JP2009262404A - Recording device and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording device and recording method by means of which the high quality of an image obtained by recording is maintained by coping with an increase in the viscosity of a liquid in a recording head after preliminary ejection. <P>SOLUTION: The recording device includes an elapsed time detecting mechanism that detects an elapsed time from a preliminary ejection, and an ejection energy changing mechanism that changes ejection energy for ejecting a liquid droplet ejected from a recording head. The ejection energy changing mechanism changes the ejection energy in accordance with the elapsed time from the preliminary ejection detected by the elapsed time detecting mechanism. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording apparatus in which preliminary ejection is performed by ejecting liquid that does not contribute to image recording to a portion other than a recording medium as a recovery operation for maintaining a good liquid ejection state by the recording head, and such The present invention relates to a recording method using a recording apparatus.

  Conventionally, as a recording apparatus that performs recording on various recording media, since high-density and high-speed recording operations are possible, inkjet recording apparatuses have been widely used as output means and the like of various apparatuses. In general, such an ink jet recording apparatus performs recording by discharging droplets from a recording head to a recording medium through an ejection port.

  Since the ink jet recording apparatus has a structure in which the liquid once stored in the recording head is discharged as droplets from the discharge port, the liquid stored around the discharge port in the recording head communicates with the atmosphere through the discharge port. Exposure to the atmosphere. Thus, when the liquid stored around the discharge port is exposed to the atmosphere, moisture contained in the liquid in the portion in contact with the atmosphere may evaporate and the viscosity of the liquid in that portion may increase. .

  If the viscosity of the liquid stored in the recording head increases, the landing accuracy of the ejected droplets may decrease, or non-ejection may occur, and the quality of the image obtained by recording may be reduced. May decrease. Therefore, it is preferable to suppress the thickening of the liquid inside the recording head.

  For this reason, depending on the recording apparatus, preliminary recording may be performed in advance of recording, in which liquid that has been thickened by discharging droplets to a portion other than the recording medium is discharged from the recording head in advance. In this way, preliminary ejection is performed in the previous stage of recording, so that during recording, the thickened liquid is discharged from the recording head and liquid in a good state is stored. The quality of the obtained image is maintained high.

  In addition to the preliminary ejection, the recording apparatus described in Patent Document 1 has been proposed as a recording apparatus corresponding to the increase in the viscosity of the liquid as described above. Japanese Patent Laid-Open No. 2004-260688 discloses an ejection that is driven when a droplet is ejected for the first time according to a non-recording time, which is a time between the previous recording and the next recording. A recording device for adjusting energy is disclosed. The means for adjusting the discharge energy is specifically disclosed for adjusting the pulse width and adjusting the voltage value of the pulse signal for the electric signal for driving the electrothermal transducer. In this way, the ejection energy when the droplet is ejected for the first time is adjusted according to the non-recording time, which is the time between the last recording and the next recording. Thus, stable discharge of droplets is maintained, and high quality of an image obtained by recording is maintained.

JP-A-4-39051

  According to the above-described preliminary ejection and the recording apparatus disclosed in Patent Document 1, the thickening occurring at the interval between the previous recording and the next recording is considered. However, it is conceivable that the thickening of the liquid around the ejection port in the recording head proceeds even during recording. Depending on the recording data, there may be a case in which a state in which liquid droplets are not ejected from some of the ejection ports continues even during recording. For example, when a part of the image is blank, there is a tendency that the ejection port of the recording head is not used as a whole, and the liquid thickening of the entire ejection port of the recording head is likely to proceed.

  As described above, when the viscosity of the liquid around the ejection port in the recording head is increased during the recording, the landing accuracy of the ejected liquid droplets is lowered or non-ejection occurs. It is possible. Thereby, the quality of the image obtained by recording may be deteriorated.

  Therefore, in view of the above circumstances, the present invention is compatible with the thickening of the liquid in the recording head after the preliminary ejection is performed, and thereby a recording apparatus and a recording method in which the quality of an image obtained by recording is maintained high. The purpose is to provide.

  The recording apparatus of the present invention is a recording apparatus capable of performing recording by discharging droplets from a recording head to a recording medium and performing preliminary discharge for discharging droplets not involved in recording from the recording head. An elapsed time detection mechanism that detects an elapsed time from the recording head, and a discharge energy change mechanism that changes discharge energy for discharging droplets from the recording head, the discharge energy change mechanism including the elapsed time detection mechanism The discharge energy is changed in accordance with the elapsed time from the preliminary discharge detected by the above.

  The recording apparatus of the present invention is a recording apparatus capable of performing recording by discharging droplets from a recording head to a recording medium and performing preliminary discharge for discharging droplets not involved in recording from the recording head. The recording head performs recording while scanning in a predetermined direction intersecting a transport direction in which the recording medium is transported, and performs preliminary ejection at a predetermined position in the predetermined direction, and ejects droplets from the recording head. A discharge energy changing mechanism for changing the discharge energy of the recording head, wherein the discharge energy changing mechanism changes the discharge energy according to a distance scanned from the predetermined position where the recording head performs preliminary discharge. To do.

  Further, the recording method of the present invention performs recording by ejecting droplets from a recording head to a recording medium, and recording by a recording apparatus capable of performing preliminary ejection for ejecting droplets not involved in recording from the recording head. In the recording method, the elapsed time detecting step for detecting the elapsed time from the preliminary ejection, and the droplets ejected from the recording head according to the elapsed time from the preliminary ejection detected in the elapsed time detecting step are discharged. And a discharge energy changing step for changing the discharge energy for every hour.

