JP2013006337A - Recording apparatus and method of controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the calibration of a temperature sensor of a recording head with high accuracy by using a simple method, even when assumed that the recording head is replaced when powered on or right after the head is mounted, or the like.SOLUTION: A recording apparatus executes a recording control based on the temperature of the recording head. The recording head includes: a first detection means for detecting an electrical signal related to a temperature of the recording head; and a memory for storing a characteristic value of the first detection means. The recording apparatus includes: a second detection means for detecting an environmental temperature; a means for amplifying a signal related to a recording head temperature detected by the first detection means; a memory for storing the characteristic value of the amplification means; and a correction means for performing correction based on a predetermined offset value to a value obtained by amplifying the signal related to the recording head temperature and for acquiring the temperature of the recording head. The offset value is calculated based on an electrical signal related to the temperature of the recording head detected by the first detection means; the environmental temperature detected by the second detection means; the characteristic value of the first detection means; and the characteristic value of the amplification means.

Description

  The present invention relates to a recording apparatus that records characters and images on a recording medium in accordance with recording data, and more particularly to a temperature detection method for a recording head.

  In recent years, performance requirements for recording devices used in printers, copiers, facsimiles, and the like are increasing, and there is a demand for high-definition image recording not only for high-speed recording and full-color recording but also for silver halide photographs. In response to such demands, the ink jet recording apparatus can discharge minute ink droplets at a high frequency, and thus is superior to recording apparatuses of other recording systems in terms of high speed recording and high image quality recording. In addition, among inkjet recording apparatuses, thermal inkjet recording type recording apparatuses that eject ink using bubbles generated by a heater (electrothermal transducer) can form high-density nozzles. High-definition image quality can be recorded.

  By the way, the above-described thermal ink jet recording method (hereinafter simply referred to as an ink jet recording method) has the following characteristics. According to the ink jet recording method, heat energy is generated by energizing the heater to generate bubbles in the ink. The growth of the generated bubbles is greatly influenced by the temperature of the nearby ink. At the interface between the bubble and the ink, there are a process in which molecules in the gas state in the bubble jump into the ink and a process in which molecules in the liquid state of the ink jump out into the bubble. Affects the latter process. When the ink temperature is high, many molecules jump out from the ink into the bubbles, and the bubbles grow relatively large. Conversely, when the ink temperature is low, relatively few molecules jump out of the ink into the bubbles, and the size of the bubbles is smaller than when the ink temperature is high. The size of the bubbles is reflected in the volume of ink pushed out from the nozzle (hereinafter referred to as ink discharge amount) and the ink discharge speed (hereinafter referred to as discharge speed).

  Therefore, in the ink jet recording apparatus, the ink discharge amount and discharge speed are strongly influenced by the ink temperature (hereinafter referred to as ink temperature) in the vicinity of the heater, and when the ink temperature is high, the ink discharge amount is large and the discharge speed is high. . On the other hand, when the ink temperature is low, the ink discharge amount is small and the discharge speed is slow.

  When the ink discharge amount changes, the output image density changes, and when the ink discharge speed changes, the ink attachment position on the recording medium changes. As a result, a density distribution occurs in the recorded image, which may cause a reduction in recording quality.

  As described above, in the ink jet recording apparatus, the ink discharge control technology that discharges ink uniformly with respect to the ink temperature is the key to improve the recording quality. It is very important to know the temperature accurately. However, since it is difficult to directly detect the ink temperature, it is common to detect the temperature of the print head substrate (hereinafter referred to as print head temperature) and perform ink ejection control or print head temperature control based on that temperature. Is. As a sensor for detecting the print head temperature, a diode sensor formed on the same silicon chip as the discharge heater is often used. This is because the film is manufactured by forming a film on a Si substrate which is low in cost and high in thermal conductivity, and has excellent responsiveness. However, when graphing the relationship between temperature and voltage in this diode sensor, it is very difficult to suppress the zero intercept (offset) within the allowable range in actual use, although the inclination can be suppressed with respect to the variation in manufacturing. . In addition, since the voltage of the diode sensor is weak, it is common to amplify the diode sensor output voltage on the recording device before A / D conversion, but the amplifier circuit also has manufacturing variations and the diode sensor output Even if the voltages are the same, the voltage value before A / D conversion varies due to individual differences of the amplifier circuits.

