Recording device and determination method

Abstract

To provide a recording device that uses a liquid discharge head having heaters which generate heat energy provided for each nozzle in order to discharge liquid, which can accurately determine a discharging state of the nozzle.SOLUTION: A recording device comprises: driving means that drives each of a plurality of heaters; a plurality of temperature sensors provided to respectively correspond to the plurality of heaters; and determining means that determines whether each of the plurality of nozzles can discharge liquid normally or not, on the basis of output of the plurality of temperature sensors. The determining means continuously applies a first driving signal and a second driving signal which is different in heat generation by a heater from the first driving signal, to the heater corresponding to the nozzle to be determined; determines whether the nozzle to be determined can discharge liquid normally, on the basis of a change rate of output of the temperature sensors at the time of applying the first driving signal and a change rate of output of the temperature sensors at the time of applying the second driving signal; and does not apply the driving signal to the heater corresponding to the nozzle not to be determined, during an interval between the applications of the first driving signal and the second driving signal.SELECTED DRAWING: Figure 11

Description

Technical Field

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

Background Art

[0002] In an inkjet recording apparatus that discharges ink droplets from nozzles and attaches them to a recording medium, there is one that uses a liquid discharge head provided with a heater that generates thermal energy for each nozzle to discharge ink. In such a recording apparatus, a method for determining non-discharge due to nozzle clogging or the like has been proposed. Patent Document 1 describes a method of providing a temperature sensor for each nozzle and determining the discharge state of the nozzle based on the temperature change of the nozzle after discharge.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the ejection determination method of Patent Document 1, first, a first process is performed in which a first pulse is input to each of a plurality of heaters corresponding to a plurality of nozzles provided in a liquid ejection head to obtain information on temperature changes of the plurality of heaters. Next, a second process is performed in which a second pulse is input to each of the plurality of heaters to obtain information on temperature changes of the plurality of heaters. Based on the information on the temperature change when the first pulse is input to the heater corresponding to the nozzle to be determined and the information on the temperature change when the second pulse is input, which are obtained in the first process and the second process, an ejection determination of the nozzle to be determined is performed. In this determination method, the time required for the first process becomes longer according to the number of heaters (nozzles) provided in the liquid ejection head, and the second process is performed after the first process is completed. That is, the interval between the timing when the first pulse is input to the heater corresponding to a certain nozzle in the first process and the timing when the second pulse is input to the heater in the second process is at least as long as the time required for the first process. Therefore, in this determination method, it has been difficult to shorten the interval between the timing when the first pulse is input to the heater corresponding to the nozzle to be determined and the timing when the second pulse is input. When the interval becomes long, various conditions that affect the ejection state such as the temperature, humidity, and state of the liquid at the timing when the first pulse is input may not match the various conditions at the timing when the second pulse is input. In that case, there is a problem that accurate ejection determination cannot be made.

[0005] An object of the present invention is to accurately determine the ejection state of nozzles in a recording apparatus using a liquid ejection head provided with a heater for generating thermal energy for each nozzle to eject a liquid.

Means for Solving the Problem

[0006] The present invention includes a plurality of nozzles for ejecting a liquid, a plurality of heaters provided corresponding to each of the plurality of nozzles for heating the liquid, driving means for driving each of the plurality of heaters, a plurality of temperature sensors provided corresponding to each of the plurality of heaters, Determination means for determining, for each of the plurality of nozzles, whether or not the liquid is being discharged normally based on the outputs of the plurality of temperature sensors; A recording apparatus that performs recording on a recording medium using a liquid discharge head including: The determination means, by the driving means, applies to the heater corresponding to the nozzle to be determined against a first drive signal and a second drive signal having a different heat generation of the heater with respect to the first drive signal, continuously; a change rate of the output of the temperature sensor when the first drive signal is applied; a change rate of the output of the temperature sensor when the second drive signal is applied; and determines for the nozzle to be determined based thereon; The determination means is characterized in that, during an interval between the first drive signal and the second drive signal, no drive signal is applied to the heater corresponding to the nozzle that is not the determination target.

[0007] The present invention relates to a recording apparatus that performs recording on a recording medium using a liquid discharge head including: a plurality of nozzles that discharge a liquid; a plurality of heaters provided corresponding to each of the plurality of nozzles for heating the liquid; driving means for driving each of the plurality of heaters; a plurality of temperature sensors provided corresponding to each of the plurality of heaters, and a determination method for determining, for each of the plurality of nozzles, whether or not the liquid is being discharged normally, the method including: applying, by the driving means, a first drive signal and a second drive signal having a different heat generation of the heater with respect to the first drive signal, continuously to the heater corresponding to the nozzle to be determined; acquiring the output of the temperature sensor when the first drive signal is applied; A step of determining the nozzle to be determined based on the change rate of the output of the temperature sensor when the first drive signal is applied and the change rate of the output of the temperature sensor when the second drive signal is applied; having During the interval between the first drive signal and the second drive signal, the drive signal is not applied to the heater corresponding to the nozzle that is not the determination target. This is a determination method characterized by this.

Effect of the Invention

[0008] According to the present invention, in a recording apparatus using a liquid ejection head provided with a heater for generating thermal energy for each nozzle to eject a liquid, the ejection state of the nozzle can be accurately determined.

Brief Description of the Drawings

[0009]

Figure 1

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Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0011] The embodiments described below will be explained by taking, as an example, a device that discharges a liquid, particularly an inkjet recording device (hereinafter referred to as a recording device) that discharges ink for recording. This recording device is a recording device that circulates a liquid between a tank and a liquid discharge device, but other forms may also be possible. For example, instead of circulating the ink, two tanks may be provided on the upstream side and the downstream side of the liquid discharge device, and the ink may flow from one tank to the other to cause the ink in the pressure chamber to flow.

[0012] Also, in the embodiments, a so-called line-type head having a length corresponding to the width of the recording medium will be described as an example, but the present invention can also be applied to a so-called serial-type liquid discharge device that performs recording while scanning the recording medium. Examples of the serial-type liquid discharge device include, but are not limited to, a configuration in which one element substrate each for black ink and color ink is mounted. A short-line head shorter than the width of the recording medium may be created by arranging a plurality of element substrates such that the nozzles overlap in the nozzle row direction and scanning it with respect to the recording medium.

[0013] (Example 1) (Explanation of Inkjet Recording Device) FIG. 1 is a diagram showing a schematic configuration of a recording device 1000 according to Example 1. The recording device 1000 includes a transport unit 1 that transports a recording medium 2 and a liquid discharge head (recording head) 3, which is a line-type liquid discharge device arranged substantially orthogonal to the transport direction of the recording medium 2. The recording device 1000 is a line-type recording device that performs continuous recording in one pass while continuously or intermittently transporting a plurality of recording media 2. The liquid discharge head 3 is connected to a liquid supply means, which is a supply path for supplying a liquid to the liquid discharge head 3.

[0014] FIG. 2 is a block diagram showing a control configuration of the recording device 1000. A control device 900 that transmits power and a discharge control signal to the liquid discharge head 3 is electrically connected to the liquid discharge head 3. The control device 900 controls the operation of the liquid discharge head 3 and inspects and determines the discharge state.

[0015] In response to an instruction from the control unit 202 of the control device 900, the signal generation unit 201 outputs a clock signal (CLK), a latch signal (LT), a block signal (BLE), a heater selection signal (DATA), and a heat enable signal (HE) to the element substrate 10. Further, sensor selection signals (SDATA), a constant current signal (Diref), and a threshold signal (Dth) related to the selection of a plurality of temperature sensors provided corresponding to each of the plurality of nozzles, the energization amount, and the processing of the output signals are output.

[0016] The determination result extraction unit 204 receives a determination result signal (RSLT) indicating a determination result regarding the ejection state of the nozzles of the element substrate 10 based on the temperature information detected by the temperature sensors, and extracts the determination result for each latch period in synchronization with the falling edge of the latch signal LT. When the determination result is non-ejection (a state where normal ejection does not occur), the block signal BLE and the sensor selection signal SDATA corresponding to the determination result are recorded in the memory 203.

