JP4836266B2 - Ink jet recording apparatus and recording method thereof - Google Patents

Description

  The present invention relates to an ink jet recording apparatus having a recording element array composed of a plurality of recording elements, and a recording method thereof.

<Recording head structure of inkjet recording apparatus>
There are various known ejection methods used in ink jet recording apparatuses. Among them, the method of ejecting ink in association with the expansion of bubbles generated by applying thermal energy to the ink has high resolution, compactness, low noise, and high speed. It has many advantages such as recording. For this reason, various recording heads of this type have been developed.

  A recording head of this type generally has an electrothermal conversion element (for example, a heat resistant resistance material such as HfB2, ZrB2, TaN2, TaSi) that generates heat by applying an electric drive pulse signal. Further, it has a printed wiring (for example, made of Al, Au, Ag, Cu, etc.) for supplying a driving pulse signal to the electrothermal conversion element. These are formed by IC technology. For example, a plurality of these are formed on a substrate such as Si, glass, or ceramic. Furthermore, liquid passages and discharge ports (hereinafter collectively referred to as nozzles) corresponding to each of the electrothermal conversion elements, a common liquid chamber for holding ink supplied to these liquid passages, and the common liquid chamber An ink chamber or the like for supplying ink is formed.

  In this case, when a plurality of nozzles are arranged at a high density, it is more preferable to arrange a plurality of nozzle rows in parallel and arrange them two-dimensionally than from one-dimensionally as a single nozzle row from the viewpoint of high-speed recording or the like. In recent years, a plurality of nozzles tend to be arranged two-dimensionally.

  As an example, two nozzle rows are shifted by half a pitch to increase the apparent resolution (see Patent Document 1), and the shifted nozzle row is composed of two types of large and small nozzles with different ink discharge amounts. There is an example (see Patent Document 2).

<Image Forming Method>
Using the above recording head, during recording, a drive pulse signal is selectively supplied to a plurality of electrothermal transducers based on image data, and ink is selectively selected from nozzles corresponding to the individual electrothermal transducers. To form a desired image.

<Problems of temperature rise>
Since the recording head using the electrothermal conversion element as described above generates thermal energy for foaming ink in accordance with the ejection operation, heat is generated in each nozzle. Most of the heat generated by this heat generation is dissipated into the atmosphere together with the ejected ink, but a part of the heat is also stored in the recording head, and the temperature of the ink in the recording head and the common liquid chamber is raised.

  Such a temperature rise affects the life of the recording head and the image reliability. Specifically, there are a discharge failure caused by a decrease in viscosity of the ink due to a temperature rise, an ink stain near the discharge port due to the discharge failure, and a discharge failure induced due to the ink stain. In addition, non-ejection due to disconnection of the electrothermal conversion element or its vicinity is likely to occur, and ejection failure due to deposition of foreign matter called scorch on the electrothermal conversion element is also likely to occur.

  In particular, when an ink containing a pigment and a dispersant that disperses the pigment is used as the ink, the dispersibility of the pigment is reduced by the high thermal energy generated by the electrothermal conversion element, and the pigment aggregates on the electrothermal conversion element. Easy to deposit as a burn.

  When the temperature of the recording head rises excessively in this way, the amount and speed of ink discharge change, causing density unevenness in the recorded image, graininess due to reduced landing accuracy of the ejected ink, and unevenness. It was a factor that lowered the recording quality.

<Explanation of conventional temperature rise measures>
Therefore, as a configuration of the conventional recording head, the peak temperature generated in a part of the heating element is provided in another part by providing a layer having a high thermal conductivity in a part of the lower part of the heating element such as an electrothermal conversion element. The structure which lowers by letting it escape is disclosed (refer patent document 3). Furthermore, a technique for detecting an abnormal temperature rise that occurs when a recording head is provided with a temperature measuring means to measure the temperature and the recording head performs an ejection operation without ink (see Patent Document 4), from a recorded image A technique for predicting the temperature rise (see Patent Document 5) has been proposed.
Japanese Patent Laying-Open No. 2001-353886 (page 18, FIG. 2) JP 2004-1489 (page 10, FIG. 1) Japanese Laid-Open Patent Publication No. 02-111552 (first page, claim 1, and third page, conventional technology) Japanese Patent Laid-Open No. 11-192724 (pages 3 to 4, means for solving the problem) JP 2004-314442 A (first page, claim 1)

  However, as described above, the integration of nozzles in the recording head has progressed. For example, when a plurality of nozzle rows are arranged in parallel and the nozzles are arranged two-dimensionally, a temperature difference occurs between the center and the end of the nozzle rows. It becomes easy.

