JP3311097B2 - Ink jet 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 an ink jet recording apparatus, and more particularly to an ink jet recording apparatus capable of detecting non-discharge.

[0002]

2. Description of the Related Art In a recording head of an ink jet recording apparatus, for example, when the recording head is left for a long period of time without discharging.
In particular, the ink may thicken in the ink liquid passage near the ejection port, and normal ejection may not be performed. Also, when ejection is performed continuously, for example, when printing is performed with a relatively high print duty, fine bubbles generated in the ink in the liquid path with the discharge grow, and the grown bubbles are And may affect the ejection, and similarly, the normal ejection may not be performed. In addition to the air bubbles generated as described above, some of the air bubbles may be mixed into the ink in the ink supply system, such as a connection portion of the ink supply path.

[0003] The above-described non-ejection not only lowers the reliability of the printing apparatus, but also attempts to perform high-duty printing with the printing head in a state in which normal printing cannot be performed. , The print head itself may be damaged, and the durability may be impaired.

In order to prevent the discharge failure due to these various causes, in an ink jet recording apparatus, for example, a capping process of covering the discharge port surface of a recording head to prevent the ink from thickening when the discharge is not performed. Ink suction that discharges the thickened ink by suctioning the ink from the discharge port in the state, discharges the ink to a predetermined ink receiver composed of an ink absorber, etc., and discharges the thickened ink in the same way as during normal recording An ejection recovery process such as idle ejection is performed.

The above-described ejection recovery process is performed automatically, for example, at a predetermined time interval during power-on of the apparatus or during a printing operation, or when a user presses a recovery button or the like as necessary. Was.

However, in an ink jet recording apparatus which performs an ejection recovery process when the apparatus is turned on, if a user who repeatedly turns the power on and off is used, the number of times the ejection recovery processing is performed is unnecessarily increased. Consumption,
There is a problem that the amount of waste ink sucked from the discharge port increases. On the other hand, in the case where the user operates the recovery button in accordance with the determination to perform the recovery processing, the user must determine whether the recording head is in a normal state or in a non-ejection state without actually performing printing. There is a problem that the user does not know and lacks reliability.

To solve this problem, there has been proposed a technique for judging whether or not the recording head is non-discharged in accordance with a rise in the temperature of the print head due to the idle discharge and a decrease in the temperature of the print head after the idle discharge. . Comparing the case where the recording head is in a normal ejection state and the case where the recording head is in a non-ejection state, when the ejection state is normal, a part of the heat generated by the idle ejection is transmitted to the ink, and a part of the heat is It is used to boil ink, and a part of the ink goes out of the recording head together with the ink droplet. That is, when the recording head is in the non-ejection state, the temperature difference between the temperature rise and the temperature decrease becomes larger than when the ejection is performed well. Therefore, for example, when the temperature change between the temperature rise and the temperature fall (for example, the sum thereof) exceeds a predetermined value, it can be determined that a non-ejection has occurred in the print head.

[0008]

However, the temperature rise of the print head due to idle discharge, which is used in the prior art to detect non-discharge, is caused by individual differences in the print head such as variations in the heat generation characteristics and heat storage characteristics of the print head. Variation due to individual differences in the recording apparatus main body such as variation in the power supply voltage and the like.
It is an object of the present invention to enable high-precision detection of non-ejection of a print head even when such variations are large.

[0009]

According to the present invention, there is provided a method for changing the driving conditions for detecting non-discharge of the recording head and measuring the thermal characteristics of the recording head according to the thermal characteristic information of the recording head and the recording apparatus. , or by changing the determination condition of said ejection failure determination according to a recording thermal JP <br/> iNFORMATION head and the recording apparatus is intended to achieve the above object.

[0010]

【Example】

(First Embodiment) Next, a first embodiment of the present invention will be described with reference to the drawings.

(1) First, an example of the configuration of an ink jet recording apparatus used in this embodiment will be described.

