 is equal to or higher than a threshold temperature Tth2, the device performs temperature-increase suppressing control before a recording operation is performed using the second discharge element substrate.

Description

  The present invention relates to a liquid ejecting apparatus that ejects ink to perform recording on a recording medium.

  In a liquid discharge apparatus that discharges ink by heating a heater arranged in a discharge nozzle portion of a liquid discharge head, the temperature of the liquid discharge element rises by continuing printing. When the temperature of the liquid ejection element becomes high, the ejection direction may be disturbed or ejection may not be possible due to a decrease in ink viscosity. As a means for preventing such problems, a control method is known in which a temperature sensor is provided on the discharge element substrate, and a standby time for stopping printing for a certain period of time when the detected temperature exceeds a threshold is provided to suppress the temperature rise. ing. In a liquid discharge head having a plurality of discharge element substrates, Patent Document 1 discloses an example in which a temperature sensor is provided on each chip to detect the temperature of each chip and temperature rise suppression control is performed.

JP 2006-43923 A

  The temperature at which ejection failure occurs due to temperature rise varies depending on the type of ink. Also, depending on the type of ink, discharge may be more stable when the temperature is raised to some extent. In such a case, the substrate temperature is preliminarily set before discharge by a method such as driving a heater provided on the discharge element substrate. Need to be raised. In the conventional temperature rise suppression control, the threshold temperature of the temperature rise suppression control in the case of using a plurality of inks having different usable temperature regions as described above is set in accordance with the ink that causes the ejection failure at the lowest temperature. The entire liquid discharge head was set uniformly. For example, the discharge element substrate A and the discharge element substrate B are mounted on one liquid discharge head, and the temperatures at which ink used in the discharge element substrates A and B may cause a discharge failure are 50 ° C. and 70 ° C., respectively. In the case of ° C, the threshold temperature of the temperature rise suppression control was set to 50 ° C. In such a control method, for example, when the ejection element substrate A is 40 ° C. and the ejection element substrate B is 55 ° C., both ejection element substrates are below the temperature at which ejection failure occurs with the ink used. Regardless, temperature rise suppression is performed. That is, by setting the threshold value for the temperature rise suppression control in accordance with the ink that causes the ejection failure at the lowest temperature, the number of times the temperature rise suppression control is performed increases, leading to a decrease in print throughput due to the standby time.

  In order to minimize the decrease in print throughput due to temperature rise suppression control as much as possible, instead of setting the threshold temperature uniformly according to the ink with the lowest upper limit of the usable area as in the past, for each ejection element substrate, A threshold temperature may be set according to the ink used. However, when the threshold temperature corresponding to the ink used is set for each ejection element substrate, the following problem may occur.

  In recent years, there has been a demand for downsizing the apparatus and speeding up printing, and the support member for supporting the ejection element substrate may have a configuration in which the number of ejection elements is increased as compared with the conventional volume while maintaining almost the same volume. is there. In such a configuration, the heat generation amount per time of the ejection element increases with respect to the volume of the support member. Further, in a configuration having a plurality of ejection element substrates, it may be necessary to arrange the ejection element substrates closer to each other than before. In such a situation, the heat effect of heat generated in a certain discharge element substrate on another discharge element substrate via the support member becomes larger than before and cannot be ignored. When there is a difference in temperature between the two ejection element substrates, the temperature can be inclined from the higher temperature substrate side to the lower temperature substrate side, and the higher temperature substrate in the lower temperature substrate. A temperature distribution occurs such that the temperature is higher on the side closer to, and the temperature is lower on the far side. As described above, when the temperature of the substrate with the higher threshold exceeds the temperature increase threshold value of another substrate in the heads having different temperature increase control threshold temperatures for the plurality of discharge element substrates, the following occurs. That is, a temperature distribution is generated in the substrate with the lower threshold, and even if the temperature is lower than the threshold at the sensor position, the threshold temperature may be exceeded at a location near the substrate with the higher threshold. In this case, if the temperature rise suppression control is performed based on the output of the temperature sensor of the substrate with the lower threshold, the temperature rise suppression control is not performed even though there is a place where the threshold is exceeded in the substrate. There is a possibility that a defect may occur in printing.