  Further, in a recording method for performing recording by discharging droplets from a recording head to a recording medium, and performing recording by a recording apparatus capable of performing preliminary discharge for discharging droplets not involved in recording from the recording head, The recording head performs preliminary ejection at a predetermined position in a predetermined direction intersecting the transport direction in which the recording medium is transported, and a liquid according to the distance scanned from the predetermined position at which preliminary ejection is performed in the preliminary ejection step. And a step of changing the discharge energy for each scanning distance for changing the discharge energy for discharging the droplets.

  According to the present invention, since the droplet is discharged from the recording head according to the time after the preliminary discharge is performed, the droplet is discharged by the thickening of the liquid inside the recording head during the recording. It is possible to suppress a drop in droplet landing accuracy. Thereby, it can suppress that the quality of the image obtained by recording falls.

  Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  In the embodiment described below, a recording apparatus using an ink jet recording method will be described.

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

  “Recording medium” means not only paper used in general recording apparatuses but also a wide range of materials that can accept ink, such as cloth, plastic film, metal plate, glass, ceramics, wood, leather, etc. Shall.

  Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. By being applied on the recording medium, it can be used for 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). It shall represent a liquid.

  The overall configuration and control configuration of the inkjet recording apparatus common to the embodiments will be described below.

  FIG. 1 is an external perspective view of an ink jet recording apparatus according to the present invention. A recording apparatus 100 shown in FIG. 1 includes a carriage 11 in which a head cartridge 50 in which a recording head and an ink tank for storing ink are integrated is housed. The carriage 11 scans in a predetermined direction that intersects the conveyance direction of the recording medium, in this embodiment, in particular, a direction orthogonal to the conveyance direction. Therefore, recording is performed while the recording head scans in a predetermined direction that intersects the transport direction in which the recording medium is transported. The scanning direction in this embodiment is hereinafter referred to as a main scanning direction.

  The carriage 11 is pierced and supported by the guide shaft 6 so as to be scanned in a direction perpendicular to the conveyance direction of the recording medium. A belt 4 is attached to the carriage 11, and a carriage motor 12 is attached to the belt 4. As a result, the driving force by the carriage motor 12 is transmitted to the carriage 11 via the belt 4, so that the carriage 11 can be moved in the main scanning direction guided by the guide shaft 6.

  In addition, a flexible cable 13 for transferring an electrical signal from a control unit to be described later to the recording head of the head cartridge 50 is attached to the carriage 11 so as to be connected to the head cartridge 50. Further, the recording apparatus 100 is provided with a cap 141 and a wiper blade 143 that are used for performing recovery processing of the recording head. The recording apparatus 100 also includes a paper feeding unit 15 that stores recording media in a stacked state, an encoder sensor 16 that optically reads the position of the carriage 11, and the like.

  FIG. 2 is a perspective view showing the configuration in the vicinity of the carriage 11 of the recording apparatus shown in FIG. 1 in more detail, and has the same configuration as that in the vicinity of the carriage of the conventional recording apparatus described above. As shown in FIG. 2, in the recording apparatus 100, the head cartridge 50 is detachably mounted inside the carriage 11. The recording head 22 in the head cartridge 50 shown in FIG. 2 is provided with six head cartridges 50 corresponding to six colors of ink in order to enable high-quality color recording with a photographic tone. These head cartridges 50 correspond to six color inks of black (K), light cyan (LC), dark cyan (C), light magenta (LM), dark magenta (M), and yellow (Y). Yes. In this embodiment, as the head cartridge 50, six color head cartridges 50 </ b> K, 50 </ b> LC, 50 </ b> C, 50 </ b> LM, 50 </ b> M, and 50 </ b> Y are arranged inside the carriage 11. In these head cartridges 50, recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y corresponding to the respective colors are formed so that six colors of ink can be ejected. These recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y are also referred to as recording heads 22 below. The head cartridge 50 includes ink tanks 21K, 21LC, 21C, 21LM, 21M, and 21Y that store ink to be supplied to the recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y. Yes. Hereinafter, the ink tanks 21K, 21LC, 21C, 21LM, 21M, and 21Y are collectively referred to as the ink tank 21. Ink from the respective ink tanks 21K, 21LC, 21C, 21LM, 21M, and 21Y is supplied to the recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y.

  A cap is disposed at one end of the recording apparatus 100 in the main scanning direction at a position corresponding to each of the recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y in the head cartridge 50. In the present embodiment, the caps 141K, 141LC, 141C, 141LM, 141M, and 141Y are arranged so as to correspond to the recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y that discharge the inks of the respective colors. . These caps 141K, 141LC, 141C, 141LM, 141M, and 141Y are collectively referred to as a cap 141 hereinafter.

  The cap 141 performs capping by closing the ejection port of the recording head 22 when performing the suction recovery of the recording head 22. In this state, for example, a suction pump is driven to form a negative pressure in the cap 141, and ink in the recording head 22 is sucked through the ejection port. As described above, by sucking the ink around the ejection port in the recording head 22, the foreign matter and the thickened ink around the ejection port are discharged to the outside of the recording head 22 and stored in the recording head 22. Ink is kept in good condition. Further, in order to prevent the ink inside the recording head from drying corresponding to a long non-recording time, the discharge port 23 is blocked by the cap 141 while the recording apparatus is not used. In this embodiment, the recording head and the ink tank are integrally formed as a head cartridge 50. However, the head cartridge 50 is configured so that the recording head and the ink tank can be separated from each other. Also good.