  Then, it is necessary to perform temperature control by measuring the temperature distribution of the recording head or to prevent temperature rise as much as possible on the premise that such temperature distribution occurs. However, the structure of the recording head that can measure the temperature distribution finely for temperature control is complicated. In addition, the amount of information communicated between the recording apparatus main body and the recording head is significantly increased. For this reason, there arises a problem that high-speed recording and high reliability are not compatible. In addition, if scanning and recording is performed while ignoring such uneven temperature rise in the recording head, non-uniformity between bands recognized as unevenness is caused, and image quality is remarkably lowered. Further, as described above, there arises a problem that the recording element constituting the central portion of the nozzle row has a short life.

  According to the present invention, by avoiding such a problem, it is possible to perform recording while preventing an extremely large temperature difference between the nozzles during image formation. Also, the recording element is prevented from shortening its life due to extreme heat storage in the central part of the nozzle array, and further, for example, head destruction caused by emptying of the recording element in the central part of the nozzle array by taking in bubbles or the like is prevented. I can do it.

  In this way, it is possible to suppress the wasteful ink consumption by shortening the life of the recording head and replacing the recording head, and to prevent a decrease in recording speed caused by acquiring a fine temperature distribution, and to achieve a stable high quality. The object is to maintain image formation.

In order to achieve the above object, the present invention provides a plurality of nozzles having electrothermal conversion elements and supplying ink from a common ink liquid chamber in one direction, and provided in parallel with a direction orthogonal to the nozzle arrangement direction. A plurality of nozzle rows arranged, a first temperature measuring element provided at an end of the plurality of nozzle rows, and a position sandwiched between the plurality of nozzle rows and an intermediate portion of the nozzle arrangement direction An ink jet recording apparatus that performs recording using a recording head including a second temperature measuring element included in
Control is performed to start recording when the temperature measured by the first temperature measuring element is in a predetermined temperature range, and the temperature measured by the second temperature measuring element is set to a predetermined upper limit temperature. Recording control means for controlling the operation of the recording head to be as follows:
Recording stop control means for temporarily stopping recording when the difference between the temperature measured by the first temperature measuring element and the temperature measured by the second temperature measuring element is equal to or greater than a predetermined threshold. When,
Recovery control means for controlling the recovery means of the ink jet recording apparatus so as to perform recovery operation of the recording head after the recording stop by the recording stop control means;
An ink jet recording apparatus characterized by comprising:

In another aspect of the present invention for achieving the above object, a plurality of nozzles each having an electrothermal conversion element and supplying ink from a common ink liquid chamber are arranged in one direction and orthogonal to the nozzle arrangement direction. A plurality of nozzle rows provided in parallel with each other, a first temperature measuring element provided at an end of the plurality of nozzle rows, and a position sandwiched between the plurality of nozzle rows and the arrangement of the nozzles A recording method of an ink jet recording apparatus that performs recording using a recording head including a second temperature measuring element provided in an intermediate portion of a direction,
A recording start step for starting recording when the temperature measured by the first temperature measuring element is within a predetermined temperature range;
A recording control step of controlling the operation of the recording head so that the temperature measured by the second temperature measuring element is equal to or lower than a predetermined upper limit temperature;
A recording stop step for temporarily stopping recording when the difference between the temperature measured by the first temperature measuring element and the temperature measured by the second temperature measuring element is equal to or greater than a predetermined threshold; ,
A recovery step of performing a recovery operation of the recording head after recording is stopped by the recording stop step;
It is a recording method characterized by having.

  According to the present invention, the above-described configuration and control can shorten the life due to the temperature distribution in the recording head, suppress image defects, and do not reduce the image quality. Provide a method.

  This makes it possible to achieve high-speed recording with a low-cost configuration that does not require a complicated configuration for predicting the temperature distribution in the recording head or a predictive calculation, and can maintain high-quality and stable high-quality image formation. it can.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  In this specification, “recording” (hereinafter also referred to as “printing”) is not only for forming significant information such as characters and figures, but also for images on a wide range of recording media, regardless of significance. A case where a pattern, a pattern, or the like is formed or a medium is processed is also expressed. It does not matter whether it has been made obvious so that humans can perceive it visually.

  “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.

  The term “ink” should be broadly interpreted in the same way as the definition of “recording”. When applied to a recording medium, the “ink” forms an image, a pattern, a pattern, or the like, or processes the recording medium. It represents a liquid that can be subjected to the treatment. Examples of the ink treatment include solidification or insolubilization of the colorant in the ink applied to the recording medium.

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port, a liquid path communicating with the ejection port, and an element that generates energy used for ink ejection.

<Inkjet recording apparatus>
FIG. 10 is a perspective view of an example of a serial scan type ink jet recording apparatus (hereinafter also referred to as a recording apparatus) that is preferably used in the present invention.

