JP2006218744A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress power consumption, a consumption of a media and ink and a degree of damage to a head for detection by detecting the failure of a head in an actual head driving sequence prior to printing. <P>SOLUTION: Prior to printing image data, a head driving means is used to perform head driving (non print driving) the consumption current of which can be estimated, then the head consumption current is detected by a head current detecting means, and an estimated current value and the detected current value are compared with each other using a controlling and estimating means to decide a head failure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printer that performs recording using a recording head.

  An image forming apparatus such as an ink jet printer has a head for ejecting ink. The head unit normally determines whether or not to eject ink from the head in accordance with an external electric control signal. As a general head structure, a switch in a state where a predetermined drive voltage is applied as a bias voltage to a heat part in an electric circuit connected in series with a heat resistance part and a transistor switch for receiving an external electric control signal. Is turned on (energization mode), current flows through the heat resistance, bubbles are generated by heat in the ink near the heat resistance area, and ink is ejected from the ink ejection holes (nozzles) toward the image recording medium. It is a mechanism to form. For this reason, when a circuit failure such as disconnection of the head or short circuit occurs due to some reason, image recording on the media is not performed satisfactorily, or in the head load short situation seen from the device power supply system due to short of heat resistance, There is a problem that a failure of the power feeding system is detected and the power feeding system is quickly stopped due to the operation of the protection circuit or the head damage is accelerated.

As such a detection method, for example, an excessive current is energized due to an electrical short circuit of a heating element of a thermal head printer, and as a result, the temperature of the heating element rises remarkably. Therefore, a temperature sensor is provided inside the heating element to constantly adjust the head temperature. By detecting, there is a method of performing stable image recording and early detection of a failure state. (For example, refer to Patent Document 1.)
In the thermal head printer, in the head disconnection detection mode, a voltage lower than a normal head driving voltage is applied to the thermal head. There is a method of detecting a head failure by simultaneously driving the heating element and electrically detecting a difference between a normal voltage drop amount and a voltage drop amount at the time of failure. (For example, see Patent Document 2.)
Japanese Patent Laid-Open No. 8-150765 (Claim 1, Claim 5) Japanese Patent Laid-Open No. 8-31030 (Claims 1, 2 and 5, FIGS. 1 and 2)

[Task]
In an ink jet printer apparatus, as a structure of a recording head for image formation, a current is passed through a heat resistance, and ink in the vicinity of the heat resistance portion of the head ink flow path is directed toward a recording medium by thermally generating bubbles. It has a mechanism for discharging ink.

  For this reason, when the heat resistance for ink ejection is disconnected or short-circuited, ink discharge does not occur. In particular, in the case of a short circuit, there is a concern that the head drive voltage as a bias voltage for causing a current to flow through the heat resistor is short-circuited, so that the power supply voltage decreases, the protection circuit operates, and power supply of the entire system stops. In addition, if the head is left in a failed state, there is a concern that electrical stress is applied to a specific heat portion every time the system power supply is turned ON / OFF, causing deterioration and damage of the head.

  Considering from the viewpoint of image formation on the recording media, the ink is not ejected normally from the specific heat part, so that the missing image (missing image in the raster scan direction) occurs. Media waste occurs.

[Objective of the present invention for solving problems]
An object of the present invention relates to head failure detection of an ink jet printer. Prior to the start of printing, the head current when non-print driving with predictable head current consumption is performed is detected, and the difference between the predicted current value and the detected current value is compared to process head failure efficiently and highly. The purpose is to detect with high accuracy and low power consumption.

  An ink jet printer comprising: a head driving unit that drives a recording head prior to printing image data; and a control / prediction unit for predicting a head failure by driving the head by the head driving unit. The head drive non-print drive (drive method that does not discharge ink) is detected, the head current consumption for detecting head failure is detected, the result is transferred to the control / prediction means, and registered in the control / prediction means in advance. The difference between the predicted current value and the detected current value is compared, and the detected current value is more than the current value within a certain variation range from the predicted current value, for example, exceeding the current consumption value of 1 heat resistance. If a current difference that is less than or equal to the current value has occurred, the user is warned that the head has failed, and printing is not performed. To the machine.

  As a first effect, by detecting that a head has failed in an actual head driving sequence prior to printing, power consumption for detection, consumption of media and ink, and head damage can be suppressed.