  In the present embodiment, six head cartridges 50 corresponding to six colors, the recording head 22, the ink tank 21, and the cap 141 are used. However, the present invention is not limited to this. A recording apparatus equipped with more head cartridges corresponding to seven or more colors may be used, or a recording apparatus corresponding to head cartridges of five or less colors may be used.

  FIG. 3 is a plan view of the recording head 22 as viewed from the recording medium side. As shown in FIG. 3, the recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y have 1280 ejection port arrays with a density of 1200 dpi. These six recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y are arranged in order in the main scanning direction. The amount of ink ejected from each ejection port 23 at a time is about 4 ng.

  In order to realize high image quality recording with these six color inks, the opening area of each discharge port 23 is adjusted so that small dots are formed when the ink is discharged.

  Next, the configuration of the recording head 22 of the head cartridge 50 will be described with reference to FIGS. FIG. 4 is a cross-sectional view along the ink flow path 31 that leads from the ink tank 21 to the recording head 22 in the recording head 22. FIG. 5 is a cross-sectional view taken along the line V-V in FIG.

  The recording head 22 has a heat generating head 25 having a heat generating resistor layer 28 used for heat-sensitive recording (such as glass, ceramic, plastic, or the like in which an ink flow path 31 is formed), but is not limited thereto. ) And are obtained. The heat generating head 25 is formed of a protective film 26 formed of silicon oxide or the like, aluminum electrodes 27-1, 27-2, a heat generating resistor layer 28 formed of nichrome or the like, a heat storage layer 29, heat dissipation formed of alumina or the like. It has a good substrate 30. The space defined by the orifice plate 33 and the substrate 30 of the recording head 22 is filled with ink, and a meniscus 34 is formed inside the ejection port 23.

  Here, when an electrical signal is applied to the electrodes 27-1 and 27-2, the region indicated by n of the heat generating head 25 is rapidly heated, and bubbles are generated in the ink 32 around this region. The ink in the recording head 22 is ejected through the ejection port 23 due to the increase in pressure due to the generation of bubbles, and becomes a recording droplet 24 that flies toward the recording medium 1. Thus, in this embodiment, the heat generating head 25 functions as an ejection energy generating element that ejects ink droplets.

  In the present embodiment, the ejection port 23 in the recording head 22 of the head cartridge 50 is formed as shown in FIG. 3, but the present invention is not limited to this. FIG. 6 shows an arrangement of the ejection ports of the recording head in another embodiment. In the recording head shown in FIG. 6, the discharge ports are arranged in two rows, and one of the two discharge port rows has a pitch in which the discharge ports are arranged with respect to the other discharge port row. Is offset by half.

  Next, a recording operation in the recording apparatus having the above configuration will be described in detail with reference to FIGS.

  First, a plurality of recording media 1 stacked on the paper supply unit 15 are supplied one by one by a paper supply roller (not shown). When the sheet is fed from the sheet feeding unit 15 by the sheet feeding roller, the recording medium 1 is moved between the recording head 22 and the platen (not shown) by a pair of conveying rollers 3 by an auxiliary conveying roller (not shown) such as a spur or a roller. Is conveyed by.

  On the other hand, ink is supplied from the ink tank 21 to the recording head 22, and the recording head 22 moves to the recording medium 1 in accordance with the image signal while moving in the arrow B direction (forward scanning direction) in FIG. 2. Recording is performed with a width corresponding to. In this recording, the carriage motor 12 is driven and scanned based on the image signal according to the reading timing of the encoder 16 while the recording medium 1 is conveyed, and an image is recorded by ejecting and adhering droplets onto the recording medium 1. ing. When recording for one scan in the direction of arrow B (main scanning direction) is completed, the recording head 22 returns to the original home position and performs recording in the direction of arrow B again. Before the next recording operation is started after the end of one recording operation (one scan) in one direction, the conveying roller pair 3 is driven to intermittently move the recording medium 1 in the direction of arrow A by a predetermined amount. Transport to.

  In this way, an image is recorded on the recording medium 1 by repeating the recording operation for one scan and the conveyance of a predetermined amount of the recording medium.

  If necessary, the recording head 22 returns to the home position, and suction recovery or wiping is performed on the recording head for the purpose of eliminating clogging of the discharge port 23 by the recovery mechanism. As described above, the cap 141 closes the ejection port 23 of the recording head 22 for the ink suction operation of the ejection port 23 or to prevent drying when left. The wiper blade 143 wipes the surface of the discharge port 23 of the recording head 22 while moving in the direction of the arrow C, and removes extra attached ink.

  Next, a control configuration for performing control when recording is performed by the above-described apparatus will be described.

  FIG. 7 is a block diagram showing the configuration of the control circuit of the entire recording apparatus according to the present invention. In the figure showing the control circuit, reference numeral 1700 denotes an interface for inputting a recording signal. Reference numeral 1701 denotes a CPU, 1702 denotes a ROM that stores a control program executed by the CPU 1701, an error processing program, and the like, and 1703 temporarily stores various data (such as the recording signal and recording data supplied to the recording head 22). RAM. Reference numeral 1704 denotes a gate array (GA) that controls supply of recording data to the recording head 22 and also performs data transfer control among the interface 1700, the CPU 1701, and the RAM 1703. Reference numeral 12 denotes a carriage motor for conveying the recording head 22, and 1709 denotes a conveyance motor for conveying the recording medium. Reference numeral 1705 denotes a head driver for driving the recording head 22, and reference numerals 1706 and 1707 denote motor drivers for driving the transport motor 1709 and the carriage motor 12, respectively.