  According to the present invention, in a liquid ejection apparatus having a plurality of ejection element substrates that use inks having different usable temperature ranges, appropriate temperature rise suppression control is performed while suppressing a decrease in printing throughput, and printing quality is kept good. An object of the present invention is to provide a liquid ejection device that can perform the above-described operation.

  The liquid ejection apparatus according to the present invention includes a support member, a first ejection element substrate that is disposed on the support member and has a ejection port that ejects the first liquid, and is disposed on the support member. A second discharge element substrate having a discharge port for discharging a liquid; a first temperature sensor provided on the first discharge element substrate for detecting a temperature T1 of the first discharge element substrate; and the second And a second temperature sensor that detects a temperature T2 of the second discharge element substrate, the liquid discharge apparatus comprising: a second temperature sensor that detects the temperature T2 of the second discharge element substrate; An estimation unit that estimates a temperature T1a near the second ejection element substrate on one ejection element substrate, and one of the temperature T1 and the temperature T1a is a threshold temperature of the first ejection element substrate If it is greater than or equal to Tth1, the first Temperature rise suppression control is performed before the recording operation using the discharge element substrate, and when the temperature T2 is equal to or higher than the threshold temperature Tth2 of the second discharge element substrate, the second discharge element substrate is used. And a controller that performs temperature rise suppression control before the recording operation is performed.

  According to the present invention, in a liquid ejection apparatus having a plurality of ejection element substrates that use inks having different usable temperature ranges, appropriate temperature rise suppression control is performed while suppressing a decrease in printing throughput, and printing quality is kept good. It is possible to provide a liquid ejecting apparatus that can perform the above operation.

1 shows a liquid discharge apparatus and a liquid discharge head according to a first embodiment of the present invention. FIG. 3 is a configuration block diagram of a control system of the liquid ejection apparatus according to the first embodiment of the present invention. It is a flowchart which shows the image recording sequence of the 1st Embodiment of this invention. It is a figure which shows the temperature distribution of the 1st Embodiment of this invention. It is a figure which shows the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A shows a liquid ejection apparatus according to the first embodiment of the present invention. The recording apparatus 50 according to the present embodiment is a serial scan type liquid discharge apparatus, and a carriage 53 is guided by guide shafts 51 and 52 so as to be movable in the main scanning direction indicated by an arrow A. The carriage 53 is reciprocated in the main scanning direction by a driving force transmission mechanism such as a carriage motor and a belt for transmitting the driving force. A liquid ejection head 300 (not shown in FIG. 1A) and an ink tank 54 that supplies ink to the liquid ejection head 300 are mounted on the carriage 53. The liquid discharge head 300 and the ink tank 54 may constitute an ink jet cartridge.

After the paper P as a recording medium is inserted from the insertion port 55 provided at the front end of the apparatus,
After the transport direction is reversed, the transport roller 56 transports the sheet in the sub-scanning direction indicated by the arrow B. The recording apparatus 50 moves the liquid ejection head 300 in the main scanning direction, ejects ink toward the print area of the paper P on the platen 57, and sub-sheets of the paper P by a distance corresponding to the recording width. The carrying operation for carrying in the scanning direction is repeated. As a result, images are sequentially recorded on the paper P. In the present embodiment, an image is formed with four colors of ink of black, C, M, and Y.

  FIG. 1B shows a liquid discharge head according to the first embodiment of the present invention. The ink supplied from the ink tank via the filters 311 to 314 reaches the liquid ejection unit 320 through a flow path component (not shown). A liquid discharge element substrate is disposed in the liquid discharge unit 320, and heaters are arranged on the substrate as liquid discharge elements. By driving the liquid ejection element, ink is ejected toward the paper, and an image is formed.