  As a second effect, as a non-print drive method, “ultra-short pulse and short-cycle drive” is used to extremely suppress head temperature rise, reduce process fluctuations in the head current, and enable high-precision detection. . Further, it is possible to detect head failure of all nozzles in a short time of about several tens of usec.

  As a third effect, by detecting a head failure with a non-print driving method that does not discharge ink, waste of ink is eliminated, and a head failure can be detected at a printer stationary position (while the printer is waiting).

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

  “Print” (sometimes referred to as “recording” or “image formation”) is not only for forming significant information such as characters and figures, but also for human beings, regardless of whether it is significant or not. Regardless of whether or not it has been manifested, it is intended to refer to a case where an image, a pattern, a pattern, or the like is widely formed on a print medium, or that the print medium is processed.

  “Battery” refers to a power / energy source for operating this device, and generally refers to a generic term for media capable of generating energy, such as fuel cells, chemical cells, physical batteries, power generation facilities, and power storage facilities. And

  "Media" refers to not only paper used in general printing equipment but also materials such as cloth, plastic, film, metal plate, glass, ceramics, wood, leather, etc. that can accept ink. And

  “Ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “print” above, and is formed on a medium to form an image, a pattern, a pattern, A liquid used for media processing or ink treatment (for example, solidification or insolubilization of a coloring material in ink applied to the media) is used.

  “Head” (sometimes referred to as “recording head” or “image forming means”) is not only used to form significant information such as characters and figures, but also for humans to perceive visually. Regardless of whether or not it has become obvious, it refers to a mechanism for widely forming images, patterns, patterns, etc. on a print medium. In particular, it refers to a mechanism incorporating a mechanism for recording the “ink” on the “media”.

  The mechanism structure has an ink flow path for discharging ink and an ink discharge port. By supplying a current to the heat resistance for a certain period of time for ink discharge, the ink foams into the ink, and the ink expands due to its volume expansion. It has a structure for discharging and thereby forming an image on a medium.

  The electric structure is an electric circuit that turns on (energized) / off (non-energized) a current switch MOS FET connected in series with the heat resistor by an external electric control signal. Since the heat resistance portion is biased with a constant head drive voltage, the current flowing through the heat resistance can be uniquely determined by the heat resistance value, the MOSFET, the heat resistance value, and the head drive voltage. When driving for a predetermined number of heat resistance units, the total current consumption of driving can be easily obtained by multiplying the current consumption of one heat resistance by the number of simultaneous driving.

  The value of the current flowing to the heat part is digitally stepped up / down for each number of simultaneous drives with the step width of the current consumption value per heat resistance.

  “Non-print driving” (also referred to as “ink non-ejection driving”) is a head driving method that does not eject ink in a printer standby state prior to printing. In particular, the head driving method can be performed in a printer standby state at a home position in which the head is capped to prevent the ink ejection surface from being fixed and dried.

  As a specific driving method, the driving time is set to be much smaller than the electric energy given to the heat resistance part of the normal printing operation with the energy not discharging ink. In other words, a driving method is used in which the pulse width time for energizing the heat resistance portion and applying heat to the ink is set to a time of about 100 nsec, for example, about 1/10 of the usual about 1 usec. With this driving method, the nozzles forming the head are divided into blocks, and only predetermined nozzles of each block are driven at the same time, and the total value of the current is detected by the head current detection means. It has a feature that can be compared and processed by the control / prediction means to see if there is a "head failure"

  Alternatively, the “non-print driving” is performed one by one for all the nozzles forming the head, and the specific nozzle can be detected from the head failure detection in units of blocks.

  As a merit of detecting a head failure by such “non-print driving”, the first is to use an extremely single pulse to facilitate detection in a very short time even if all nozzles are detected. This shortens the print operation start time. Second, there is no ink consumption due to the extremely short pulse, or the ink flow path is cleaned by actual heat by non-ejection of ink, and the ink ejection characteristics during actual printing operation are stabilized. The third is an extremely short pulse, so that power consumption required for head detection can be extremely suppressed. For example, in battery-driven ink jet printer products, there is an advantage that the battery life can be extended.

  “Head failure” means that even if an electric control signal for driving the head is given from the outside due to the heat resistance of the head or the disconnection or short circuit of the MOS FET, ink ejection will not be performed, or power supply for driving the head due to a short circuit. The system protection circuit is activated and the power supply is stopped.