  In FIG. 10, reference numeral 100 denotes a recording apparatus. Reference numeral 102 denotes a carriage. The carriage 102 includes recording head units 101A and 101B and a cartridge guide 103, and is provided on the guide shafts 104 and 105 so as to be scanned by a scanning mechanism (not shown).

  Each of the recording head units 101A and 101B has a recording head for discharging a plurality of colors of ink. That is, the recording head unit 101A includes a recording head (not shown) that can eject black (K), light cyan (C1), and cyan (C2) ink. The recording head unit 101B includes a recording head (not shown) that can eject light magenta (M1), magenta (M2), and yellow (Y) ink.

  110A and 110B are ink tanks filled with three types of ink corresponding to the recording head units 101A and 101B, respectively. When the two ink tanks are pushed into insertion openings provided separately in the cartridge guide 103, rubber seal portions (not shown) provided below the respective ink tanks and stainless steel provided in the recording head unit are provided. Pipes etc. are joined. By doing so, the ink can be supplied from the ink tanks 110A and 110B to the recording head corresponding to each ink.

  Reference numeral 109 denotes a recording head recovery unit, which includes a suction unit that sucks ink in the recording head. The recovery means 109 can also receive ink discharged by preliminary ejection from the recording head performed after recovery of suction by the suction means.

<Control configuration of inkjet recording apparatus>
FIG. 11 is a block diagram showing a control configuration of the recording apparatus shown in FIG.

  As shown in FIG. 11, the controller 600 includes an MPU 601, a ROM 602 that stores a program corresponding to a control sequence described later, a required table, and other fixed data. In addition, a special application integrated circuit (ASIC) 603 that generates control signals for controlling the carriage motor 650, the transport motor 651, and the print head 200 is provided. In addition, a system bus 605 is provided to connect the RAM 604, the MPU 601, the ASIC 603, and the RAM 604, which are provided with an image data development area, a work area for program execution, and the like to exchange data. Furthermore, an analog signal from a sensor group described below is input, A / D converted, and an A / D converter 606 that supplies a digital signal to the MPU 601 is configured.

  In FIG. 11, reference numeral 610 denotes a computer or the like as a supply source of image data, which is generically called a host device. Image data, commands, status signals, and the like are transmitted and received between the host device 610 and the recording device via an interface (I / F) 611.

  Further, reference numeral 620 denotes a switch group, such as a power switch 621, a print switch 622 for instructing the start of printing, and a recovery switch 623 for instructing the start of the recovery process. Consists of A sensor group 630 includes a position sensor 631 such as a photocoupler, a temperature sensor 210, and the like. Note that this temperature sensor in the present embodiment is a temperature measuring element, and is provided at the central portion and the end portion of the recording element array of the recording head 200 and can measure the temperatures of both portions.

  Further, 640 is a carriage motor driver that drives the carriage motor 650, and 642 is a conveyance motor driver that drives the conveyance motor 651. Reference numeral 644 denotes a head driver that drives the recording head 200.

<Recording head>
The arrangement of the nozzles of the recording head 200 (200K to 200Y) will be described in detail with reference to FIG.

  In the recording head 200 (200K, 200C1, 200C2, 200M1, 200M2, and 200Y), the nozzles 21 that discharge ink droplets are arranged in a line in one direction.

  A plurality of nozzle rows for each color are provided in parallel to the direction orthogonal to the nozzle arrangement direction. Specifically, there are A rows and B rows each having an even number and an odd number of nozzle rows for each color. There are a total of 4 columns. The four nozzle rows are arranged in the scanning direction of the recording head as shown in FIG. For example, in the recording head 200K for black (K), the even-numbered column 201K-Aev of the A column and the odd-numbered column 201K-Aod of the A column are arranged as shown in the figure, and the even-numbered columns 201K-Bev, B of the B column are also arranged. The odd-numbered column 201K-Bod is also arranged as shown in the figure. In this embodiment, the recording heads for other colors have the same configuration.

  FIG. 2 is an enlarged cross-sectional view of the black (K) recording head.

  In the recording head 200K for black (K), each nozzle 21 is provided with an ejection port, and each nozzle 21 is provided with one electrothermal conversion element 20 each. Ink is supplied from the common ink chamber 22 to each nozzle 21 for the recording head having such a configuration.

  As can be seen from this cross-sectional view, the central two nozzle rows (201K-Aod, 201K-Bev) are arranged at the end of the print head by the discharge ports and the ink flow paths of the nozzle rows (201K-Aev, 201K-Bod) at both ends. There is less area communicating with the part. That is, the stored heat is difficult to be transmitted in a direction perpendicular to the nozzle row. In particular, when there are bubbles in the ink flow path, it can be seen that this tendency becomes remarkable because heat is more difficult to be transmitted.

