JP3262384B2 - Recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus for applying thermal energy during recording, and more particularly to a temperature control for the recording apparatus.

[0002]

2. Description of the Related Art Recording devices such as printers, copiers, and facsimile machines are configured to record an image composed of dot patterns on a recording material such as paper or a plastic thin plate based on image information. I have.

[0003] The recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type and the like according to a recording system. An ink (recording liquid) droplet is ejected and ejected from an ejection port of a recording head, and is adhered to a recording material to perform recording.

[0004] In recent years, a large number of recording apparatuses have been used, and high-speed recording, high resolution, high image quality, low noise, and the like have been required for these recording apparatuses. The above-mentioned ink jet recording apparatus can be cited as a recording apparatus that meets such demands. In this ink jet recording apparatus, thermal energy is applied to the ink in the nozzle to generate foam, and the ink is discharged from the recording head by the foaming force to perform recording. The stabilization of the ejection and the stabilization of the ink ejection amount largely depend on the temperature of the recording head.

For this reason, in a conventional ink jet recording apparatus, a high-cost temperature sensor is provided in the recording head.
A head temperature is detected by a so-called closed-loop method of detecting the temperature of the head, and a method of controlling the temperature of the recording head to a desired range based on the detected temperature of the recording head, and controlling an ejection recovery process. A control method was adopted.

As the heater for controlling the temperature, a heating heater member joined to the recording head portion or a heat energy member is used.
An ejection heater is used in an ink jet recording apparatus that forms flying droplets by using the above method, and ejects ink droplets by bubble growth due to ink film boiling. Further, when using the above-mentioned discharge heater, it is necessary to supply electricity to such an extent that foaming does not occur.

In recent years, with the advent of portable OA equipment typified by laptop personal computers, high-quality portable printers and the like have been required. For such a portable type, it is considered that a replaceable type, in which the head and the ink tank are integrated, will become more mainstream in the future due to the structural downsizing design. In addition, from the viewpoint of maintenance due to an increase in the number of word processors, personal computers, and facsimiles of home personal use, it is considered that a replaceable cartridge type will become increasingly mainstream.

In detecting the temperature of the recording head of an ink jet recording apparatus, there are the following problems and disadvantages.

Further, when the temperature control of the closed loop configuration is to be strictly performed using a temperature sensor for temperature control, there are roughly the following three problems.

[0010] The first problem is responsiveness. When applied to the case of the above-described ink jet recording apparatus, the target portion to be detected in order to control the temperature is strictly the temperature of the heater surface in contact with the ink or the temperature of the ink in contact with the heater surface. However, it is difficult for the temperature sensor to directly detect the temperature of the above-mentioned portion, and there is a time delay between the detected temperature and the portion to be detected, that is, a problem of responsiveness.

The second problem is a measurement error of the temperature sensor. A typical temperature sensor is a type such as a thermistor or a thermocouple whose resistance value and electromotive force change according to temperature, but completely removes electrical noise generated when detecting the fluctuation value. It is extremely difficult.

The third problem is cost. Detecting the temperature leads to a corresponding increase in cost, such as a thermistor and a thermocouple, as well as a detection value amplifier and an antistatic component. In particular, in the case of a type in which a temperature sensor for controlling temperature, a heater, and the like are built in a replaceable cartridge, there are the following disadvantages.

(1) Variations in Temperature Control Measured Values Due to Variations in Temperature Sensors Since replaceable heads are consumables, when viewed from the printer body side, a sensor whose characteristics vary every time the head is replaced is connected. It will be.

In a recording head which forms flying liquid droplets by using thermal energy and performs recording, since a discharge heater is formed by a semiconductor process, a diode for detecting the temperature of the recording head is used. It is indispensable to manufacture the sensor in the same process from the viewpoint of cost reduction. Since the diode sensor has manufacturing variations, it does not have the same accuracy as a temperature sensor of a sorted product, and a difference of 15 ° C. or more may occur between manufacturing lots in environmental temperature measurement values.

For this reason, in the closed-loop temperature control using the printhead temperature sensor, the variation of the printhead temperature sensor is adjusted by including an adjustment step, or is measured and ranked. Complicated adjustment work was required in which correction was performed with a changeover switch for adjustment after the device was mounted on the main body.

[0016] The increase in manufacturing cost and the deterioration of usability due to these are very large. In addition, the increase in signal processing and the great increase in MPU processing due to the closed loop control itself impose a heavy load on the design of a small and portable printer main unit.

(2) Countermeasures against static electricity and nozzles Since the replaceable head is a consumable item, the user frequently repeats attachment and detachment from the main body. Therefore, the contacts on the main unit are always exposed. In addition, since the output of the temperature sensor is guided from the interchangeable head to the circuit on the printed circuit board of the main body through the carriage and further through the flexible wiring as it is, the temperature measurement circuit is very sensitive to electrostatic noise. Becomes or,
In the case of small and portable types, there is sufficient sealing for the exterior.
It is weaker because it does not have a field effect.

Therefore, in the conventional temperature detection method, electrostatic shields and electrostatic countermeasures are provided at various places for one temperature sensor.
However, it is disadvantageous in miniaturization, cost reduction, and quality.