Basic configuration
A basic configuration of a printing apparatus according to the present invention will be described with reference to FIG.

  The apparatus main body A100 employs a system in which ink and media for print recording are attached to and detached from the apparatus. The ink is contained in the ink container A101, and the print recording medium A103 is contained in the medium container A102.

  As the power feeding method of this apparatus, two methods of battery driving and AC adapter driving can be exclusively selected. In the battery driving method, the battery pack main body A104 can be connected to a dedicated connection location of the apparatus main body A100, and DC voltage feeding can be performed via the battery terminal A105. On the other hand, in the AC adapter driving method, a commercial power supply AC outlet A107 can be connected to a commercial power supply, and the AC adapter main body (AC / DC) A106 can be connected to a dedicated connection location of the apparatus main body A100 to perform direct voltage supply. In these two types of device drive modes (battery drive, AC adapter drive), a DC voltage converter (DC / DC converter) is provided inside the device main body A100 to answer various load voltage requirements, and a desired load voltage value is obtained. Has been converted to.

  As a print data acquisition method of this apparatus, print data from digital information device devices such as a memory card A 108, a digital camera 109, a personal computer A 110, and a mobile phone A 112 can be received and printed by the apparatus main body A100. In either case, the print mode (device selection) is exclusively determined by the operation key A116 on the apparatus main body side, and printing is performed.

  The memory card A108 can be connected to a dedicated card slot of the apparatus main body A100, and the user can print from various card media. For memory card A108, a standard memory card such as CF (usually CompactFlash (registered trademark), SM (smart media) card, MS (memory stick) card, SD (Secure Digital) card, etc.) can be exclusively connected in 4 in One It is.

  In this case, the digital camera A 109 and the personal computer A 110 can connect the communication cable to the USB connector A 111 of the dedicated connection connector, transfer the data to the apparatus main body A 100, and print.

  In addition, the mobile phone A112 can receive by the infrared (irDA) communication unit A113 by the infrared communication (irDA) of wireless communication and can print by the apparatus main body A100.

  For the image forming unit, the carriage A 114 has ink acquired from the ink container, a head for image formation, and a control line for driving the head. In response to a control signal based on print data from the control / prediction means of the apparatus main body A100, the head is driven to print on the print medium A103. The carriage A114 scans the print medium A103 with a motor in the sub-scanning direction, and feeds paper in the main scanning direction by the paper transport motor of the apparatus main body A100. It is assumed that image formation is performed by discharging.

  Normally, the carriage-mounted head of the image forming unit is arranged at a fixed distance in the vertical direction with respect to the surface of the print medium A103, and ink is directly ejected from the head during image formation. For this reason, when printing is performed, ink remains in the ink flow path and the ink discharge surface of the head every time, and preliminary discharge (stop standby) is performed with the carriage A114 stopped in order to avoid the influence of ink fixation and color mixing on the image. Vomit).

  In addition to the stop preliminary ejection, non-print driving is performed by a method that does not eject ink. Prior to printing, in a situation where the head is at the home position during print standby, a protective cap is usually provided on the ink ejection surface of the head in order to avoid ink sticking on the ink ejection surface and the ink flow path of the head. In this state, the head is driven without ejecting ink (non-print driving for head failure detection in the present invention), and the ink flow path is properly formed to prepare for image formation without problems when recording images on media. Do. In addition to this, as the role of non-print driving is head driving with predictable current consumption, head driving is performed for head failure detection, and current consumption during head driving is detected by the head current detecting means, The result of the predicted current value and the detected current value are compared by the control / prediction means built in the apparatus main body A100 to determine whether or not “head failure” has occurred. As a result, if it is “head failure”, a warning is given to the warning means, and a standby operation is performed without performing a printing operation.

  As for the user interface, it is assumed that the data is printed directly from the memory card A108, or the data is confirmed by the warning display means (Viewer) A115, assuming that there is no print data confirmation means in the device such as the digital camera A109 or the mobile phone A112. It has a configuration that can. It also has a battery life warning, print condition (media, image format, communication method, failure notification, etc.) notification function, and head failure detection warning. These warnings / displays are performed under the control of the control / prediction means of the apparatus main body A100.

"Printer head failure detection system"
A head failure detection system B100 as a printing apparatus for a portion related to the present invention will be described with reference to FIG.