  The operation of the above control configuration will be described. When an image signal is input to the interface 1700, the image signal is converted into recording data for recording between the gate array 1704 and the CPU 1701. The motor drivers 1706 and 1707 are driven, and the recording head 22 is driven in accordance with the recording data sent to the head driver 1705 to perform recording.

  In the present embodiment, a control program executed by the CPU 1701 is stored in the ROM 1702. However, the present embodiment is not limited to this, and a configuration is also possible in which a control program can be changed from a host computer connected to the recording apparatus 100 by further adding an erasable / writable storage medium such as an EEPROM. it can.

  Further, the temperature control inside the recording head 22 is performed by the CPU 1701 driving the heat retaining heater 1710 according to a value obtained from the thermistor 1708 that detects the ambient temperature where the recording apparatus 100 is installed. The heat retaining heater 1710 is provided in the vicinity of the ejection unit row where the heat generating heads for ejecting ink are arranged, and is driven ON / OFF to control the temperature of the ink. Further, the internal temperature of the recording head 22 is detected by a temperature sensor 1711 provided in the recording head 22.

  An interface 1700 is an image processing unit (not shown) such as a connected host device that converts input image signals input in RGB or CMYK into print data for six colors including dark ink and light ink. The output image signal is received.

  The conversion in this process is to convert the input image density signal level to the output image density signal level as shown in FIG. Here, in order to simplify the description, a case will be described as an example where two types of light cyan and dark cyan are used as the same color inks having different densities and the density signal level takes a value of 0 to 255.

  As shown in this figure, the input image density signal levels 0 to 128 are converted so that only light cyan is recorded, and the input image density signal levels 129 to 255 are converted to light cyan and dark. Performs conversion to record in cyan. The signal value obtained by adding the light cyan output density signal level and the dark cyan output density signal level to the input image density signal levels 129 to 255 is always 255. For this reason, in this input image density signal level region, the light cyan output density signal level inverted is a dark cyan signal, and conversely, the dark cyan output density signal level inverted is light cyan. Signal. Accordingly, print data for dark cyan and print data for light cyan can be generated by performing only table conversion for light cyan input density signal levels or table conversion for dark ink input density signal levels. it can.

  Hereinafter, an embodiment relating to recording by the ink jet recording apparatus having the above-described configuration will be described.

<First embodiment>
The recording operation of the first embodiment will be described below with respect to the main part of the present invention. FIG. 9 shows a main part of the control system shown in FIG. 7 in the recording apparatus of the present embodiment. The control unit 200 in FIG. 9 includes a CPU 1701, a ROM 1702, a RAM 1703, and the like, and recording is performed by outputting recording data received from the outside to the driving unit 202. The control means 200 stores drive pulse changing means 207, measuring means 204, change determining means 205, and storage means 206. The recording head 22 includes a memory 107 capable of writing information about the recording head 22 including a use history (driving history) for each recording head. When the recording head 22 is mounted, the control unit 200 acquires the usage history of the recording head 22 from the information about the recording head for each recording head 22 stored in the memory 107. In addition, the control unit 200 appropriately stores information in the storage unit 206 in the memory 107 as head information. Thereby, even when the recording head 22 is attached / detached, the use history of the memory 107 in the previous recording head 22 is grasped, and an appropriate driving pulse corresponding to the use history is set for each recording head 22. Can do.

  During recording, ink is ejected from the recording head, and ink droplets are landed on the recording medium to perform recording. At this time, the recording head performs recording while scanning in the main scanning direction, and after the recording for one scan is performed, the recording medium is transported in a direction orthogonal to the main scanning direction, so that the recording medium is conveyed. Recording is performed.

  When recording is performed, the measuring unit 204 in the control unit 200 measures the number of times the heating head 25 is driven as its usage history (driving history). The measured number of driving of the heat generating head 25 for each recording head 22 is stored in the memory 107 capable of storing data for each recording head 22. Then, the measurement result is transferred to the control unit 200 and stored in the storage unit 206. In addition, the number of times the heating head 25 is driven for each recording head 22 is updated each time it is measured. At the start of recording, the determination unit 205 determines the drive pulse change timing for each recording head 22 based on the number of times of driving for each recording head 22 stored in the storage unit 206. For the recording head 22 that has reached the change timing, the drive pulse changing means 207 changes the drive pulse. When the drive pulse is changed, the optimum drive pulse is selected for each recording head 22 based on the measurement result of the measuring unit 204 and the data of the drive condition table (drive pulse table) 203. In the driving condition table 203, the number of times of driving as a measurement result of the measuring unit 204 and driving pulses (driving energy) are associated with each other, and a driving pulse corresponding to the former number of times of driving can be selected. The driving unit 202 drives the heat generating head 25 for each recording head by the selected driving pulse. In this way, the drive pulse that is a reference when ink is ejected is set for each recording head.

