Recording device

Abstract

To provide a recording device that can accurately measure the minimum driving energy even with inks that have low ejection performance. [Solution] A recording device comprising a liquid chamber containing a liquid and provided with a discharge port, a recording head having a recording element that generates driving energy for discharging liquid when a driving pulse is applied, a discharge detection unit that detects the discharge of liquid from the discharge port, and a control unit that controls the driving energy, wherein the control unit measures the minimum driving energy required for liquid discharge by repeatedly detecting the presence or absence of liquid discharge by the discharge detection unit while changing the driving energy from the initial driving energy in predetermined units, the initial driving energy is calculated by correcting the minimum driving energy in the previous measurement, and the initial driving energy is set so that the number of times the discharge detection unit repeats detection is less than or equal to a predetermined number.

Description

Technical Field

[0001] The present invention relates to a recording apparatus.

Background Art

[0002] An inkjet recording apparatus including a recording head provided with a plurality of nozzles for ejecting ink is known. Such a recording apparatus forms an image on a recording medium by ejecting ink from the plurality of nozzles according to recording data.

[0003] One method of ejecting ink is the thermal inkjet method. In a recording apparatus using the thermal inkjet method, an electric pulse is applied to a discharge energy generating element such as a heating heater provided in each nozzle to generate heat. Due to the pressure generated by the bubbles instantaneously generated in the ink by this heat generation, the ink is ejected. At this time, if the drive energy applied to the discharge energy generating element is excessive or insufficient, there is a concern that problems such as shortening of the life of the recording head, image defects, and main body defects may occur.

[0004] Regarding such concerns, a technique for measuring the minimum drive energy required for a nozzle to eject ink and determining the drive energy to be applied during recording based on the measurement is known. For example, in Patent Document 1, the pulse width of the applied voltage that allows the ink to be sufficiently ejected is set as the initial drive pulse width. Then, while detecting the ejection state of the ink by a photoelectric sensor, the minimum drive energy capable of ejecting the ink is measured by gradually reducing the pulse width by a predetermined value from the initial drive pulse width.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, Patent Document 1 does not disclose the pulse when using ink with low ink ejection performance after a period of non-ejection (hereinafter also referred to as "single-shot ejection performance"). With ink with low single-shot ejection performance, the ink is difficult to eject or ejection becomes irregular after a period of non-ejection, which affects the process of measuring the minimum drive energy and leads to incorrect measurement results. If the drive energy during recording is determined based on such an incorrect minimum drive energy, it may lead to problems such as a shortened lifespan of the recording head, image defects, and malfunctions of the main unit.

[0007] The present invention aims to solve the above problems and to provide a recording device that can accurately measure the minimum driving energy even with inks that have low ejection properties. [Means for solving the problem]

[0008] This invention employs the following configuration: A recording head having a liquid chamber capable of containing a liquid and provided with a liquid discharge port, and a recording element that, when a drive pulse, which is an electrical signal of a predetermined pulse width, is applied, is driven to generate drive energy to discharge the liquid from the liquid chamber, A discharge detection unit for detecting whether or not the liquid is discharged from the discharge port, A control unit that controls the drive energy by changing the drive pulse applied to the recording element, A recording device comprising, The control unit, The minimum driving energy required for the discharge of the liquid is measured by repeatedly detecting the presence or absence of liquid discharge by the discharge detection unit while changing the driving energy from the initial driving energy in predetermined units. The initial drive energy is calculated by correcting the minimum drive energy from the previous measurement, and, The initial drive energy is set such that the number of times the discharge detection unit repeats detection is less than or equal to a predetermined number. A recording apparatus characterized by the above.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a recording apparatus capable of accurately measuring the minimum driving energy even with ink having low ejection properties.

Brief Description of the Drawings

[0010] [Figure 1A] A diagram showing the configuration of the recording apparatus [Figure 1B] A diagram showing the configuration of the recording head [Figure 2A] A schematic diagram showing the ejection surface of the recording head [Figure 2B] A cross-sectional view showing the ejection port and the recording element of the recording head [Figure 3] A diagram showing each component of the recording medium and the recording apparatus [Figure 4] A cross-sectional view of the ejection detection unit [Figure 5] A control block diagram [Figure 6] A flowchart of the minimum driving energy measurement method in the first embodiment [Figure 7] A correspondence table of pulse numbers and pulse widths [Figure 8] A table showing the offset amount O for each ink color in the first embodiment [Figure 9] A cross-sectional view of the recording head showing the state when ejection is performed after rest [Figure 10] A flowchart of the minimum driving energy measurement method in the second embodiment [Figure 11] Offset amount table TBL1 [Figure 12] Offset amount table TBL2 [Figure 13] A table of the difference in the minimum driving pulses between the ink for shipping inspection and the recording ink [Figure 14] A flowchart of the minimum driving energy measurement method in the third embodiment [Figure 15]Minimum drive pulse calculation table in the third embodiment [Figure 16] Offset amount table in the third embodiment [Figure 17] Flowchart of the minimum drive energy measurement method in the fourth embodiment [Figure 18] Offset amount table TBL3 [Figure 19] Offset amount table TBL4 [Figure 20] Offset amount table TBL5 [Figure 21] Flowchart for explaining the operation sequence of the fifth embodiment [Figure 22] Diagram showing the correction value of the fifth embodiment [Figure 23] Flowchart for explaining the operation sequence of the sixth embodiment [Figure 24] Diagram showing the correction value of the sixth embodiment [Figure 25] Flowchart for explaining the operation sequence of the seventh embodiment [Figure 26] Diagram showing the correction value of the seventh embodiment [Figure 27] Flowchart for explaining the operation sequence of the eighth embodiment [Figure 28] Diagram showing the correction value of the eighth embodiment [Figure 29] Flowchart for explaining the operation sequence of the ninth embodiment [Figure 30] Diagram showing the correction value of the ninth embodiment

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following embodiments The dimensions, materials, shapes, and relative arrangements of the components described in the examples should be appropriately modified depending on the configuration and various conditions of the apparatus to which the present invention is applied. Therefore, unless otherwise specifically stated, this is not intended to limit the scope of the present invention. Although multiple features are described in the examples, not all of these features are essential to the invention, and the features may be combined in any way.

[0012] [First Embodiment] Hereinafter, with reference to the drawings, a recording device 200 as one embodiment of the present invention will be described. The recording device 200 is an inkjet-type image recording device.

[0013] (Recording device configuration) Figure 1A is a perspective view showing the recording device 200 with its exterior removed to expose its internal mechanism. Figure 1B is a perspective view illustrating the configuration of the recording head 9.

[0014] In the recording device 200, the carriage 1 is equipped with a recording head 9 (see Figure 1B) that ejects ink to perform the recording operation. An ink tank 11 is detachable from the recording head 9. The carriage 1 moves back and forth in the X direction in the figure via a timing belt 2 along the guide shaft 3, driven by the carriage motor 4. A recording medium P (see Figure 3) is transported from the upstream side in the Y direction in the figure. The recording head 9 mounted on the carriage 1 repeatedly ejects ink onto the recording medium while moving back and forth, thereby recording an image on the recording medium.

[0015] Furthermore, a platen 10 is positioned in the area where the recording head 9 records images. The platen 10 supports the recording medium P from below and maintains a constant distance between the surface of the recording medium and the ejection port surface of the recording head 9.

[0016] Figure 1B shows how ink tanks 11, each independently holding nine different inks, are attached to the recording head 9 mounted on the carriage 1. The recording device 200 of this embodiment records images on a recording medium using these nine different inks. Each ink tank 11 is independently detachable from the recording head 9. In this embodiment, nine different inks—cyan (Cy), magenta (Ma), yellow (Ye), black (Bk), red (Re), light cyan (LC), light magenta (LM), gray (Gy), and clear ink (CO)—are stored in different ink tanks 11.

[0017] Figure 2A is a schematic diagram showing the ejection port surface of the recording head 9 as seen from the recording medium side. The recording head 9 has multiple ejection ports 5 arranged in rows, forming an ejection port row 6. Multiple ejection port rows 6 (6a to 6i) are also provided on the ejection port surface. In this specification, "ejection port" refers collectively to the nozzle as an opening, the flow path communicating with the nozzle, and the recording element that generates energy for ejecting ink droplets. The nine ejection port rows 6a to 6i correspond to nine different types of ink. In each ejection port row 6a to 6i, 640 ejection ports are arranged at a density of 600 dpi (600 per inch).

[0018] The recording head 9 of this embodiment is a so-called thermal inkjet recording head equipped with a recording element that converts electrical signals (hereinafter referred to as "drive pulses") into thermal energy, and ejects ink droplets from an ejection port using thermal energy. The form of the recording head 9 is not limited to the above example, and any form that records an image by ejecting ink droplets using one or more recording elements is acceptable.