Therefore, in order to calibrate this offset, the following processing is conventionally performed. That is, the temperature (Tdef) corresponding to the voltage value when the recording head is not heated and equivalent to the room temperature and the room temperature (Tr) obtained by the thermistor of the recording apparatus main body are stored, and in a certain state If the temperature corresponding to the value obtained by amplifying the voltage value of the head diode sensor is Tdi, the recording head temperature (Th) is Th = Tdi + Tadj.
Tadj = Tr−Tdef
Can be obtained at Tadj in the above formula is the offset of the head diode sensor.

  However, since this process is based on the premise that the environmental temperature is the same as that of the recording head, the recording head is replaced with the temperature of the recording head raised, or the power of the recording apparatus main body is repeatedly turned ON / OFF. When the user performs the above operation, since the temperature of the recording head becomes higher than the room temperature, Tdef which is the reference temperature of the head indicated by the diode sensor is set to an incorrect value.

  In order to solve such a problem, a proposal has been made for a method for calibrating the recording head temperature. According to Patent Document 1, the recording head temperature is first calibrated when the power is turned on or the head is mounted, and the offset value is made closer to a more accurate value by successively updating after a predetermined time has elapsed. When the difference is excessively large, a method has been proposed in which the offset value is limited to reduce the damage against a situation where calibration is performed with an abnormal correction value.

JP 7-209031 A

  Patent Document 1 proposes a method of limiting the correction value. However, the limit value is determined by a manufacturing variation range of a diode sensor or a circuit that amplifies the sensor output, and the offset variation is described above. As shown, it is not an acceptable level in actual use. That is, even if the recording head can be prevented from reaching a high temperature due to the presence of the limit value, it is difficult to perform accurate temperature acquisition for the purpose of improving the recording quality.

  As described above, an incorrect correction value is acquired when there is a difference between the actual temperature of the print head and the environmental temperature of the printing apparatus immediately after the power is turned on or the head is mounted. In particular, when the actual temperature of the recording head is higher than the environmental temperature of the recording apparatus, there is a possibility that correction is performed in a direction higher than the environmental temperature. That is, if the actual temperature of the recording head is higher than the environmental temperature of the recording apparatus, the recording apparatus recognizes that the temperature is low even though the recording head temperature is high. Even if this occurs, recording is continued without stopping the recording operation, and as a result, insufficient ink refilling to the nozzle due to a decrease in ink viscosity causes ejection failure.

  In order not to cause this problem, it is important to suppress the manufacturing variation of the diode sensor and the amplifier circuit. However, suppressing the tolerance without changing the manufacturing technology as it is leads to a decrease in yield, resulting in an increase in cost.

  The present invention has been made in view of the above-described problems, and can calibrate the temperature sensor of the recording head with high accuracy by a simple method.

  In order to achieve the above object, the recording apparatus of the present invention has the following configuration.

That is, a recording apparatus that performs recording control based on the temperature of the recording head,
A recording apparatus that performs recording control based on the temperature of a recording head,
The recording head is
First detection means for detecting an electrical signal related to the temperature of the recording head;
A memory for storing a characteristic value of the first detection means,
The recording device comprises:
Second detection means for detecting an environmental temperature that is a temperature around the recording head;
Means for amplifying a signal related to the print head temperature detected by the first detection means;
A memory for storing characteristic values of the amplification means;
A correction means for performing a correction based on a predetermined offset value for a value obtained by amplifying a signal related to the recording head temperature, and obtaining a head temperature which is a temperature of the recording head;
The offset value includes an electrical signal related to the temperature of the recording head detected by the first detection unit, the environmental temperature detected by the second detection unit, a characteristic value of the first detection unit, and a previous amplification unit. It is calculated based on the characteristic value.