  In setting the drive pulse, in the present embodiment, the drive pulse width applied to the heat generating head 25 of the recording head 22 is fixed (1.0 μs: the drive pulse having the minimum ejection energy at the drive voltage of 16.24 V is set. )is doing. In this embodiment, as will be described later, the ejection energy is changed by changing the drive voltage. The drive voltage at which the minimum discharge energy is obtained is set as a reference voltage. And the discharge energy at this time is set as the reference discharge energy. As described above, the reference ejection energy is set in advance before the preliminary ejection and recording are performed.

  By the way, if the recording head does not perform recording to some extent, the water content of the ink inside the recording head evaporates, and the color material density of the ink near the ejection port increases. Accordingly, in order to prevent the ink around the ejection port in the recording head from being in such a state, the preliminary ejection for discharging the ink around the ejection port to the outside at the stage before recording or during the recording. Discharging is performed. The preliminary ejection is performed when the recording head 22 ejects ink droplets that are not involved in recording to a place other than the recording medium. FIG. 10 shows the positional relationship between the position of the recording head where the preliminary ejection is performed and the recording medium.

  Preliminary ejection is performed at a predetermined position in a predetermined direction in a direction that intersects the conveyance direction in which the recording medium is conveyed and in which the recording head scans. In the present embodiment, as shown in FIG. 10, the preliminary ejection is performed in a state where the recording head 22 is located at a position corresponding to the ink receiving portion 62 provided on the home position side. As described above, the recording head 22 performs preliminary ejection before recording at the receiving portion 62 in FIG. 10, and after performing preliminary ejection, the recording head 22 scans in the main scanning direction and moves onto the recording medium. Recording will be performed.

  In the present embodiment, the drive pulse for the heat generating head 25 that is driven to eject droplets from the recording head when recording is performed is changed according to the time after the preliminary ejection. In the present embodiment, the drive pulse changing unit 207 of the control unit 200 adjusts the drive pulse as a discharge energy changing mechanism that changes the discharge energy for discharging the droplets discharged from the recording head. Hereinafter, the change amount (ratio) of the drive voltage with respect to the preset reference voltage is referred to as a K value. FIG. 10 shows the divided areas on the recording medium. The drive pulse when ink is ejected from the recording head 22 changes according to the divided areas. In the present embodiment, the recording medium is divided into a plurality of areas. In particular, in the present embodiment, the recording medium is divided into three areas. Region A is the position closest to the receiving portion 62 where preliminary ejection is performed, region B is the next closest region to the receiving portion 62, and region C is the farthest region from the receiving portion 62. As described above, the path scanned by the recording head in this embodiment is divided into three regions according to the distance from the position corresponding to the receiving portion 62 that is a predetermined position. In each of the three divided areas, a K value as a coefficient is set according to the distance from the position corresponding to the receiving portion 62 that is a predetermined position. In the present embodiment, the recording medium is divided into three areas. However, the present invention is not limited to this, and the recording medium may be divided into three or more areas. May be.

  Here, since the area A is the area closest to the receiving portion 62 where the recording head 22 performs preliminary ejection, the time after the preliminary ejection is performed is short when the recording head 22 passes through the area A. Therefore, while the recording head 22 is in this region A, the discharge is performed satisfactorily even if the discharge energy for discharging the ink is relatively small. Here, in this embodiment, the scanning speed of the carriage moves at a constant speed, and the speed is 25 inches per second. For this reason, the time for passing through the region A is from when preliminary discharge is performed until 1 second elapses.

  Subsequently, when the recording head 22 passes through the region B, the time since the preliminary discharge is performed is longer than when the recording head 22 passes through the region A, and thus there is a possibility that the discharge is not performed normally. is there. Here, “possible” means that there is a discharge port that ejects ink to perform recording in the area A and a discharge port that does not eject ink, depending on the recording data, and is stored by the discharge port. This is because there is variation in the state of the ink. In the ejection port where recording is frequently performed in the area A, since the new ink is continuously filled, the degree of increase in the viscosity of the stored ink is small. When the ink is sufficiently discharged from the discharge port in the area A, since the discharge port is left in the region B for a short time, the ink is normally discharged from the discharge port. On the other hand, in the ejection port where recording is not performed in the area A, the water contained in the ink is evaporated by exposing the periphery of the ejection port to the atmosphere, and the viscosity of the ink increases. Therefore, when the recording head 22 passes through the region B, there is a possibility that a larger ejection energy is required when ejecting ink than when the recording head 22 passes through the region A.

  Further, depending on the recording data, when the recording head 22 passes through the region C, there is a possibility that a larger amount of ejection energy is required. Here, the time passing through the region B is between 1 second and 1.5 seconds after the preliminary ejection. In the region C, there is a possibility that the thickening of the ink around the ejection port further proceeds. The time for the carriage to pass through the region C is between 1.5 seconds and 2 seconds after the preliminary ejection.

  Thus, the ejection energy required for ink ejection changes according to the time since preliminary ejection has been performed. Corresponding to this, in the present embodiment, in the region B and the region C, the ejection energy for ejection is changed. FIG. 11 shows the relationship between the area and the K value indicating the amount of change in ejection energy. Since the K value varies from nozzle to nozzle, it is defined with a certain range. In the present embodiment, in the region A, the K value is set to 1.1 to 1.2 with respect to the standard discharge energy. In the areas B and C, the K value is gradually increased. In region B, 1.15 to 1.25 is set, and in region C, 1.2 to 1.3 are set. Then, the drive pulse changing means 207 serving as the ejection energy changing mechanism is adapted to the area by multiplying the reference ejection energy used as a reference by the K value as the coefficient set in the area where the recording head 22 is located. Change to the discharged energy. As described above, the drive pulse changing unit 207 as the ejection energy changing mechanism functions as a pulse voltage adjusting mechanism that adjusts the voltage in the pulse signal for driving the heat generating head 25 when ejecting ink droplets.