  FIG. 1C is a diagram schematically showing the arrangement of the liquid discharge element substrate when viewed from the lower surface direction of FIG. Two liquid discharge element substrates are disposed on the support member 350 made of alumina. The first liquid discharge element substrate 330 is for discharging color (C, M, Y) ink and has six ink supply ports from a supply port 331a to a supply port 331f. 331a and 331f are for supplying C ink, 331b and 331e are for supplying M ink, and 331c and 331d are for supplying Y ink. Each ink flow path is formed to be bifurcated in the flow path component, and ink is supplied from one ink tank to two supply ports. Discharge element arrays 332a1 and 332a2 are arranged on both sides of the supply port 331a. Similarly, each of the supply ports 331b to 331f is provided with one discharge element array on each side, and the first discharge element substrate has a total of 12 parallel discharge element arrays. The second liquid ejection element substrate is for ejecting black ink, has one ink supply port 341g, and has ejection element rows 342g1 and g2 (not shown) on each side. Each discharge element substrate has diode sensors (first temperature sensor and second temperature sensor) 333 and 343 for detecting the substrate temperature. The position is substantially the center in the arrangement direction of the ejection element arrays on each substrate. In consideration of the temperature distribution in the substrate when each substrate is driven independently, it is arranged in a place where the temperature is most likely to rise. The black ink discharge substrate is provided with a sub-heater 344 separately from the discharge elements in order to increase the base temperature of the substrate.

  Next, the configuration of the control system of the liquid ejection apparatus in the present embodiment will be described with reference to FIG. The interface 20 transmits and receives data such as image data and control commands between the host apparatus H and the inkjet recording apparatus main body. An MPU (Micro-Processing Unit) 21 performs various processes such as calculation, determination, and setting, and also executes various controls of the entire recording apparatus. Programs and fixed data for the MPU 21 to control are stored in a ROM (Read Only Memory) 22. A DRAM (Dynamic Random Access Memory) 23 temporarily stores various data (such as recording data to be supplied to the liquid ejection head 300) or is used as a work area for processing performed by the MPU 21. The MPU 21, ROM 22, and DRAM 23 constitute a control unit, standby control unit, and temperature estimation unit of the present invention.

  The gate array 24 controls recording data supply to the liquid ejection head 300. The gate array 24 also controls data transfer among the interface 20, MPU 21, and DRAM 23. The motor drivers 25 and 26 drive the carriage motor 6 and the transport motor 1, respectively. The head driver 27 drives the liquid ejection head 300. Further, output data (temperature value) from the diode sensors 333 and 343 for detecting the temperature of the liquid ejection head 300 is sent to the MPU 21.

A sequence in the case of executing the recording of the present embodiment using the recording apparatus described above will be specifically described. FIG. 3 is a flowchart showing a process for recording an image for one page.

  When the recording operation is started, first, temperatures T1 and T2 of each ejection element substrate are acquired from the diode sensors 333 and 343 in step S201.

  In subsequent step S202, the temperature T1 obtained in step S201 is compared with the threshold temperature Tth1 of the first ejection element substrate, and the temperature T2 is compared with the threshold temperature Tth2 of the second ejection element substrate. When the temperature T1 is equal to or higher than the threshold temperature Tth1 or the temperature T2 is equal to or higher than the threshold temperature Tth2, after performing step S203, which is a temperature rise suppression sequence, the process proceeds to step S206, and one recording operation is performed. If the acquired temperature of either ejection element substrate does not exceed the threshold temperature, the process proceeds to step S204. In step S204, based on the temperatures T1 and T2 acquired in step S201, an estimated temperature T1a of the discharge element row 332a1 closest to the second discharge element substrate is calculated among the first discharge element substrates. Subsequently, in step S205, T1a is compared with the threshold temperature Tth1. If T1a is equal to or higher than the temperature Tth1, after step S203, which is a temperature rise suppression sequence, is performed, the process proceeds to step S206, and one recording operation is performed. If T1a does not exceed Tth1, it is determined that the temperature of the entire first ejection element substrate is equal to or lower than Tth1, and the process proceeds to step S206 as it is to perform one recording operation. If all the recording operations are not completed after the end of one recording operation, the process returns to step S201, and this sequence is repeated until all the recording operations are completed. Here, the temperature rise suppression sequence is to provide a waiting time during which a recording operation is not performed for a certain period of time.