  According to another aspect of the invention, the characteristic value of the first detection means is a value based on a value output from the first detection means in a predetermined temperature environment.

  According to another invention, the characteristic value of the amplifying unit is a value based on a value obtained by amplifying a signal output from the first detecting unit when the same recording head is mounted on the recording apparatus. It is characterized by.

  According to the present invention, it is possible to calibrate the temperature sensor of the recording head with high accuracy by a simple method.

1 is a diagram showing a schematic configuration of a recording apparatus equipped with an ink jet recording head that is a typical embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a recording head. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. It is a block diagram which shows the structure of a head temperature control circuit. It is a flowchart which shows the recording operation in Embodiment 1 of this invention. 3 is a flowchart showing print head temperature acquisition control in Embodiment 1 of the present invention. 6 is a flowchart illustrating the update timing of the print head temperature correction value when the power is turned on and the print head is mounted in the first embodiment of the present invention. 6 is a flowchart illustrating the update timing of the print head temperature correction value at the start of printing in Embodiment 1 of the present invention. 6 is a flowchart illustrating print head temperature correction value update control according to the first exemplary embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Basic Configuration of Inkjet Recording Apparatus (FIGS. 1 to 3)>
FIG. 1 is a diagram showing a schematic configuration of a recording apparatus which is a typical embodiment of the present invention. 1A is a perspective view of the recording apparatus, and FIG. 1B is a YZ sectional view passing through the recording head in FIG. In FIG. 1, reference numerals 100 and 101 denote recording heads that are integrated with an ink tank. The recording head 100 stores black ink, light cyan ink, and light magenta ink in an ink tank, and the recording head 101 stores cyan ink, magenta ink, and yellow ink in an ink tank. The recording heads 100 and 101 have the same configuration except for the ink to be stored. Further, the recording heads 100 and 101 have a plurality of ejection openings 102 arranged in correspondence with each color ink. Reference numeral 103 denotes a conveyance roller, and reference numeral 104 denotes an auxiliary roller. These rollers cooperate to rotate in the direction of the arrow in the drawing while suppressing the recording medium P, and convey the recording medium P in the Y direction as needed. Reference numeral 105 denotes a paper feed roller that feeds the recording medium P and plays the role of suppressing the recording paper P, like the transport roller 103 and the auxiliary roller 104. A carriage 106 supports the recording heads 100 and 101 and moves them together with recording. The carriage 106 waits at the home position h at the position indicated by the dotted line in the figure when recording is not being performed or when the recovery operation of the recording head is performed. A platen 107 serves to stably support the recording medium P at the recording position. A carriage belt 108 scans the carriage 106 in the X direction.

  FIG. 2 is a diagram illustrating the configuration of the recording head. Since the recording heads 100 and 101 have the same structure, the configuration of the recording head 101 will be described here. 2A is a perspective view of the recording head 101, FIG. 2B is a bottom view when the recording head is viewed in the Z direction, and FIG. 2C is an enlarged view around the ejection port in FIG. . In FIG. 2A, reference numeral 201 denotes a contact pad, through which a recording signal is received from the recording apparatus main body, and power necessary for driving the recording head is supplied. In FIG. 2B, reference numeral 102 denotes a recording head chip, and 202 denotes a diode sensor that detects the temperature of the recording head substrate. Reference numeral 203 denotes an ejection port array that ejects cyan ink, 204 an ejection port array that ejects magenta ink, and 205 an ejection port array that ejects yellow ink. The ejection ejection port structure other than the ink color is the same. Reference numeral 206 denotes a sub-heater for heating an ink having a resistance of 100Ω, which exists in a shape that largely surrounds the ejection port arrays 203, 204, and 205. The print head substrate is heated or not heated depending on whether or not a voltage of 20V is applied. And Thereby, the print head temperature (ink temperature) is adjusted. In the recording apparatus of the present embodiment, feedback control is performed by switching heating / non-heating of the recording head substrate so as to approach the adjustment temperature based on temperature information detected by the diode sensor 202 and a thermistor 315 described later. . FIG. 2C is an enlarged view of the ejection port array 203 that ejects cyan ink. Reference numeral 207 denotes an ink liquid chamber through which cyan ink flows. On both sides of the ink chamber 207, there are an ejection port 208 for ejecting 5 pl of ink and an ejection port 210 for ejecting 2 pl of ink. Immediately below each nozzle (+ Z direction side) is for 5 pl ejection with a resistance value of 500Ω. A heater 209 and a 2 pl discharge heater 211 having a resistance value of 700Ω are arranged. The heaters 209 and 211 both generate heat and generate bubbles when a voltage of 20 V is applied, and eject ink from each nozzle. The number of ejection ports 208 and 211 is both 600, and the interval between the ejection ports is 1/600 inch, so that the recording pixel density is 600 dpi.