[0019] Figure 2B is a schematic cross-sectional view showing one discharge port 5 included in the discharge port row 6 and the corresponding recording element 86. The recording element 86 is formed as a thin film on the surface of the element substrate 88. Its surface is covered with a protective film 89. Between the element substrate 88 and the faceplate 120 of the recording head 9, a liquid chamber 122 capable of containing ink is formed. Liquid ink is supplied to the liquid chamber 122 from the ink tank 11 via a liquid supply port 97. When a drive pulse is applied to the recording element 86 via a conductive member 151, the recording element 86 heats up, causing the temperature of the ink in the liquid chamber to rise instantaneously, resulting in foaming and ejection of ink from the ejection port 5. The ejection method of the recording head 9 is not limited to a thermal inkjet method, but may also be a piezo method or the like.

[0020] (Platen section and maintenance section) Figure 3 illustrates the positions of the recording medium P, platen 10, ejection detection unit 12, and maintenance unit 13 during recording. The platen 10 extends in the X direction along the path of the carriage 1, which is equipped with the recording head 9, to support the recording medium P passing over it. The ejection detection unit 12 is located within the path of the recording head 9.

[0021] The maintenance unit 13 includes a cap member capable of covering the ejection port surface of the recording head 9 and a pump (not shown) that generates negative pressure, in order to restore the ejection performance of the recording head 9. By ejecting ink with the ejection port surface covered by the cap member, ink clogging can be improved. This type of ejection operation is called pre-ejection. In addition, by operating the pump with the ejection port surface covered by the cap member, a suction operation can be performed to forcibly expel the ink from inside the nozzle. The ink discharged by pre-ejection or suction operation is forcibly discharged from the cap member to the waste ink pack by the pump drive. The maintenance unit 13 may also include a wiper to wipe the ejection port surface. By performing the above pre-ejection, the ink ejection performance from the recording head 9 can be maintained. The timing of pre-ejection may be before the image recording operation or in the middle of the recording operation. For example, for nozzles that are not used frequently during the recording operation, the solvent inside the nozzle evaporates during the recording operation and the ink viscosity increases, but pre-ejection can be performed while the carriage 1 is moving.

[0022] (Discharge detection unit) Figure 4 is a cross-sectional view of the ejection detection unit 12 for detecting the ink ejection state. The ejection detection unit 12 in this embodiment is an optical sensor including a light-emitting element 7 and a light-receiving element 8. As shown in Figure 4(a), the light-emitting element 7, such as an LED, emits light, and the light-receiving element 8, such as a photodiode, which is provided opposite the light-emitting element 7, receives the light emitted from the light-emitting element 7. In the Y direction, the distance between the light-emitting element 7 and the light-receiving element 8 is wider than the width of the ejection port row 6 provided on the recording head 9. The light-emitting element 7 and the light-receiving element 8 are arranged so that the direction of the optical axis 14, which is the center of the light emitted from the light-emitting element 7, and the direction in which the multiple ejection ports 5 arranged in the ejection port row 6 are aligned are substantially parallel. The ejection detection unit 12 outputs a signal based on the amount of light received by the light-receiving element 8. The control unit 100, which will be described later, determines the ejection state of ink droplets from each ejection port 5 based on this signal level.

[0023] When ink droplets ejected from each ejection port 5 of the recording head 9 block the light emitted from the light-emitting element 7, the amount of light received by the light-receiving element 8 decreases. By detecting this decrease in light intensity, it is possible to determine whether or not the ink droplets were ejected correctly. In other words, if the ink droplets are not ejected correctly from the ejection port 5, the ink droplets will not pass along the optical axis 14 as shown in Figure 4(a). In this case, the light emitted from the light-emitting element 7 reaches the light-receiving element 8 without any decrease in light intensity. Therefore, the signal level output from the light-receiving element 8 does not decrease, and it is determined that there is an ejection failure.

[0024] On the other hand, the ejection port 5 of the recording head 9 is located at a position corresponding to the detection range of the optical sensor, and if ink droplets are ejected normally from the ejection port 5, the ejected ink droplets 15 will obstruct the optical axis 14, as shown in Figure 4(b). As a result, the amount of light received by the light-receiving element 8 decreases, and from the light-receiving element 8 The output signal level decreases. In this case, the ink droplets are ejected normally, and it is determined that there is no ejection failure.

[0025] If not all ink droplets ejected from the ejection port 5 are detected by the light-emitting element 7 and the light-receiving element 8, it can be determined that the recording head 9 and the optical sensor may not be aligned in the X direction. In this case, the recording head 9 needs to be moved in the X direction. Once the detection operation for one row of ejection ports 6 is completed, the recording head 9 is moved in the X direction, and the detection operation for the next row of ejection ports 6 is repeated.

[0026] Alternatively, the light-emitting element 7 and the light-receiving element 8 may be arranged such that the optical axis 14 intersects diagonally with respect to the direction in which the ejection ports 5 are arranged. In this configuration as well, the ink ejection state from each ejection port 5 can be detected by ejecting ink droplets while moving the recording head 9 in the X direction.

[0027] Furthermore, the ink droplets 15 ejected during the detection operation are received by the ink receiver 17, discharged as waste ink 16 from the ink outlet 37, and absorbed by a waste ink absorber (not shown). Alternatively, instead of absorbing the ink droplets with a waste ink absorber, the waste ink 16 may be collected in an ink reservoir container with sufficient volume.

[0028] (Control block diagram) Figure 5 is a block diagram showing the control system configuration of the recording device 200 of this embodiment. The control unit 100 includes a CPU 101 that performs processing operations such as calculation, control, discrimination, and setting; a ROM 102 that stores control programs to be executed by the CPU 101; a RAM 103 used as a buffer for storing binary recording data representing ink droplet ejection or non-ejection and as a work area for processing by the CPU 101; and input / output ports 104.

[0029] The input / output port 104 is connected to various drive circuits 105-108, including the transport motor (LF motor) 113, carriage motor (CR motor) 4, recording head 9, and the maintenance unit 13 that performs recovery processing in the transport unit. The input / output port 104 is also connected to sensors such as a head temperature sensor 112 that detects the temperature of the recording head, an encoder sensor 111 fixed to the carriage 1, and a temperature and humidity sensor 109 that detects the ambient temperature and humidity in which the recording device is used.

[0030] Furthermore, the control unit 100 is connected to the host computer 115 via the interface circuit 110. The recovery processing counter 116 counts the amount of ink ejected when the maintenance unit 13 forcibly ejects ink from the recording head 9. The pre-ejection counter 117 counts the amount of pre-ejection performed before recording starts, at the end of recording, and during recording. The borderless ink counter 118 counts the amount of ink recorded outside the recording medium area when performing borderless recording, and the ejection dot counter 119 counts the amount of ink ejected during recording.

[0031] (Ink level management) In this embodiment, the amount of ink remaining in the ink tank 11 is managed by a so-called dot counting method, which measures the number of times ink droplets are ejected from the recording head 9. Specifically, the number of ink droplets ejected from the recording head 9 for image formation and preliminary ejection is measured, and the amount of ink consumed from the ink tank 11 is calculated by multiplying the measured number by the amount of liquid per ink droplet (also referred to as the ink ejection amount). Then, the remaining ink amount is determined by subtracting the amount of ink consumed from the initial amount of ink when the ink tank 11 is installed, that is, the amount of ink when the ink tank 11 is full. Note that the amount of suction when the maintenance unit 13 performs a suction operation is also included in the amount of ink consumed. For this purpose, one suction operation is performed in advance. The ink consumption during operation is set in ROM102, and each time a suction operation is performed, it is subtracted from the tank amount before the suction operation.

[0032] (Minimum driving energy measurement) Figure 6 is a flowchart showing the method for measuring the minimum drive energy in this embodiment. The minimum drive energy is measured, for example, during the initial setup of the recording device 200, when replacing the recording head 9, or when the number of ejections from the nozzle exceeds a predetermined number. The minimum drive energy is the energy generated by driving the recording element 86 and refers to the minimum energy required for ink to be ejected from the ejection port 5 of the recording head 9. Due to individual differences and manufacturing tolerances of the recording element 86, the minimum drive energy differs between ejection ports. When the recording head 9 has multiple ejection ports 5, in the ejection presence / absence determination described later, if at least one of the multiple ejection ports 5 ejects ink, it is determined that ejection has occurred. On the other hand, if ejection is not detected from any of the ejection ports 5, it is determined that there is no ejection. In this embodiment, the minimum drive energy is measured by fixing the voltage of the drive pulse and changing the pulse width, but the minimum drive energy may also be measured by fixing the pulse width and changing the voltage. Whether it is pulse width or voltage, the drive energy can be changed by controlling the control value used for voltage control.

[0033] Here, to determine the pulse width of the drive voltage applied to the recording element, a correspondence table between pulse numbers and pulse widths, as shown in Figure 7, is used. The CPU 101 controls the pulse width during voltage control by changing the pulse number to be set by referring to the correspondence table stored in the ROM 102. Alternatively, the pulse width may be controlled directly without going through the pulse number. Furthermore, the method for obtaining the pulse width is not limited to a table format; for example, a mathematical formula may be used.

[0034] In this embodiment, the minimum pulse width required to cause the nozzle to discharge a substance corresponding to the lowest driving energy is called the minimum driving pulse Pth. The measurement of the lowest driving energy is also referred to as the minimum driving pulse Pth measurement.