  In the present embodiment, the threshold temperature Tth2 of the second ejection element substrate is 70 ° C., but the color ink may cause a printing defect even at a lower temperature. Therefore, the threshold temperature of the first ejection element substrate is low. Tth1 is 55 ° C. In the present embodiment, since the black ink to be used is an ink whose discharge state is likely to become unstable when the temperature is low, the sub-heater is driven to keep the temperature at 35 ° C. or higher for the second discharge element substrate. Recording is performed in the state.

  Next, the temperature distribution in the first ejection element substrate and the calculation of T1a in step S204 will be described with reference to FIG. FIG. 4A is a cross-sectional view of the first and second ejection element substrates and the supporting member, taken along the line AA in FIG. The heat generated by driving the ejection elements and the sub-heater of the second ejection element substrate is transmitted from the substrate to the support member, and is transmitted to the first ejection element substrate side by the heat conduction of the support member. At this time, if the support member is a material having a high thermal conductivity such as metal, the heat conduction speed in the support member is fast, so the temperature distribution generated in the support member is eliminated in a short period of time, and the first discharge Temperature distribution is unlikely to occur in the element substrate. However, in the present embodiment, the support member is formed using alumina having a large heat capacity in order to suppress the rate of temperature increase. The thermal conductivity of alumina is 24 W / m · K. For example, the thermal conductivity of aluminum is 234 W / m · K, which is 1/10. As described above, when the support member is formed of a material having a low thermal conductivity, it takes time until the heat generated in the second discharge element substrate is transmitted to the first discharge element substrate. Temperature distribution occurs in the support member below the discharge element substrate. Since heat is transmitted from the support member to the first ejection element substrate, a temperature distribution similar to that of the support member is generated in the first ejection element substrate. There is a possibility that the ejection element array 332a1 to which heat is transmitted before the temperature sensor 333 has a higher temperature than the temperature detected by the temperature sensor. Therefore, it is necessary to calculate the estimated temperature T1a of the ejection element array 332a1 and determine whether to perform the temperature rise suppression control based on T1a.

  As an example of a method for estimating T1a from T1 and T2, there is a method of preparing a conversion table based on experimental values. That is, a table indicating the relationship between T1 and T2 and T1a is stored in the liquid ejection device. For example, with respect to the difference between T2 and T1, T1a can be estimated from T1 and T2 by using a correspondence table of how many degrees C. of T1 is a temperature added to T1.

  As another example of the method of estimating T1a from T1 and T2, there is a method of performing calculation based on the distance from the heat source. FIG. 4B is a graph simply showing how heat is transmitted from the heat source. Here, as an example, a case is shown in which an amount of heat that keeps the temperature of the heat source constant is continuously input. The temperature distribution has a larger slope as the distance from the heat source is closer, and the slope becomes gentler as the distance from the heat source is farther away. As time goes by, the range of heat influence spreads and becomes almost linear in the part close to the heat source. In this embodiment, when calculating T1a from T1 and T2, the temperature distribution between the second ejection element substrate and the temperature sensor on the first ejection element substrate is calculated in order to estimate the safety side more safely. Think linear.