  In this way, when there are a plurality of nozzle rows, the configuration is not limited to this configuration, and as the number of nozzle rows is increased, the temperature rises more easily as heat is accumulated. In particular, the temperature rise is most severe in the nozzles at the center of the nozzle row in the central nozzle row, as compared to the nozzles at the end of the nozzle row in the nozzle row at both ends and the central nozzle row.

  Here, the ink ejection operation is as follows. An electrothermal conversion element (hereinafter also referred to as a discharge heater) 20 that generates thermal energy by supplying an applied voltage corresponding to each nozzle, and a transistor (not shown) that controls ON / OFF of a drive voltage to the discharge heater. It is disposed on the heater board 202. The discharge heater is heated by applying a drive pulse signal to the discharge heater based on the image data. Then, the ink on the upper part of the discharge heater changes from liquid to gas, and the ink is ejected from the discharge port by a shock wave due to rapid volume expansion at the time of this change.

<Recording operation>
The recording operation will be described with reference to FIG. 10. When a recording command is received from the host device, the recording medium 106 is fed by the paper feeding roller 108 and the paper feeding roller 107 and set at the recording position. Thereafter, the carriage 102 on which the recording head units 101A and 101B are mounted reciprocates along the guide shafts 104 and 105. At that time, a drive pulse signal is applied to the electrothermal transducer 20 provided in each nozzle of the recording head 200 (200K to 200Y) based on the image data, and ink based on the image data is ejected from each nozzle. Perform image formation. The recording operation is performed on the recording medium by alternately scanning the recording head and transporting the recording medium.

  The ink jet recording apparatus according to the present embodiment is a serial scan type recording apparatus that records a predetermined area pixel in a plurality of scans by performing known multipass recording.

<Temperature measuring element arrangement>
Next, the position of the temperature measuring element as the temperature sensor 210, which is one of the features of the present invention, will be described by taking a black (K) recording head as a representative.

  FIG. 4 shows an arrangement example of the temperature measuring elements. As described above, the nozzle array at the position where the first temperature measuring element 210B is sandwiched between the two central nozzle arrays (201K-Aod, 201K-Bev) where the temperature rises most easily at the end of the nozzle array. The second temperature measuring element 210A is provided in the middle part (here, the central part). In other words, the second temperature measuring element 210B is provided at the downstream end portion in the transport direction in the nozzle row (or may be the upstream end portion in the transport direction). In this embodiment, a multicolor printer is also targeted. In this case, of course, the same configuration and control may be performed for other colors individually.

<Drive pulse signal>
Next, an example of the drive pulse signal is shown.

  As shown in FIG. 6, the recording apparatus of this embodiment applies a drive pulse signal having a double pulse waveform composed of a pre-pulse and a main pulse to the heater, thereby heating the heater and ejecting ink. As is well known, the drive pulse signal having a double pulse waveform can control the foaming of the ink on the heater to some extent by changing the ratio of the pre-pulse signal and the main pulse signal. By utilizing this principle, it is possible to correct a change in the discharge amount or the like accompanying a temperature rise of the print head, or to correct a discharge amount variation or the like for each print head. Those details are omitted. In this embodiment, an example using a double pulse signal is described. However, the present invention is not particularly limited to a double pulse signal, and can be applied to a single pulse signal.

  A Heat Trigger in the figure is a trigger signal that specifies the timing for heating each heater, and is generated based on positional information of the carriage 102 sent from an encoder (not shown) during the reciprocating scanning of the carriage 102. In the recording apparatus of the present embodiment, the drive pulse signal (Heat Enable) is determined by designating P0, P1, P2, and P3 in the figure, which are times from the timing designated by the Heat Trigger.

  Hereinafter, as an example of a method for determining the drive pulse signal, a procedure for determining the drive pulse signal in the recording apparatus of the present embodiment will be described. However, the method for determining the drive pulse signal is not limited to the following method.

  The flow for determining P0, P1, P2, and P3 in this embodiment will be described with reference to the flowchart of FIG.

  In this embodiment, P0, P1, P2, and P3 are determined based on the print head temperature and the print head Rank information when printing for one scan (one scan) is started.

  First, prior to starting recording for one scan, Rank information (Head Rank) of the recording head is acquired in Step S110. Here, the Rank information of the recording head is information for correcting variation in resistance value of each recording head. Measure the resistance value of each recording head in advance and rank it, and write it as Rank information in a ROM (not shown) mounted on the recording head, or measure it on the recording device side and store it as Rank information. Keep it.

  Next, in step S120, the print head temperature (Head Tmp (° C.)) is acquired. Here, the temperature of the recording head is acquired by a temperature sensor 210 provided for each recording head.