  According to the recording apparatus of the present embodiment, the ejection energy is set according to the distance from the position corresponding to the ink receiving portion 62 where the preliminary ejection is performed to the position of the recording head. In this embodiment, the K value at the time of ink ejection is increased according to the distance from the position at the time of preliminary ejection in the region to the current position of the recording head. As a result, at a position away from the position where the preliminary ejection is performed, ink is ejected with high ejection energy according to the distance. Therefore, even if the ink around the ejection port thickens as time elapses from the preliminary ejection, the ink is ejected by the ejection energy that overcomes it. Accordingly, it is possible to perform ejection without being affected by the increase in the viscosity of the ink, and it is possible to accurately land the ejected ink droplet at a predetermined position without lowering the landing accuracy of the ink due to the increased viscosity. Therefore, the quality of the image obtained by the recording of the recording apparatus according to the present embodiment is maintained high.

  In the present embodiment, the recording head 22 moves at a constant speed in the main scanning direction during scanning. Therefore, changing the ejection energy according to the movement distance from the preliminary ejection position of the recording head 22 results in changing the ejection energy according to the elapsed time from the preliminary ejection. Thus, it can be said that the recording apparatus of the present embodiment is a recording apparatus that changes the ejection energy in accordance with the elapsed time after the preliminary ejection.

  FIG. 12 is a table evaluating the ejection stability after being left when the K value is changed in the present embodiment. The time shown here is a time during which the recording head does not discharge, and evaluation of the stability of the ink droplets discharged immediately after that is shown. Here, the criteria for ◯, Δ, and X will be described. X indicates ink droplets at a level that is visually unacceptable in terms of image quality, as a result of the ink being ejected, and a drop in landing accuracy can be confirmed visually. Δ is a level where it is difficult to visually recognize a drop in landing accuracy when ink is ejected, and is an ink droplet with an acceptable level of image quality. ○ is a drop of ink with no problem.

  As shown in FIG. 12, by increasing the ejection energy by changing the K value, the ink droplets are ejected satisfactorily, and the landing accuracy of the ink droplets by recording is maintained high without decreasing. In the case of this embodiment, in the case of normal recording immediately after the preliminary ejection, the vicinity of the K value of 1.15 is used, and when the time after the preliminary ejection is long, a large K value is used. Set. The time after the preliminary ejection is performed is determined by the moving distance of the recording head because the recording head scans at a constant speed. For example, in the region B, by setting the K value near 1.2, the ejection performance from 1 second to 1.5 seconds after the preliminary ejection is maintained satisfactorily. High accuracy is maintained. In the area C, by setting the K value to around 1.25, the ejection performance during the elapsed time from the preliminary ejection between 1.5 seconds and 2 seconds is maintained well, and the ink droplet landing accuracy is kept high. It becomes possible to do.

  Then, when the recording medium is subjected to half-reciprocal recording in the scanning of the recording head in this way, the predetermined amount of recording medium is transported and then moved back to the receiving portion 62 where preliminary ejection has been performed. Recording is performed.

  At this time, the preliminary ejection may be performed at the end opposite to the receiving portion 62 in the main scanning direction before moving in the direction of returning to the receiving portion 62. In the main scanning direction, preliminary ejection may be performed each time half-reciprocal scanning is performed. At this time, when scanning is performed in a direction in which the recording head 22 returns to the receiving unit 62 while performing recording, the distance after the preliminary ejection is performed is the same as in scanning in a direction away from the receiving unit 62. Accordingly, the discharge energy may be increased.

  Further, after the half-reciprocal recording is performed, the recording head 22 performs recording while scanning in a direction to return to the receiving unit 62 without performing preliminary ejection, and returns to the receiving unit 62 again. Therefore, preliminary discharge may be performed. Then, every time the recording head 22 performs one reciprocating scan, preliminary ejection may be performed by the receiving unit 62. At this time, the K value for converting the discharge energy may be set so as to increase in the direction returning to the receiving unit 62 even when scanning in the direction returning to the receiving unit 62 is performed. As a result, the recording medium may be divided into six regions by combining the reciprocating amounts, and the K value for converting the ejection energy may be set for each of the six regions. Further, the number of areas into which the recording medium is divided is not limited to six, and the recording medium may be divided more finely or larger.

  A method of changing the drive pulse by the recording apparatus in the present embodiment will be described based on the flowchart of FIG.

  First, the control means 200 receives the recording data and further receives a recording start command (step S100). Here, before printing is performed, preliminary ejection is performed at a position corresponding to the receiving portion 62 as a predetermined position in the main scanning direction (preliminary ejection step). Next, the determination unit 205 measures the movement distance of the recording head 22 after the preliminary ejection is performed in the measurement unit 204, and determines whether or not a predetermined amount is exceeded (steps S101 and S102). If the predetermined moving distance is not exceeded, recording is performed using the center K value 1.15 which is a normal K value. Then, when the threshold value is exceeded, the K value is set according to the time after the preliminary ejection.