[0019]

As means for solving the above-mentioned problems, the present applicant treats the temperature transition of a recording head as a stack of discrete values per unit time in Japanese Patent Application No. Hei 4-16526. Discrete value stacking calculating means, already calculated table means for calculating a temperature change of the recording head temperature according to the discrete value in advance within a range of inputtable energy, and forming a table; In addition to the conventional temperature calculation algorithm having a two-dimensional table forming means constituted by a two-dimensional matrix of input energy and elapsed time, a recording head constituted by combining a plurality of members having different heat conduction times is modeled. Modeling means for substituting a smaller number of thermal time constants than the actual one, and a required operation interval and required data retention for each model unit (thermal time constant) And a plurality of heat source calculation algorithm means for setting a plurality of heat sources, calculating the temperature rise width in the above-mentioned modeling unit for each heat source, and then adding the calculated head temperature together. Proposed that.

According to the above-mentioned means, it is possible to calculate the entire change of the temperature of the recording head by the arithmetic processing even in an inexpensive recording apparatus without providing a temperature sensor in the recording head. Further, it is possible to provide a printing apparatus capable of stabilizing printing such as stabilization of an ejection amount and stabilization of an ejection in accordance with a temperature transition of a printing head with high accuracy and high response obtained by the above calculation. It was possible.

However, the more accurate the method of estimating the temperature, the more serious the problem of estimation error and disturbance of the estimation. This is because the temperature information obtained by accurate temperature estimation strictly changes the parameters of the recording head in a highly controllable manner to obtain a wide controllability. In such a case, the ejection failure and the density unevenness occur in reverse.

One of the disturbances is a power on / off operation. In the past, there were timers, etc. for operating the temperature rise correction inside the machine, etc., and the dot counter continued to count for the correction count for the heater for warming, but it was changed to the discharge pulse by complete heat conduction calculation. Since there was nothing to control, there was not much need to continue the temperature calculation itself strictly. However, in the case of changing up to the ejection pulse, it greatly affects the change in ejection density and the ejection stability. Therefore, it is important to reduce the influence of disturbance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and all changes in the temperature of a recording head are detected by arithmetic processing, and a temperature at which arithmetic processing can be performed even by an inexpensive printing apparatus. It is an object of the present invention to provide a device that has an arithmetic algorithm and is not affected by disturbance such as turning on and off a power supply.

Another object of the present invention is to stabilize recording, such as stabilization of discharge amount and stabilization of discharge, when a power supply is turned on again without providing a temperature sensor in the recording head. It is an object of the present invention to provide a recording device which can perform the recording.

[0025]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a recording apparatus using a recording head which fluctuates in temperature during recording, comprising: an energy inputting means for inputting energy to the recording head; Temperature calculation means for calculating a temperature change of the recording head based on an energy supply supplied to the recording head per unit time, wherein the temperature calculation means is operated even after a power switch is turned off, and the calculation is performed. It is characterized by continuing.

Further, at least a portion of the power supply necessary for the operation of the arithmetic processing circuit in a state where the power switch of the recording apparatus is turned off is determined based on a designated time or a degree at which the temperature rise decreases to a certain level. Features.

Further, the present invention is characterized in that a discharge stabilization control means for performing discharge stabilization control at the time of turning on the power again according to the predicted temperature predicted by the prediction means even after the power is turned off.

[0028]

【Example】

[Embodiment 1] Next, an embodiment in which the present invention is applied to an ink jet recording apparatus will be described.

(Apparatus Configuration) FIG. 1 is a perspective view showing the configuration of a preferred inkjet recording apparatus IJRA to which the present invention is applied or applied. In FIG. 1, reference numeral 5001 denotes an ink tank (IT), and reference numeral 5012 denotes a recording head (IJH) coupled thereto. As shown in FIG.
The 001 ink tank and the 5012 recording head form an integral exchangeable cartridge (IJC). Reference numeral 5014 denotes a carriage (HC) for attaching the cartridge (IJC) to the printer main body, and reference numeral 5003 denotes a guide for scanning the carriage in the sub-scanning direction.

Reference numeral 5000 denotes a platen roller for scanning a printing object indicated by P in the main scanning direction. 5024
Is a temperature sensor for measuring the environmental temperature in the apparatus. The carriage 5014 has a recording head 50
Flexible cable (not shown) for supplying a signal pulse current for driving or a current for controlling the head temperature to 12
Are connected to a printed board (not shown) provided with an electric circuit (such as the temperature sensor 5024) for controlling the printer.

FIG. 2 shows a replaceable cartridge,
Numeral 029 denotes a nozzle for discharging ink droplets. Further, the inkjet recording apparatus IJRA having the above configuration will be described in detail. This recording apparatus IJRA is driven by a driving motor 50.
13 and the driving force transmission gears 5011 and 511
The carriage HC that engages with the spiral groove 5004 of the lead screw 5005 rotating via 009 has a pin (not shown) and is reciprocated in the directions of arrows a and b.
Reference numeral 5002 denotes a paper pressing plate, which presses the paper against the platen 5000 in the carriage movement direction. 500
7, 5008 are photocouplers for leverage of the carriage HC.
Reference numeral 5006 denotes a home position detecting means for confirming the presence in this area and switching the rotation direction of the motor 5013. Reference numeral 5016 denotes a member that supports a cap member 5022 that caps the front surface of the recording head. Reference numeral 5015 denotes a suction unit that suctions the inside of the cap, and performs suction recovery of the recording head 5012 through an opening 5023 in the cap.

Reference numeral 5017 denotes a cleaning blade.
Numeral 019 denotes a member which allows the blade 5017 to move in the front-rear direction, and these are supported by a main body support plate 5018. It is needless to say that a well-known cleaning blade can be applied to this embodiment. Reference numeral 5021 denotes a lever for starting suction for recovery of suction. The lever 5021 moves with the movement of the cam 5020 engaging with the carriage HC, and the driving force from the driving motor is transmitted by a known transmission such as clutch switching. The movement is controlled by means.