[0017] The control unit 202 receives the non-ejection block signal BLE and the sensor selection signal SDATA recorded in the memory 203. When the drive target heater includes one corresponding to the non-ejection nozzle, the one corresponding to the non-ejection nozzle is erased from the heater selection signal DATA of the corresponding block. Then, a heater corresponding to a nozzle for ejection compensation is added to the heater selection signal DATA of the corresponding block and output to the signal generation unit 201.

[0018] (Description of the structure of the element substrate) FIG. 3 is a diagram showing the configuration of the element substrate 10 provided in the liquid ejection head 3 of the first embodiment. FIG. 3(a) shows a plan view of the surface of the element substrate 10 on which the nozzles 13 are formed, FIG. 3(b) shows an enlarged view of the portion indicated by the reference sign A in FIG. 3(a), and FIG. 3(c) shows a plan view of the back surface of the surface shown in FIG. 3(a).

[0019] As shown in FIG. 3(a), four nozzle rows corresponding to the four colors of ink are formed on the nozzle forming member 12 of the element substrate 10. Hereinafter, the direction in which the nozzle row in which a plurality of nozzles 13 are arranged extends is referred to as the "nozzle row direction".

[0020] As shown in FIG. 3(b), the element substrate 10 has a plurality of nozzles 13 (discharge ports) for discharging liquid, and heaters 15 (heating elements, heating resistors) provided at positions corresponding to each of the nozzles 13 for heating the liquid by thermal energy to cause foaming. A pressure chamber 23 having the heater 15 therein is partitioned by a partition wall 22. The heater 15 is electrically connected to the terminal 16 in FIG. 3(a) by an electrical wiring (not shown) provided on the element substrate 10. The heater 15 has a heating resistor that generates heat based on a pulse signal input from a control device 900 as a driving means via a flexible wiring board, and boils the liquid. The liquid is discharged from the nozzle 13 by the force of foaming caused by this boiling. As shown in FIG. 3(b), a liquid supply path 18 extends along each nozzle row on one side in a direction intersecting the nozzle row direction, and a liquid recovery path 19 extends along each nozzle row on the other side. The liquid supply path 18 and the liquid recovery path 19 are flow paths extending in the nozzle row direction provided on the element substrate 10, and communicate with the nozzles 13 via supply ports 17a and recovery ports 17b, respectively.

[0021] As shown in FIG. 3(c), a sheet-like lid member 20 is laminated on the back surface of the surface of the element substrate 10 on which the nozzles 13 are formed, and the lid member 20 is provided with a plurality of openings 21 communicating with the liquid supply path 18 and the liquid recovery path 19 described later. In Example 1, three openings 21 are provided in the lid member 20 for one of the liquid supply paths 18, and two openings 21 are provided in the lid member 20 for one of the liquid recovery paths 19.

[0022] FIG. 4 is a perspective view showing a cross-section of the element substrate 10 and the lid member 20 along the V-V line in FIG. 3(a). As shown in FIG. 4, the lid member 20 functions as a lid that forms a part of the walls of the liquid supply path 18 and the liquid recovery path 19 formed in the substrate 11 of the element substrate 10. As the material of the lid member 20, it is preferable to use a photosensitive resin material or a silicon plate and provide the opening 21 by a photolithography process. In this way, the lid member 20 converts the pitch of the flow path by the opening 21, and considering the pressure loss, it is desirable that the thickness is thin and it is preferably composed of a film-like member.

[0023] Next, the flow of the liquid in the element substrate 10 will be described. The element substrate 10 is formed by laminating a substrate 11 made of Si and a nozzle forming member 12 made of a photosensitive resin, and the lid member 20 is joined to the back surface of the substrate 11. The nozzle forming member 12 is a first layer member provided with nozzles 13 on its surface, and the substrate 11 is a second layer member fixed to the back surface of the nozzle forming member 12 which is the first layer member.

[0024] The nozzle forming member 12 is provided with a pressure chamber 23 which is a first flow path communicating with the nozzles 13. A heater 15 is formed on one surface side of the substrate 11, and grooves forming the liquid supply path 18 and the liquid recovery path 19 extending along the nozzle row are formed on the back surface side thereof. The substrate 11 is provided with a supply port 17a communicating with the pressure chamber 23 and the liquid supply path 18, and a recovery port 17b communicating with the pressure chamber 23 and the liquid recovery path 19. The liquid supply path 18 and the liquid recovery path 19 formed by the substrate 11 and the lid member 20 are respectively connected to a common supply flow path and a common recovery flow path in a flow path member (not shown), and a differential pressure is generated between the liquid supply path 18 and the liquid recovery path 19.

[0025] When performing recording by discharging liquid from a plurality of nozzles 13 of the liquid discharge head 3, there are nozzles 13 that are not performing a discharge operation. In such nozzles 13, due to this differential pressure, the liquid in the liquid supply path 18 provided in the substrate 11 flows into the liquid recovery path 19 via the supply port 17a, the pressure chamber 23, and the recovery port 17b (the flow indicated by the arrow C in FIG. 4). Due to this flow, in the nozzles 13 and the pressure chambers 23 where recording is paused, thickened ink generated by evaporation from the nozzles 13, bubbles, foreign substances, etc. can be recovered into the liquid recovery path 19. Also, thickening of the ink in the nozzles 13 and the pressure chambers 23 can be suppressed.

[0026] The liquid recovered into the liquid recovery path 19 is recovered in the order of the communication port, the individual recovery flow path, and the common recovery flow path in a flow path member (not shown) through the opening 21 of the lid member 20, and is finally recovered into the supply path of the recording apparatus 1000.

[0027] FIG. 5 is a cross-sectional view of the vicinity of the nozzle 13 of the element substrate 10. The element substrate 10 is formed by laminating a plurality of insulating layers and wiring layers on a substrate 11 formed of silicon. The heater 15 and the temperature sensor 120 are connected to an external control device 900 via wiring patterns, conductive plugs, and pads (terminals) provided in a plurality of wiring layers. A plurality of heaters 15 and temperature sensors 120 are provided corresponding to the plurality of nozzles 13. The wiring pattern is formed of a metal material such as Al, Al—Si, or Al—Cu, and the conductive plug is formed of, for example, tungsten.

[0028] The heater 15 is disposed at a position facing the nozzle 13 in the insulating layer 130. The heater 15 is composed of a rectangular thin film resistor made of a material having a high specific resistance and being thermally stable, such as TaSiN.

[0029] A wiring 150 is connected to the heater 15 via a plug 14. The heater 15 is electrically connected to an external control device 900 via the wiring 150.

[0030] A protective layer 140 is disposed on the heater 15. The protective layer 140 is formed of an SiO film, a SiN film, or the like. An anti-cavitation layer 160 is formed on the protective layer 140. The anti-cavitation layer 160 protects the surface of the heater 15 from chemical and physical impacts associated with the heat generation of the heater 15.

[0031] Below the heater 15, a temperature sensor 120 is provided via an insulating layer 130 so as to partially overlap the heater 15 in plan view. The temperature sensor 120 detects the temperature change of the heater 15 and is a sensor for doing so. Although not shown in FIG. 5, the temperature sensor 120 is also electrically connected to an external control device 900 via wiring and a plug in the same manner as the heater 15. Note that the position of the temperature sensor 120 may be arranged at any place such as above or beside the heater 15 as long as it is within the range where heat reaches from the heater 15. As the material of the temperature sensor 120, Ti / TiN, TaSiN, etc. can be used, and as the shape, a bar shape or a meandering shape can be used.

[0032] Inside the pressure chamber 23, a liquid flow path internal ink circulation configuration is adopted in which liquid is supplied from the supply port 17a and recovered to the recovery port 17b. During printing on the heating resistor 126, the liquid flows from the supply port 17a (upstream side) toward the recovery port 17b (downstream side).

[0033] FIG. 6 is a diagram showing the configuration of the heater 15. The heater 15 has a configuration in which a resistor 801 and a transistor 802 are connected between a VH (power supply) wiring and a GNDH (ground) wiring. The heater 15 is provided for each nozzle 13.