[0035] First, in step S601, the CPU 101 controls the recording head 9 to a preset temperature for measuring the minimum drive pulse Pth by referring to the head temperature sensor 112 and sending a signal to the drive circuit 107. Specifically, the CPU 101 may apply a drive pulse that does not eject ink to the recording element to generate heat, or it may mount a separate heating element on the recording head 9.

[0036] Next, in step S602, the CPU 101 ejects the ink from the nozzle by performing a preliminary ejection. Then, in step S603, the CPU 101 determines the initial drive pulse Pini and applies it to the recording head 9 through the drive circuit 107. Here, the initial drive pulse Pini is the drive pulse width used first when measuring the minimum drive pulse Pth, and generates the initial drive energy. It is calculated as the sum of the previous minimum drive pulse Pth measurement result and the offset amount Os. The offset amount Os will be described later. For example, if the previous minimum drive pulse Pth was pulse number 22 and the offset amount Os was 3, the current initial drive pulse Pini will be pulse number 25. If the previous minimum drive pulse Pth cannot be obtained for any reason, such as not being saved, a predetermined value that has been measured in advance and stored in the ROM 102 may be used instead of the previous Pth.

[0037] In step S604, the CPU 101 uses the ejection detection unit 12 to determine whether or not ink is ejected from the nozzle when the initial drive pulse Pini is applied to the recording element. At this time, the nozzles to be determined for ejection may be all the nozzles included in the ejection port row 6, or one or more nozzles selected as representatives.

[0038] In step S605, the CPU 101 determines the next process to perform. First, it ejects the ink. If it is determined that there is no nozzle (S605=No), the process proceeds to step S606. In step S606, the CPU 101 increases the pulse width of the drive pulse by controlling the drive circuit 107, and returns to the ejection determination in step S604. In this way, if it is determined that there is no ejection in step S605, the pulse width is increased until ink is ejected from the nozzle. In this embodiment, the increase in pulse width in step S606 is performed by adding 5 to the pulse number. For example, if the pulse number of the initial drive pulse Pini is 25, then pulse number 30 is used for the second ejection detection. The increment of 5 in the pulse number at this time is defined as the relatively large first unit.

[0039] On the other hand, if it is determined that there is a nozzle that has ejected ink (S605=Yes), the process proceeds to step S607. In step S607, the CPU 101 reduces the pulse width of the drive pulse. In this embodiment, the reduction in pulse width in step S607 is performed by subtracting 1 from the pulse number. The number of increments in the pulse number at this time, 1, is set to a second unit smaller than the first unit. For example, if the pulse number of the initial drive pulse Pini is 25, then in S607, the pulse number is set to 24. In this way, by making the decrease in pulse width in step S607 (by 1 pulse number) smaller than the increase in pulse width in step S606 (by 5 pulse numbers), the minimum drive pulse Pth can be measured with high accuracy.

[0040] Subsequently, in step S608, the CPU 101 uses the discharge detection unit 12 to determine whether or not discharge is occurring, and in step S609, it determines the subsequent processing based on the result of the discharge determination. If a discharge nozzle is present (S609=Yes), the process returns to step S607, the pulse width is reduced, and the discharge determination is performed again in step S608. Steps S607 to S609 are repeated in this manner, and the pulse width is reduced until there is no discharge nozzle.

[0041] If the ejection nozzle is depleted (S609=No), the CPU 101 proceeds to step S610 to calculate the minimum drive pulse Pth. At this time, the CPU 101 adds 1 to the pulse number for which the ejection nozzle was depleted in step S609 and uses this as the minimum drive pulse Pth. In other words, the minimum drive pulse Pth is the pulse number corresponding to the minimum pulse width required for ink to be ejected. The measurement of the minimum drive pulse Pth is completed by performing the above flow.

[0042] (Offset amount) Next, we will explain the offset amount Os described in step S603. Figure 8 is a table showing the offset amount Os for each ink color in this embodiment.

[0043] First, as a comparative example, we consider the case where the offset amount Os is not added in step S603, that is, the lowest drive pulse Pth from the previous measurement is set as the initial drive pulse Pini. Here, the actual lowest drive energy in the recording head 9 may fluctuate between the previous measurement and the current measurement due to changes in the surface condition of the recording element over time and measurement errors. Therefore, if the lowest drive pulse Pth from the previous measurement is used as the initial drive pulse Pini, there is a possibility that ink will not be ejected in step S604.

[0044] If ink is not ejected in step S604, the CPU 101 will repeat the processing in steps S605 and S606, increasing the pulse width until ink ejection is detected. In such cases, problems arise, especially when using ink with low ejection properties. In our investigation, we confirmed that with ink with low ejection properties, even when the pulse width is increased to the level that should be sufficient for ejection in step S606, the ink does not eject. This is because the nozzle is in a non-ejecting state between steps S604 and S606. This is thought to be because the ink inside the tube evaporates, increasing its viscosity and reducing its ejection performance. When this happens, even with pulse widths that should allow for ejection, accurate measurement of the minimum drive pulse Pth becomes impossible.

[0045] Therefore, especially for inks with low single-shot ejection performance, after the preliminary ejection in step S602 to discharge the ink from the nozzle, it is necessary to avoid a period of non-ejection as much as possible. In other words, the initial drive pulse Pini should be set to have a pulse width larger than the minimum drive pulse Pth from the previous measurement result, and to ensure ejection at the first ejection determination. It is also possible to eliminate the effect of single-shot ejection performance by performing preliminary ejection with sufficient drive energy at a high frequency, but this is expected to increase the amount of waste ink and shorten the lifespan of the ejection detection unit due to ink adhesion. On the other hand, if the initial drive pulse Pini is increased as in this embodiment, it is not necessary to increase the frequency of preliminary ejection.

[0046] On the other hand, problems can also arise if the initial drive pulse Pini set in step S603 is too large. In this case, ink is ejected in step S604, so step S605 = Yes, and the process proceeds to step S607. Steps S607 to S609 are then repeated until there are no ejection nozzles in step S609. At this time, since the nozzles are in a non-ejecting state in steps S609 and S607, step S608 will repeatedly perform ejection after the non-ejecting state. Hereafter, in this specification, ejection after the non-ejecting state will be referred to as post-pause ejection.

[0047] Here, the issues that arise when dispensing is performed multiple times after a pause will be explained using Figure 9. Figure 9(a) is a cross-sectional view showing how ink droplets 15 adhere to the vicinity of the dispensing port 5, forming attached ink 18. Figure 9(b) is a cross-sectional view showing how the accumulation of ink droplets 15 near the dispensing port 5 has resulted in the attached ink 18 blocking the dispensing port 5.

[0048] When ink with low ejection properties is used and ejection is performed after a pause, as shown in Figure 9(a), in addition to the flying ink droplets 15, adhesive ink 18 may be generated that adheres to the vicinity of the nozzle. If this type of ejection after a pause is repeated multiple times, the generated adhesive ink 18 will merge and grow, eventually blocking the ejection port 5 as shown in Figure 9(b). In this state, even if the driving energy that would normally cause the ink to be ejected is applied to the recording element, the adhesive ink 18 will obstruct it, preventing the ink from being ejected.

[0049] As described above, if the initial drive pulse Pini is set excessively high and post-pause ejection is performed multiple times, it becomes impossible to accurately measure the minimum drive pulse Pth. On the other hand, by investigating how many post-pause ejection is required to form the attached ink 18 that affects ejection, it is possible to determine the upper limit of the initial drive pulse Pini that allows for accurate measurement of the minimum drive pulse Pth. For example, suppose that attached ink 18 that affects ejection is formed after 7 repetitions of post-pause ejection. In this case, if post-pause ejection is performed 6 times or less, ejection is possible without being affected by the attached ink 18. That is, if the number of repetitions of steps S607 to S609 from the initial drive pulse Pini to the minimum drive pulse Pth is 6 times or less, it is possible to accurately measure the minimum drive pulse Pth. This number of repetitions is not limited to 6, but can be any number less than or equal to a predetermined number depending on the device configuration and other conditions.

[0050] Although there may be some fluctuations, the minimum drive pulse Pth is expected to be roughly close to the previous measurement result. Therefore, in this embodiment, the previous measurement result of the minimum drive pulse Pth is used as a reference. In this embodiment, the pulse step size during minimum drive pulse measurement is in units of 0.01 μs, as shown in Figure 7. Therefore, if the previous measurement result was 0.84 μs (pulse number 22), the current initial drive pulse Pini should be set to 0.90 μs or less in order to keep the number of repetitions within 6. In this way, the discharge effect is... The pulse width that can be changed down to the minimum drive pulse Pth in predetermined increments is called the upper limit pulse Pul.

[0051] As described above, for inks with low ejection properties, the initial drive pulse Pini must be greater than or equal to the lowest drive pulse Pth from the previous measurement, and less than or equal to the upper limit pulse Pul. To achieve this, in step S603 of this embodiment, the initial drive pulse Pini is calculated as the sum of the previous measurement result of the lowest drive pulse Pth and the offset amount Os. The value of the offset amount Os is determined by first investigating the ejection characteristics of each ink color, and storing a value that takes these ejection characteristics into account in ROM 102. For example, in the example in Figure 8, the offset amount Os for each color from Gy to CO is 3, so the pulse number obtained by adding 3 to the pulse number of the previous lowest drive pulse Pth is set as the initial drive pulse Pini.