  Further, the discharge frequency of the heaters 209 and 211 for stably discharging ink droplets is 24 kHz. The speed in the main scanning direction of the carriage equipped with the recording heads 100 and 101 is 24000 (dots / second) ÷ 1200 (dots / inch) = 20 inches / second when ink droplets are recorded in the main scanning direction at an interval of 1200 dpi. Second. As ink characteristics, the black, light cyan, light magenta, cyan, magenta, and yellow inks packed in the recording heads 100 and 101 all have the same discharge characteristics such as discharge amount / discharge speed with respect to temperature. When the ink discharge rate is 5 pl and 2 pl, the ink discharge speed is 15 m / s, the optimum conditions for recording are satisfied, and the ink temperature that satisfies this condition is 50 ° C. At a temperature of 30 ° C. or lower, the ink ejection speed is slow, so that it does not reach the recording medium, and the recording quality is lowered. At a temperature as low as room temperature (about 25 ° C.), the ink is highly viscous and may not be ejected. . On the other hand, even at a high temperature of 70 ° C. or higher, the ink discharge amount increases excessively, and the ink supply is not in time for discharge, resulting in discharge failure.

  FIG. 3 is a block diagram illustrating a control configuration of the recording apparatus. In FIG. 3, each component of this control configuration can be broadly divided into a software system control means and a hardware system processing means. The software control means includes processing means such as an image input unit 303 accessing the main bus line 305, an image signal processing unit 304 corresponding to the image input unit 303, and a central control unit CPU300. The hardware processing means includes an operation unit 308, a recovery operation control circuit 309, a head temperature control circuit 314, a head drive control circuit 316, a carriage drive control circuit 306 in the main scanning direction, and a conveyance control circuit in the sub scanning direction. Processing means 307 is included. The CPU 300 normally includes a ROM 301 and a RAM 302, gives appropriate recording conditions to input information, and drives the ink ejection heater 208 in the recording heads 100 and 101 to perform recording.

  The RAM 302 stores a program for executing a recording head recovery timing chart in advance, and applies recovery conditions such as preliminary ejection conditions to the recovery operation control circuit 309, the recording heads 100, 101, and the like as necessary. . The recovery motor 310 drives the recording heads 100 and 101, the cleaning blade 311, the cap 312, and the suction pump 313 facing and separating from the recording heads 100 and 101. The head temperature control circuit 314 determines the driving conditions for the sub-heaters 206 on the recording heads 100 and 101 based on the output values of the thermistor 315 that detects the ambient temperature of the recording apparatus and the diode sensor 202 that detects the recording head temperature. Then, the drive control circuit 316 drives the head sub heater 206 based on the drive conditions. The head drive control circuit 316 drives not only the sub heater 206 but also the 5 pl ink ejection heater 209 and the 2 pl ink ejection heater 211 on the recording heads 100 and 101 for preliminary ejection, ink ejection, and temperature control. Ink temperature adjustment is performed by the recording heads 100 and 101. A program for executing the temperature control is stored in, for example, the RAM 302, and the print head temperature is detected and the sub heater 206 is driven via the head temperature control circuit 314, the head drive control circuit 316, and the like.