[0034] FIG. 7 is a timing chart conceptually showing the operation of the heater 15. The heater 15 takes the latch signal LT as a timing reference, and a heater drive signal HE is input. When the pulse input as the heater drive signal HE is at the H level, the transistor 802 turns on, current flows through the resistor 801, and heat is generated. As a result, the liquid in the pressure chamber 23 is heated and foamed, and the liquid is discharged from the nozzle 13.

[0035] FIG. 8 is a circuit diagram schematically showing the configuration of the temperature sensor 120. The temperature sensor 120 has a resistor 803 and a voltage follower 804. A constant current is supplied to the resistor 803, and the voltage between the terminals of the resistor 803 is detected. Since this detected voltage has a temperature dependence, when the heat of the heater 15 is transmitted to the temperature sensor 120 and the temperature changes, it is output as a waveform 805 indicating a change in the detected voltage. The temperature sensor 120 is provided for each heater 15.

[0036] FIG. 9 is a timing chart conceptually showing the operation of the temperature sensor 120. After a time t has elapsed since the rising edge of the latch signal LT serving as a timing reference, a pulse of the heater drive signal HE is input to the heater 15. As a result, a current flows through the heater 15 to generate heat, the heat of the heater 15 is transmitted to the temperature sensor 120, and a signal indicating a temperature change is output from the temperature sensor 120 after a time T has elapsed since the rising edge of the latch signal LT.

[0037] FIG. 10 is a block diagram of a drive circuit for the heater 15 mounted on the element substrate 10 and a processing circuit for the output signal of the temperature sensor 120. Each of the n nozzles 13 has one heater 15 and one temperature sensor 120. In the following description, when the nozzles 13 are not particularly distinguished, the subscripts (a to n) indicating each nozzle 13 are omitted.

[0038] The element substrate 10 includes a constant voltage source 302 for driving the heater 15, a constant current source 304 for supplying power to the temperature sensor 120, and an input / output unit (pad or terminal) for inputting / outputting signals and information from / to the outside. The constant voltage source 302 is connected between the VH pad and the GNDH pad. Also, a constant voltage source 303 supplies power to the constant current source 304. For example, VHTA of 5V is applied to the high voltage side of the constant current source 304, and VSS as GND is applied to the low voltage side.

[0039] The constant current source 304 is composed of a constant current source 309. Using the same current type DAC 307 as a reference current source, a constant current Iref is mirrored to the constant current source 309 with the same amplification factor by the mirroring circuit 308.

[0040] The set value Diref of the constant current Iref is transferred to the shift register 305 in synchronization with the clock signal CLK. Then, it is latched in the latch circuit 306 in synchronization with the latch signal LT, and output to the current output type digital-to-analog converter (DAC) 307. That is, the DAC 307 outputs an output current Irefin based on the set value Diref.

[0041] The output signal of the latch circuit 306 is held until the next latch timing, during which the next set value Diref is transferred to the shift register 305. The output current Irefin of the DAC 307 is mirrored to the constant current source 309 and amplified, for example, 12 times to be output as the constant current Iref.

[0042] The drive circuit 316 of the heater 15 is configured as a circuit that controls the application of the voltage VH of the constant voltage source 302 to the heater 15. When the outputs of the gate circuits 317 and 318 both become High and the switch element 701 is turned on, for example, VH of 24V is applied to the high voltage side of the heater 15, and the source terminal of the switch element 701 is grounded to GNDH.

[0043] The block signal BLE is transferred to the shift register 311 in synchronization with the clock signal (CLK), latched in the latch circuit 312, decoded by the decoder 313, and output to the wiring B1. The wiring B1 is connected to the gate circuit 317. Therefore, if the signal on the wiring B1 becomes valid (High active), the heater 15 can be driven.

[0044] The heater selection signal DATA is transferred to the shift register 314 in synchronization with the clock signal (CLK), latched in the latch circuit 315, and output to the wiring D1. The signal on the wiring D1 is held until the next latch timing, during which the next heater selection signal is transferred to the shift register 314. The wiring D1 is connected to the gate circuit 317. Therefore, if the signal on the wiring D1 becomes valid (High active), the heater 15 can be driven.

[0045] The signal of wiring B1, together with the signal of wiring D1, is input to the gate circuit 317. The output signal of the gate circuit 317, together with the heat enable signal (HE), is input to the gate circuit 318. The gate circuit 318 outputs a pulse signal to the wiring H1. The wiring H1 is connected to the switch element 701, and the heater 15 is driven by the pulse signal.

[0046] The sensor drive circuit 326 is composed of a temperature sensor 120, and switch elements 327 and 328. The switch element 327 controls the power supply of the current of the constant current source 309 to the temperature sensor 120. Also, the switch element 328 controls the output to the voltage follower 331 of the voltage generated in the temperature sensor 120. The switch elements 327 and 328 are turned on simultaneously, and at this time, the temperature sensor 120 outputs a temperature signal for inspecting the discharge state of the liquid from the nozzle 13 corresponding to the heater 15 to the voltage followers 331 and 332 through the wirings V1 and V2.

[0047] The sensor selection signal SDATA is transferred to the shift register 323 in synchronization with the clock signal (CLK), latched by the latch circuit 324, and output to the wiring SD1. The signal of the wiring SD1 is held until the next latch timing, and during that time, the next sensor selection signal is transferred to the shift register 323.

[0048] The wiring SD1 is connected to the gate circuit 325. Therefore, if the signal of the wiring SD1 becomes valid (High active), the temperature sensor 120 can be selected as the temperature sensor corresponding to the driving heater.

[0049] The block signal for selecting the temperature sensor 120 diverts the signal of the wiring B1. That is, the signal of the wiring B1, together with the signal of the wiring SD1, is input to the gate circuit 325.

[0050] The gate circuit 325 outputs a pulse signal to the wiring S1. The wiring S1 is the switch element It is connected to 327 and 328, and a constant current Iref is supplied from the constant current source 309 to the temperature sensor 120 by a pulse signal.

[0051] The resistance Rs1 at the temperature T1 of the temperature sensor 120 is expressed by the following formula (1), where the normal temperature is T0, the resistance at that time is Rs0, and the temperature coefficient of resistance of the temperature sensor 120 is TCR. Rs1 = Rs0·{1 + TCR·(T1 - T0)} ··· (1)

[0052] And the output signal Vs1 generated at the constant current supply side terminal of the temperature sensor 120 is expressed by the following formula (2). Vs1 = Iref·Rs1 = Iref·Rs0·{1 + TCR·(T1 - T0)} ··· (2)

[0053] The output signal Vs1 expressed by formula (2) is output to the voltage follower 331 through the wiring V1.

[0054] The output signal Vs2 of the voltage follower 332 and the output signal Vs1 of the voltage follower 331 are differentially amplified by the differential amplifier 333 and output to the band - pass filter 1302 as a signal Vdif representing the voltage across the temperature sensor 120. The band - pass filter 1302 removes high - frequency noise from the signal Vdif and cuts low - frequency components by differential processing and outputs it as a filter output signal VF. The inverting amplifier 1303 inverts and amplifies the filter output signal VF and outputs it as a signal Vinv. A positive peak corresponding to the discharge state of the nozzle 13 appears in the signal Vinv.

[0055] (Judgment method of the comparative example) Here, the nozzle discharge judgment method of the comparative example for comparing with the nozzle discharge judgment method of Example 1 will be described.

[0056] When discharging a liquid from the nozzle 13 by using the thermal energy of the heater 15, during normal discharge, the derivative of the temperature change output from the temperature sensor 120 has a large peak value, while during non-discharge, the peak value of the derivative of the temperature change is small. Therefore, as a method for determining the discharge state, when a drive pulse is applied to the heater 15, the peak value of the derivative of the output of the temperature sensor 120 is compared with a threshold value. If it is equal to or greater than the threshold value, it is determined as normal discharge, and if it is smaller than the threshold value, it is determined as non-discharge. Here, in order to determine the discharge state regardless of the variations in the heater 15 and the temperature sensor 120 for each nozzle 13, it is desirable to set a threshold value corresponding to the nozzle 13. As a method for setting such a threshold value, for example, for the nozzle 13 to be determined, a drive pulse is continuously applied to the heater 15 while sequentially increasing the threshold value to perform a discharge determination, and the threshold value at which the determination result changes from discharge to non-discharge is detected. In the case of non-discharge from the beginning, a drive pulse is continuously applied to the heater 15 while sequentially decreasing the threshold value to perform a discharge determination, and the threshold value at which the determination result changes from non-discharge to discharge is detected. By performing the discharge determination using the threshold value detected by such a process (hereinafter referred to as the threshold value setting process), a discharge determination that is not affected by the variations for each nozzle is performed.