The capping, cleaning, and suction recovery are performed so that when the carriage HC comes to the home position side area, desired operations can be performed at the corresponding positions by the action of the lead screw 5005. However, if a desired operation is performed at a known timing, any of the embodiments can be applied.

FIG. 3 shows the details of the recording head 5012. A heater 5100 formed by a semiconductor manufacturing process is provided on the upper surface of a support 5300. The heater 5100 is provided with a temperature control heater (heater for heating) 5110 formed by the same semiconductor manufacturing process to keep the temperature of the recording head 5012 and to control the temperature. Reference numeral 5200 denotes a wiring board provided on the support 5300, and the wiring board 5200, a heater 5110 for temperature control, and a (main) heater 511 for ejection.
3 are wired by wire bonding or the like (the wiring is not shown). Further, the temperature control heater 5110 may be a heater in which a heater member formed by a process different from that of the heater board 5100 is attached to the support 5300 or the like.

Reference numeral 5114 denotes a bubble generated by being heated by the discharge heater 5113. Reference numeral 5115 denotes a discharged ink droplet. Reference numeral 5112 denotes a common liquid chamber into which the ejection ink flows into the recording head.

Next, an embodiment in which the present invention is applied to the above-described recording apparatus will be specifically described with reference to the drawings.

(Control Configuration) Next, a control configuration for executing recording control of each unit of the above-described apparatus configuration will be described with reference to FIG.
This will be described with reference to the block diagram shown in FIG. In FIG. 1 showing a control circuit, 10 is an interface for inputting a recording signal, 11 is an MPU, 12 is a program ROM for storing a control program executed by the MPU 11, and 13 is various data (supplied to the recording signal and the head). This is a dynamic RAM that stores recorded data to be recorded. 1
Reference numeral 4 denotes a gate array for controlling supply of print data to the print head 18;
11. It also controls the transfer of data between the RAMs 13. Reference numeral 20 denotes a carrier motor for transporting the recording head 18;
Denotes a transport motor for transporting the recording paper. Reference numeral 15 denotes a head driver for driving the head, and reference numerals 16 and 17 denote motor drivers for driving the transport motor 19 and the carrier motor 20, respectively.

(Overall Control) In this embodiment, when printing is performed by ejecting ink droplets from the print head, an environmental temperature sensor for measuring the environmental temperature is provided on the main body side, and the temperature of the print head relative to this environmental temperature is measured. By knowing the behavior from the past to the present and the future through calculation processing, it is possible to perform optimal temperature control and ejection control without providing a head temperature sensor or the like having a correlation with the head temperature. Further, it is intended to prevent a calculation error by continuing the temperature estimation calculation even when the power is turned off.

Specifically, based on the head temperature calculated by the temperature calculation algorithm in the present invention, a heater (sub-heater) for raising the temperature of the head and a divided pulse width modulation driving method (PWM driving method) for the discharge heater Is intended to control the head. As one of the driving methods of this control, when the deviation from the temperature control target value is large, the temperature is raised to near the target value by using the sub-heater, and the remaining temperature deviation is made constant by the PWM discharge amount control. There is something that tries to control it. Therefore, when using the PWM which is a high-response head ejection amount control means, a response delay of temperature detection due to a sensor position, a detection error due to noise, and the like as in the case of using a head temperature sensor are calculated. Therefore, it is possible to perform control that makes the most of this merit. As a result, it is possible to perform in-line PWM without having a head temperature sensor as described above, and it is possible to eliminate density unevenness in one line and density unevenness in a page.

Further, if a calculation error occurs, large density unevenness and ejection failure will occur. Therefore, the temperature estimation calculation may be continued even when the power is turned off as in the present invention. Is very important. Specifically, FIG.
In the block diagram shown in FIG. 11, 11 MPUs and 12 ROMs, 13 DRAMs, 14
In this case, all the power supplied to portions other than the gate array is turned off. In other words, it is close to cutting off all voltage systems other than the logic system in some voltage systems.

FIG. 8 shows a flowchart of this embodiment.
8, it is assumed that the AC plug is inserted in step S100. In step S101, power is supplied only to the logic circuit. In step S102, various timers and memories are reset. In step S103, the temperature estimation calculation starts. In step S104, the temperature is calculated by the temperature estimation calculation subroutine, and the process returns. The flowchart in the temperature estimation subroutine will be described later.

In step S105, it is checked whether the power switch has been turned on. If not, the temperature estimation calculation is continued. Since the power switch is turned on in step S106, power is turned on to all circuits. In step S107, the history of the temperature estimated and calculated in step S104 is read. In step S108, the parameters of the power-on sequence are determined based on the temperature history, and executed in step S109. Here, the parameters of the power-on sequence are parameters such as a recovery process performed when the power is turned on, and the recovery process is performed according to the parameters.

In step S110, the power supply SW is checked again. In step S111, the temperature estimation calculation is continued.
In step S112, a print signal is waited for. When a print signal arrives, printing is started in step S113, and steps S110 to S113 are repeated in a loop. If the power switch is turned off in step S110, the process goes to step S114 to perform a power-off sequence such as a capping process. In step S115, power other than the power required for the temperature estimation calculation is turned off. Then, the process returns to step S104, and the same control is repeated thereafter.