FIG. 1 shows a serial type ink jet color printer of this embodiment. The recording head 1 is a device that has a plurality of nozzle arrays and performs image recording by forming dots on a recording medium 12 by discharging ink droplets. (In this drawing, the recording head is covered with the recording head fixing lever 4 and is not directly shown in the drawing.) Further, as described later, in this embodiment, a plurality of ink droplets of a plurality of colors are ejected. The recording head 1 is formed integrally with the printing head. Different color inks are ejected from different print heads, and the recording medium 1
2, a color image is formed.

The print data is transmitted from the electric circuit of the printer body to the print head by the flexible cable 10. Print head row 1K (black), 1C (cyan),
In the present embodiment, 1M (magenta) and 1Y (yellow) are configured such that recording heads for four colors are integrated. The recording head 1 is detachable from the carriage 3. In the forward scan, ink is ejected in this order. For example, when making red (hereinafter R), magenta (hereinafter M) is first landed on the recording medium 12, and then yellow (hereinafter Y) is landed on the M dot, so that it can be seen as red dots. Similarly, in the case of green (hereinafter referred to as G), C and Y are in order, and in the case of blue (hereinafter referred to as B), C,
They land in the order of M and form colors. However, since the print heads are arranged at a fixed interval (P1), for example, when performing solid printing of G, printing of Y is performed with a delay of 2 * P1 after printing of C. That is, the Y solid is printed on the C solid.

The carriage 3 detects the scanning speed and printing position of the carriage by a position detecting means (not shown) and controls the movement in the main scanning direction. This power source is a carriage drive motor, which is transmitted by a timing belt 8 and moves on guide shafts 6 and 7 in directions of arrows a and b. Printing is performed during this main scanning operation. The printing operation in the digit direction includes one-way printing and two-way printing. Normally, in one-way printing, printing is performed only when the carriage moves in the opposite direction from the home position (hereinafter, HP) (forward direction), and no printing operation is performed in the direction returning to HP (return direction). On the other hand, in bidirectional printing, a printing operation is performed in both the forward and backward directions. Therefore, high-speed printing becomes possible.

In the sub-scanning direction, the recording medium 12 is fed by a platen roller 11 driven by a paper feed motor (not shown). The paper is fed in the direction of the arrow c in the figure, and when the printing position is reached, a printing operation is performed by the printing head array.

Next, the recording head 1 on the carriage 3 will be described. As shown in FIG. 4 and FIG.
Inside, are mounted four print heads (FIG. 2) for respectively discharging K, C, M, and Y inks, and ink tanks 2bk, 2c, 2m, and 2y for storing and supplying the ink. Each of these four ink tanks is detachable from the carriage 3, and a new ink tank can be replaced for each color when the ink runs out.

The recording head fixing lever 4 is connected to the recording head 1.
The boss 3b of the carriage 3 and the recording head fixing lever 4
The hole 4a is rotatably fitted, and the recording head 1 can be replaced by opening and closing the lever.
Further, the recording head 1 is accurately fixed on the carriage 3 by engaging the recording head fixing lever 4 with the stopper 3d of the carriage 3. Further, the recording head 1
By joining the upper contact group, the drive signal for driving the discharge heater of the print head for four colors, the above-described head characteristics, the diode sensor value, and the like can be transmitted or detected from the recording apparatus main body.

The details of the recording head 1 will be described. As shown in FIG. 2 and FIG. 3, the print head is supplied with an applied voltage to generate thermal energy in order to discharge ink droplets from a plurality of discharge ports A provided in a row. Hereinafter, a discharge heater B) is provided on the heater board 20G for each discharge port. Then, by applying the drive signal, all the discharge heaters B are heated to discharge ink droplets. The heater board 20G is provided with a discharge heater array 20D in which a plurality of discharge heaters B are arranged side by side.
E is provided. Since the dummy resistor 20E is formed under the same conditions as the discharge heater B, the energy generated by the discharge heater (Watt / hour) when a constant voltage is applied can be detected by measuring the resistance value. . The energy generated by the discharge heater is the applied voltage V
(Volt), V ² / R at discharge heater resistance R (Ω)
Therefore, the characteristics of the discharge heater vary depending on the variation of the resistor. These resistors are
For example, there may be a variation of ± 15% during manufacturing. By detecting the variation in the characteristics of the discharge heater and setting the optimum driving conditions for each printhead, it is possible to extend the life of the printhead and improve the image quality.