  Next, in step S130, the PwNo. Is determined from the Rank information acquired in step S110 and the print head temperature acquired in step S120 with reference to the pulse number (PwNo.) Determination table shown in FIG. Is determined.

  PwNo. Is determined in step S140 from a drive pulse table (drive pulse signal determination table) (not shown) stored in storage means such as a ROM. The values of P0, P1, P2, and P3 corresponding to are determined.

  In step S150, printing for one scan is executed with the drive pulse signals based on P0, P1, P2, and P3 determined in step S140.

  In this embodiment, each PwNo. Is used as a drive pulse signal determination table to be referred to when determining the drive pulse signal. A drive pulse corresponding to is prepared in advance.

<Temperature control>
In the recording head having the above-described configuration, recording was performed with a drop size of 4 pl and a driving frequency of 25 kHz, with all nozzles being thinned out by 50%. On the other hand, when recording was performed under the same conditions except that bubbles were extremely contained in the ink liquid chamber, the temperature at the center of the nozzle row increased instantaneously, and the temperature difference ΔT from the end of the nozzle row was 30 ° C. or more. Also reached.

  When ink is contained in the ink chamber (with ink) and empty (without ink) in the recording head having such a configuration, the value measured by the non-contact thermometer from the ejection surface of the recording head is used. The graph shown is FIG.

  From FIG. 1, there is a significant difference in the temperature rise at the center (center) of the nozzle row of the recording head. However, since the end (end) of the nozzle row is easy to radiate heat, Don't be. In particular, at the end of the nozzle row when there is ink, the temperature rises more gently than in other cases. Conversely, the temperature rise at the center of the nozzle array is abrupt because it is difficult to dissipate heat without ink. Based on such a result, the present invention simply detects application (driving) of a drive pulse to the electrothermal conversion element in a state where there is no ink in the ink liquid chamber. In other words, it is possible to take measures to prevent the temperature drop or the temperature rise without distinguishing between a normal temperature rise and an abnormal temperature rise, but this will continue to air. In that case, damage to the electrothermal conversion element is large, and it is related to the life of the recording head.

  Therefore, first, let us consider performing temperature rise suppression means such as temporarily stopping recording when the central portion of the nozzle row reaches a predetermined temperature.

  However, it is very difficult to distinguish from the case where the temperature in the center of the nozzle row is gradually raised to a predetermined temperature in a normal recording state. This is because the temperature will continue to rise if ink is continuously ejected even in the presence of ink. In addition, there is a method of judging based on the rising temperature per predetermined time, but in the output of a normal natural image (hereinafter referred to as natural image), it is judged how often each nozzle is used. It is necessary to calculate in time series according to the frequency. However, this requires very high speed and complicated calculation, and in some cases, the recording speed may be affected.

  Therefore, in order to detect whether ink is contained in the ink liquid chamber, the following control was performed. First, based on the above temperature distribution, when the boundary temperature Tth serving as a predetermined threshold is Tth = 30 ° C. and ΔT (= TA−TB) ≧ Tth, the ink drop that does not contain ink in the ink liquid chamber It was controlled to detect. TA is a temperature measured by the temperature measuring element 210A, and TB is a temperature measured by the temperature measuring element 210B. In this embodiment, when it is detected that the ink has run out in the above relational expression, control is performed so that the operation is stopped after one scan during the recording and the recovery operation is performed.

  In addition, nozzles with an extremely large number of discharges per unit time have a high temperature rise. For this reason, when only some of the nozzles are extremely used, the temperature difference between the vicinity of the frequently used nozzle and the vicinity of the lowly used nozzle becomes large. In such a case, there may be a case where an erroneous detection is detected in the ink drop detection. For example, even when multi-pass printing is performed, if an image that is ejected only by the nozzles in the center of the nozzle row is printed, there is a possibility of erroneous detection if only the above relational expression is used. Therefore, when there are nozzles whose number of discharges per unit time is larger than a predetermined upper limit number of times, the above relational expression is not validated, and erroneous detection is prevented by suppressing the recovery operation. Specifically, this threshold value is a value that is 75% of the number of possible discharges per unit time. Note that the number of ejections per unit time can be measured by the controller 600 of the printing apparatus.

  However, when performing multi-pass printing, the same image position is superimposed and recorded several times, so it is very rare that the used (discharge) nozzles are biased only at the center of the nozzle row. For this reason, it is not an essential control of the present invention that the relational expression is not validated when the image density exceeds a predetermined value.