(Temperature calculation control) Generally, the calculation is performed by evaluating the temperature change of the head using a matrix calculated in advance within the range of the thermal time constant of the head and the energy that can be input. Specific means for calculating and estimating the temperature behavior of the recording head conforms to the following heat transfer equation.

During heating Δtemp = a ｛1−exp [−m * T]｝ (1) ・ Cooling during heating △ temp = a ｛exp [−m (T−T1)] − exp [ −m * T]｝ (2) where temp; temperature of the object to be heated a; equilibrium temperature of the object by the heat source T; elapsed time m; thermal time constant of the object T1; time at which the heat source was removed

If the recording head is treated as a concentrated constant system, it is theoretically possible to calculate and estimate the temperature behavior by a combination of the above equations (1) and (2). However, the heat source is ON
Each time the power is turned on / off, the above formulas (1) and (2) must be developed according to the printing duty in the case of the recording device, and in a system where the heat source is frequently turned on / off, the processing capacity It is difficult to realize it. Therefore, in the present invention, in order to simplify the arithmetic processing, the above equation is expanded and applied as follows.

<Temperature fluctuation after elapse of nt time after turning on heat source> a {1-exp [-m * n * t]} ------ <1> = a {exp [-m * t] -exp [-m * t] + exp [-2 * m * t] -exp [-2 * m * t] + …… + exp [-(n-1) * m * t] -exp [-(n- 1) * m * t] + 1-exp [-n * m * t]} = a {1-exp [-m * t]} + a {exp [-m * t] -exp [-2 * m * t]} + a {exp [-2 * m * t] -exp [-3 * m * t]} ……… + a {exp [-(n-1) * m * t] -exp [- n * m * t]} = a {1-exp [-mt]} ------ <2-1> + a {exp [-m * (2t-t)]-exp [-m * 2t ]} ------ <2-2> + a {exp [-m * (3t-t)]-exp [-m * 3t]} ------ <2-3> ……… + a {exp [-m * (nt-t)]-exp [-m * nt]} ------ <2-n>

By expanding as described above, the expression <1> matches <2-1> + <2-2> + <2-3> + ---- + <2-n>. Here, <2-n>formula; heating from time 0 to nt, and heating from time t to nt
This is equal to the temperature of the target object at time nt when heating is turned off until.

<2-3> Expression: Heating from time (n-3) t to (n-2) t and heating off from time (n-2) t to nt
It is equal to the temperature of the object at time nt.

<2-2> Equation: Heating from time (n-2) t to (n-1) t and heating off from time (n-1) t to nt
It is equal to the temperature of the object at time nt.

<2-1>Equation; Equal to the temperature of the object at time nt when heating from time (n-1) t to nt.

The fact that the sum of the above equations is equal to the equation <1> means that the behavior of the temperature of the recording head (heating temperature) is determined by increasing the temperature of the recording head by the energy applied per unit time. The number of times the temperature should be lowered after each time is calculated (corresponding to each <2-1>, <2-2>, ---, <2-n> formula). Calculate the sum of how many times the temperature that has risen per unit time has dropped at this time (<2-1> + <2-1> + ----- <2-n> ) Makes it possible to estimate the operation.

The calculation time of the temperature change of the temperature rise and fall of the head is set by tabulating a matrix calculated in advance within the range of the thermal time constant of the head and the energy that can be input as shown in FIG. It has been significantly reduced. In the present embodiment, the print duty is set in increments of 2.5%, and the unit time (temperature estimation interval) is set to 0.1 second.

In the head used in this embodiment, the temperature that has risen per unit time falls to approximately 0 ° C. when the elapsed time is 60.0 seconds. I do not have. On the other hand, in the case of a head having a thermal time constant with slow heat conduction, it is preferable to have a table until the temperature rises to 0 ° C. and the effect is eliminated.

In this embodiment, as described above, the temperature estimation calculation is continued even when the power is turned off.

(PWM Control) Next, the discharge amount control method of this embodiment will be described in detail with reference to the drawings. FIG. 3 is a diagram for explaining a divided pulse according to one embodiment of the present invention. In the figure, VOP is a drive voltage, P1 is a pulse width of a first pulse (hereinafter, referred to as a preheat pulse) of a plurality of divided heat pulses, P2 is an interval time, and P3 is a second pulse (hereinafter, a main heat pulse). ). T1, T2, T3 are P1,
The time for determining P2 and P3 is shown. The driving voltage VOP is one of the values indicating electric energy required for the electrothermal transducer to which the voltage is applied to generate thermal energy in the ink in the ink liquid path formed by the heater board and the top plate. is there. The value is determined by the area and resistance of the electrothermal transducer, the film structure, and the liquid path structure of the recording head. In the divided pulse width modulation driving method, a pulse is sequentially applied with a width of P1, P2, P3. The preheat pulse is a pulse for mainly controlling the foaming volume of the ink in the liquid path. It plays an important role in discharge rate control. The preheat pulse width is set to a value that does not cause a bubbling phenomenon in the ink due to the thermal energy generated by the electrothermal converter when applied.

The interval time is also a period for controlling the foaming volume of the ink in the liquid path, similarly to the preheat pulse, and plays an important role in the discharge amount control of this embodiment. The main heat pulse is for generating bubbling in the ink in the liquid path and discharging the ink from the discharge port, and its width P3 is determined by the area of the electrothermal transducer, the resistance value,
It is determined by the film structure and the structure of the ink liquid path of the recording head.