Further, in the ink jet printer of this system, thermal energy is applied to the ink to discharge the ink, and therefore, it is necessary to control the temperature of the recording head. Therefore, a diode sensor 20C is provided on the heater board.
Is provided to measure the temperature in the vicinity of the discharge heater and control the input energy for ink discharge or temperature adjustment.

(2) Measurement of Discharge Heater Characteristics In this embodiment, the recording head 1 has a replaceable configuration, and discharge head characteristics and discharge heater thermal characteristics are measured when the head is replaced. (The measurement of the thermal characteristics of the discharge heater will be described later.) As for the discharge heater characteristics, the resistance value of the dummy resistor 20E (FIG. 3) is measured. When the constant voltage drive is used to drive the print head, it is possible to know how much energy should be applied if the resistance value of the discharge heater is known.

In this embodiment, the case where the variation of the dummy resistor 20E is 272.1Ω ± about 15% will be described. As shown in FIG. 6, the variation in the resistance value is divided into 13 ranks. The center value is rank 7, and the width of the resistance value in one rank is about 8Ω, which is about 2.3% of the entire variation. If the number of ranks is finely divided, the head rank can be set with higher precision, but the rank reading circuit on the main body of the recording apparatus also requires higher precision. If the recording device reads the head rank and then writes to the storage member (EEPROM, NVRAM, etc.) in the recording device body,
Thirteen numbers for four heads are stored.

(3) Basic Waveform of Driving Pulse The basic waveform of the driving pulse corresponding to the head rank will be described. (Hereinafter, the basic waveform of the driving pulse corresponding to the head rank in the present embodiment is simply referred to as "basic waveform.") The basic waveform of this driving pulse is important, and based on this, various types of recording heads are driven. I do.

First, driving at the time of printing is performed on the basis of the basic waveform. The driving waveform is set according to the head rank so that the ejection state of the recording head is stable and the life of the ejection heater can be extended. Therefore,
In a normal environment, printing may be performed with the basic waveform as long as the recording head does not self-heat due to high-duty printing. In this embodiment, a double pulse waveform is used as a basic waveform. If the recording head temperature is lower than the predetermined temperature, the ejection amount is compensated by adjusting the temperature by the sub-heater. Conversely, when the temperature of the recording head is equal to or higher than the predetermined temperature, the ejection amount is adjusted by modulating the pulse width of the preceding pulse (preheat pulse) in a shorter direction (PWM control).

Second, the preliminary ejection is driven based on the basic waveform. The preliminary ejection is performed for the purpose of refreshing the inside of the ejection nozzles of the recording head, and it is not necessary to adjust the ejection amount even if the recording head becomes hot and the ejection amount increases. The preheat pulse has a maximum pulse width (that is, a basic pulse waveform itself) to improve the recoverability.

When performing the above-mentioned PWM control, it is required that the pulse width of the preheat pulse of the basic waveform be sufficiently long. That is, in the PWM control, since the preheat pulse is shortened as the temperature of the recording head becomes higher, if the width of the preheat pulse in the basic waveform is shorter, the PWM
The controllable temperature range in the control is narrowed. Therefore, it is not preferable to set the width of the preheat pulse of the basic waveform too small.

However, if the resistance value of the discharge heater (ie, the head rank) is reduced, the preheat pulse must be made correspondingly short in pulse width to cause foaming of the ink by the preheat pulse (hereinafter referred to as pre-foaming), resulting in a stable operation. Discharge will not be possible.

Therefore, it is necessary to set the pre-heat pulse of the basic waveform within a range where the above-mentioned adverse effects do not occur, and the pre-pulse width is not set in proportion to the resistance value of the discharge heater.