  Further, in the case of the ink jet system, the ink viscosity decreases as the temperature of the recording head or ink rises, so that ink droplets tend to be large, the discharge speed increases, and the amount of mist tends to increase. In order to avoid such an influence on the recording due to the temperature rise, the recording head is driven by increasing the recording time interval so that the temperature measured by the temperature measuring element 210A is not more than a predetermined upper limit temperature. It was effective to perform temperature control such as control. On the other hand, when the temperature is low, the viscosity of the ink becomes high and it may be difficult to eject the ink. Further, as described above, generally, the temperature at the end of the nozzle array is often lower than that at the center of the nozzle array, and the temperature of the recording head is often the lowest at the start of recording. Therefore, a good result was obtained with a simple configuration by using the measured value of the temperature measuring element 210B as the recording start permission temperature.

  Based on the above, in this embodiment, the recordable temperature range at the start of recording in each scan is 30 ° C. or more and 60 ° C. or less, and recording can be started when TB is 30 ° C. or more and 60 ° C. or less. did. The drive pulse in each recording head is a PwNo. Determined based on the average temperature measured by each temperature measuring element (210A and 210B). The drive pulse is equivalent to Further, as described above, when TA-TB was 30 ° C. or higher, control was performed so as to perform the recovery operation. Furthermore, conversely, it is also possible to adopt a configuration in which when the TB-TA is equal to or higher than a predetermined temperature, it is detected that ink has been dropped and control is performed to perform a recovery operation. In this case, for example, the threshold can be set to a lower temperature than in the case of TA-TB.

  Details of the ink jet recording method will be described with reference to the flowchart of FIG.

  When the recording process is started, first, in step S310, the temperature measuring element 210B measures TB to determine whether TB is 30 ° C. or higher and 60 ° C. or lower. When TB is not 30 ° C. or more and 60 ° C. or less, standby is performed so that TB becomes 30 ° C. or more and 60 ° C. or less. When TB reaches 30 ° C. or more and 60 ° C. or less, recording starts in step S320. During recording, each temperature measuring element (210A and 210B) measures TA and TB. At this time, in order to prevent TA from exceeding a predetermined upper limit temperature, recording is performed under recording control such as by providing a standby time depending on circumstances. When ΔT is equal to or greater than a predetermined threshold (30 ° C. or more) (step S330), recording stop control for temporarily stopping recording is performed, and after stopping recording, the process proceeds to step S340 to perform a recovery operation. The recovery operation is performed by the recovery control of the recovery means 109 by the controller 600. And after completion | finish of recovery operation | movement, it returns to step S330 again and it is judged whether (DELTA) T is 30 degreeC or more. If ΔT does not become 30 ° C. or higher after the start of recording, or if ΔT does not become 30 ° C. or higher after the end of the recovery operation, the recording is continued and resumed in step S350 and finished.

  In the present embodiment, a case where the present invention is applied to a so-called preliminary ejection operation in which the recording head ejects ink other than during normal image recording will be described.

  In particular, in the ink jet recording system, it is known that bubbles are accumulated in the nozzle when ink is continuously ejected. In order to discharge the air bubbles in the nozzle, it is common to perform an operation (so-called recovery operation) forcibly discharging ink from the recording head separately from the recording operation. After performing this recovery operation, preliminary ejection is performed in order to prevent recording with mixed ink. That is, mixed ink is consumed by performing ejection that is not involved in image formation. This preliminary ejection operation is performed with the number of shots peculiar to each printing apparatus. However, in the printing apparatus of this embodiment, color mixing can be prevented by performing 1000 ejections for each color and each nozzle in a non-image area. It was. However, since the preliminary ejection operation is performed for all nozzles, the total number of ejection operations is very large. If this discharge operation is performed at a low discharge frequency, it takes time and induces a reduction in the throughput of the main body. Therefore, it is necessary to perform at a certain high discharge frequency. In addition, when such a discharge operation is performed, the temperature may be increased to the same level or higher during recording.

  Therefore, in this embodiment, after the suction recovery operation as the recovery operation, when the measured temperature of the temperature measuring element 210A is 30 ° C. or higher and the measured temperature of the temperature measuring element 210B is 40 ° C. or lower, the preliminary discharge operation is started. did. If the temperature serving as the threshold is less than 30 ° C., ink may not be stably ejected, and if it exceeds 40 ° C., the temperature of the recording head after the preliminary ejection operation may be too high. Although it is the temperature set from this, it is not limited to these temperatures.

  When ΔT (= TA−TB) ≧ Tth and Tth = 30 ° C. after the preliminary ejection operation is completed, the recording operation to be performed after the recovery operation is stopped, the suction recovery operation is performed again, and again in the same state. An error is displayed when there is. The details will be described with reference to the flowchart of FIG.