For example, the operation of the preheat pulse in the recording head having the structure shown in FIGS. 4A and 4B will be described. FIGS. 7A and 7B are a schematic vertical sectional view and a schematic front view, respectively, showing an example of the configuration of a recording head to which the present invention can be applied, along an ink liquid path.
In the figure, an electrothermal transducer (ejection heater) generates heat by application of the divided pulse. The electrothermal transducer is disposed on a heater board together with electrode wiring for applying a divided pulse thereto. The heater board is formed of silicon, and is supported by an aluminum plate forming a substrate of the recording head. A groove for forming an ink liquid path and the like is formed on the top plate, and the ink liquid path and a common liquid chamber for supplying ink to the ink liquid path by joining the top plate and a heater board (aluminum plate). Is configured. Further, ejection openings are formed in the top plate, and ink passages communicate with the respective ejection openings.

In the recording head shown in FIG. 4, the driving voltage VOP = 18.0 (V) and the main heat pulse width P
When 3 = 4.114 [μsec] and the preheat pulse width P1 is changed in the range of 0 to 3.000 [μsec], the discharge amount Vd [ng / dot] and the preheat pulse width P1 as shown in FIG. [Μsec] is obtained.

FIG. 5 is a diagram showing the dependency of the discharge amount on the preheat pulse. In the figure, V0 is P1 = 0 [μsec
c], and this value is determined by the head structure shown in FIG. Incidentally, in this embodiment, V0 is 18.0 [ng / dot] when the ambient temperature TR is 25 ° C.
Met. As shown by the curve a in FIG. 5, as the pulse width P1 of the preheat pulse increases, the discharge amount Vd increases linearly from the pulse width P1 of 0 to P1LMT,
In the range where the pulse width P1 is larger than P1LMT, the change loses linearity, and the change is saturated at the pulse width P1MAX and becomes maximum.

As described above, the range up to the pulse width P1LMT in which the change in the discharge amount Vd with respect to the change in the pulse width P1 shows linearity is effective as a range in which the discharge amount can be easily controlled by changing the pulse width P1. It is. Incidentally, in the present embodiment shown by the curve a, P1LMT = 1.87 (μsec), and the discharge amount at this time is VLMT = 24.0 [ng / d].
ot]. The pulse width P1MAX when the discharge amount Vd is saturated is P1MAX = 2.1 [μsec], and the discharge amount VMax at this time is 25.5 [ng / do].
t].

When the pulse width is larger than P1MAX, the discharge amount Vd becomes smaller than VMAX. This phenomenon is that when a preheat pulse having a pulse width in the above range is applied, fine bubbling (a state immediately before film boiling) occurs on the electrothermal transducer, and the next main heat pulse is generated before the bubble disappears. The ejection rate is reduced by the applied micro bubbles, which disturb the bubbling by the main heat pulse. This region is called a pre-foaming region, and in this region, it becomes difficult to control the discharge amount via a preheat pulse.

P1 = 0 to P1LMT [μsec] shown in FIG.
Is defined as the preheat pulse dependence coefficient, the preheat pulse dependence coefficient: KP is KP = ΔVdP / ΔP1 [ng / μsec · do
t]. The coefficient Kp is determined by the head structure, driving conditions, physical properties of the ink, and the like irrespective of the temperature. That is, curves b and c in FIG. 5 show the case of another print head, and it can be seen that the ejection characteristics change when the print head is different. As described above, since the upper limit value P1LMT of the preheat pulse P1 differs for different printheads, the discharge amount control is performed by setting the upper limit value P1LMT for each printhead as described later.
Incidentally, in the recording head and ink indicated by the curve a in the present embodiment, Kp = 3.209 [ng / μsec ·
dot].

Another factor that determines the ejection amount of the ink jet recording head is the recording head temperature (ink temperature).
There is. FIG. 6 is a diagram showing the temperature dependence of the discharge amount.
As shown by a curve a in FIG.
The discharge amount Vd increases linearly with an increase in (= head temperature TH). If the slope of this straight line is defined as a temperature-dependent coefficient, the temperature-dependent coefficient: KT becomes KT = .DELTA.VdT / .DELTA.TH [ng / .degree. This coefficient KT is determined by the structure of the head, the physical properties of the ink, etc., without depending on the driving conditions. In FIG. 6, curves b and c show the case of another recording head. By the way, in the recording head of this embodiment, KT = 0.3 [ng / ° C.do]
t].

As described above, the discharge amount control according to the present embodiment can be performed by using the relationships shown in FIGS. Regarding the method of controlling the ejection amount, any of the on-time and off-time of a plurality of pulses or a combination thereof may be controlled.

(Temperature Calculation, Driving Time Setting, Print Control) Next, each flow of the control system will be described with reference to FIGS.

FIG. 10 is an interrupt routine for setting the temperature calculation, the PWM drive value for discharge, and the sub-heater drive time. Steps S107 and S111 in FIG.
Corresponding to This interrupt routine is generated every 50 msec. Therefore, the PWM value and the sub-heater driving time are always updated every 50 msec, regardless of whether printing is being performed, pausing, or an environment in which driving of the sub-heater is necessary or unnecessary.

Although the recording head described above is strictly composed of a combination of many members having different heat conduction times, in the present embodiment, in the model relating to heat conduction, the recording head is composed of two heat conduction members. Time constant (hereinafter, short range,
Long range).