  A head failure detection system B100 as a printing apparatus is mainly composed of an image forming unit (hereinafter referred to as a head or a print head) B101, a control / prediction unit B104, and respective peripheral units.

  The head B101 is composed of a series connection of a heat resistance part (heating element) B102 and a current switch control transistor (MOS FET) B103 for performing energization / non-energization switch control of the current flowing therethrough on a silicon substrate. Is done. This connection has a configuration in which n nozzles are arranged and wired in multiple stages in parallel for each ink color (C, M, Y) necessary for image formation. Note that a cartridge-type head that can be replaced by a user equipped with both the head and the ink has the predicted current storage unit B110 as a built-in head.

  The printing apparatus of the present invention has a non-print driving predicted current value, which will be described later, as a default at the time of shipment from the factory, as a head current storage unit of the control / prediction means B104 means. The main purpose is to correct the difference from the default value of the predicted current value due to process variations in the case where the predicted current storage means B110 in the head has the head rank information and the predicted current value, and the cartridge is replaced. The default value can be reset.

  Here, in order to perform ink discharge, taking a circuit for one nozzle connected in series as an example, in order to obtain energy necessary for ink discharge, the heat resistance portion B102 is heated, and the ink there is heated. In this structure, bubbles are generated from ink discharge holes (nozzles) toward the recording medium by generating bubbles. The electrical energy for the ink bubbling is that the heat resistance portion B102 is biased in advance with a constant head drive voltage VH, and a desired head control signal is given from the control / prediction means B104 to the gate portion of the MOS FET B103. Then, the MOS FET is turned on (energized) / off (non-energized), a constant current is passed through the heat resistance portion B102, and the heat resistance portion B102 is heated to control ink foaming / non-foaming. Ink ejection control is performed by time-division driving for each specific nozzle block for n nozzles for each color (C, M, Y) necessary for forming a color image in addition to one nozzle. Finally, an image is formed on the recording medium.

  Control of the amount of electrical energy required for ink foaming is such that the current flowing through the heat resistance portion B102 is constant (the value obtained by dividing the series connection value of the heat resistance value R and the ON resistance of the MOS FET by the head drive voltage VH) Therefore, the head control signal is controlled by ON / OFF time control. Actually, if the current is kept flowing for a certain period of time, the ink foaming time is reached. Therefore, when the ink foaming is performed reliably and there is no ink in the heat part B102, the current is turned off once and the ink is turned off. The pulse width control method of the pulse current is adopted so as to prevent the head from being burnt and damaged by the empty heat without any ink and to perform the ink filling (Refill) for the next ink foaming.

  In such an ink ejection mechanism, in the present invention, non-print driving is performed prior to the printing operation in order to detect a head failure. The head driving unit of the control / prediction unit B104 performs head driving capable of predicting the head driving current for each nozzle of the head B101. Specifically, in a printer home position state, heating is performed at a level where ink is not ejected in a state where the cap for protecting ink adhesion on the head ink ejection surface is attached. The head current is monitored and a head failure is detected from the current difference between the predicted current value and the detected current value.

  When head failure is detected, the control / prediction means B104 sets the head current detection switch B105 to the side to which the head current detection resistor (Rs) B106 is connected. Thereafter, when non-print driving of the predictable head consumption current is performed by the head driving unit built in the control / prediction unit B104, a current flows to each nozzle of the head B101, and the total value of these currents is detected. Since the current detection switch B103 set in advance is set on the head current detection resistor (Rs) B106 side, a current flows through Rs, and a product of the flowing current and the Rs value becomes a voltage drop. It is converted into digital data by an AD (analog to digital) converter, and this is taken into the control / prediction means. After that, since the predicted current value is registered in the control / prediction unit, the current difference between this registered value and the detected current value from the AD converter B109 is compared, and the current exceeds or falls below the current for one nozzle. In the case of a current difference, it is identified that either the energized system of the driven heat resistance part B102 or MOS FET B103 is faulty.

  When “head failure” is identified, information is transferred from the control / prediction means B104 to the warning / display means B107 side to notify the user of “head failure”. Even if the printing operation is confirmed from the operation means B108, the printing operation is not performed because of a head failure, and the printing standby state is set. If it is necessary to perform a printing operation, the power is once turned off by the operation means B108, the head is replaced, and then the power is newly turned on to detect the head failure. The print operation can be performed.