[0057] Since this threshold value setting process assumes that the nozzle is in a normal discharge state, when the nozzle is in a non-discharge state, an appropriate threshold value cannot be set. Therefore, a method for determining the discharge state in a comparative example for comparison with Example 1 as a method for determining the discharge state of the nozzle will be described. A second pulse having a pulse width shorter than the minimum drive pulse to be applied to the heater for the ink to be discharged from the nozzle is continuously applied to perform a threshold value setting process, and a threshold value is set (second threshold value). Next, a first pulse having a pulse width longer than the minimum drive pulse is continuously applied to perform a threshold value setting process, and a threshold value is set (first threshold value).

[0058] When the heater 15 is driven by the second pulse, a temperature sensor output corresponding to a non-ejection state is obtained. Therefore, the second threshold value becomes a small value. On the other hand, when the heater 15 is driven by the first pulse, if the nozzle 13 is normal, a temperature sensor output corresponding to a normal ejection state is obtained. Therefore, the first threshold value becomes a large value. However, if the nozzle 13 is in a non-ejection state, even when the heater 15 is driven by the first pulse, a temperature sensor output corresponding to non-ejection is obtained. In this case, the second threshold value becomes a value similar to the first threshold value. Therefore, when the nozzle is in a normal ejection state, the first threshold value and the second threshold value are significantly different, but when the nozzle is in a non-ejection state, the first threshold value and the second threshold value are close. Therefore, based on the difference between the first threshold value and the second threshold value, it is determined whether the nozzle is in a normal ejection state or a non-ejection state. Specifically, if the difference is equal to or greater than a predetermined threshold value, it is determined as normal ejection, and if the difference is smaller than the threshold value, it is determined as non-ejection.

[0059] (Flowchart of the comparative example) FIG. 15 is a flowchart showing a discharge determination method of a comparative example. First, the first process (steps S101 to S104) is performed. In step S101, the control unit sets the target nozzle for the threshold setting process. In step S102, the control unit applies a second pulse to the heater to perform a threshold setting process for the target nozzle. In step S103, the control unit stores, in the memory, as the second threshold value, the threshold value when the determination result changes in the threshold setting process of step S102. In step S104, the control unit determines whether the second threshold value has been stored for all nozzles, and repeats the processes of steps S101 to S103 until the second threshold value has been stored for all nozzles.

[0060] After the first process is completed, next, the second process (steps S105 to S108) is performed. In step S105, the control unit sets the target nozzle for the threshold setting process. In step S106, the control unit applies a first pulse to the heater to perform threshold setting processing for the target nozzle. In step S107, when the determination result changes in the threshold setting process of step S106, the control unit stores the threshold value in the memory as the first threshold value. In step S108, the control unit determines whether the first threshold value has been stored for all nozzles, and repeats the processes of steps S105 to S107 until the first threshold value has been stored for all nozzles.

[0061] After the second process is completed, the discharge determination process (steps S109 to S113) for each nozzle is performed. In step S109, the control unit sets the target nozzle for the discharge determination process. In step S110, the control unit compares the first threshold value and the second threshold value detected for the target nozzle. In step S111, the control unit performs a discharge determination for the target nozzle. In step S112, the control unit stores the result of the discharge determination for the target nozzle in the memory. In step S113, the control unit determines whether the results of the discharge determination have been stored for all nozzles, and repeats the processes of steps S110 to S112 until the results of the discharge determination have been stored for all nozzles.

[0062] (Timing chart of the comparative example) FIG. 16 is a timing chart schematically showing a heater drive signal HE applied to the heater in the nozzle discharge determination process of the comparative example. Assume that there are n nozzles in total to be determined, and X The nozzle at the [[ID=]] position is represented by segX. In the discharge determination process of the comparative example, first, a first process is performed in which the second pulse 102 is applied to the nozzles seg1, seg2, seg3, ···, segn in this order. Next, a second process is performed in which the first pulse 101 is applied to the nozzles seg1, seg2, seg3, ···, segn in this order. Based on the information on the temperature change when the first pulse is input to the heater corresponding to the nozzle to be determined obtained in the first process and the information on the temperature change when the second pulse is input, the discharge determination of the nozzle to be determined is performed.

[0063] The time required for the first process becomes longer in proportion to the number n of nozzles. Also, the second process is performed after the first process ends. That is, during the interval between the timing when the first pulse is input to the heater corresponding to a certain nozzle in the first process and the timing when the second pulse is input to the heater in the second process, the first pulse for the heater other than the said heater The input of the pulse is performed. Therefore, the interval between the timing when the first pulse is input to the heater corresponding to a certain nozzle in the first process and the timing when the second pulse is input to the heater in the second process is at least as long as the time required for the first process. For this reason, there is a long interval TinX between the timing when the second pulse is input to the heater corresponding to the nozzle to be determined and the timing when the first pulse is input to the heater. For example, as shown in FIG. 16, there is a period during which pulses are applied to other nozzles (seg2 to segn) from the application of the second pulse 102 to the nozzle seg1 until the application of the first pulse 101 to the nozzle of the nozzle seg1. Therefore, the interval TintX between the timing when the second pulse 102 is applied to the nozzle seg1 and the timing when the first pulse 101 is applied becomes longer in proportion to the number of nozzles. When the interval TintX becomes long, various conditions that affect the discharge state such as temperature, humidity, and the state of the liquid change between the application of the second pulse 102 and the application of the first pulse 101, and accurate determination may not be possible. In the nozzle discharge determination process of the comparative example, the order of continuous application of the first pulse 101 and continuous application of the second pulse 102 may be reversed from the order illustrated in FIGS. 15 and 16.

[0064] (Determination method of Example 1) Next, the nozzle discharge determination method of Example 1 will be described. As described above, during normal discharge, the peak value of the differentiation of the temperature change output from the temperature sensor 120 is large, and during non-discharge, the peak value of the differentiation of the temperature change is small. Based on this property, the discharge state of the nozzle 13 is determined. Here, the minimum drive pulse to be applied to the heater 15 for the ink to be discharged from the nozzle 13 is defined as the minimum pulse. First, a second pulse having a pulse width shorter than the pulse width of the minimum pulse is applied to the heater 15 corresponding to the nozzle 13 to be determined, and the peak value of the differentiation of the output of the temperature sensor 120 is detected (second peak value). Next, a first pulse having a pulse width longer than the pulse width of the minimum pulse is applied to the heater 15 corresponding to the nozzle 13 to be determined, and the peak value of the differentiation of the output of the temperature sensor 120 is detected (first peak value).

[0065] When the heater 15 is driven by the second pulse, a temperature sensor output corresponding to a non-discharge state can be obtained. Therefore, the second peak value becomes a small value. On the other hand, when the heater 15 is driven by the first pulse, if the nozzle 13 is normal, a temperature sensor output corresponding to a normal discharge state can be obtained. In this case, the first peak value becomes a large value. However, if the nozzle 13 is in a non-discharge state, even when the heater 15 is driven by the first pulse, a temperature sensor output corresponding to the non-discharge state can be obtained. In this case, the first peak value becomes a small value similar to the second peak value. Therefore, if the nozzle 13 is in a normal discharge state, the first peak value and the second peak value will be significantly different, but if the nozzle 13 is in a non-discharge state, the first peak value and the second peak value will be close. Therefore, based on the difference between the first peak value and the second peak value, it can be determined whether the nozzle 13 is in a normal discharge state or a non-discharge state. Specifically, if the difference between the first peak value and the second peak value is equal to or greater than a predetermined threshold, the nozzle 13 is in a state of normally discharging the liquid. If the difference between the first peak value and the second peak value is smaller than the threshold, it can be determined that there is no discharge (not in a state of normally discharging the liquid).