On the other hand, a pulse relatively later than the basic waveform (hereinafter referred to as a main heat pulse) cannot obtain a stable ejection state unless it is changed according to the head rank. As the rank grows,
The pulse width is set to be long.

For the above reasons, a basic waveform is formed as shown in FIG.

[0030] (4) by the air discharge to be used for the detection of non-ejection of the measurement recording head of the thermal characteristics of the recording head, the temperature change of the temperature increase and the idle discharge after the end of the temperature drop of the recording head, Ya heating characteristics of the recording head It is greatly affected by heat storage characteristics. In the present embodiment, the ejection heater is driven by the pre-pulse of the above-described basic waveform according to the head rank, and the temperature difference between the temperature rise of the recording head and the temperature difference between the temperature drop from the end of the pulse application to a predetermined time after that. , Record
Measuring the thermal properties of the head.

The heat storage characteristics of the printheads differ from printhead to printhead due to the degree of bonding between members and variations in the discharge amount. The recording head that easily accumulates heat even when the same energy is applied to the discharge heater rises to a high temperature,
The recording head which does not easily store heat dissipates heat as soon as thermal energy is generated, and thus does not raise the temperature much. Further, the heat generation characteristics vary from printhead to printhead due to variations in sheet resistance of the discharge heater. In addition, the heat generation characteristic differs for each main body due to the variation of the driving voltage of the heater driving main body power supply of the recording apparatus main body.

In this embodiment, a pulse having a pre-pulse width of the above-mentioned basic waveform corresponding to the head rank is applied to the discharge heater at 15 kHz for one second, and the thermal characteristics of the recording head are measured from the temperature change before and after the pulse.

The method for measuring the thermal characteristics will be described in detail with reference to FIG. First, the temperature (T _{1 in the} figure) of the recording head before pulse application is measured. As described above, a pulse having a preheat pulse width of the above-described basic waveform is applied at 15 kHz for one second, and the temperature (T _{2 in the} figure) of the recording head immediately before the end of the application is measured. The head temperature is constantly acquired every 20 msec., And a moving average of four times is taken to suppress noise.

From the measurement results obtained as described above,
The value ΔTs indicating the thermal characteristics of the recording head is calculated as follows.

ΔTs = (T ₂ −T ₁ ) + (T ₂ −T ₃ ) The difference between the temperature rise and the temperature drop is added because, for example, the temperature of the recording head changes after high-duty printing. This is in order to avoid the effects of the situation. In addition,
The pre-pulse width of the above basic waveform is sufficiently short, and the foaming of the ink does not occur by the application of the pulse for measuring the thermal characteristics. In addition, by using a table of basic waveforms for measuring the thermal characteristics of the recording head, there is an advantage that less tables need to be prepared.

(5) Non-ejection detection In this embodiment, a drive pulse having a basic waveform corresponding to the head rank is applied to the ejection heater, and the temperature difference between the temperature rise of the recording head and the subsequent temperature drop is measured. , The value ΔTi indicating the magnitude of the temperature change is calculated. The ΔTi
And the threshold value ΔTth of the determination determined by the thermal characteristic ΔTs of the discharge heater, and the non-discharge of the recording head is determined.

With reference to FIG. 9, a method of measuring the value ΔTi indicating the magnitude of the temperature change due to idle discharge for detecting non-discharge will be specifically described. First, the temperature (T _{4 in the} figure) of the recording head before the application of the driving pulse is measured. Subsequently, the drive pulse having the basic waveform according to the head rank is given by 6.125 k.
5000 pulses (approximately 0.8 seconds) are applied at the same time, and the temperature (T _{5 in the} figure) of the recording head immediately before the application is completed is measured. Thereafter, the recording head temperature (T _{6 in the} figure) 0.8 seconds after the end of the application of the driving pulse is measured. The recording head temperature is constantly acquired every 20 msec., And a moving average is taken four times to suppress noise.