First, when an interruption of 50 msec occurs, the print duty for 50 msec immediately before is referred to (S2010). However, the printing du referred to at this time is
The ty is a value obtained by multiplying the number of actually ejected dots by a weight coefficient for each PWM value, as described in the section of (PWM control). Duty for the 50 msec and the past 0.8
Based on the print history of the second, the heating source is the discharge heater, and the temperature constant of the member group whose time constant is in the short range is calculated (△ Tmh) (S2020). Next, similarly, the driving duty of the sub-heater for 50 msec is referred to (S2030), and
Based on the driving duty of the sub-heater for msec and the driving history of the sub-heater for the past 0.8 seconds, the heating source is the sub-heater, and the temperature constant of the member group whose time constant is in the short range (△ Tsh)
Is calculated (S2040). Then, the temperature rise (ΔTmb) of the member group having a long time constant and the heat source is a discharge heater, and the temperature rise temperature (△ Tmb) of the member group having a long range and the time constant of the member group having a long time constant are calculated in a main routine described later. By referring to the temperature rise temperature (△ Tsb) and adding them, (= △ Tmh + △ Tsh + △ Tmb + △ Ts)
b) The head temperature is calculated (S2050).

Next, the target temperature is set from the target temperature table (S2060), and the temperature difference (ΔT) between the head temperature and the target temperature is obtained (S2070). The temperature difference ΔT and PW
From the M table, a PWM value which is an optimum head driving condition corresponding to ΔT is set (S2080). Further, based on the selected sub-heater table (S2090), the sub-heater driving time which is the optimum head driving condition according to the temperature difference ΔT is set (S2100). Thus, the interrupt routine ends.

FIG. 11 is a main routine of the print control, and corresponds to step S113 in FIG. Step S3
When a print command is input at 010, the print duty for the past one second is referred to (S3020). However, the print duty referred at this time is a value obtained by multiplying the number of dots actually ejected by the weight coefficient for each PWM value as described in the section of (PWM control). From the duty for one second and the printing history for the past 512 seconds, the heating source is the discharge heater, and the temperature constant of the member group having a long range of time constant (時 Tmb) is calculated.
It is stored and updated in a memory location determined so that it can be easily referred to when an interrupt occurs after sec (S3030). Next, similarly, the driving duty of the sub-heater for one second is referred to (S3040), and the driving duty of the sub-heater for one second is referred to.
Based on y and the driving history of the sub-heater for the past 512 seconds, the temperature rise temperature (ΔTsb) of the member group whose heat source is the sub-heater and whose time constant is a long range is calculated. As in the case where ΔTmb is stored and updated, the storage is updated in a memory location determined so that it can be easily referred to at the time of interruption after 50 msec (S3050).

Then, the sub-heater is first driven in accordance with the PWM value and the sub-heater driving time which are updated each time an interrupt occurs every 50 msec (S306).
0), and then print one line (S3070).

As described above, in the ink jet recording apparatus for applying thermal energy to the head, (1) a discrete value stacking operation means for treating the temperature fluctuation of the head as a stack of discrete values per unit time; An already-calculated table means in which the temperature variation of the temperature of the head according to the discrete value is calculated in advance within the range of the inputtable energy and is tabulated; and (3) the table indicates the input energy per unit time and (2) a two-dimensional table forming means constituted by a two-dimensional matrix of elapsed time; and (4) a divided pulse width of a heater (sub-heater) for raising the temperature of the head in accordance with the head temperature calculated by the calculation algorithm and a discharge heater. A head control means such as a modulation drive method (PWM drive method); and (5) a print head temperature estimation calculation even when the power is turned off. By having the system to continue to continue, 1, it is possible to eliminate the response of the problem.

2. It is possible to eliminate a measurement error of the temperature sensor such as electric noise which is extremely difficult to completely remove.

3. The problem of direct and indirect cost increase caused by providing the temperature sensor can be solved.

4. Since it is free from disturbances that cause a calculation error such as turning on and off the power supply, the head temperature can be controlled accurately, so that the ejection can be stabilized and the ejection amount can be controlled. In addition, since there is no error, not only the sub-heater but also the discharge pulse can be directly modulated without causing a discharge failure, such as PWM control, so that discharge control within a line becomes possible, and density unevenness within one line and density unevenness within a page. Can be eliminated.

Further, in this embodiment, a temperature sensor is not required, and if the input energy to be applied to the head in the future is known, the change in the temperature of the head over the future can be predicted. In addition, various controls can be performed before actual energy application, so that more appropriate control can be performed. In the present algorithm, the temperature calculation can be mainly performed only by referring to the already-calculated table and adding the data, so that the calculation control is simplified.

In the present embodiment, although the time axis of the table created by calculating the temperature fluctuation in advance is an arithmetic progression, it is not always necessary to use an equality. That is, in order to save memory for the table, the time axis of the already-calculated table is set roughly in the area where the temperature change is small, and the temperature rise / fall data for each unit time is calculated and estimated from the preceding and following data. There may be.

[Second Embodiment] In the first embodiment, the calculation could be continued with the power switch turned off, but the calculation could not be continued with the power plug removed. Example 2
In, the calculation can be continued by the built-in battery even if the power plug is unplugged. This prevents a calculation error from occurring when the power is turned on again, even if an unexpected power failure occurs or the power plug is accidentally unplugged. The battery only needs to have a duration that is calculated until the recording head temperature approaches the ambient temperature.
A short battery having a duration of about 30 minutes even if it has a short heat capacity of 60 seconds and a large heat capacity and is hard to cool is usually charged automatically and works as a backup when the AC power is turned off. If the power is turned on again after that time, it can be assumed that the print head temperature has already become the same as the ambient temperature, so it is possible to reprint without any problem even if calculation can not be continued. Become. By doing so, the battery can be built-in without unnecessarily increasing the size of the battery, and can be adopted even in a small desktop printer.