“Non-Print Drive for Head Failure Detection as a Printing Apparatus in the Present Invention”
FIG. 3 shows non-print driving for detecting a head failure as a printing apparatus according to the present invention.

  First, for comparison, a waveform during a normal printing operation is shown as a print driving waveform in the first stage timing chart. Control of ON (energization) / OFF (non-energization) of the current switch control transistor (MOS FET) B103 of the image forming unit (head, print head) B101 is performed with High / Low logic for the head. In other words, in the timing chart, in the High section, the MOS FET is turned on (energized), a current is passed through the heat resistance portion B102, and the ink around the heat resistance portion B102 is caused to thermally vaporize by flowing a current. Ink bubbling.

  Usually, the ON (energization) time of the MOS FET is given as a pulse waveform from the control / prediction means B104, and has an ON time of about 1 usec, for example. Thereafter, an OFF (non-energization) time of about 3 usec is provided, and ink ejection / non-ejection for one nozzle is determined at a cycle of about 4 usec.

  Here, taking the time width of the heat pulse width 1 as an example, the ink bubbling will be described. From the viewpoint that the head performs constant voltage driving, when the MOS FET is turned on (energized), the heat resistance is a predetermined resistance value. A constant current flows. Therefore, if the time width is short, if the electrical energy (power amount) that promotes ink bubbling is smaller than the bubbling energy, ink bubbling cannot be performed, and the ink is not discharged. For this reason, it is necessary to foam the ink properly from the head at the time of printing, so the pulse driving is set to the minimum driving time T0 or more. On the other hand, if the pulse width is too long, foaming can be performed, but the head needs to be thermally destroyed. Therefore, the foaming time is also set within T1 time. Therefore, the head drive time T during printing is set to T0 ≦ T ≦ T1, and ink foaming is performed.

  On the other hand, a head driving method (“non-print driving”) for head failure detection according to the present invention is shown as a second stage timing chart. The pulse width of non-print driving is extremely shorter than the pulse width of about 1 usec during normal print driving, for example, about 100 nsec, the cycle is about 200 nsec, and a pulse driving method of about 1/10 is employed. The first is to provide an environment in which the user can smoothly perform a printing operation smoothly by shortening the detection time when detecting head failure when the printer power is turned on. The ink discharge is not performed by taking a short time, so that wasteful consumption of ink can be eliminated. The third is a sufficiently short pulse compared to the pulse width of the actual print drive, but there is a failure that causes current to flow, even a slight head Therefore, non-print driving of ultrashort pulse driving is performed from the viewpoint that the head current can be properly detected by the current monitor while suppressing the process fluctuation of the head current.

  When non-print driving is performed for each nozzle, a head consumption current is generated. The total current of the individual currents is supplied to the current sense resistor Rs, and the voltage drop of this resistor is obtained by an AD converter. Thus, the head current is detected. The generation timing of the head current is as shown in the timing chart of the third stage, and is generated almost in synchronization with the ON (energization) timing of non-print driving. In synchronization with this timing, AD acquisition is performed as shown in the timing chart of the fourth stage, the detected current is transferred to the control / prediction means side in voltage format, and the predicted current registered in the control / prediction means in advance The value is compared with the detected current value to determine the head failure.

"Printing operation control method when head failure is detected as a printing apparatus in the present invention"
5 shows a printing operation sequence S100 based on the head failure detection system shown in FIG.

  In the operation sequence S100, when the user turns on the power switch of the operation unit of this apparatus S101, the control / prediction unit sets the head current detection switch to the Rs side of the current detection mode in order to detect head failure prior to printing. I do. Thereafter, “non-print driving” S103 in which the head consumption current can be predicted by the control / prediction means is performed. At this time, the predicted current value is registered in the storage unit inside the control / prediction means. When non-print driving is performed, the head consumption current is supplied to the current detection resistor Rs, and the voltage drop is detected by the AD converter in step S104.

  This AD converter detection voltage is transferred to the control / prediction means side, divided again by the current detection resistance value Rs, converted to the original current value, and the detected current value and the predicted current value (registered value, this implementation) In the example, in the case of divided driving of head nozzles, the total current consumption value of specific nozzles in a specific block (in the case of single nozzle driving, one nozzle current value) is within a certain range (in this embodiment, one nozzle). The comparison process S105 is performed. If the comparison results are almost equal, it is regarded as “head normal”, and preparations for normal printing are complete, so that the user can perform print confirmation selection S106 from the operation means. If it is confirmed, the operation proceeds to the print operation mode, and the selected image is ejected from the head to form an image on the medium. If it is not confirmed, the apparatus is set in the standby state as it is and waits for the apparatus.