  In the present embodiment, the threshold value C is a distance from the receiving unit 62 where the preliminary ejection is performed to the boundary between the region C and the region B. The threshold B is the distance from the receiving unit 62 to the boundary between the region A and the region B. As a result of detecting the moving distance, if the moving distance of the recording head 22 exceeds the threshold C, recording is performed at the center K value of 1.25, and if the moving distance exceeds the threshold B, the center K value is 1.2. Recording is done. A predetermined amount of raster is recorded using the K value determined in the above steps. In the present embodiment, 64 raster recording is performed. Then, by repeating this recording and determination, the recording of one line is finished (step S103). Thus, in the discharge energy changing step for each scanning distance, the drive pulse changing means 207 as the discharge energy changing mechanism discharges according to the distance scanned from the receiving portion 62 as the predetermined position where the preliminary discharge is performed in the preliminary discharge step. Change energy. By repeating this operation, recording with an appropriate K value becomes possible.

<Second embodiment>
Next, a recording apparatus according to the second embodiment will be described with reference to FIG. In addition, about the part which can be comprised similarly to said 1st embodiment, the same code | symbol is attached | subjected in a figure, description is abbreviate | omitted, and only a different part is demonstrated. In the first embodiment, since the recording head is scanning at a constant speed, the elapsed time after the preliminary ejection is performed is determined based on the moving distance of the recording head. Has been. In contrast, in the second embodiment, the recording apparatus includes a timer capable of measuring the elapsed time, and the elapsed time after the preliminary ejection is performed is measured by the timer. This timer functions as an elapsed time detection mechanism that detects the elapsed time from the preliminary ejection.

  A method of changing the drive pulse by the timer in the recording apparatus of the second embodiment will be described based on the flowchart of FIG.

  First, the control means 200 receives recording data, and further receives a recording start command (step S100 '). Here, preliminary ejection is performed before recording is performed, and the timer is once reset. Next, the determination unit 205 measures, with a timer, the time after the preliminary discharge is performed in the measurement unit 204 as an elapsed time detection step for detecting the elapsed time from the preliminary discharge. Then, it is determined whether or not the measured elapsed time exceeds a predetermined amount (steps S101 'and S102'). If the predetermined time is not exceeded, recording is performed using the center K value 1.15, which is a normal K value. Then, when the threshold value is exceeded, the K value is set according to the time after the preliminary ejection. As described above, in the discharge energy change step by time as S101 'and S102', the discharge energy is changed according to the elapsed time from the preliminary discharge detected by the timer of the measuring means 204 as the elapsed time detection mechanism.

  In this embodiment, the threshold A is 1.5 seconds and the threshold B is 1.0 seconds. If the timer has elapsed 1.5 seconds, recording is performed with the center K value of 1.25, and if 1.0 second has elapsed, recording is performed with the center K value of 1.2. In addition, when the elapsed time after the preliminary ejection is less than 1.0 second, the central K value is 1.15, and the recording is performed with the K value between 1.1 and 1.2. A predetermined amount of raster is recorded using the K value determined in the above steps. In the present embodiment, 64 raster recording is performed. Then, by repeating this recording and determination, recording for one line is completed (step S103 ').

  As shown in FIG. 12 described above, if the elapsed time since the preliminary discharge is performed is less than 1.0 second, the discharge performance can be realized at the Δ level or more. Subsequently, when the elapsed time is 1.0 second or more and less than 1.5 seconds, it is preferable that the center K value is set to 1.2 and the K value range is set from 1.15 to 1.25. It is shown that the discharge is performed. In addition, as shown in FIG. 12, when the elapsed time after the preliminary discharge is less than 1.5 seconds, the discharge performance should be more than Δ level if the K value range is 1.15 to 1.25. Is possible.

  By adopting the method as described above, it is possible to maintain good discharge performance using a relatively simple method. Accordingly, the ink droplet landing accuracy can be kept high by a simple method, and the quality of an image obtained by recording can be kept high.

<Third embodiment>
Next, a recording apparatus according to the third embodiment will be described with reference to FIGS. In addition, about the part which can be comprised similarly to said 1st embodiment, the same code | symbol is attached | subjected in a figure, description is abbreviate | omitted, and only a different part is demonstrated.

  The present embodiment relates to a method for changing the ejection energy according to the elapsed time from the preliminary ejection, measuring the humidity around the recording head, and further changing the K value according to the measured value. FIG. 15 is a table showing how the ejection performance changes depending on the environmental humidity, the standing time, and the K value. As shown in the table of FIG. 15, the degree of thickening changes with changes in environmental humidity, and this changes the discharge performance. Particularly in a low-humidity environment, the discharge performance is greatly deteriorated due to the passage of time without being discharged. Here, the evaluation criteria for O, Δ, and X in FIG. 15 are the same as the evaluation criteria for FIG. 14 in the first and second embodiments.

  FIG. 16 shows the setting range of the K value in this embodiment. As shown in FIG. 16, in a low-humidity environment, there is a high possibility that the water content of the ink around the ejection port in the recording head is evaporated and thickened. Is set higher. By such a method, it is possible to perform optimum control according to the environmental humidity, and it is possible to improve the quality of an image obtained by recording.

  In the present embodiment, the control is performed by combining the environmental humidity in addition to the time after the preliminary discharge is performed. However, the drying conditions of ink droplets during recording vary depending on the temperature of the recording head itself and the temperature of the environment. Therefore, a threshold for changing the discharge energy may be determined by adding these conditions.