  The head drive control circuit 316 can also perform PWM control by driving the ink ejection heater 207 with a drive signal composed of a pre-pulse and a main pulse. The Fuse ROM 212 stores the characteristic value of the recording head by a combination of cutting / uncutting of fuses. The recorded recording head characteristics are roughly classified into those recorded in the manufacturing process of the recording head and those recorded on the recording apparatus. The former includes a destination number indicating the destination of the recording head, and on the recording apparatus. 5pl discharge pulse number for selecting the optimal pulse for 5 pl nozzle, 2 pl discharge pulse number for selecting the optimal pulse for 2 pl nozzle, manufacturing time number indicating the date of manufacture, diode sensor offset There is a diode sensor rank indicating a range of values, and the latter includes an ink remaining rank indicating a range of remaining ink. The storage capacity of the Fuse ROM 212 is 24 bits for both the recording heads 100 and 101. The breakdown is as follows: the destination number is 3 bits, the 5 pl discharge pulse number is 4 bits, the 2 pl discharge pulse number is 4 bits, the manufacturing number is 4 bits, the diode sensor rank is 4 bits, The ink remaining rank is 5 bits. Regarding the diode sensor rank, the offset error Di_offset due to the manufacturing variation of the diode sensor in the same environment is + 16 ° C. to −16 ° C. By performing the ranking for 4 bits as shown in Table 1, in the diode sensor of the same rank, The output is within an error range of 2 ° C. in the range.

  In this embodiment, the individual identification information (ID) of the recording head is not written in the Fuse ROM 212 from the viewpoint of storage capacity. Similarly to the diode sensor rank, a rank is provided for the amplifier that amplifies the diode sensor output voltage, and the rank corresponding to the ROM 301 is written. The offset error Amp_offset due to manufacturing variation corresponding to Table 2 of the amplifier when the reference diode sensor is attached is + 8 ° C. to −8 ° C. As shown in Table 2, by performing ranking for 3 bits, In the rank amplifier, the output is within an error range of 2 ° C. in the range.

  A supplementary explanation will be given for the head temperature acquisition control. FIG. 4 is a block diagram showing a flow of processing in the head temperature control circuit 314 and software processing through the ROM 301 / RAM 302. When a voltage based on the print head temperature is input from the diode sensors 202 of the print heads 100 and 101 to the head temperature control circuit 314, the voltage value is amplified by the amplifier 401, and the voltage value is digitized by the AD converter 402. The digitized diode sensor voltage value ADdi is converted into a diode temperature Tdi by an ADdi-temperature conversion table 403 in the ROM 301. In the Tdi correction unit 407, the diode sensor offset Di_offset corresponding to the diode sensor rank and the amplifier circuit offset Amp_offset corresponding to the amplifier circuit rank as corrections for the individual variation of the diode sensor and the individual variation of the amplifier with respect to the diode temperature Tdi, Are added to derive the diode correction temperature Tdical.

  On the other hand, when a voltage based on the ambient temperature of the printing apparatus is input from the thermistor 315 to the head temperature control circuit 314, digitization is performed by the AD converter 405. The digitized thermistor voltage value ADtm is converted into the thermistor temperature Ttm by the ADtm-temperature conversion table 406 in the ROM 301. The diode temperature Tdi and the thermistor temperature Ttm obtained as described above are input to the head temperature detection unit 404. The head temperature detection unit 404 sets the offset value of the diode correction temperature Tdic using the thermistor temperature Ttm and acquires the printhead temperature.

  Hereinafter, an embodiment of a recording method of the recording head in the recording apparatus having the above configuration will be described.