From the measurement results obtained as described above,
A value indicating the magnitude of the temperature rise and fall of the print head due to idle discharge, Δ
Ti is calculated as follows.

ΔTi = (T ₅ −T ₄ ) + (T ₅ −T ₆ ) With respect to a plurality of print heads, ΔTi is determined when the print head is in a non-discharge state and when the print head is in a normal discharge state.
FIG. 10 is a plot of Ti versus ΔTs. When the recording head is in a non-ejection state, ΔTi is almost proportional to ΔTs. When the recording head is in a normal ejection state, the rate of change of ΔTi with respect to ΔTs is small, and is not strictly proportional. The cause is Δ
It is considered that the discharge amount is changed by Ts. That is, if ΔTs is large, the temperature rise due to idle discharge in non-discharge detection is large, the ink temperature near the heater rises, and the discharge amount increases, so that the thermal energy taken out of the recording head by the discharged ink droplets is reduced. Increase, Δ
Ti becomes slightly smaller (than when ΔTi is proportional to ΔTs).

In consideration of the above and the variation in ΔTs of the print head, the threshold ΔTt for non-discharge determination is determined from ΔTs.
h is calculated as follows. (This is indicated by a broken line in FIG. 10.) ΔTth = 0.571 · ΔTs + 17 From the relationship between the threshold value ΔTth for this determination and the measured ΔTi, ΔTi ≧ ΔTth -----> non-ejection ΔTi <ΔTth --- −−> Normal discharge is determined. As can be seen from FIG. 10, there is a sufficient margin for non-ejection determination.

In this embodiment, the idle ejection performed in the non-ejection detection is performed by a driving pulse having a basic waveform corresponding to the head rank, thereby improving the durability of the recording head and protecting the recording head by preventing an excessive temperature rise. To achieve.

When non-ejection is detected and thermal characteristics are corrected with a fixed driving pulse without changing the driving pulse corresponding to the head rank, for a recording head with a large sheet resistance, idle ejection is detected. Therefore, there is a possibility that a problem that the margin of the non-ejection determination becomes small because the amount of heat generated is small. In the present embodiment, as described above, the drive of idle discharge for non-discharge detection and the measurement of the thermal characteristics of the print head are performed by the drive pulse according to the rank of the print head. Inject more energy. As a result, a sufficiently large determination margin can be obtained.

As described above, in this embodiment, for setting the basic waveform, the thermal energy generated by the idle discharge in the non-discharge detection and the thermal energy generated by the application of the pulse for measuring the thermal characteristics of the recording head are set. Is not constant regardless of the head rank. However, in comparison with the case where the idle discharge for non-discharge detection and the pulse application for measuring the thermal characteristics are performed by a fixed drive regardless of the head rank, the drive of the present embodiment depends on the head rank of the heat energy generated. The difference is much smaller, less than the variation due to the measurement of ΔTs, ΔTi.

The ratio between the heat ranks generated when the corresponding driving pulse having the above-mentioned basic waveform is applied to the recording head of each head rank, and when the pre-pulse having the basic waveform is applied in the same manner. The basic waveform is designed so that the ratio of generated thermal energy between head ranks is as constant as possible (6% or less in this embodiment). If there is a recording head having a large head rank and a recording head having a small head rank, and there is no measurement error or any difference in characteristics other than the head rank, ΔTs and ΔTi measured for the head will be different for the recording head having a large head rank. The measurement should be somewhat larger than the other. However, the above ΔTs due to the difference in thermal energy generated due to the difference in head rank
The difference between ΔTs and ΔTi has almost the same variation in the directions as ΔTs and ΔTi due to the thermal characteristics (ΔTs) of the recording head in FIG. For example, in the case of normal ejection, if the generated thermal energy is large, the ejection amount also increases, that is, the difference in the amount of generated thermal energy is substantially the same as the difference in the thermal characteristics of the recording head and the phenomenon of the recording head. This has an effect on the temperature rise. Therefore, it can be seen that the margin of the non-ejection determination is unlikely to be small depending on the difference in the generated thermal energy depending on the head rank.