  On the other hand, if there is a difference between the detected current value and the predicted current value as a result of the comparison, there is a possibility that the head part is disconnected or short-circuited. A warning S107 “head failure” is issued from the prediction means to the warning / display means. After that, even if the print confirmation selection is made by the user from the operation means, not only the proper image formation cannot be performed when the head is operated while the head is broken, but the head damage is accelerated, so that the head drive is not always performed. Wait for the device in the standby state. If you want to avoid this situation and perform print operation, follow the instructions of “Head Failure” in the warning means, the user will turn off the device power properly to the operation means, replace the head and turn on the power again, then head failure again If “no head failure” is detected in the detection sequence S100, the print operation mode can be shifted and a desired image can be recorded on the medium.

  FIG. 5 shows another embodiment relating to the predicted current value registration / storage. FIG. 5 shows a replaceable head portion of the portion related to the present invention. When the head unit of the printing apparatus of the present invention is replaceable, for example, consider a cartridge type head in which a head and ink necessary for image formation are set. The head rank (details will be described later) becomes arbitrary when the user replaces the cartridge in the state of “no ink remaining” or “unclear printing due to head deterioration”. For this reason, there is a possibility that the head current information previously registered in the head current storage unit of the control / prediction means B104 described in the previous embodiment cannot be used. That is, there is a situation in which the detected current value and the predicted current value include a variation in the predicted current value due to the process variation of the head other than the detection difference, and the “head failure” due to the head current detection cannot be detected.

  Therefore, with respect to the head configuration of FIG. 2 of the above-described embodiment, a predicted current storage means (head built-in) D103 is newly provided in the head, and the head rank and predicted current value data are provided for each set head. It has a mechanism to access the predicted current value from the control / prediction means B104 side, acquire data, reset the default predicted current value setting value at the time of factory shipment, and correct the difference in predicted current value due to head variation .

  Note that the head rank information of the predicted current detecting means (head built-in) D103 is measured in advance in the head manufacturing process at the time of shipment from the factory, the rank value is determined according to the resistance value, and stored as head rank information. The stored data is accessed from the control / prediction means B104 to acquire data.

1 is a basic configuration of a printing apparatus according to the present invention. 3 is a head failure detection system as a printing apparatus for a portion related to the present invention; Non-printing drive for head failure detection as a printing apparatus in the present invention. A printing operation control method as a printing apparatus according to the present invention. The replaceable head of the part related to the present invention.

Explanation of symbols

A100 Device main body A101 Ink storage container A102 Media storage container A103 Print recording medium A104 Battery pack main body A105 Battery terminal
A106 Commercial power supply AC outlet A107 AC adapter body (AC / DC)
A108 Memory card A109 Digital camera (Digital camera)
A110 Personal computer A111 USB connector A112 Mobile phone A113 Infrared (irDA) communication unit A114 Carriage A115 Warning / display means A116 Operation means (operation keys)
B100 Head failure detection system as a printer device B101 Image forming unit (head, print head)
B102 Heat resistance part B103 Current switch control transistor (MOS FET)
B104 Control / prediction means B105 Head current detection switch B106 Head current detection resistor (Rs)
B107 Warning / display means B108 Operation means (operation keys)
B109 AD (Analog to Digital) Conversion Unit C100 Non-Print Drive for Head Failure Detection S100 Head Failure Detection Operation Sequence as a Printing Apparatus in the Present Invention D100 Replaceable Head (Cartridge Built-in Head)
D101 Heat resistance part D102 Current switch control transistor (MOS FET)
D103 Predicted current storage means (head built-in)

Claims (4)

  An ink jet printer, comprising: a head driving unit that drives a recording head prior to printing of image data; and a head current detecting unit that detects a consumption current when the head is driven by the head driving unit.   The printer according to claim 1, wherein when detecting the consumption current, driving without discharging ink is performed.   2. The printer according to claim 1, wherein the detection result of the current value from the head current detection unit is compared with a predicted current value registered in advance in the control / prediction unit.   The printer according to any one of claims 1 to 4, further comprising setting means for setting the predicted current value at the time of factory shipment or at the time of head replacement.

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