[0052] If there is no previous minimum drive pulse Pth measurement result (for example, the first measurement since the recording device 200 started being used), a reference value may be stored in ROM 102 beforehand, or the measurement result from the shipping inspection of the recording head 9 may be referred to.

[0053] By following the flow described in steps S601 to S610, the minimum drive pulse Pth can be accurately measured even with inks that have low ejection performance. Furthermore, based on this measurement result, the optimal drive pulse for recording can be determined. For example, a drive pulse equal to 1.2 times the pulse width based on the measured minimum drive pulse Pth, taking ejection stability into account, is applied to the recording head 9 via the drive circuit 107. Here, the coefficient multiplied by the minimum drive pulse Pth is not limited to 1.2 times, but can be greater than 1.

[0054] The initial drive pulse Pini can be arbitrarily set within a range that is greater than or equal to the previous minimum drive pulse Pth measurement result and less than or equal to the upper limit pulse Pul. Setting it close to the upper limit pulse Pul allows for more reliable ejection in the initial ejection determination in step S604. On the other hand, setting it close to the previous minimum drive pulse Pth measurement result reduces the number of repetitions in steps S607 to S609, thereby shortening the measurement time. The value of the initial drive pulse Pini can be arbitrarily set taking into account the ink ejection characteristics. For example, for inks with relatively high single-shot ejection performance, the offset amount Os may be set to 0, as shown for the Bk ink in Figure 8. In this case, the initial drive pulse Pini will be the same as the previous minimum drive pulse Pth measurement result. On the other hand, for inks with relatively low single-shot ejection performance, it is preferable to set the offset amount to a value greater than 0.

[0055] Furthermore, regarding the pulse step size when measuring the minimum drive pulse Pth, the finer the step size, the higher the measurement resolution. On the other hand, if the step size is too fine, the difference between the upper limit pulse Pul and the minimum drive pulse Pth becomes small, and the initial drive pulse Pini cannot be made sufficiently large. From the viewpoint of measurement resolution and the degree of freedom in setting the initial drive pulse Pini, it is desirable for the pulse step size to be 0.005 μs to 0.05 μs, and in this embodiment, it is set to 0.01 μm.

[0056] Furthermore, our research showed that even when using ink with low ejection efficiency, if the number of ejections after a pause was six or less, no adhering ink 18 affecting ejection occurred. Therefore, it is desirable that the upper limit pulse Pul be the minimum drive pulse Pth plus a value obtained by multiplying the pulse step width by a predetermined multiple (6 times). Since the number of ejections after a pause contributes significantly to the occurrence of adhering ink 18, the above predetermined multiple is 6 times regardless of the pulse step width.

[0057] [Second Embodiment] In this embodiment, the minimum drive pulse Pth is measured when the recording head 9 is shipped. The following describes the process for performing inspections. For such shipping inspections, a different ink may be used than the ink used for image recording, as it is suitable for transportation and storage after shipment. If the minimum drive pulse Pth differs between the image recording ink and the shipping inspection ink, the value of the previous minimum drive pulse Pth measurement result referenced in step S603 of the first embodiment will also differ. As a result, it becomes impossible to set the optimal initial drive pulse Pini in the flow chart of Figure 6. Therefore, in this embodiment, different offset amounts Os are set depending on whether the current minimum drive pulse Pth measurement is the first or second or later measurement after the shipping inspection.

[0058] Figure 10 is a flowchart showing the method for measuring the minimum drive pulse Pth in this embodiment. Steps S1001 to S1002 in Figure 10 are the same as steps S601 to S602 in the first embodiment, and steps S1010 to S1016 are the same as steps S604 to S610 in the first embodiment, so their explanation is omitted here. Steps S1003 to S1009, which are characteristic parts of this embodiment, will be described below.

[0059] In step S1003, the CPU 101 determines the subsequent processing depending on whether the minimum drive pulse Pth measurement is the first measurement after the factory inspection. For this purpose, it is advisable to store a history in the ROM 102 each time the minimum drive pulse Pth measurement is completed. The CPU 101 refers to the history stored in the ROM 102 to determine whether it is the first measurement. The CPU 101 also writes a new measurement history after the current inspection is complete.

[0060] If the minimum drive pulse Pth measurement is the second or later (S1003=No), the process proceeds to step S1004, where the CPU 101 selects the offset amount table TBL1, which is pre-stored in the ROM 102. The offset amount table TBL1 is shown in Figure 11. This table TBL1 is used when the ink is the same for both the previous minimum drive pulse Pth measurement and the current measurement, and does not take into account the ink difference in the offset amount Os. Subsequently, in step S1005, the CPU 101 determines the offset amount Os by referring to table TBL1. Then, in S1006, the CPU 101 calculates the initial drive pulse Pini by adding the previous minimum drive pulse Pth measurement result and the offset amount Os.

[0061] On the other hand, if the minimum drive pulse Pth measurement is being performed for the first time (S1003=Yes), the process proceeds to step S1007, and the CPU 101 selects the offset amount table TBL2, which is pre-stored in the ROM 102. This table TBL2 takes into account the difference in ink between the factory inspection ink and the recording ink. In other words, table TBL2 shows the offset amount Os when the ink used in the previous measurement was the factory inspection ink and the current measurement is performed with the image recording ink. Figure 12 shows the offset amount table TBL2, and Figure 13 shows the difference table of minimum drive pulses between the factory inspection ink and the recording ink.

[0062] For example, the -1 for Gy in Figure 13 indicates that the minimum drive pulse Pth for the recording ink Gy is one pulse number smaller than the minimum drive pulse Pth for the shipping inspection ink. The CPU 101 can create an offset amount table TBL2 that takes the ink difference into account, as shown in Figure 12, by adding the ink difference in Figure 13 to table TBL1, which does not take the ink difference into account, as shown in Figure 11. Alternatively, instead of using the difference table, the offset amount table TBL2 may be saved directly to ROM 102.

[0063] Subsequently, in step S1008, the CPU 101 determines the offset amount Os by referring to table TBL2. Then, in step S1009, the CPU 101 calculates the initial drive pulse Pini by adding the measurement result from the factory inspection and the offset amount Os, and applies it to the recording head 9 through the drive circuit 107.

[0064] After calculating the initial drive pulse Pini, the process proceeds in the same manner as in the first embodiment. By following steps S1001 to S1016, accurate measurements become possible even when there is a difference in the minimum drive pulse Pth between the ink used for shipping inspection and the ink used for recording.

[0065] [Third Embodiment] In this embodiment, the offset amount Os is changed according to the temperature of the environment in which the recording head 9 is placed. Figure 14 is a flowchart of the minimum drive pulse measurement method in this embodiment. Steps S1401 to S1402 are the same as steps S601 to S602 in the first embodiment, and steps S1405 to S1411 are the same as steps S603 to S609 in the first embodiment, so their explanations are omitted.

[0066] First, steps S1403 to S1404 will be explained. Here, the minimum drive pulse also fluctuates as the viscosity of the ink changes with temperature. Therefore, it is desirable to change the offset amount Os according to the temperature. Thus, in step S1403, the CPU 101 obtains the head temperature T_head using the head temperature sensor 112. In step S1404, the CPU 101 refers to the offset amount table stored in the ROM 102 and determines the offset amount Os according to the temperature. Figure 16 is an example of the offset amount table, showing the change in pulse number according to the ink color and head temperature T_head. For example, for Gy ink, if the head temperature T_head is 20°C or less, the offset amount Os is +5.

[0067] An offset amount table like the one shown in Figure 16 can be created by first investigating the variation characteristics of the minimum drive pulse Pth according to temperature. Then, the process from the calculation of the initial drive pulse Pini in step S1405 to steps S1406 to S1411 is carried out in the same manner as in the first embodiment.

[0068] Next, we will explain the processing in steps S1412 to S1413 after the minimum drive pulse Pth has been acquired. If the minimum drive pulse Pth varies due to the influence of temperature, the drive pulse during image recording, which is determined based on the minimum drive pulse Pth, will also vary. As a result, there is a risk that an inappropriate drive pulse will be applied. Therefore, in this embodiment, the minimum drive pulse Pth obtained by measurement is corrected to correspond to the value at a reference temperature.

[0069] First, in step S1412, the CPU 101 obtains the head temperature T_head using the head temperature sensor 112. In step S1413, the CPU 101 calculates the corrected minimum drive pulse Pthc by correcting the minimum drive pulse measurement result according to the head temperature T_head.

[0070] Figure 15 shows the correction calculation table used in step S1413. In this calculation table, the pulse number for step S1411 where there is no discharge nozzle is on the vertical axis, and the head temperature T_head obtained in step S1412 is on the horizontal axis. In Figure 15, 25°C is used as the reference temperature. Such a correction calculation table can be created by first investigating the variation characteristics of the minimum drive pulse Pth with respect to temperature.