In this embodiment, the thermal characteristic ΔTs of the recording head is measured using the pre-heat pulse having the basic waveform, and the magnitude ΔTi of the temperature rise and fall due to idle discharge is measured using the basic waveform. The present invention is not limited to this configuration, and a table based on the head rank of the drive pulse waveforms for measuring ΔTs and ΔTi may be prepared. (ΔT
The measurement of s uses the preheat pulse of the table)
Also, a table may be prepared for each of the measurement of ΔTs and the measurement of ΔTi. Alternatively, a calculation formula may be prepared, and the drive pulse waveform may be calculated based on the formula.

In the present embodiment, the drive pulse waveform is changed according to the head rank. However, the present invention is not limited to this configuration, and the drive voltage, the drive voltage, and the number of pulses of the drive pulse can be changed within the range of the durability of the recording head. You may change it. In this embodiment, the head rank controls the amount of heat generated by the recording head by detecting non-ejection or the energy applied to the recording head, and performs high-precision non-ejection detection while protecting the recording head.

In the present embodiment, the threshold ΔT for non-ejection determination
Although th was calculated as a linear function of ΔTs, the present invention is not limited to this configuration.
th may be obtained, or an appropriate threshold value may be selected from a table based on ΔTs.

In the present embodiment, the measurement of ΔTs and ΔTi was performed using the temperature difference between the temperature rise by driving the discharge heater and the subsequent temperature decrease. However, the present invention is not limited to this configuration. For example, when measuring ΔTs and ΔTi only when the head temperature is stable,
The measurement can be performed with sufficient accuracy by using only one of the temperature increase and the temperature decrease.

In this embodiment, in order to widen the controllable temperature range of the PWM control, the drive waveform table (basic waveform) according to the head rank is such that the input energy becomes constant depending on the head rank as described above. Did not set. However, in a recording apparatus in which the temperature rise due to printing does not pose a significant problem, for example, when the drive frequency is slow, a table corresponding to the basic waveform of this embodiment is set so that the input energy is constant or independent of the head rank. The heat quantity may be designed to be constant regardless of the head rank. In this case, the head rank ΔTi
There is an advantage that there is no influence on the environment.

Conversely, if there is a large difference in the amount of heat generated in the measurement of ΔTs and ΔTi depending on the head rank more than in the present embodiment, the threshold value of the non-discharge determination is corrected not only by ΔTs but also by the head rank. You may go.

In a recording apparatus having a configuration in which a plurality of types of recording heads are used at the same time or replaced with a recording apparatus, it is effective to change each condition according to the characteristics of the head. As a result, non-ejection can be detected in a print head of a different type with settings suitable for the print head.

(Second Embodiment) In the second embodiment, idle ejection for non-ejection detection is performed by using a drive pulse having the above-described basic waveform according to the head rank, and the idle ejection corresponding to the thermal characteristics of the recording head. Change the number of ejections. Thereby, the accuracy of non-discharge detection is improved. Configuration of the recording apparatus used in the present embodiment,
The measurement of the discharge heater characteristics (head rank) and the basic waveform of the drive pulse are the same as in the first embodiment.

(1) Non-ejection detection In the configuration of the first embodiment, as shown in FIG. 10, the temperature rise due to ejection is small for a head with a small ΔTs, so that it is relatively small compared to the case where ΔTs is large. The margin for non-discharge determination is small. Thus, in the present embodiment, the number of idle discharges is changed according to the thermal characteristics of the discharge heater, and a certain or more non-discharge determination margin is secured regardless of the head rank. Conversely, for a print head having a large ΔTs and an unnecessarily large margin, the number of idle discharges for non-discharge detection is reduced to prevent unnecessary input of energy and unnecessary temperature rise of the print head.