FIG. 4C is a diagram illustrating an estimated temperature distribution between the second ejection element substrate and the temperature sensor of the first ejection element substrate. In order to estimate on the safer side, the region (discharge element, sub-heater part) that generates heat in the second discharge element substrate is considered as a constant temperature. The distance between the heat generation region of the second discharge element substrate and the temperature sensor of the first discharge element substrate is ds, and the distance between the heat generation region of the second discharge element substrate and the discharge element row 332a1 of the first discharge element substrate is Assuming that da, the temperature T1a of the ejection element array 332a1 is
T1a = T2− (T2−T1) × da / ds (Formula 1)
Estimated by

  In this embodiment, da is 12 mm and ds is 18 mm. For example, when T1 is 52 ° C. and T2 is 67 ° C., the temperatures of T1 and T2 are both lower than the threshold temperature (Tth1: 55 ° C., Tth2: 70 ° C.). However, when the estimated temperature T1a of the ejection element row 332a1 is calculated using (Equation 1), T1a = 57 ° C., and it is determined that the ejection element row 332a1 may be equal to or higher than the threshold temperature, and the temperature rise suppression control is performed. Done.

  In this way, even when a temperature distribution occurs in the substrate due to the thermal effect of other ejection element substrates arranged on the same support member, appropriate temperature rise suppression control can be implemented by means for estimating the effect. Thus, it is possible to maintain good print quality.

  In the present embodiment, the second discharge element substrate has a sub-heater, but the same means can be applied to a configuration without a sub-heater. In a configuration without a sub-heater, the starting points of da and ds may be the discharge element row of the second discharge element substrate that is closest to the first discharge element substrate.

  In the present embodiment, the temperature rise suppression sequence waits for a certain period of time before performing the recording operation. For example, the waiting time is changed after changing the waiting time parameter according to the difference between the substrate temperature and the threshold temperature. Is also possible.

  In the present embodiment, the case where the recording operation is performed using both the first and second ejection element substrates has been described. However, for example, the present invention can also be applied to a case where a color mode recording operation using only the first ejection element substrate is performed after a monochrome mode recording operation using only the second ejection element substrate. . In this case, only T2 and Tth2 are compared during the monochrome mode recording operation, and after switching to the color mode, T1 and Tth1, and T1a and Tth1 are compared. The comparison between T1a and Tth1 may be performed throughout the color mode recording operation. For example, the number and period of comparison may be limited based on the temperature of T2 at the end of the monochrome mode.

  Further, in the present embodiment, the support member is made of alumina. However, even when the support member is made of a material other than alumina, the present invention is used when the substrate temperature is inclined due to the low thermal conductivity of the support member. Applicable.

  Subsequently, a second embodiment of the present invention will be described. Since the configuration of the apparatus and the control of temperature rise suppression are the same as those in the first embodiment, a description thereof is omitted. The recording element substrate mounted on the head has a configuration in which the recording element array of the color element substrate 330 is shorter than the recording element array of the black element substrate 340.

  The color element substrate 330 is arranged so as to be closer to one side of the black element row in the direction in which the elements are arranged.

  Further, the diode sensor 343 for detecting the substrate temperature of the black element substrate 340 is disposed at a position far from the color element substrate 330. The diode sensor 333 for detecting the substrate temperature of the color element substrate 330 is provided at the end of the color element substrate 330 opposite to the side where the black diode sensor 343 is provided. It has been.

  In the second embodiment, in addition to the print mode (print mode 1) using the entire discharge element array shown in FIG. 5A, the discharge shown in FIGS. 5B and 5C. It has a recording mode (recording mode 2, recording mode 3) in which only a part in the element array direction is used.

  The recording mode 1 in FIG. 5A is a mode in which a recording operation is performed using all of the element arrays for both black and color.

  The recording mode 2 in FIG. 5B is a mode in which recording is performed using a part of the element array for black and the element array for color. At this time, with respect to the direction in which the recording elements are arranged, a part of the area used for black and the area for color do not overlap.

  The recording mode 3 in FIG. 5C is a mode in which recording is performed using a part of the element array for black and a part of the element array for color. At this time, with respect to the direction in which the recording elements are arranged, a part of the area used for black and a part of the area used for color are provided so as to have an interval.