[0071] Here, let's assume that the head temperature T_head is 25°C, as per the reference temperature, and that the pulse number at step S1411 where the ejection nozzle was absent was 26. At this time, the CPU 101 calculates pulse number 27, which occurred just before ejection stopped, as the minimum drive pulse Pth, similar to the first embodiment. In this case, it may be assumed that the minimum drive pulse Pth before correction is used as is, or that the minimum drive pulse Pth before correction and the minimum drive pulse Pthc after correction are the same value.

[0072] Next, let's assume that the head temperature T_head is 30°C, which is different from the reference temperature, and that the pulse number that resulted in no ejection nozzle in step S1411 was 24. In this case, the ink viscosity is lower than at the reference temperature of 25°C, and the measurement result is in a state where the ink is easily ejected. Therefore, it is expected that at the reference temperature of 25°C, the ink will be more difficult to eject than at the time of measurement. So the CPU 101 refers to the correction calculation table stored in ROM 102 and sets pulse number 27 as the corrected minimum drive pulse Pthc.

[0073] By following the flow steps S1401 to S1413 described above, the minimum drive pulse Pth can be corrected after setting the optimal offset amount Os according to the temperature. As a result, it is possible to calculate the accurate minimum drive pulse Pth regardless of the temperature. Although it is possible to calculate the corrected minimum drive pulse Pthc even without setting the offset amount Os according to the temperature, it is preferable to calculate the offset amount according to the temperature from the viewpoint of obtaining a more appropriate initial drive pulse Pini.

[0074] Furthermore, by utilizing the characteristic that ink ejection becomes easier at higher temperatures, as described above, it is possible to accurately measure the minimum drive pulse Pth by controlling the temperature to be higher during Pth measurement than during recording in step S1401.

[0075] In this embodiment, the offset amount Os is set according to the head temperature T_head, but the offset amount Os may also be set according to the head temperature T_head estimated using the ambient temperature obtained by the temperature and humidity sensor 109.

[0076] [Fourth Embodiment] In the fourth embodiment, a recording apparatus 200 in which a pump as an ink circulation mechanism is mounted on a recording head 9 will be described. The pump mounted on the recording head 9 circulates ink in a flow path including nozzles. Thereby, an increase in the viscosity of the ink at the nozzles can be suppressed, and the ejection performance can be kept high. However, there are variations in the circulation capacity of the pump due to manufacturing tolerances and the like, and the ejection performance depends on such variations. Therefore, in the present embodiment, an optimal offset amount Os is determined according to the circulation tolerance information of the pump.

[0077] A flowchart of the minimum drive pulse measurement method in the present embodiment is shown in FIG. 17. Here, since steps S1701 to S1702 are the same as steps S601 to S602 in the first embodiment, and steps S1706 to S1713 are the same as S603 to S610 in the first embodiment, the description thereof is omitted.

[0078] In step S1703, the CPU 101 acquires circulation tolerance information indicating the manufacturing tolerance regarding the circulation capacity of the pump, and sets it as the circulation tolerance Rf. This may be a value stored in the ROM 102 during the shipment inspection, or a value obtained by inspecting the circulation tolerance after arrival. Here, the average circulation capacity is set as the circulation tolerance Rf = 0, and it is an integer that becomes larger as the circulation capacity is higher and smaller as the circulation capacity is lower.

[0079] Next, in step S1704, the CPU 101 selects an offset amount table stored in the ROM 102 in advance according to the circulation tolerance Rf acquired in step S1703. FIG. 18 shows an offset amount table TBL3 to be referred to when the circulation tolerance Rf is medium (-3 < Rf < +3). FIG. 19 shows an offset amount table TBL4 to be referred to when the circulation tolerance is small (Rf ≦ -3) and the circulation capacity is low. FIG. 20 shows an offset amount table TBL5 to be referred to when the circulation tolerance is large (+3 ≦ Rf) and the circulation capacity is high.

[0080] In step S1705, the CPU 101 selects the table in step S1704 The offset amount Os is determined by referring to the reference. Here, a large value is set for the offset amount Os because the lower the pump's circulation capacity, the lower the discharge performance. This ensures that even if the pump's circulation capacity is low, discharge can be reliably performed in the initial discharge determination in step S1707. The subsequent processing is the same as in the first embodiment.

[0081] By following the steps S1701 to S1713 described above, it becomes possible to set the optimal offset amount Os according to the cyclic tolerance Rf, enabling accurate measurement of the minimum drive pulse regardless of the value of the cyclic tolerance Rf.

[0082] In this embodiment, the offset amount Os is increased as the pump's circulation capacity decreases, but the adjustment method is not limited to this. Depending on the ink's ejection characteristics, the offset amount Os may be decreased as the circulation capacity decreases. For example, if the ink has a low circulation capacity, ink adhesion near the nozzle increases due to ejection after pause, and the upper limit pulse decreases. In such cases, it is desirable to set the offset amount to be smaller as the circulation capacity decreases. The pump may be mounted on the recording head 9 or on the main body of the device.

[0083] (modified version) In this embodiment, the offset amount Os was changed according to the circulation tolerance Rf of the pump, but another factor that contributes to the single-shot ink discharge performance is ambient humidity. The lower the ambient humidity, the faster the ink evaporation rate and the more rapidly the viscosity increases, which tends to reduce the single-shot discharge performance. Therefore, it is preferable to use a table in which the offset amount increases as the ambient humidity decreases. Thus, the same effect as in the above embodiment can be obtained by acquiring ambient humidity instead of circulation tolerance information in step S1703 and selecting an offset amount table according to the result in step S1704.

[0084] [Fifth Embodiment] In the fifth embodiment, the process for when the minimum drive pulse Pth could not be detected in the first embodiment will be described. Specifically, in the flowchart of Figure 6, for example, if dust such as paper dust adheres to the nozzle, even if the pulse width is increased by a considerable number (e.g., 10 steps) in step S606, it may be determined that there is no discharge nozzle. In that case, applying a pulse increased by 10 steps as the drive pulse may result in an excessive discharge amount. Therefore, in this embodiment, if the discharge nozzle cannot be detected even after increasing the pulse width by a considerable number, it is treated as undetectable, and the subsequent processing is skipped, ending the flowchart of Figure 6. After that, the process moves to the flowchart of Figure 21, where the processing for the undetectable case is performed.

[0085] In step S2101 of Figure 21, the CPU 101 performs a minimum drive pulse Pth detection process. This process is the minimum drive pulse measurement method of the first embodiment and corresponds to the entire flow in Figure 6. If the minimum drive pulse Pth cannot be detected, the CPU 101 stores a note in the ROM 102 indicating that it could not be detected.

[0086] In step S2102, the CPU 101 determines whether the detection of the minimum drive pulse Pth was successful or unsuccessful. If successful, the process proceeds to step S2106; otherwise, it proceeds to step S2103.

[0087] In step S2103, the CPU 101 determines whether it is the first measurement after the recording head 9 has been installed. If it is the first measurement, the process proceeds to step S2104; otherwise, it proceeds to step S2105. For example, when the first inspection is completed, the CPU 101 may write to a predetermined area in the ROM 102, and then in S2103, it may read the information from this area to make the determination.

[0088] In step S2104, the CPU 101 performs corrections based on the head's factory settings and the offset values ​​for each color. Specifically, it refers to the initial correction table, as shown in Figure 22, stored in the ROM 102, and sets the correction values. Here, the factory settings refer to the default values ​​pre-set for the recording head 9.

[0089] In the table in Figure 22, the first row shows the value of the minimum drive pulse Pth written using the inspection ink at the time of head shipment. As mentioned above, the ink used for image recording and the inspection ink at the time of head shipment have different properties. This is because, when measuring the minimum drive pulse at the time of head shipment, it is sufficient to grasp the difference between heads, so an ink is used that does not cause scorching or adhesion to the recording element and can maintain stability even after going through processes such as logistics.

[0090] As shown in Figure 2, the ejection port row 6 of this embodiment is divided into three rows: rows a-c, rows d-f, and rows g-i. The correspondence between rows and colors (ink types) is as follows: row a: gray (Gy), row b: cyan (Cy), row c: red (Re), row d: magenta (Ma), row e: light magenta (LM), row f: light cyan (LC), row g: yellow (Ye), row h: clear ink (CO), and row i: black (BK). Furthermore, since three rows form a set of recording elements, the same value is written to every three rows: the value for rows a-c is 18, the value for rows d-f is 16, and the value for rows g-i is 14. The value here refers to the pulse number shown in Figure 7. For example, if the pulse number is 18, the pulse width is 80 μs.

[0091] Next, we will explain the offset values ​​for each color in the second row of the table in Figure 22. In this embodiment, nine inks are used to record an image, but some inks are prone to scorching and depositing residue on the recording element surface. When scorching residue adheres to the recording element, the transfer of thermal energy changes, and the minimum drive pulse Pth also changes. Therefore, the value to be used for the actual image recording ink is calculated by adding an offset value to the minimum drive pulse Pth of the ink used for factory inspection. However, since the degree of scorching (i.e., the degree of change in the minimum drive pulse Pth) differs depending on the type of ink, the offset value also needs to be set for each ink color. Specifically, in this embodiment, for colors other than black (Bk), an offset value of "3" is set for the ink used for factory inspection. On the other hand, since the ink for black (Bk) is the same during factory inspection and during image recording, the offset value is set to "0" (no offset). In other words, the offset values ​​in this embodiment are 0 or greater.