[Embodiment 3] In Embodiment 2, a small desktop printer was assumed. However, a portable notebook type printer or the like originally requires a large rechargeable battery to be used outdoors. Considered built-in. Therefore, the same operation can be performed without the need for a built-in battery for maintaining the calculation as in the second embodiment. However, if the calculation is continued forever, the battery will be completely discharged in a few days,
As shown in FIG. 13, the power of the arithmetic unit for temperature calculation is turned off in a certain time. As a rough guide, the maximum time that is assumed according to the heat capacity of the recording head mounted on the recording apparatus may be input as described above.

As another method, the number of minutes in the future from the past temperature history at the time of turning off the power, how long the temperature of the recording head becomes substantially equal to the environmental temperature, is calculated at that time. A timer may be set at the time, and the calculation may be continued until the timer counts up. Since the method of estimating the temperature in the calculation process is used in this way, the temperature is calculated at the moment when the power is turned off in response to the cooling curve that changes according to the degree of heat accumulation in the past. The timing of turning off the power can be calculated instantaneously.

Embodiment 4 Another method is shown in FIG.
As shown in FIG. 4, by turning on the temperature determination subroutine in the temperature calculation algorithm from the moment the power is turned off, the power for the arithmetic processing is turned off when the deviation from the environmental temperature becomes smaller than a certain value. The same effect can be obtained by doing so.

[Embodiment 5] In this embodiment, the average head temperature in the past during the period after the power is turned off is estimated, and the recovery means when the power is turned on again is operated in accordance with the average head temperature. 8 shows a specific example of steps S108 and S109 in FIG. The recovery means controlled according to the average head temperature in this embodiment is preliminary discharge and wiping performed before printing in order to stabilize the discharge when the power is turned on again. As is well known in the ink jet technology, the preliminary ejection is performed for the purpose of preventing non-ejection, density change, and the like caused by evaporation of ink from a nozzle opening. Focusing on the fact that the evaporation of ink differs depending on the head temperature, in the present embodiment, the optimal preliminary ejection conditions are set according to the average head temperature to perform efficient preliminary ejection in terms of time or ink consumption. It is.

The open-loop temperature control, which is a main component of the present embodiment, that is, the method of calculating and estimating the temperature at that time from the temperature detected by the reference temperature sensor provided in the main body and the past printing duty, is used in this embodiment. The average temperature of the head required in the past for a predetermined period can be easily obtained. This embodiment focuses on the fact that the evaporation of ink is related to the head temperature at each point in time, and the total amount of ink evaporation during a predetermined period has a strong correlation with the average head temperature during that period. On the other hand, in the method of directly detecting the head temperature, it is relatively easy to control in real time according to the head temperature at each point in time, but in order to obtain the past average head temperature required for the control of this embodiment. Requires a special storage / arithmetic circuit.

The wiping, which is another ejection stabilizing means controlled in this embodiment, is intended to remove unnecessary liquids such as ink and water vapor adhered on the orifice forming surface and solid foreign matters such as paper powder and dust. Is what you do. In this embodiment, the amount of wetting by ink or the like differs depending on the temperature of the head, and furthermore, the evaporation of the wetting that makes it difficult to remove ink and foreign matter is caused by the head temperature (temperature of the orifice forming surface)
The wiping is performed efficiently by setting an optimum wiping interval at the time of turning on the power again according to the past average temperature of the head. The above-mentioned wetting amount and evaporation of the wetting related to the wiping have a stronger correlation with the average temperature of the past head than the head temperature at the time of performing the wiping. Therefore, the head temperature estimating means of the present embodiment is preferable. .

[Sixth Embodiment] In the present embodiment, as in the fourth embodiment, as an example of the recovery control based on the estimation of the average head temperature, suction based on the estimated value of the past average head temperature over a relatively long period of time is performed. FIG. 8 shows an example of recovery, which is performed in step S
108 and S109 show other specific examples. In some cases, the recording head of the ink jet recording apparatus is configured to have a negative head pressure at the nozzle port for the purpose of stabilizing the meniscus shape at the nozzle port. Inadvertent air bubbles in the ink flow path cause various problems in the ink jet recording apparatus, but particularly easily in a system maintained at a negative head pressure.

In other words, even if the recording operation is not performed, simply leaving the apparatus alone will cause bubbles disturbing the normal ejection due to the dissociation of the dissolved gas in the ink and the gas exchange through the flow path components. It grows on the road and becomes a problem. The suction recovery means is provided for the purpose of removing bubbles in the flow path and ink thickened by evaporation at the tip of the nozzle opening. As described above, the evaporation of the ink changes depending on the temperature of the head. However, the growth of bubbles in the flow path is more susceptible to the head temperature, and the higher the temperature, the more likely it is to generate. In this embodiment, as shown in FIG. 12, the suction recovery interval is set in accordance with the average head temperature in the past 12 hours, and the higher the average head temperature, the more frequently the suction recovery is performed.

As described in the first embodiment, the head temperature is not limited to the estimated temperature at the present time, and a future head temperature can be easily predicted. Therefore, the optimal suction recovery control may be set in consideration of the future ejection state.