[First Embodiment]
FIG. 5 is a flowchart showing a recording operation when the recording head 101 performs recording with cyan, magenta, and yellow ink. When the recording data is received, the temperature control of the recording head is started in S501. In the temperature control in the present embodiment, the print head temperature based on the diode sensor 202 of the print head 100 and the print head 101 is acquired, and when the print head temperature of each print head is less than 50 ° C., The recording head is heated by applying a voltage of 20 V to the sub-heater 206. When the temperature is 50 ° C. or higher, no voltage is applied to the sub-heater 206.

  The print head temperature is acquired according to the flow shown in FIG. In the flow of FIG. 6, since the recording heads 100 and 101 are executed in the same flow, the description of specifying the recording heads 100 and 101 is omitted. When the power of the recording apparatus is turned on, the diode sensor AD value ADdi is acquired from the diode sensor 202 of the recording head in S601 by an interrupt routine at intervals of 10 ms. In step S602, the diode sensor AD value ADdi is converted into the diode temperature Tdi using the diode sensor ADdi value-temperature conversion table in the ROM 301. In S603, in order to correct the individual variation of the diode and the individual variation of the amplifier, the offset Di_offset of the diode sensor and the offset Amp_offset of the amplifier circuit are added to derive Tdical. At this time, Di_offset uses the corresponding value in Table 1 from the diode sensor rank written in the Fuse ROM 212 of the recording head. Amp_offset uses the corresponding value in Table 2 from the amplifier rank written in the ROM 301 of the recording apparatus. In step S604, the print head temperature Th is obtained by adding the print head temperature correction value Tadjust for the print head to the diode correction temperature Tdical. A method for obtaining the print head temperature correction value Tadjust will be described later. The recording head temperature Th acquired in S603 is updated again by the above-described flow after 10 ms. By this temperature acquisition control, the temperature control of the present embodiment determines whether or not the temperature is 50 ° C. or more at 10 ms intervals, and controls ON / OFF of the sub heater 202 with a resolution of 10 ms.

  Returning to FIG. 5 again, after temperature control is started in S501, the process moves to S502, and the recording medium P is fed. In S503, the carriage 106 is scanned in the + X direction to perform recording for one scan. When the recording for one scan is completed, it is determined whether or not the recording data remains in S504. If print data still remains, the process moves to S505 to transport the print medium P to the position to be printed in the + Y direction, and then moves to S503 again. The carriage 106 is now moved in the −X direction so that the scanning directions are alternated. Scan to record. When the recording for one scan is completed, the process returns to S504 to determine whether or not the recording data remains. If no recording data remains, the process proceeds to S506 to end the temperature control, and after the recording medium P is discharged in S507, the recording is ended.

  As described above, in this embodiment, it is important to accurately acquire the print head temperature, that is, to accurately acquire the print head temperature correction value Tadjust, in order to perform temperature control of the print head.

  A method for obtaining the printhead temperature correction value Tadjust described above will be described with reference to the flowchart shown in FIG. In the flow of FIG. 7, since the recording heads 100 and 101 are executed in the same flow, the description of specifying the recording heads 100 and 101 is omitted. When the recording apparatus is turned on, the environmental temperature is updated in S701. The thermistor temperature Ttm is acquired from the head temperature detection unit 404 in FIG. 4, and the value is set as the environmental temperature Tenv and stored in the RAM 302 on the recording apparatus. Next, in S702, it is determined whether or not the recording head is already mounted. In this embodiment, since the recording apparatus is not shipped with the recording head mounted, the determination in S702 is No, and the process ends without acquiring the temperature correction value. Next, when the recording head is mounted, the process proceeds to S704 to enter a recording head temperature correction value update sequence. FIG. 9 shows a print head temperature correction value update sequence.