[0092] In Figure 22, the corrected setting value in the third row is obtained by adding the offset value in the second row to the value in the first row. The CPU 101 may perform the correction by referring to the corrected setting value previously stored in the ROM 102, or it may calculate the corrected setting value based on the values ​​in the first and second rows and store it in the RAM 103 for use. By this method, even if detection is not possible during the initial minimum drive pulse detection process after head installation, a correction value that takes into account the value at the time of head shipment and the offset value for each color can be set.

[0093] On the other hand, if the initial detection process was unsuccessful (S2103=No), in step S2105, the CPU 101 reads the previously detected minimum drive pulse Pth value from RAM 103 or similar and sets it as the current minimum drive pulse Pth. By this method, even if detection is unsuccessful during the minimum drive pulse measurement process, the previous setting value can be used to utilize a setting value corresponding to the actual ink used for image recording.

[0094] In step S2106, the CPU 101 determines the value set in either step S2101, S2104, or S2105 as the minimum drive pulse Pth and stores it in RAM 103. According to the above flow, even if the detection process fails due to paper dust or other reasons and detection is deemed impossible, an appropriate minimum drive pulse Pth can be set.

[0095] [Sixth Embodiment] In the fifth embodiment, if detection was not possible during the minimum drive pulse detection process, the minimum drive pulse Pth was calculated for all colors according to the same flow. On the other hand, in the sixth embodiment, if detection was possible for some colors and not for others during the minimum drive pulse detection process, the same processing as in the fifth embodiment was performed only for the colors that could not be detected.

[0096] Figure 23 shows the flow of this embodiment. In step S2301, the CPU 101 performs the lowest drive pulse Pth detection process. This process is performed in the same way as in step S2101 in Figure 21.

[0097] In step S2302, the CPU 101 determines whether the detection of the minimum drive pulse Pth was successful or unsuccessful. This determination is based on the detection results in step S2301. If the detection process is successful for all colors, the CPU 101 proceeds to step S2306; if there are any colors that were unsuccessful, i.e., undetectable, the CPU 101 proceeds to step S2303.

[0098] In step S2303, the CPU 101 determines whether it is the first measurement after head installation. If it is the first measurement, the process proceeds to step S2304; otherwise, it proceeds to step S2305. The method for determining whether it is the first measurement is the same as in the fifth embodiment.

[0099] In step S2304, the CPU 101 performs corrections based on the head's factory settings, the offset values ​​for each color, and the measurement results from the main unit. Specifically, it refers to the initial correction table, as shown in Figure 24, stored in the ROM 102, and sets the correction values.

[0100] In Figure 24, the values ​​in the first row (head shipment values) and the color offset values ​​in the second row are the same as those in the correction table in Figure 22 used in the fifth embodiment. In the third row (main unit measurement results), only gray (Gy) has the value "19" written in it. On the other hand, the values ​​for colors other than Gy are left blank. This indicates that in the detection process of step S2301, only Gy could be measured, and the other colors could not be measured, i.e., they could not be detected. The first and second rows of the table may be stored in ROM 102, and the third row may be written to RAM 103 after the detection process is completed. Then, in subsequent processes, the CPU 101 may refer to ROM 102 and RAM 103 to proceed with processing.

[0101] Focusing on the Gy value, the correction value for Gy in the table in Figure 22 used in the fifth embodiment was 21, whereas the measurement result in this embodiment is 19. In other words, comparing the measurement result in the sixth embodiment with the correction value in the fifth embodiment (i.e., the value obtained by adding the offset value to the value at the time of head shipment), the sixth embodiment has a value that is 2 lower. This difference is thought to be a result of the recording head used in this embodiment having the characteristic of transferring energy more easily than a standard recording head due to individual differences such as the wiring condition of the main body of the recording head 9. Therefore, it is desirable to set the correction value to -2 for colors other than Gy, which could not be measured. As a result, the correction values ​​for each color from Cy to Bk shown in the fourth row of the table in Figure 24 are -2 compared to the fifth embodiment.

[0102] By using the method described above, even if there are colors that cannot be detected during the initial minimum drive pulse detection process after head installation, a desirable correction value can be set that takes into account the head's factory settings, the offset value for each color, and the measurement results.

[0103] On the other hand, if the initial detection process was unsuccessful (S2303=No), in step S2305, the CPU 101 reads the previously detected minimum drive pulse Pth value from RAM 103 or similar and sets it as the current minimum drive pulse Pth. By this method, even if detection is unsuccessful during the minimum drive pulse detection process, the previous setting value can be used to utilize the setting value corresponding to the actual ink used for image recording.

[0104] In step S2306, the CPU 101 determines the value set in either step S2301, S2304, or S2305 as the minimum drive pulse Pth and stores it in RAM 103.

[0105] Through the above process, if the minimum drive pulse detection process fails for some colors, it becomes possible to set a more desirable minimum drive pulse Pth using the detection results for the colors where detection was successful.

[0106] [Seventh Embodiment] The sixth embodiment describes a case where there is a mixture of colors in which the minimum drive pulse Pth could be measured and colors in which it could not. The seventh embodiment describes a case in which the minimum drive pulse Pth could not be detected for any of the ink colors during the detection process.

[0107] In step S2501 of the flowchart in Figure 25, the CPU 101 performs the minimum drive pulse Pth detection process. This process is performed in the same way as in step S2101 in Figure 21.

[0108] In step S2502, the CPU 101 determines whether the detection of the minimum drive pulse Pth was successful or unsuccessful. This determination is based on the detection result in the S2501 process and is similar to step S2302 in Figure 23. If detection is successful, the process proceeds to step S2506; otherwise, it proceeds to step S2503.

[0109] In step S2503, the CPU 101 determines whether it is the first measurement after head installation. If it is the first measurement, the process proceeds to S2504; otherwise, the process proceeds to step S2505. The method for determining whether it is the first measurement is the same as in the fifth embodiment.

[0110] In step S2504, the CPU 101 performs corrections based on the head's initial offset values ​​for each color and the main unit offset value. Specifically, it refers to the initial correction table, as shown in Figure 26, stored in the ROM 102, and sets the correction amount.

[0111] The values ​​for the head at shipment in the first row and the offset values ​​for each color in the second row are set to the same values ​​as in Figure 22. The value "1" is written for each color in the main unit offset value in the third row. This is the device-specific offset amount based on the results of the minimum drive pulse Pth measurement performed during the shipment inspection. The CPU 101 calculates the correction value in the fourth row based on the offset values ​​for each color in the second row and the main unit offset value in the third row.

[0112] Here, the correction value in the seventh embodiment shown in Figure 24 is 3 higher than the correction value in the sixth embodiment shown in Figure 22. This is thought to be because, as mentioned above, the recording head 9 in the sixth embodiment had the characteristic of easily transferring energy through the main body, whereas the recording head 9 in the seventh embodiment has the characteristic of being relatively difficult to transfer energy through.

[0113] By using the above method, even if each color cannot be detected during the initial minimum drive pulse detection process after head installation, a desirable correction value can be set that takes into account the value at the time of head shipment, the offset value for each color, and the offset value that reflects the characteristics of the main unit.

[0114] On the other hand, if the initial detection process was unsuccessful (S2503=No), step S2505 sets the previously detected minimum drive pulse Pth value. This process is the same as step S2305 in Figure 22.

[0115] In step S2506, the CPU 101 determines the value set in either step S2501, S2504, or S2505 as the minimum drive pulse Pth and stores it in the RAM 103.

[0116] Through the above process, if the detection of the minimum drive pulse Pth is unsuccessful for each color, a more desirable Pth can be set in the actual configuration.

[0117] [Eighth Embodiment] The eighth embodiment describes a case where the recording head 9 includes three groups of sub-recording heads 91a to 91c, and each sub-recording head 91 is provided with three rows of ejection ports 6. In the eighth embodiment, the case where, in the minimum drive pulse Pth detection process, there is only one color for which the minimum drive pulse Pth can be detected in each sub-recording head is described. The following description will mainly focus on the differences from the sixth embodiment.

[0118] In the flowchart of Figure 27, in step S2701, the CPU 101 performs the minimum drive pulse Pth detection process. This process is performed in the same way as in step S2101 in Figure 21.

[0119] In step S2702, the CPU 101 determines whether the detection of the minimum drive pulse Pth was successful or unsuccessful. This determination is based on the detection results in step S2701. If the detection process is successful for all colors, the process proceeds to step S2706; if there are any colors that could not be detected, the process proceeds to step S2703.

[0120] In step S2703, CPU101 determines whether it is the first measurement after head installation. If it is the first measurement, proceed to S2704; otherwise, proceed to step S2705.

[0121] In step S2704, the CPU 101 performs corrections based on the head's factory settings, the offset values ​​for each color, and the measurement results for each output port row group. Specifically, it refers to the initial correction table, as shown in Figure 28, stored in the ROM 102, and sets the correction values.