[0066] ​In Example 1, in the ejection determination process of the nozzle 13, the first peak value and the second peak value are detected by continuously applying the first pulse and the second pulse to the heater 15 corresponding to the nozzle 13 to be determined, and the ejection determination is performed. By repeating this process for the number of nozzles, the ejection determination for all the nozzles 13 provided in the liquid ejection head 3 is performed. According to the ejection determination process of Example 1, the first pulse is input continuously to the heater 15 corresponding to the nozzle 13 to be determined after the second pulse. In other words, during the interval between the input of the second pulse and the input of the first pulse to the heater 15 corresponding to the nozzle 13 to be determined, no pulse is input to the heater 15 corresponding to the nozzle 13 that is not the determination target. In the above comparative example, during the interval between the input of the second pulse and the input of the first pulse to the heater 15 corresponding to the nozzle 13 to be determined, pulses are input to the heaters 15 corresponding to all the other nozzles 13 that are not the determination target. Therefore, the interval Tint existing between the timing when the second pulse is input and the timing when the first pulse is input to the heater 15 corresponding to the nozzle 13 to be determined can be made shorter than the interval TintX in the above comparative example. Therefore, since it is possible to make the various conditions that affect the ejection state, such as temperature, humidity, and the state of the liquid, hardly change between the application of the second pulse and the application of the first pulse, accurate ejection determination becomes possible.

[0067] In order to realize such a nozzle ejection determination process of Example 1, as shown in FIG. 10, the element substrate 10 has a peak hold circuit 1308. The peak hold circuit 1308 temporarily holds the first peak value P1 that appears at Vinv when the first pulse is applied to the heater 15 and the second peak value P2 that appears at Vinv when the second pulse is applied to the heater 15. The peak hold circuit 1308 outputs the first peak value P1 and the second peak value P2 to the circuit 1309. The circuit 1309 outputs the difference Δ between the first peak value P1 and the second peak value P2 to the determination circuit 1311. The determination circuit 1311 compares the difference Δ with the threshold value Δth, and determines the ejection state of the nozzle 13 as normal ejection when the difference Δ is equal to or greater than the threshold value Δth, and non-ejection when the difference Δ is smaller than the threshold value Δth.

[0068] The determination circuit 1311 outputs a determination result signal RSLT that becomes high level during the next latch period when normal ejection occurs. The determination result signal RSLT is extracted by the determination result extraction unit 5 shown in FIG. 2, together with the block signal BLE delayed by the latch period and the sensor selection signal SDATA, in synchronization with the fall of the latch signal LT.

[0069] Although the configuration in which the determination unit from the differential amplifier 333 to the determination circuit 1311 is provided inside the element substrate 10 has been described, it may be provided inside a control chip provided in the liquid ejection head 3 outside the element substrate 10. Further, the determination unit may be provided in a control device 900 provided in the recording device 1000 outside the liquid ejection head 3. The determination unit and the control device 900 are determination means for determining whether or not liquid is normally ejected for each of the plurality of nozzles 13 based on the output of the temperature sensor 120.

[0070] The ejection determination method for the nozzle 13 of Example 1 will be described. FIG. 11 is a flowchart showing an outline of the ejection determination method of Example 1.

[0071] (Schematic flowchart of Example 1) An outline of the flow of the ejection determination process for the nozzle 13 in Example 1 is shown in FIG. 11. In step S201, the control device 900 sets the nozzle to be determined. In step S202, the control device 900 applies a second pulse to the heater 15 to acquire the output of the temperature sensor 120. In step S203, the control device 900 applies a first pulse to the heater 15 to acquire the output of the temperature sensor 120. In step S204, the control device 900 compares the temperature sensor output in step S202 with the temperature sensor output in step S203. In step S205, the control device 900 determines the ejection state of the nozzle 13 to be determined based on the comparison result in step S204. In step S206, the control device 900 stores the determination result of step S205 in the memory 203. In step S207, the control device 900 determines whether the ejection determination results for all the nozzles 13 have been stored, and repeats the processes of steps S201 to S206 until the ejection determination results for all the nozzles 13 have been stored.

[0072] (Flowchart of Example 1) FIG. 12 is a flowchart showing details of the nozzle ejection determination method of Example 1. In step S301, the control device 900 selects a nozzle 13 to be determined. In step S302, the control device 900 selects a temperature sensor 120 corresponding to the nozzle 13 to be determined. In step S303, the control device 900 calls a threshold value Δth for determination from the memory 203. In step S304, the control device 900 applies a second pulse to the heater 15 to drive the heater 15. In step S305, the control device 900 obtains a peak value (second peak value P2) of the change rate (time differentiation) of the output of the temperature sensor 120 when the heater 15 is driven by the second pulse. The second peak value P2 is temporarily held by the peak hold circuit 1308 shown in FIG. 10.

[0073] In step S306, the control device 900 applies a first pulse to the heater 15 to drive the heater 15. In step S307, the control device 900 obtains a peak value (first peak value P1) of the change rate (time differentiation) of the output of the temperature sensor 120 when the heater 15 is driven by the first pulse. The first peak value P1 is temporarily held by the peak hold circuit 1308 shown in FIG. 10. In step S308, the control device 900 obtains a difference Δ = |P1 - P2| between the first peak value P1 and the second peak value P2.

[0074] In step S309, the control device 900 determines the discharge state of the nozzle 13 to be determined based on the difference Δ obtained in step S308. The control device 900 determines that it is normal discharge when the difference Δ is greater than or equal to the threshold value Δth, and determines that it is non-discharge when the difference Δ is less than the threshold value Δth. Note that the threshold value Δth can be changed according to the usage status of the liquid discharge head 3 and the like, and can be appropriately set in step S303. In step S310, the control device 900 stores the determination result of step S309 in the memory 203. In step S311, the control device 900 determines whether the discharge determination results for all the nozzles 13 have been stored, and repeats the processes of steps S301 to S310 until the discharge determination results for all the nozzles 13 are stored.

[0075] Note that the peak value temporarily held in the peak hold circuit 1308 is rewritten with the peak value obtained at the time of determination of the next nozzle 13 to be determined. Therefore, the memory capacity can be reduced compared to the comparative example described later.

[0076] (Timing chart of Example 1) FIG. 13 is a timing chart schematically showing the heater drive signal HE applied to the heater 15 in the nozzle discharge determination process of Example 1. Assume that there are a total of n nozzles 13 to be determined, and the Xth nozzle 13 is represented by segX. In the discharge determination process, first, the second pulse 102 and the first pulse 101 are continuously applied to the nozzle seg1, the peak value is obtained at each application, and the discharge determination of the nozzle seg1 is performed. Next, the second pulse 102 and the first pulse 101 are continuously applied to the nozzle seg2 and the same process is performed. This is repeated up to the nozzle segn.

[0077] The second pulse 102 and the first pulse 101 are continuously applied to the nozzle seg1. Therefore, there is no period during which a pulse is applied to other nozzles (seg2 to segn) from the application of the second pulse 102 to the nozzle seg1 until the application of the first pulse 101. Thus, the interval Tint between the timing of applying the second pulse 102 and the timing of applying the first pulse 101 to the nozzle seg1 is short and independent of the number of nozzles. Accordingly, since it is possible to make it so that various conditions that affect the discharge state such as temperature, humidity, and the state of the liquid hardly change between the application of the second pulse 102 and the application of the first pulse 101, nozzle discharge determination can be performed with high accuracy. In the nozzle discharge determination process of the first embodiment, the application order of the first pulse 101 and the second pulse 102 in each nozzle 13 may be the reverse of the order illustrated in FIGS. 11, 13, and 12.