  In the recording mode 1 and the recording modes 2 and 3, the distance from the heat generation region of the second ejection element substrate to the temperature sensor of the first ejection element substrate is different. For this reason, the ds value is switched according to the recording mode. In the present embodiment, ds is 18 mm in the recording mode 1 and ds is 21 mm in the recording mode 1, and the estimated value of T1a differs depending on the recording mode. In the case of the recording mode as shown in FIG. 5C, both ds and da are different from those in the recording mode 1. Therefore, the values of ds and da are switched according to the recording mode, or a temperature estimation table for T1a is prepared for each recording mode, and the table to be used is switched according to the recording mode. By doing so, it is possible to perform appropriate temperature rise suppression control even in an ink jet recording apparatus having a plurality of recording modes that use different recording element regions.

300 Liquid discharge head 330, 340 Discharge element substrate 332 Discharge element row 333, 343 Temperature sensor 350 Support member

Claims (10)

A support member; a first discharge element substrate disposed on the support member and having a discharge port for discharging a first liquid; and a discharge port disposed on the support member and discharging a second liquid. A second ejection element substrate; a first temperature sensor provided on the first ejection element substrate for detecting a temperature T1 of the first ejection element substrate; and provided on the second ejection element substrate. A liquid ejection apparatus comprising: a second temperature sensor that detects a temperature T2 of the second ejection element substrate;
An estimation unit that estimates a temperature T1a at a position near the second ejection element substrate on the first ejection element substrate based on the temperature T1 and the temperature T2.
When one of the temperature T1 and the temperature T1a is equal to or higher than the threshold temperature Tth1 of the first ejection element substrate, the temperature rise is suppressed before the recording operation using the first ejection element substrate is performed. A control unit that controls the temperature rise before the recording operation using the second ejection element substrate is performed when the temperature T2 is equal to or higher than the threshold temperature Tth2 of the second ejection element substrate; And a liquid ejection device.   The liquid ejection apparatus according to claim 1, wherein a threshold temperature Tth1 of the first ejection element substrate is lower than a threshold temperature Tth2 of the second ejection element substrate.   The liquid ejecting apparatus according to claim 1, wherein the position is between the first temperature sensor and the second temperature sensor.   4. The liquid ejection apparatus according to claim 1, wherein the first ejection element substrate has a plurality of ejection port arrays. 5.   5. The liquid ejection apparatus according to claim 1, wherein the controller performs temperature rise suppression control by providing a certain waiting time before performing the recording operation. 6.   6. The liquid ejection apparatus according to claim 1, wherein the first ejection element substrate has one or a plurality of ink supply ports, and the ink supply ports have ejection element arrays on both sides thereof. . Storage means for storing a table indicating a relationship between the temperature T1 and the temperature T2 and the temperature T1a;
The liquid ejecting apparatus according to claim 1, wherein the estimation unit estimates the temperature T1a using the table.   The estimation unit estimates the temperature T1a from the temperature T1 and the temperature T2 by linearly interpolating a temperature between the first temperature sensor and the second temperature sensor. The liquid discharge apparatus according to any one of the above. A plurality of relations between the temperature T1 and the temperature T2 and the temperature T1a for each of a plurality of recording modes having different use areas in the direction of the ejection element array of the first ejection element substrate and the second ejection element substrate. Storage means for storing the table of
The liquid ejection apparatus according to claim 1, wherein the estimation unit estimates the temperature T1a by using the table of the corresponding recording mode. A plurality of recording modes having different use areas in the discharge element row direction of the first discharge element substrate and the second discharge element substrate;
The estimation unit estimates the temperature T1a from the temperature T1 and the temperature T2 by linearly interpolating the temperature between the first temperature sensor and the second temperature sensor for each recording mode. The liquid ejection device according to claim 1, wherein

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