[0122] In this embodiment, as shown in Figure 28(b), the recording head 9 includes three sub-recording heads 91a to 91c. Sub-recording head 91a has output rows 6a to 6c (Gy, Cy, Re), sub-recording head 91b has output rows 6d to 6f (Ma, LM, LC), and sub-recording head 91c has output rows 6g to 6i (Ye, CO, BK). Here, it is assumed that each sub-recording head 91 has at least one color that has been successfully detected. If all three colors in a particular sub-recording head 91 are undetectable, a correction value may be set for that group based on the method of other embodiments.

[0123] In Figure 28(a), the values ​​for the head at shipment in the first row and the offset values ​​for each color in the second row are the same as in Figure 24. For the main unit measurement results in the third row, the values ​​Gy=19, LM=18, and Bk=17 are written. This indicates that Gy, LM, and BK could be measured in the minimum drive pulse Pth measurement result, but the other colors could not be measured. In other words, in this embodiment, the Gy ink was detected for sub-recording head 91a, the LM ink for sub-recording head 91b, and the Bk ink for sub-recording head 91c.

[0124] As explained in the sixth embodiment, there are individual differences in how easily energy is transferred within the recording head. In a configuration like this embodiment, these individual differences differ for each sub-recording head 91. Therefore, in this embodiment, a correction value is set considering the ease of energy transfer for each sub-recording head 91.

[0125] Specifically, for the sub-recording head 91a, the measured value for the Gy ink is 19. This is 2 lower than the value obtained by adding the Gy offset value of 3 to the value of 18 at the time of shipment of the head. In other words, it is thought that the sub-recording head 91a has the characteristic of transferring energy more easily than a standard recording head. Therefore, similarly for the other two colors (Cy and Re) included in the sub-recording head 91a, a correction value of -2 from each color offset value is used.

[0126] Similarly, for the sub-recording head 91b, a value obtained by subtracting 1 from each color offset value is used, based on the measurement results of the LM ink in the main unit. For the sub-recording head 91c, a value obtained by adding 3 to each color offset value is used, based on the measurement results of the BK ink in the main unit.

[0127] As a result, even if there are colors that cannot be detected during the initial minimum drive pulse detection process after head installation, a desirable correction value can be set considering the head's factory settings, the offset value for each color, and the measurement results for each sub-recording head.

[0128] On the other hand, if the initial detection process was unsuccessful (S2703=No), in step S2705, the CPU 101 reads the previously detected minimum drive pulse Pth value from the RAM 103 and sets it as the current minimum drive pulse Pth. By this method, even if the minimum drive pulse Pth cannot be detected, the previously set value can be used to utilize the setting value corresponding to the actual image recording ink.

[0129] In step S2706, the CPU 101 determines the value set in either step S2701, S2704, or S2705 as the minimum drive pulse Pth and stores it in RAM 103.

[0130] Through the above process, even if there are colors in the sub-recording head 91 that were not successfully detected, the desired Pth can be set using the detection results for the colors that were successfully detected.

[0131] In this embodiment, a configuration in which the recording head 9 is divided into sub-recording heads 91 has been described. In Figure 28(b), a configuration in which multiple sub-recording heads are arranged in close proximity to each other is shown, but this embodiment can also be applied when the distance between the sub-recording heads is large.

[0132] Furthermore, in Figure 2, three chips are mounted inside one recording head 9 (chip 1: ejection port rows 6a-6c, chip 2: ejection port rows 6d-6f, chip 3: ejection port rows 6g-6h). The concept of this embodiment can also be applied to such a configuration. That is, if the minimum drive pulse Pth measurement is successful for only one color of ink within a chip, and the other two colors cannot be detected, the correction values ​​for the other two colors may be set based on the measurement results for the successful color.

[0133] [Ninth Embodiment] The ninth embodiment describes a case where the minimum drive pulse Pth detection process could not be performed for the second time or later after the head was mounted.

[0134] In the flowchart of Figure 29, at step S2901, the CPU 101 is at minimum operation. The pulse Pth is detected. This process is performed in the same manner as in step S2101 in Figure 21.

[0135] In step S2902, the CPU 101 determines whether the detection of the minimum drive pulse Pth was successful or unsuccessful. This determination is based on the detection result in S2901. If detection is successful, the process proceeds to step S2906; otherwise, it proceeds to step S2903.

[0136] In step S2903, CPU101 determines whether it is the first measurement after head installation. If it is the first measurement, proceed to step S2904; otherwise, proceed to step S2905.

[0137] In step S2904, the CPU 101 performs corrections based on the head's factory settings and the offset values ​​for each color. The correction process is the same as in step S2104 in Figure 21 and is therefore omitted here.

[0138] On the other hand, if the initial detection process was unsuccessful (S2903=No), in step S2905, the CPU 101 performs a correction based on the previous minimum drive pulse Pth value and the dot count offset value. Figure 30 shows the correction table for this embodiment. The first row shows the minimum drive pulse Pth value from the previous measurement. The second row is the dot count offset value, which is determined based on the dot count result. The CPU 101 adds the dot count offset value to the previous minimum drive pulse Pth value to calculate the correction value in the third row. The correction value is then stored in the RAM 103.

[0139] Here, the dot count value is the number of ink dots ejected, as measured by the ejection dot counter 119, which acts as a counter unit. When the amount of ink ejected from the ejection port 5 increases, burnt residue may adhere to the inside of the head, or the recording element surface may be damaged by the impact during ejection. Because the way energy is transmitted changes due to such burnt residue or changes in the state of the recording element surface, the appropriate minimum drive pulse Pth value also changes. Furthermore, the degree of such changes differs not only depending on the number of ink ejections but also on the type of ink. Therefore, for detection from the second time onward, the CPU 101 obtains a dot count offset value, which is set in advance according to the ink, from the ROM 102 or the like, and adds it to the previous minimum drive pulse Pth value. This makes it possible to set a more desirable correction value that reflects the changes in the state of the recording head due to ink ejection.

[0140] In step S2906, the CPU 101 determines the value set in either step S2901, S2904, or S2905 as the minimum drive pulse Pth and stores it in the RAM 103.

[0141] Through the above process, if detection fails from the second time onward, the previous measurement results can be corrected based on the dot count value, allowing for the setting of a more desirable Pth.

[0142] [Other embodiments] In any embodiment, the method for detecting the minimum drive pulse Pth is not limited to using an optical sensor. For example, a method may be employed in which the minimum drive pulse Pth is detected by performing multiple print jobs while changing the pulse number and determining whether or not printing has been done on the recording medium.

[0143] Furthermore, the recording device 200 is not limited to a serial printer; for example, it may be a printer equipped with a full multi-head, which is a recording head sized to cover the width of the recording medium. Also, the ink ejection method of the recording device 200 is not limited to a thermal method; for example, it may be a piezo method.