  First, in S901, 5 points of the AD value ADdi of the diode sensor are acquired in 50 ms, and the average value ADave of 5 points acquired in S902 is calculated. The 5 points mentioned here are processes for avoiding instantaneous electric noise, and there is no problem even if the number is larger than 5 points. In step S903, ADave is converted to a diode temperature Tdi using an ADdi-temperature conversion table. In step S904, in order to correct the individual variations of the diode sensor and the amplifier, the diode sensor offset Di_offset and the amplifier offset Amp_offset are added to derive a diode correction temperature Tdical. In step S905, the print head temperature correction value Tadjust is derived from the difference between the environmental temperature Tenv and the diode correction temperature Tdical. At this time, if the ambient temperature and the print head temperature are not sufficiently adjusted, an abnormal value is entered for the print head temperature correction value Tadjust. For this reason, in the subsequent steps S906 to S909, a process for limiting the print head temperature correction value Tadjust is set up. First, in S906, it is determined whether or not the calculated print head temperature correction value Tadjust is greater than the maximum correction value Tadjust_max. Tadjust, which is the difference between Tdical and Tenv, may have a deviation from the actual temperature of ± 2 ° C, which is the error within the same rank of the diode sensor ± 1 ° C and the error within the same rank of the amplifier ± 1 ° C. Therefore, Tadjust_max is set to + 2 ° C. If Tadjust is greater than + 2 ° C., Tadjust is overwritten and set to Tadjust_max (+ 2 ° C.) in S907 to limit the correction value because the print head temperature is higher than the ambient temperature. If Tadjust is not more than + 2 ° C. in S906, the process proceeds to S908 to determine whether the print head temperature correction value Tadjust is smaller than the minimum correction value Tadjust_min. As described above, since ± 2 ° C. of the in-rank error of the diode sensor and the amplifier exists as an error, Tadjust_max is set to −2 ° C. If Tadjust is less than −2 ° C., Tadjust is overwritten to Tadjust_min (−2 ° C.) in S907 to limit the correction value because the print head temperature is lower than the ambient temperature. When the Tadjust acquired in S905 is within ± 2 ° C., the Tadjust calculated as it is is used.

  As described above, according to the present invention, it is possible to perform correction with an error of ± 2 ° C. even when the print head temperature is not compatible with the environmental temperature. In the past, when the recording head was temperature-controlled to 50 ° C. in a 20 ° C. environment and was removed immediately after recording, etc., when the recording head and the ambient temperature were significantly deviated from each other, a manufacturing variation error in the diode sensor Correction correction was applied at ± 24 ° C. taking into account ± 16 ° C. and amplifier manufacturing variation error of ± 8 ° C. (Tadjust_max = + 24 ° C., Tadjust_min = −24 ° C.). In this case, even if a recording head with a diode sensor manufacturing variation error of 0 ° C. and an amplifier with a manufacturing variation error of 0 ° C. is used, a correction of + 24 ° C. is applied, and the temperature is adjusted to 50 ° C. in the next recording. However, since the temperature is actually adjusted to 74 ° C. and the recording head is 70 ° C. or higher, there is a possibility of causing ejection failure. In this embodiment, only the correction of + 2 ° C. is required even under the same conditions. Therefore, in the next recording, the temperature control at 50 ° C. is actually recorded at the temperature control at 52 ° C., so that remarkable image deterioration is suppressed. Can be recorded.

  As described above, according to the present invention, the temperature sensor of the recording head can be calibrated with high precision even when there is a difference between the recording head and the environmental temperature, but an error of ± 2 ° C. at maximum still occurs. In order to carry out the present invention in a more optimal form, when the temperature control is stopped and a long time has passed and the heated print head becomes equal to the ambient temperature, the print head temperature correction value Tadjust is updated again. It is desirable. As a specific example, if it is determined that the elapsed time from the end of the previous recording is 30 minutes or more as in S703 of FIG. 7, the print head correction value is updated assuming that the print head is familiar with the environmental temperature. A method of moving to a sequence, or when it is determined in S801 that the elapsed time from the end of the previous recording is 30 minutes or more before receiving recording data and starting recording as shown in the recording preparation flow of FIG. There is a method of moving to a print head correction value update sequence, assuming that the print head is familiar with the ambient temperature.

  In this embodiment, the method of ranking and storing the individual variations of the diode sensors and the individual variations of the amplifiers in order to reduce the memory capacity of the recording head and the recording apparatus as much as possible has been described. A method of writing the temperature to be corrected up to the decimal point level in the memory may be used.