As described above, by continuing to calculate the temperature even when the power is turned off, the history of the head temperature can be understood, and optimal recovery control can be performed when the power is turned on again.

The present invention brings about an excellent effect particularly in a recording head and a recording apparatus which use thermal energy among ink jet recording methods.

The typical structure and principle are described, for example, in US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding nucleate boiling, to the electrothermal transducer disposed corresponding to the sheet or the liquid path in which is held, This is effective because thermal energy is generated in the electrothermal transducer, and the film is boiled on the heat-acting surface of the recording head. As a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. Examples of the drive signal in the form of a pulse include those described in U.S. Pat.
Suitable are those described in US Pat. No. 45,262. If the conditions described in U.S. Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

The configuration of the recording head may be a combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above specification. U.S. Pat. No. 4,558,333 and U.S. Pat.
A configuration using the specification of Japanese Patent No. 459600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication (Kokai) No. 123670/1984 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461 which discloses a configuration corresponding to a discharge unit.

[0093]

As described above, according to the present invention, the temperature of an object with respect to the input energy can be changed by providing an accurate temperature estimation calculation even after the power is turned off. Since the calculation and estimation can be continued without any error, it becomes possible to obtain the temperature of the object accurately and timely without generating a calculation error.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a preferred inkjet recording apparatus to which the present invention is applied or applied.

FIG. 2 is a perspective view showing a replaceable cartridge.

FIG. 3 is an explanatory diagram of a divided pulse width modulation driving method.

FIGS. 4A and 4B are a schematic longitudinal sectional view and a schematic front view, respectively, showing an example of the configuration of a recording head to which the present invention can be applied;

FIG. 5 is a diagram showing the dependence of a discharge amount on a preheat pulse.

FIG. 6 is a diagram showing temperature dependence of a discharge amount.

FIG. 7 is a schematic block diagram of a control circuit.

FIG. 8 is a control flowchart of one embodiment of the present invention.

FIG. 9 is a temperature calculation table according to one embodiment.

FIG. 10 is a flowchart illustrating an interrupt routine for setting a temperature calculation, a PWM drive value, and a sub-heater drive time.

FIG. 11 is a flowchart illustrating a print control routine.

FIG. 12 is a table showing intervals of preliminary ejection, the number of preliminary ejections, and intervals of wiping according to an average head temperature according to another embodiment of the present invention.

FIG. 13 is a flowchart of another embodiment of the present invention.

FIG. 14 is a flowchart of another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 Interface 15 Head driver 16, 17 Motor driver 18 Recording head 19 Transport motor 20 Carrier motor

──────────────────────────────────────────────────続 き Continuing on the front page (72) The inventor Kiichiro Takahashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) The inventor Osamu Iwasaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Hitoshi Nishikori Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo (72) Kentaro Yano Canon Inc. 58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/05

Claims (11)

(57) [Claims] 1. A recording apparatus using a recording head which varies in temperature when performing recording, comprising: an energy input unit for inputting energy to the recording head; and an energy supply input to the recording head per unit time. Temperature calculation means for calculating the temperature fluctuation of the recording head, comprising: operating the temperature calculation means even after a power switch is turned off;
A recording apparatus wherein the calculation is continued. 2. The arithmetic processing circuit is included in an arithmetic processing circuit, and the arithmetic processing circuit has a circuit configuration in which at least a part necessary for the arithmetic operation is not turned off when a power switch is off. 2. The recording device according to 1. 3. The arithmetic processing means is included in an arithmetic processing circuit, wherein the arithmetic processing circuit has a circuit configuration in which at least a part of the power required for the arithmetic operation is not turned off for a predetermined time in a power-off state. The recording device according to claim 1. 4. The recording apparatus according to claim 3, wherein the predetermined time is determined according to a time when a temperature rise of the recording head decreases to a certain level. 5. An environmental temperature measuring means for measuring an environmental temperature, based on the environmental temperature measured by the environmental temperature measuring means and the temperature fluctuation calculated by the temperature calculating means, when power is turned on again. 2. A printing apparatus according to claim 1, further comprising an ejection control means for controlling said printing head. 6. The discharge control means controls at least one of a discharge pulse given to a discharge heater by the print head control means, a pulse not leading to discharge, or a pulse given to a heater for keeping heat in the print head. 6. The recording device according to claim 5, wherein the recording device is a recording device. 7. A printhead that performs printing by discharging ink from a discharge port using thermal energy, a temperature measuring unit that measures an environmental temperature, a thermal time constant of the printhead, and a printhead during a reference period. Temperature calculating means for calculating the temperature fluctuation of the recording head based on the energy supply of the recording head; and, based on the temperature fluctuation calculated by the temperature calculating means and the environmental temperature measured by the temperature measuring means, It is characterized by comprising prediction means for predicting temperature, and discharge stabilization control means for performing discharge stabilization control when the power switch is turned on again according to the predicted temperature predicted by the prediction means even after the power switch is turned off. Recording device. 8. The printing apparatus according to claim 7, wherein the ejection stabilization control unit performs a recovery process of the print head under a condition according to the predicted temperature. 9. The printing apparatus according to claim 7, wherein said ejection stabilization control means performs preliminary ejection of said print head under conditions corresponding to said predicted temperature. 10. The printing apparatus according to claim 7, wherein said ejection stabilization control means performs suction recovery of said print head under conditions corresponding to said predicted temperature. 11. The recording head according to claim 1, wherein the recording head causes a state change in the ink by thermal energy, and discharges the ink based on the state change.
The recording device according to any one of the above.