[0078] (Operation example of the first embodiment) FIG. 14 is a timing chart showing the operations of the heater 15 and the temperature sensor 120 in the nozzle discharge determination process of the first embodiment. FIG. 14(A) is the latch signal LT. FIG. 14(B) is the drive signal HE-1 input to the heater 15 of the nozzle seg1, FIG. 14(C) is the output signal of the temperature sensor 120 corresponding to the nozzle seg1, and FIG. 14(D) is the time derivative of the output signal of the temperature sensor 120 corresponding to the nozzle seg1. FIG. 14(E) is the drive signal HE-2 input to the heater 15 of the nozzle seg2, FIG. 14(F) is the output signal of the temperature sensor 120 corresponding to the nozzle seg2, and FIG. 14(G) is the time derivative of the output signal of the temperature sensor 120 corresponding to the nozzle seg2.

[0079] The second pulse 102 (pulse width 0.15 μsec) is input to the heater 15 corresponding to the nozzle seg1 after the elapse of time t from the entry of the first LT signal. Then, the first pulse 101 (pulse width 0.35 μsec) is input after the elapse of the interval Tint (10 μsec). In the time derivative of the output signal of the temperature sensor 120 corresponding to the nozzle seg1, the second peak value P2_seg1 due to the second pulse 102 and the first peak value P1_seg1 due to the first pulse 101 appear.

[0080] After the second LT signal enters the heater 15 corresponding to the nozzle seg2, the second pulse 102 (pulse width 0.15 μsec) is input after the elapse of time t. Then, after the elapse of the interval Tint (10 μsec), the first pulse 101 (pulse width 0.35 μsec) is input. In the time differentiation of the output signal of the temperature sensor 120 corresponding to the nozzle seg2, the second peak value P2_seg2 due to the second pulse 102 and the first peak value P1_seg2 due to the first pulse 101 appear.

[0081] For example, let the second peak value P2_seg1 = 140, the first peak value P1_seg1 = 175, and the threshold value Δth of the difference Δ between the peak values be 30 for the nozzle seg1. In this case, the difference Δseg1 between the two peak values is 175 - 140 = 35, and since Δseg1 ≥ Δth, the nozzle seg1 is determined to be discharging normally.

[0082] Also, let the second peak value P2_seg2 = 140 and the first peak value P1_seg2 = 165 for the nozzle seg2. In this case, the difference Δseg2 between the two peak values is 165 - 140 = 25, and since Δseg2 < Δth, the nozzle seg2 is determined not to be discharging.

[0083] (Operation example of the comparative example) FIG. 17 is a timing chart showing the operations of the heater and the temperature sensor in the nozzle discharge determination process of the comparative example. FIG. 17(A) is the latch signal LT. FIG. 17(B) is the drive signal HE-1 input to the heater of the nozzle seg1, FIG. 17(C) is the output signal of the temperature sensor corresponding to the nozzle seg1, and FIG. 17(D) is the time differentiation of the output signal of the temperature sensor corresponding to the nozzle seg1. FIG. 17(E) is the drive signal HE-2 input to the heater of the nozzle seg2, FIG. 17(F) is the output signal of the temperature sensor corresponding to the nozzle seg2, and FIG. 17(G) is the time differentiation of the output signal of the temperature sensor corresponding to the nozzle seg2.

[0084] After a time t1 has elapsed since the first LT signal was received, a second pulse 102 (pulse width 0.15 μsec) is input to the heater corresponding to nozzle seg1 (state A), and continuously, the second pulse 102 is input to the heater corresponding to nozzle seg2 (state C). The second pulse 102 is continuously input up to the heater corresponding to nozzle segn.

[0085] Thereafter, after an interval TintX has elapsed, a first pulse 101 (pulse width 0.35 μsec) is input to the heater corresponding to nozzle seg1 (state B), and continuously, the first pulse 101 is input to the heater corresponding to nozzle seg2 (state D). The first pulse 101 is continuously input up to the heater corresponding to nozzle segn.

[0086] For example, assume that an environmental change occurs between state A and state B, and the second peak value P2_seg1 = 140 of nozzle seg1 obtained in state A and the first peak value P1_seg1 = 165 obtained in state B. In this case, the difference between the two peak values is Δseg1 = 165 - 140 = 25, and since Δseg1 < Δth, nozzle seg1 is determined to be non-discharging.

[0087] Also, assume that an environmental change occurs between state C and state D, and the second peak value P2_seg2 = 140 of nozzle seg2 obtained in state C and the first peak value P1_seg2 = 175 obtained in state D. In this case, the difference between the two peak values is Δseg2 = 175 - 140 = 35, and since Δseg2 ≧ Δth, nozzle seg2 is determined to be discharging normally.

[0088] As shown by the dashed line in Fig. 17, in state B, after applying the first pulse 101, assume that the second pulse 102 is continuously applied with a short interval Tint of the same length as in Example 1, and the peak value is obtained. In this case, the environmental change is small between the application of the first pulse 101 and the application of the second pulse 102. Therefore, the second peak value P2_seg1X when the second pulse 102 is applied tends to be smaller than in state A, similar to the first peak value P1_seg1 when the first pulse 101 is applied. For example, assume that the second peak value P2_seg1X = 130. In this case, the difference Δseg1X = 165 - 130 = 35, and since the difference Δseg1X ≥ Δth, the nozzle seg1 is correctly determined to be normally discharging.

[0089] Also, as shown by the dashed line in Fig. 17, in state D, after applying the first pulse 101, assume that the second pulse 102 is continuously applied with a short interval Tint of the same length as in Example 1, and the peak value is obtained. The second peak value P2_seg2X when the second pulse 102 is applied tends to be larger than in state C, similar to the first peak value P1_seg2 when the first pulse 101 is applied. For example, assume that the second peak value P2_seg2X = 150. In this case, the difference Δseg2X = 175 - 150 = 25, and since the difference Δseg2X < Δth, the nozzle seg2 is correctly determined to be non-discharging.

[0090] Thus, when the interval between the timing of detecting the first peak value and the timing of detecting the second peak value becomes long, there is a possibility that accurate determination cannot be made due to environmental changes. In that regard, according to the nozzle discharge determination method of Example 1, since the interval between the timing of detecting the first peak value and the timing of detecting the second peak value is short, accurate determination can be performed.

[0091] As described above, in the nozzle discharge determination method of the first embodiment, the first pulse and the second pulse with different heat generations of the heater 15 are continuously applied to the heater 15 to be determined, and the determination is made based on the change rate of the output of the temperature sensor 120 when each pulse is applied. Therefore, the interval between the first pulse application timing and the second pulse application timing is short, and the environmental change between the liquid discharge due to the first pulse application and the liquid discharge due to the second pulse application is small. As a result, the determination accuracy of the discharge state of the nozzle 13 based on the temperature change caused by the first pulse and the temperature change caused by the second pulse becomes good.

[0092] In the above description, the drive pulse having a pulse width shorter than the minimum pulse width capable of discharging ink from the nozzle 13 is set as the second pulse, and the drive pulse having a pulse width longer than the pulse width of the minimum pulse is set as the first pulse. Conversely, the drive pulse having a pulse width shorter than the minimum pulse width may be set as the first pulse, and the drive pulse having a pulse width longer than the pulse width of the minimum pulse may be set as the second pulse.

[0093] Also, in the above description, the first pulse and the second pulse are set in relation to the minimum pulse width capable of discharging ink from the nozzle 13, but they may be two different pulses with different heat generations of the heater 15. That is, two pulses with different thermal energies generated by the heater 15 may be set as the first pulse and the second pulse. In this case, it is preferable to determine the pulse width of each pulse so that the difference Δ between the first peak value and the second peak value when the nozzle 13 is in the non-discharge state and the difference Δ between the first peak value and the second peak value when the nozzle 13 is in the normal discharge state are sufficiently different values.

[0094] In the above description, the case where the drive signal for driving the heater 15 is a signal for pulse control of the heat generation of the heater 15 has been exemplified. However, the drive signal is not limited to a signal for pulse control of the heat generation of the heater 15. That is, the first drive signal and the second drive signal, for which the heat generation of the heater 15 is different from the first drive signal, may be continuously applied, and the discharge state of the nozzle may be determined based on the change rate of the output of the temperature sensor 120 when each drive signal is applied. The above description is an example of a case where the first drive signal includes a first pulse having a predetermined pulse width and the second drive signal includes a second pulse having a pulse width different from the pulse width of the first pulse. Further, in the above description, the case where the heat generation of the heater 15 is controlled by changing the pulse width of the drive signal has been exemplified. However, the method of pulse control is not limited to the method of changing the pulse width as long as the heat generation of the heater 15 can be controlled.