  First, in step S210, a suction recovery operation is performed to replace the ink in the recording head. Next, in step S220, it is determined whether or not the measured temperature TA of the temperature measuring element 210A is 30 ° C. or higher and the measured temperature TB of the temperature measuring element 210B is 40 ° C. or lower. If TA is not lower than 30 ° C. and TB is not lower than 40 ° C., a temperature control operation is performed in step S230, and the process returns to step S220. If TA is 30 ° C. or higher and TB is 40 ° C. or lower, preliminary ejection is performed in step S240, and the process proceeds to step S250. In step S250, it is determined whether or not ΔT is 30 ° C. or less. If it exceeds 30 ° C., the process proceeds to step S260. In step S260, it is determined whether ΔT has exceeded 30 ° C. for the first time or the second time after the suction recovery operation and the preliminary discharge operation. If it is the second time, the process proceeds to step S270 to display an error and the process ends. If it is the first time, the process returns to step S210. If ΔT is equal to or lower than 30 ° C. in step S250, the process proceeds to step S280 and recording is completed.

  In this embodiment, the preliminary discharge operation start temperature range is set to a range where TA is 30 ° C. or higher and TB is 40 ° C. or lower, and control is performed so that no trouble occurs even when recording is performed at the temperature at the end of preliminary discharge. is doing. The temperature control range at the start of the preliminary ejection operation and the temperature control range at the time of actual recording are not necessarily the same. The present invention relates to controlling to use a recording apparatus in a predetermined temperature range, and the temperature range may be individually designated by each type of operation.

  In the first and second embodiments, the case of a recording head having two temperature measuring elements for one nozzle array group has been described. However, the present invention is not necessarily limited to two. The recording head of this embodiment has three temperature measuring elements, and an example of a recording head provided with temperature measuring elements 210A to 210C will be described with reference to FIG. In other words, the temperature measuring element 210B and the temperature measuring element 210C are provided at the downstream end and the upstream end of the nozzle row in the transport direction.

  FIG. 8 is a schematic diagram for explaining the nozzle arrangement when the recording head is viewed from the ejection surface as shown in FIG. As shown in FIG. 8, the temperature measuring element 210C newly added from FIG. 4 is located in the direction opposite to the temperature measuring element 210B. Since the recording head of this embodiment has a substantially symmetrical structure with respect to the top and bottom in the figure, the nozzle heat storage and heat dissipation state are almost symmetrical with respect to the top and bottom in the figure. However, since the nozzles are not necessarily used evenly, there is a slight difference between the temperatures measured by the temperature measuring elements 210B and 210C.

  Therefore, in this embodiment, the average value of the temperature measured three times with the temperature measuring element 210A is Tα, the average value of the temperature measured three times with the temperature measuring element 210B is Tβ, and the temperature measured three times with the temperature measuring element 210C. The average value was Tγ, and the average value of Tβ and Tγ was AveT. Then, when controlling the temperature of the recording head during recording, if ΔT = (Tα−AveT) ≧ 30 ° C. using this AveT, it is determined that there is no ink (abnormal temperature rise due to an empty state), and recording is interrupted. Recovery operation.

  The reason why the average values (Tα, Tβ, Tγ) of the measured temperatures by the temperature measuring elements and the average value AveT of Tβ and Tγ are used in the present example is as follows. The recording head used in this embodiment is substantially symmetric in the nozzle row direction, and Tβ and Tγ are usually at the same temperature when recording at a uniform density, so the temperature difference between Tβ and Tγ is biased by the nozzles used. Is considered to be the case. However, when recording a general image such as a natural image, it is rare that the nozzles on the temperature measuring element 210B side or the temperature measuring element 210C side are used evenly. In addition, it is rare that only the nozzle in the center of the nozzle row is used at a much higher frequency. Therefore, in this embodiment, Tα, Tβ, and Tγ are used to average temperature fluctuations for a very short time, and AveT is used to average a temporary temperature difference generated at each nozzle end. By doing so, it was possible to effectively detect the temperature rise of the recording head and the ink drop even when the nozzles used successively changed.

  As shown in the present embodiment, in the present invention, the number of temperature measuring elements is not necessarily limited to two. Further, in order to more accurately grasp the temperature around each temperature measuring element, the temperature measured by each temperature measuring element is measured a plurality of times, and the average value is used to determine the temperature rise of the recording head and ink drop. This calculation is also within the scope of application of the present invention.

  That is, in the present invention, when recording an image, a plurality of temperature measuring elements are arranged at locations where the temperature of the recording head is substantially different, and the temperature is controlled according to the temperature measured by them. In addition, when the temperature difference becomes wider than a predetermined threshold value, it is determined that ink has dropped.