  As described above, according to the present invention, it is possible to easily and accurately calibrate the temperature sensor of the recording head even when the power is turned on or immediately after the head is mounted.

100, 101 Recording head 102 Recording head chip 103 Paper feed roller 104 Auxiliary roller 105 Paper feed roller 106 Carriage 107 Platen 108 Carriage belt P Recording medium h Home position 201 Contact pad 202 Diode sensor 203, 204, 205 Discharge port array 206 Sub heater 207 Ink liquid chamber 208, 210 Discharge port 209, 211 Discharge heater 212 FuseROM
300 Central control unit (CPU)
301 ROM
302 RAM
303 Image input unit 304 Image signal processing unit 305 Main bus line 306 Carriage drive control circuit 307 Paper feed control circuit 308 Operation unit 309 Recovery system control circuit 310 Recovery system motor 311 Blade 312 Cap 313 Pump 314 Head temperature control circuit 315 Thermistor 316 Head Drive control circuit 401 Amplifier 402, 405 A / D converter 403, 405 AD value-temperature conversion table 407 Diode temperature correction unit 404 Recording head temperature detection unit

Claims (13)

A recording apparatus that performs recording control based on the temperature of a recording head,
The recording head is
First detection means for detecting an electrical signal related to the temperature of the recording head;
A memory for storing a characteristic value of the first detection means,
The recording device comprises:
Second detection means for detecting an environmental temperature that is a temperature around the recording head;
Means for amplifying a signal related to the print head temperature detected by the first detection means;
A memory for storing characteristic values of the amplification means;
A correction means for performing a correction based on a predetermined offset value for a value obtained by amplifying a signal related to the recording head temperature, and obtaining a head temperature which is a temperature of the recording head;
The offset value includes an electrical signal related to the temperature of the recording head detected by the first detection unit, the environmental temperature detected by the second detection unit, a characteristic value of the first detection unit, and a previous amplification unit. And a characteristic value of the recording apparatus. In the offset value calculating means, a value corresponding to the characteristic value of the first detecting means and a value corresponding to the characteristic value of the amplifying means are added to the electrical signal relating to the recording head temperature acquired by the first detecting means. The recording apparatus according to claim 1, wherein the offset value is set so that the measured temperature becomes equal to the environmental temperature by the second detection unit. The recording apparatus according to claim 1, wherein the characteristic value of the first detection unit is a value based on a value output from the first detection unit at a predetermined environmental temperature. 4. The recording apparatus according to claim 3, wherein the characteristic value of the first detection means written in the memory of the previous recording head is written in the memory during the manufacturing process of the recording head. 5. The recording apparatus according to claim 3, wherein the characteristic values of the first detection means written in the memory of the previous recording head are ranked in a plurality of ranks. The characteristic value of the amplifying unit is a value based on a value obtained by amplifying a signal output from the first detecting unit when the same recording head is mounted on the recording apparatus. The recording apparatus according to claim 2. 7. The recording apparatus according to claim 6, wherein the characteristic value of the amplifying means written in the memory of the previous recording apparatus is written in the memory during the manufacturing process of the recording apparatus. 8. The recording apparatus according to claim 6, wherein the characteristic values of the amplifying means written in the memory of the previous recording apparatus are ranked in a plurality of ranks. The recording according to any one of claims 1 to 8, wherein the first detection unit and the second detection unit have higher absolute temperature detection accuracy than the second detection unit. apparatus. The recording apparatus according to claim 1, wherein the predetermined timing is when the recording apparatus is powered on or when a recording head is mounted. . The recording apparatus according to claim 1, wherein an ink tank that stores ink used for recording is attached to the recording head. The recording apparatus according to claim 1, wherein the recording apparatus performs recording while heating / non-heating the recording head and adjusting a temperature of the recording head. apparatus. The recording apparatus according to claim 1, wherein the recording head is a thermal ink jet system.

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