[0144] [Configuration 1] A recording head having a liquid chamber capable of containing a liquid and provided with a liquid discharge port, and a recording element that, when a drive pulse, which is an electrical signal of a predetermined pulse width, is applied, is driven to generate drive energy to discharge the liquid from the liquid chamber, A discharge detection unit for detecting whether or not the liquid is discharged from the discharge port, A control unit that controls the drive energy by changing the drive pulse applied to the recording element, A recording device comprising, The control unit, The minimum driving energy required for the discharge of the liquid is measured by repeatedly detecting the presence or absence of liquid discharge by the discharge detection unit while changing the driving energy from the initial driving energy in predetermined units. The initial drive energy is calculated by correcting the minimum drive energy from the previous measurement, and, The initial drive energy is set such that the number of times the discharge detection unit repeats detection is less than or equal to a predetermined number. A recording device characterized by the following features. [Configuration 2] In measuring the minimum drive energy, if the liquid is not discharged at the initial drive energy, the control unit increases the drive energy by a predetermined first unit from the initial drive energy while detecting whether or not the liquid is discharged using the discharge detection unit, and determines the minimum drive energy based on the drive energy at which the liquid is discharged. A recording device according to configuration 1, characterized in that it is a recording device. [Configuration 3] The control unit detects whether or not the liquid is being discharged by the discharge detection unit, while decreasing the drive energy in increments of a second unit smaller than the first unit, starting from the drive energy when the discharge of the liquid is detected, and determines the minimum drive energy based on the drive energy when the discharge of the liquid stops. A recording device according to configuration 2, characterized in that... [Structure 4] The control unit determines the minimum drive energy by adding a value corresponding to the second unit to the drive energy at the time when the liquid discharge ceases. A recording device according to configuration 3, characterized in that it is a recording device. [Composition 5] The control unit sets the driving energy when recording an image with the liquid to a value obtained by multiplying the minimum driving energy by a predetermined coefficient greater than 1. A recording device according to any one of configurations 1 to 4, characterized in that it is a recording device. [Composition 6] The control unit calculates the initial drive energy by adding an offset value to the minimum drive energy from the previous measurement. A recording device according to any one of configurations 1 to 5, characterized by the above. [Composition 7] The recording head has multiple outlets corresponding to multiple types of liquid, The control unit uses different offset values ​​for each type of liquid. A recording device according to configuration 6, characterized in that... [Structure 8] The control unit increases the offset value as the liquid's dispensing performance decreases. A recording device according to configuration 7, characterized by the features described above. [Composition 9] The control unit changes the offset value depending on whether the liquid used in the previous measurement of the minimum driving energy is the same liquid used when recording the image. A recording device according to any one of the configurations 6 to 8, characterized in that it is a recording device. [Configuration 10] The control unit sets the upper limit of the initial drive energy to a value obtained by adding six times the predetermined unit of drive energy to the lowest drive energy measured in the previous measurement. A recording device according to any one of configurations 1 to 9, characterized in that it is a recording device. [Composition 11] The control unit performs a correction such that the value of the initial drive energy decreases as the temperature of the environment in which the recording head is placed increases. A recording device according to any one of configurations 1 to 10, characterized in that it is a recording device. [Composition 12] The control unit performs a correction such that the value of the initial drive energy increases as the humidity of the environment in which the recording head is placed decreases. A recording device according to any one of configurations 1 to 11, characterized by the above. [Composition 13] The system further comprises a circulation mechanism for circulating the liquid in the recording head, The recording device according to any one of configurations 1 to 12, characterized in that the control unit changes the initial drive energy according to the circulation capacity of the circulation mechanism. [Composition 14] The control unit increases the initial drive energy as the circulation capacity of the circulation mechanism decreases. A recording device according to configuration 13, characterized in that it is a recording device. [Composition 15] The system further includes a temperature control unit that controls the temperature of the recording head, The temperature control unit raises the temperature of the recording head when measuring the minimum drive energy compared to when recording an image with the liquid. A recording device according to any one of configurations 1 to 14, characterized by the above. [Composition 16] If the minimum drive energy cannot be detected during the measurement, the control unit determines whether the measurement was the first measurement after the recording head was mounted on the recording device. If it was the first measurement, it determines the minimum drive energy by correcting the drive energy set at the time of shipment of the recording head. If it was the second or subsequent measurement, it corrects the minimum drive energy from the previous measurement. A recording device according to any one of configurations 1 to 15, characterized in that it is a recording device. [Composition 17] The control unit, when correcting for the minimum drive energy being undetectable during the first measurement after the recording head is installed, adds an offset value corresponding to the type of liquid to the drive energy set at the time of shipment of the recording head. A recording device according to configuration 16, characterized in that it is a recording device. [Composition 18] The recording head has multiple outlets corresponding to multiple types of liquid, If, during the first measurement after the recording head is installed, the control unit finds that there are liquids for which the minimum drive energy could not be detected and liquids for which the minimum drive energy could be detected, it corrects the drive energy set at the time of shipment of the recording head based on an offset value corresponding to the type of liquid and the measurement results for the liquids for which the minimum drive energy could be detected. A recording device according to configuration 16, characterized in that it is a recording device. [Composition 19] The control unit, in the first measurement after the recording head is installed, determines the minimum drive energy When correction is performed in the event that detection is not possible, the drive energy set at the time of shipment of the recording head is corrected based on an offset value corresponding to the type of liquid and an intrinsic offset value of the recording head. A recording device according to configuration 16, characterized in that it is a recording device. [Configuration 20] The inherent offset value of the recording head is an offset value that reflects the characteristics of the energy transfer properties of the recording head. A recording device according to configuration 19, characterized by the above. [Composition 21] The recording device further comprises a counter unit for measuring the number of dots of the liquid discharged from the discharge port, The control unit, when correcting for the lowest drive energy that could not be detected in the second or subsequent measurements after the recording head was installed, corrects the lowest drive energy from the previous measurement based on the number of liquid dots measured by the counter unit. A recording device according to configuration 16, characterized in that it is a recording device. [Explanation of symbols]

[0145] 5: Discharge port, 9: Recording head, 11: Ink tank, 12: Discharge detection unit, 86: Recording element, 100: Control unit, 200: Recording device

Claims

1. A recording head having a liquid chamber capable of containing a liquid and provided with a liquid discharge port, and a recording element that, when a drive pulse, which is an electrical signal of a predetermined pulse width, is applied, is driven to generate drive energy to discharge the liquid from the liquid chamber, A discharge detection unit for detecting whether or not the liquid is discharged from the discharge port, A control unit that controls the drive energy by changing the drive pulse applied to the recording element, A recording device comprising, The control unit, The minimum driving energy required for the discharge of the liquid is measured by repeatedly detecting the presence or absence of liquid discharge by the discharge detection unit while changing the driving energy from the initial driving energy in predetermined units. The initial drive energy is calculated by correcting the minimum drive energy from the previous measurement, and, The initial drive energy is set such that the number of times the discharge detection unit repeats detection is less than or equal to a predetermined number. A recording device characterized by the following features.

2. In measuring the minimum drive energy, if the liquid is not discharged at the initial drive energy, the control unit increases the drive energy by a predetermined first unit from the initial drive energy while detecting whether or not the liquid is discharged using the discharge detection unit, and determines the minimum drive energy based on the drive energy at which the liquid is discharged. The recording device according to feature 1.

3. The control unit detects whether or not the liquid is being discharged by the discharge detection unit, while decreasing the drive energy in increments of a second unit smaller than the first unit, starting from the drive energy when the discharge of the liquid is detected, and determines the minimum drive energy based on the drive energy when the discharge of the liquid stops. The recording device according to feature 2.

4. The control unit determines the minimum drive energy by adding a value corresponding to the second unit to the drive energy at the time when the liquid discharge ceases. The recording device according to feature 3.

5. The control unit sets the driving energy when recording an image with the liquid to a value obtained by multiplying the minimum driving energy by a predetermined coefficient greater than 1. A recording device according to any one of claims 1 to 4.

6. The control unit calculates the initial drive energy by adding an offset value to the minimum drive energy from the previous measurement. A recording device according to any one of claims 1 to 4.

7. The recording head has multiple outlets corresponding to multiple types of liquid, The control unit uses different offset values ​​for each type of liquid. The recording device according to feature 6.

8. The control unit increases the offset value as the liquid's dispensing performance decreases. The recording device according to feature 7.

9. The control unit changes the offset value depending on whether the liquid used in the previous measurement of the minimum driving energy is the same liquid used when recording the image. The recording device according to feature 6.

10. The control unit sets the upper limit of the initial drive energy to a value obtained by adding six times the predetermined unit of drive energy to the lowest drive energy measured in the previous measurement. A recording device according to any one of claims 1 to 4.

11. The control unit performs a correction such that the value of the initial drive energy decreases as the temperature of the environment in which the recording head is placed increases. A recording device according to any one of claims 1 to 4.

12. The control unit performs a correction such that the value of the initial drive energy increases as the humidity of the environment in which the recording head is placed decreases. A recording device according to any one of claims 1 to 4.

13. The system further comprises a circulation mechanism for circulating the liquid in the recording head, The recording device according to any one of claims 1 to 4, characterized in that the control unit changes the initial drive energy according to the circulation capacity of the circulation mechanism.

14. The control unit increases the initial drive energy as the circulation capacity of the circulation mechanism decreases. The recording device according to feature 13.

15. The system further includes a temperature control unit that controls the temperature of the recording head, The temperature control unit raises the temperature of the recording head when measuring the minimum drive energy compared to when recording an image with the liquid. A recording device according to any one of claims 1 to 4.

16. If the minimum drive energy cannot be detected during the measurement, the control unit determines whether the measurement was the first measurement after the recording head was mounted on the recording device. If it was the first measurement, it determines the minimum drive energy by correcting the drive energy set at the time of shipment of the recording head. If it was the second or subsequent measurement, it corrects the minimum drive energy from the previous measurement. A recording device according to any one of claims 1 to 4.

17. The control unit, when correcting for the minimum drive energy being undetectable during the first measurement after the recording head is installed, adds an offset value corresponding to the type of liquid to the drive energy set at the time of shipment of the recording head. The recording device according to feature 16.

18. The recording head has multiple outlets corresponding to multiple types of liquid, If, during the first measurement after the recording head is installed, the control unit finds that there are liquids for which the minimum drive energy could not be detected and liquids for which the minimum drive energy could be detected, it corrects the drive energy set at the time of shipment of the recording head based on an offset value corresponding to the type of liquid and the measurement results for the liquids for which the minimum drive energy could be detected. The recording device according to feature 16.

19. The control unit, when correcting for the minimum drive energy that could not be detected during the first measurement after the recording head was installed, corrects the drive energy set at the time of shipment of the recording head based on an offset value corresponding to the type of liquid and an intrinsic offset value of the recording head. The recording device according to feature 16.

20. The inherent offset value of the recording head is an offset value that reflects the characteristics of the energy transfer properties of the recording head. The recording device according to feature 19.

21. The recording device further comprises a counter unit for measuring the number of dots of the liquid discharged from the discharge port, The control unit, when correcting for the lowest drive energy that could not be detected in the second or subsequent measurements after the recording head was installed, corrects the lowest drive energy from the previous measurement based on the number of liquid dots measured by the counter unit. The recording device according to feature 16.

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