5 is a graph showing values obtained by measuring the temperature of a recording head when ink is contained in an ink liquid chamber and when ink is empty. FIG. 3 is an enlarged cross-sectional view of a recording head used in an example of the present invention. It is a figure which shows an example of a pulse number determination table. FIG. 4 is a schematic diagram illustrating nozzle arrangement when the recording head is viewed from the ejection surface. It is a flowchart which shows the head rank acquisition sequence used in the Example of this invention. It is a figure which shows an example of a drive pulse signal. It is a flowchart which shows the detail of an example of recovery operation | movement. FIG. 4 is a schematic diagram illustrating nozzle arrangement when the recording head is viewed from the ejection surface. FIG. 3 is a diagram illustrating an arrangement of nozzles of a recording head used in an example of the present invention. 1 is a perspective view of an example of a serial scan type inkjet recording apparatus that is preferably used in the present invention. FIG. FIG. 11 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 10. It is a flowchart which shows an example of the inkjet recording method of this invention.

Explanation of symbols

20 Electrothermal conversion element 21 Nozzle 22 Ink liquid chamber 109 Recovery means 200 Recording head 210 Temperature sensor 210A Temperature measurement element 210B Temperature measurement element 210C Temperature measurement element 600 Controller

Claims (7)

A plurality of nozzle rows each having an electrothermal conversion element and supplying a plurality of nozzles supplying ink from a common ink liquid chamber in one direction and provided in parallel to a direction orthogonal to the arrangement direction of the nozzles; A first temperature measuring element provided at an end of the nozzle row, and a second temperature measuring element provided at an intermediate portion in the arrangement direction of the nozzles and sandwiched between the plurality of nozzle rows An ink jet recording apparatus that performs recording using a recording head comprising:
Control is performed to start recording when the temperature measured by the first temperature measuring element is in a predetermined temperature range, and the temperature measured by the second temperature measuring element is set to a predetermined upper limit temperature. Recording control means for controlling the operation of the recording head to be as follows:
Recording stop control means for temporarily stopping recording when the difference between the temperature measured by the first temperature measuring element and the temperature measured by the second temperature measuring element is equal to or greater than a predetermined threshold. When,
Recovery control means for controlling the recovery means of the ink jet recording apparatus so as to perform recovery operation of the recording head after the recording stop by the recording stop control means;
An ink jet recording apparatus comprising: A storage means for storing a plurality of predetermined drive pulses for the recording head, and a drive pulse table in which the temperature of the recording head is associated with the plurality of the drive pulses;
The inkjet recording apparatus performs recording with a driving pulse corresponding to an average temperature of a temperature measured by the first temperature measuring element and a temperature measured by the second temperature measuring element. Item 10. The ink jet recording apparatus according to Item 1. The first temperature measuring elements are respectively provided at both ends of the nozzle row,
3. The temperature measured by the first temperature measuring element is an average value of the temperatures measured by the first temperature measuring elements provided at both ends. 2. An ink jet recording apparatus according to 1. A measuring means for measuring the number of discharges per unit time of each of the nozzles;
The said recovery control means suppresses performing said recovery operation, when there exists a nozzle in which the frequency | count of discharge per unit time exceeds the predetermined upper limit frequency | count. 2. An ink jet recording apparatus according to item 1.   The recording control means has a difference between the temperature measured by the first temperature measuring element and the temperature measured by the second temperature measuring element smaller than the threshold value after completion of the recovery operation by the recovery control means. The inkjet recording apparatus according to claim 1, wherein the recording is resumed when the recording time is reached. The inkjet recording apparatus is an inkjet recording apparatus that performs recording by reciprocatingly scanning the recording head,
When the difference between the temperature measured by the first temperature measuring element and the temperature measured by the second temperature measuring element is equal to or greater than a predetermined threshold, the recording stop control means 6. The ink jet recording apparatus according to claim 1, wherein the recording is temporarily stopped after the end of the scanning at the time described above. A plurality of nozzle rows each having an electrothermal conversion element and supplying a plurality of nozzles supplying ink from a common ink liquid chamber in one direction and provided in parallel to a direction orthogonal to the arrangement direction of the nozzles; A first temperature measuring element provided at an end of the nozzle row, and a second temperature measuring element provided at an intermediate portion in the arrangement direction of the nozzles and sandwiched between the plurality of nozzle rows A recording method of an ink jet recording apparatus that performs recording using a recording head comprising:
A recording start step for starting recording when the temperature measured by the first temperature measuring element is within a predetermined temperature range;
A recording control step of controlling the operation of the recording head so that the temperature measured by the second temperature measuring element is equal to or lower than a predetermined upper limit temperature;
A recording stop step for temporarily stopping recording when the difference between the temperature measured by the first temperature measuring element and the temperature measured by the second temperature measuring element is equal to or greater than a predetermined threshold; ,
A recovery step of performing a recovery operation of the recording head after recording is stopped by the recording stop step;
A recording method characterized by comprising:

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