[0095] (Example 2) In Example 2, the drive pulse applied to the heater 15 when the nozzle discharge determination is executed has a main pulse and a sub-pulse having a shorter pulse width than the main pulse that follows it. As a result, the sensitivity of the temperature sensor 120 increases, so the peak value increases and the determination can be made more accurately.

[0096] FIG. 18 is a timing chart showing the operations of the heater 15 and the temperature sensor 120 in the nozzle discharge determination process of Example 2. FIG. 18(A) is the latch signal LT. FIG. 18(B) is the drive signal HE-1 input to the heater 15 of the nozzle seg1, FIG. 18(C) is the output signal of the temperature sensor 120 corresponding to the nozzle seg1, and FIG. 18(D) is the time derivative of the output signal of the temperature sensor 120 corresponding to the nozzle seg1.

[0097] After the first LT signal enters the heater 15 corresponding to the nozzle seg1, the second pulse 102 (pulse width 0.15 μsec), which is the main pulse, is input after the elapse of time t. Then, after an interval t2 (0.5 μsec), the post-pulse 102a (pulse width 0.075 μsec), which is the sub-pulse, is input. And after the elapse of the interval Tint (10 μsec), the first pulse 101 (pulse width 0.35 μsec), which is the main pulse, is input. Then, after an interval t1 (0.5 μsec), the post-pulse 101a (pulse width 0.175 μsec), which is the sub-pulse, is input. In the time derivative of the output signal of the temperature sensor 120 corresponding to the nozzle seg1, the second peak value P2_seg1Y due to the second pulse 102 and the first peak value P1_seg1Y due to the first pulse 101 appear.

[0098] In Example 1, the second peak value P2_seg1 of the nozzle seg1 was 140, but in Example 2, it is assumed that due to the effect of the post-pulse, the second peak value P2_seg1Y = 150. Also, in Example 1, the first peak value P1_seg1 was 175, but in Example 2, it is assumed that due to the effect of the post-pulse, the first peak value P1_seg1Y = 195. In this case, the difference Δseg1Y between the two peak values is 195 - 150 = 45, and since Δseg1Y ≧ Δth, the nozzle seg1 is determined to be discharging normally. Thus, by applying the post-pulse, the sensitivity of the temperature sensor 120 increases and the difference Δ between the peak values becomes larger, so that a more accurate determination can be made.

[0099] Note that in Example 2, an example in which the post-pulse is performed for both the first pulse and the second pulse is shown, but the post-pulse may be performed only for the pulse with the larger calorific value of the heater 15 (the first pulse in Example 2).

[0100] (Example 3) In Example 3, when the second pulse and the first pulse are continuously applied to the heater 15 during the execution of the nozzle discharge determination, the interval between the second pulse and the first pulse is made shorter than that in Example 1. This interval is set to be shorter than, for example, the time until the temperature of the heater 15 increased by the preceding pulse (the second pulse in Example 3) returns to the temperature before the application of the pulse. As a result, since the first pulse is applied while the heat due to the second pulse remains near the temperature sensor 120, the sensitivity of the temperature sensor 120 can be increased, and the determination can be performed with higher accuracy.

[0101] FIG. 19 is a timing chart showing the operations of the heater 15 and the temperature sensor 120 in the nozzle discharge determination process of Example 3. FIG. 19(A) is the latch signal LT. FIG. 19(B) is the drive signal HE-1 input to the heater 15 of the nozzle seg1, FIG. 19(C) is the output signal of the temperature sensor 120 corresponding to the nozzle seg1, and FIG. 19(D) is the time derivative of the output signal of the temperature sensor 120 corresponding to the nozzle seg1.

[0102] After the elapse of time t from when the first LT signal is input to the heater 15 corresponding to the nozzle seg1, the second pulse 102 (pulse width 0.15 μsec) is input. Then, after the elapse of the interval TintZ (6 μsec), the first pulse 101Y (pulse width 0.35 μsec) is input. In the time derivative of the output signal of the temperature sensor 120 corresponding to the nozzle seg1, the second peak value P2_seg1 due to the second pulse 102 and the first peak value P1_seg1Z due to the first pulse 101 appear. As shown by the broken line, the interval TintZ between the second pulse 102 and the first pulse 101Y is shorter than the interval Tint (10 μsec) between the second pulse 102 and the first pulse 101 in Example 1.

[0103] In Example 1, the second peak value P2_seg1 of the nozzle seg1 was 140. However, in Example 3, since the conditions of the second pulse 102 are the same as those in Example 1, it is assumed that the second peak value P2_seg1Z = 140. Also, in Example 1, the first peak value P1_seg1 = 175 However, in Example 3, it is assumed that the interval from the second pulse became shorter, resulting in a first peak value P1_seg1Z = 185. In this case, the difference between the two peak values is Δseg1Z = 185 - 140 = 45, and since Δseg1Y ≧ Δth, nozzle seg1 is determined to be discharging normally. Thus, by shortening the interval between the second pulse and the first pulse, the sensitivity of temperature sensor 120 increases and the difference Δ between the peak values becomes larger, enabling more accurate determination.

[0104] (Example 4) In Example 4, when continuously applying the second pulse and the first pulse to heater 15 during nozzle discharge determination, the order of the second pulse and the first pulse is made different from that in Example 1.

[0105] Figure 20 is a timing chart showing the operations of heater 15 and temperature sensor 120 in the nozzle discharge determination process of Example 4. Figure 20(A) is the latch signal LT. Figure 20(B) is the drive signal HE-1 input to heater 15 of nozzle seg1, Figure 20(C) is the output signal of temperature sensor 120 corresponding to nozzle seg1, and Figure 20(D) is the time derivative of the output signal of temperature sensor 120 corresponding to nozzle seg1.

[0106] After the lapse of time t from when the first LT signal enters, the first pulse 101 (pulse width 0.35 μsec) is input to heater 15 corresponding to nozzle seg1. Then, after the lapse of the interval TintW (12 μsec), the second pulse 102 (pulse width 0.15 μsec) is input. In the time derivative of the output signal of temperature sensor 120 corresponding to nozzle seg1, the first peak value P1_seg1W due to the first pulse 101 and the second peak value P2_seg1W due to the second pulse 102 appear.

[0107] In Example 1, the first peak value P1_seg1 of nozzle seg1 was 175. However, in Example 4, since the conditions of the first pulse 101 were the same as those in Example 1, it is assumed that the first peak value P1_seg1W became 175. Also, in Example 1, the second peak value P2_seg1 of nozzle seg1 was 140. However, in Example 4, since the conditions of the second pulse 102 were the same as those in Example 1, it is assumed that the second peak value P2_seg1W became 140. In this case, the difference between the two peak values Δseg1W = 175 - 140 = 35, and since Δseg1W ≧ Δth, nozzle seg1 is determined to be discharging normally. Thus, even when nozzle discharge determination is performed by continuously applying the first pulse and the second pulse in this order, the determination can be made accurately in the same manner as in Example 1.