  As described above, the drive pulse changing unit 207 as the discharge energy changing mechanism changes the discharge energy according to the time after the preliminary discharge. At that time, at least one of temperature information and humidity information may be detected, and the ejection energy may be further changed depending on the value.

  In the first to third embodiments, the driving pulse is fixed and the driving voltage is adjusted to change the ejection energy. However, the present invention is not limited to this, and the driving voltage is fixed and driven. The width of the pulse may be changed. As described above, the ejection energy changing mechanism may be a pulse width adjusting mechanism that adjusts the pulse width in the pulse signal for driving the ejection energy generating element when ejecting the ink droplet.

1 is a perspective view of a recording apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view schematically showing a main part by disassembling the recording apparatus of FIG. 1. FIG. 2 is a plan view illustrating a discharge port surface of a recording head used in the recording apparatus of FIG. 1. FIG. 4 is a cross-sectional view illustrating a main part of the recording head of FIG. 3. FIG. 5 is a cross-sectional view taken along line VV of the recording head in FIG. 4. FIG. 6 is a plan view illustrating a discharge port surface of a recording head in another embodiment. FIG. 2 is a block diagram for explaining a control circuit of the recording apparatus in FIG. 1. 2 is a table for converting an input image density signal level into an output image density signal level in the recording apparatus of FIG. 1. It is a block diagram for demonstrating the principal part about the block diagram of FIG. FIG. 2 is a plan view showing a positional relationship between a receiving portion where preliminary ejection is performed and a recording medium in the recording apparatus of FIG. 1. 2 is a table showing K values that are set according to the time after preliminary ejection is performed in the recording apparatus of FIG. 1. 2 is a table showing an evaluation of ink droplets ejected when the time after preliminary ejection and the K value are changed in the recording apparatus of FIG. 1. It is a flowchart which shows the control process by the recording device of FIG. It is a flowchart which shows the control process by the recording device which concerns on 2nd embodiment of this invention. 10 is a table showing evaluation of ink droplets ejected when the time after preliminary ejection, K value, and ambient humidity are changed in the recording apparatus according to the third embodiment of the present invention. 10 is a table showing K values set according to time after preliminary ejection and ambient humidity in the recording apparatus according to the third embodiment.

Explanation of symbols

22 Recording head 62 Receiving part
204 Measuring means 207 Driving pulse changing means

Claims (8)

Recording by discharging droplets from the recording head to the recording medium,
In a recording apparatus capable of performing preliminary discharge for discharging droplets not involved in recording from the recording head,
An elapsed time detection mechanism for detecting the elapsed time from the preliminary discharge;
A discharge energy changing mechanism for changing discharge energy for discharging droplets from the recording head,
The recording apparatus according to claim 1, wherein the ejection energy changing mechanism changes the ejection energy according to an elapsed time from the preliminary ejection detected by the elapsed time detection mechanism. Recording by discharging droplets from the recording head to the recording medium,
In a recording apparatus capable of performing preliminary discharge for discharging droplets not involved in recording from the recording head,
The recording head performs recording while scanning in a predetermined direction intersecting a conveyance direction in which the recording medium is conveyed, and performs preliminary ejection at a predetermined position in the predetermined direction,
A discharge energy changing mechanism for changing discharge energy for discharging droplets from the recording head,
The recording apparatus according to claim 1, wherein the discharge energy changing mechanism changes the discharge energy according to a distance scanned from the predetermined position where the recording head performs preliminary discharge. The path that the recording head scans is divided into a plurality of regions according to the distance from the predetermined position,
In each of the plurality of regions, a coefficient is set according to the distance from the predetermined position,
The ejection energy changing mechanism changes the ejection energy according to the area by multiplying the preset reference ejection energy by the coefficient set in the area where the recording head is located. The recording apparatus according to claim 2.   4. The pulse width adjustment mechanism according to claim 1, wherein the ejection energy changing mechanism is a pulse width adjustment mechanism that adjusts a pulse width in a pulse signal for driving an ejection energy generation element when ejecting a droplet. 5. Recording device.   5. The recording according to claim 1, wherein the ejection energy changing mechanism is a pulse voltage adjustment mechanism that adjusts a voltage in a pulse signal for driving an ejection energy generating element when ejecting a droplet. apparatus.   The discharge energy changing mechanism changes the discharge energy according to a time after the preliminary discharge is performed, and further changes the discharge energy according to at least one of temperature information and humidity information. The recording apparatus according to claim 1. Recording by discharging droplets from the recording head to the recording medium,
In a recording method for recording by a recording apparatus capable of performing preliminary discharge for discharging droplets not involved in recording from the recording head,
An elapsed time detecting step for detecting an elapsed time from the preliminary discharge;
A discharge energy change step for each hour for changing discharge energy for discharging droplets discharged from the recording head according to the elapsed time from the preliminary discharge detected in the elapsed time detection step. Recording method. Recording by discharging droplets from the recording head to the recording medium,
In a recording method for recording by a recording apparatus capable of performing preliminary discharge for discharging droplets not involved in recording from the recording head,
A preliminary ejection step in which the recording head performs preliminary ejection at a predetermined position in a predetermined direction intersecting a conveyance direction in which the recording medium is conveyed;
A recording method comprising: a step of changing ejection energy for each scanning distance to change ejection energy for ejecting droplets according to a distance scanned from a predetermined position where preliminary ejection is performed in the preliminary ejection step.

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