[0108] The disclosure of this embodiment includes the following configurations. (Configuration 1) A plurality of nozzles for discharging liquid, A plurality of heaters provided corresponding to each of the plurality of nozzles for heating the liquid, Drive means for driving each of the plurality of heaters, A plurality of temperature sensors provided corresponding to each of the plurality of heaters, Determination means for determining, for each of the plurality of nozzles, whether or not the liquid is being discharged normally based on the outputs of the plurality of temperature sensors, A recording apparatus that performs recording on a recording medium using a liquid discharge head provided with: The determination means, by the drive means, for the heater corresponding to the nozzle to be determined, continuously applies a first drive signal and a second drive signal whose heat generation of the heater is different from that of the first drive signal, the rate of change of the output of the temperature sensor when the first drive signal is applied, the rate of change of the output of the temperature sensor when the second drive signal is applied, and makes a determination about the nozzle to be determined based on these, The determination means is a recording apparatus characterized by not applying a drive signal to the heater corresponding to the nozzle that is not the determination target during the interval between the first drive signal and the second drive signal. (Configuration 2) The recording apparatus according to Configuration 1, wherein the first drive signal and the second drive signal are signals for pulse-controlling the heat generation of the heater. (Configuration 3) The first drive signal includes a first pulse having a predetermined pulse width, The recording apparatus according to Configuration 2, wherein the second drive signal includes a second pulse having a pulse width different from the pulse width of the first pulse. (Configuration 4) The first pulse has a pulse width shorter than the minimum pulse width capable of discharging liquid from the nozzle, The recording apparatus according to Configuration 3, wherein the second pulse has a pulse width longer than the minimum pulse width capable of discharging liquid from the nozzle. (Configuration 5) The first pulse has a pulse width longer than the minimum pulse width capable of discharging liquid from the nozzle, The recording apparatus according to Configuration 3, wherein the second pulse has a pulse width shorter than the minimum pulse width capable of discharging liquid from the nozzle. (Configuration 6) The determination means, a first peak value indicating a peak of the change rate of the output of the temperature sensor when the first drive signal is applied, a second peak value indicating a peak of the change rate of the output of the temperature sensor when the second drive signal is applied, Based on this, the recording apparatus according to any one of Configurations 1 to 5 for determining the nozzle to be determined. (Configuration 7) The recording apparatus according to Configuration 6, wherein the determination means determines the nozzle to be determined based on the difference between the first peak value and the second peak value. (Configuration 8) The determination means, When the difference is equal to or greater than the threshold value, it is determined that the nozzle to be determined is in a state of normally discharging liquid, The recording apparatus according to configuration 7 that determines that the nozzle to be determined is not in a state of normally discharging liquid when the difference is smaller than the threshold value. (Configuration 9) The recording apparatus according to any one of configurations 1 to 8, wherein at least the driving signal with larger heat generation of the heater among the first driving signal and the second driving signal has a main pulse and a sub-pulse having a shorter pulse width than the main pulse following the main pulse. (Configuration 10) The recording apparatus according to any one of configurations 1 to 8, wherein the first driving signal and the second driving signal have a main pulse and a sub-pulse having a shorter pulse width than the main pulse following the main pulse. (Configuration 11) The recording apparatus according to any one of configurations 1 to 10, wherein an interval between a timing at which the first driving signal is applied to the heater and a timing at which the second driving signal is applied to the heater is shorter than a time until the temperature of the heater increased by the first driving signal returns to the temperature before the first driving signal is applied. (Method 1) A plurality of nozzles for discharging liquid, A plurality of heaters provided corresponding to each of the plurality of nozzles for heating the liquid, Driving means for driving each of the plurality of heaters, A plurality of temperature sensors provided corresponding to each of the plurality of heaters, In a recording apparatus that performs recording on a recording medium using a liquid discharge head including: for each of the plurality of nozzles, a determination method for determining whether or not the liquid is in a state of being normally discharged, A step of continuously applying, by the driving means, a first driving signal and a second driving signal having different heat generation of the heater with respect to the first driving signal to the heater corresponding to the nozzle to be determined, A step of acquiring an output of the temperature sensor when the first driving signal is applied, A step of acquiring an output of the temperature sensor when the second driving signal is applied, A step of determining the nozzle to be determined based on the rate of change of the output of the temperature sensor when the first drive signal is applied and the rate of change of the output of the temperature sensor when the second drive signal is applied; having In an interval between the first drive signal and the second drive signal, a drive signal is not applied to the heater corresponding to the nozzle that is not the determination target. A determination method characterized by this.

Explanation of symbols

[0109] 10: Element substrate 13: Nozzle 15: Heater 120: Temperature sensor 201: Signal generation unit 900: Control device 1000: Recording device

Claims

1. A plurality of nozzles for discharging a liquid, a plurality of heaters provided corresponding to each of the plurality of nozzles for heating the liquid, driving means for driving each of the plurality of heaters, a plurality of temperature sensors provided corresponding to each of the plurality of heaters, determination means for determining, for each of the plurality of nozzles, whether or not the liquid is being discharged normally based on the outputs of the plurality of temperature sensors, A recording apparatus that performs recording on a recording medium using a liquid discharge head including: The determination means, by the driving means, applies, to the heater corresponding to the nozzle to be determined, a first driving signal and a second driving signal having a different heat generation of the heater with respect to the first driving signal, continuously, a change rate of the output of the temperature sensor when the first driving signal is applied, a change rate of the output of the temperature sensor when the second driving signal is applied, Based on the above, the determination is made for the nozzle to be determined, The determination means is characterized in that, during an interval between the first driving signal and the second driving signal, no driving signal is applied to the heater corresponding to the nozzle that is not the determination target.

2. The recording apparatus according to claim 1, wherein the first driving signal and the second driving signal are signals for pulse control of heat generation of the heater.

3. The first driving signal includes a first pulse having a predetermined pulse width, The recording apparatus according to claim 2, wherein the second driving signal includes a second pulse having a pulse width different from the pulse width of the first pulse.

4. The first pulse has a pulse width shorter than the minimum pulse width capable of discharging liquid from the nozzle, The recording apparatus according to claim 3, wherein the second pulse has a pulse width longer than the minimum pulse width capable of discharging liquid from the nozzle.

5. The first pulse has a pulse width longer than the minimum pulse width capable of discharging liquid from the nozzle, The recording apparatus according to claim 3, wherein the second pulse has a pulse width shorter than the minimum pulse width capable of discharging liquid from the nozzle.

6. The determination means, a first peak value indicating a peak of the change rate of the output of the temperature sensor when the first driving signal is applied, a second peak value indicating a peak of the change rate of the output of the temperature sensor when the second driving signal is applied, The recording apparatus according to any one of claims 1 to 5, wherein the determination is made for the nozzle to be determined based on the above.

7. The recording apparatus according to claim 6, wherein the determination means determines the nozzle to be determined based on the difference between the first peak value and the second peak value.

8. The determination means when the difference is equal to or greater than a threshold value, determines that the nozzle to be determined is in a state of normally discharging liquid and when the difference is less than the threshold value, determines that the nozzle to be determined is not in a state of normally discharging liquid. The recording apparatus according to claim 7.

9. Among the first drive signal and the second drive signal, at least the drive signal with a larger heat generation of the heater has a main pulse and a sub-pulse having a shorter pulse width than the main pulse following the main pulse. The recording apparatus according to any one of claims 1 to 5.

10. The first drive signal and the second drive signal have a main pulse and a sub-pulse having a shorter pulse width than the main pulse following the main pulse. The recording apparatus according to any one of claims 1 to 5.

11. The interval between the timing when the first drive signal is applied to the heater and the timing when the second drive signal is applied is shorter than the time until the temperature of the heater increased by the first drive signal returns to the temperature before the first drive signal is applied. The recording apparatus according to any one of claims 1 to 5.

12. A plurality of nozzles for discharging liquid, A plurality of heaters provided corresponding to each of the plurality of nozzles for heating the liquid, Drive means for driving each of the plurality of heaters, A plurality of temperature sensors provided corresponding to each of the plurality of heaters, In a recording apparatus that performs recording on a recording medium using a liquid discharge head including: a determination method for determining whether or not each of the plurality of nozzles is in a state of normally discharging liquid, a step of continuously applying, by the drive means, a first drive signal and a second drive signal having a different heat generation of the heater with respect to the first drive signal to the heater corresponding to the nozzle to be determined; a step of acquiring the output of the temperature sensor when the first drive signal is applied; a step of acquiring the output of the temperature sensor when the second drive signal is applied; a step of determining the nozzle to be determined based on the change rate of the output of the temperature sensor when the first drive signal is applied and the change rate of the output of the temperature sensor when the second drive signal is applied; and having A determination method characterized by not applying a drive signal to the heater corresponding to the nozzle not being a determination target during an interval between the first drive signal and the second drive signal.

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