FIG. 11 shows a table for selecting the number of idle discharges for non-discharge detection in accordance with ΔTs of the print head. Increasing or decreasing the number of idle discharges also changes the time required for idle discharge,
Also changes the time interval until T ₆ measured from the time of idle discharge ends accordingly (see FIG. 9). As described above, T ₄ and T ₅ ,
Except that the time interval of the measurement of T ₅ and T ₆ is changed by ΔTs, the measurement method of the specific ΔTi is the same as that of the first embodiment.

In the setting of the number of idle discharges in the present embodiment, both the case where the recording head discharge state is normal and the case where the discharge state is non-discharge state are ΔT irrespective of the head rank and ΔTs.
Since i is almost constant, the threshold ΔTt for non-ejection determination
h is determined with a fixed value of ΔTth = 32 (° C.). The determination criterion is the same as in the first embodiment. ΔTi ≧ ΔTth −−−−> non-discharge ΔTi <ΔTth −−−−> normal discharge If the number of idle discharges is increased, the margin of the non-discharge determination increases. This will be described with reference to FIG. FIG. 12 shows a change in the temperature of the print head when idle discharge is continuously performed from a state where the print head temperature is stable at room temperature. In the drawing, the solid line indicates that the recording head is in a normal ejection state.
The broken line shows the case of non-ejection. When the idle discharge is started, the temperature of the recording head rises. Then, the number of idle discharges increases (that is, as the idle discharge time increases in the figure), the temperature rise gradually becomes saturated.

As shown in the figure, the temperature rise is not yet saturated in 5000 empty ejections ((a) in the figure), and when the number of ejections increases, the recording head is in a normal ejection state. The temperature difference in the non-ejection state also increases. Therefore, by changing the number of times of idle discharge, the degree of temperature rise due to idle discharge also changes, and the margin for non-discharge determination also changes.

As described above, ΔTs mainly reflects the heat storage characteristics of the recording head in the configuration of the present embodiment. A head having a small ΔTs has a quick heat radiation of the heat generated by the discharge heater. Therefore, even if the number of idle ejections is increased to generate more heat energy, it is unlikely to cause damage to the head due to excessive temperature rise. Conversely, Δ
A recording head having a large Ts is a head that easily stores heat,
As shown in FIG. 10 of the first embodiment, the temperature was greatly increased. Therefore, reducing the number of times of idle discharge prevents unnecessary temperature rise, which leads to protection of the head.

In this embodiment, the margin for non-discharge determination is made substantially constant by setting the change in the number of idle discharges for non-discharge detection. However, there is no problem as long as the margin for non-discharge determination is not less than a certain value in practical use. For example, only the print head with ΔTs smaller than a predetermined value is set to the minimum necessary number of idle discharges for non-discharge detection. May be increased as necessary to obtain. In such a case, the threshold value ΔTth for the non-ejection determination is ΔTs
, Or by correcting both ΔTs and the head rank, non-ejection detection can be performed with high accuracy.

In this embodiment, the thermal characteristic value ΔT of the recording head
By changing the number of idle discharges for non-discharge detection according to s, a margin for determination that is equal to or greater than a certain value is secured regardless of thermal characteristics. However, the configuration of the present invention is not limited to this.
The drive voltage of the idle discharge may be changed by ΔTs,
The drive pulse may be changed. That is, in the present embodiment, a margin of non-discharge determination equal to or greater than a certain value is secured regardless of ΔTs by changing the input energy of non-discharge detection within a range where there is no problem in the durability of the print head by ΔTs. It is.

(Third Embodiment) In the third embodiment, idle discharge for non-discharge detection is performed by driving a fixed pulse waveform. Then, the determination condition in the determination of non-ejection is corrected based on the head rank and the thermal characteristics of the recording head. The printing apparatus used in this embodiment and the method for obtaining the thermal characteristics of the print head are the same as those in the first embodiment.

In this embodiment, idle discharge for non-discharge detection is performed by the drive pulse waveform corresponding to the head rank 7 of the above-mentioned basic waveform (FIG. 7), and a value ΔTi indicating the magnitude of the temperature rise and fall is obtained. The threshold ΔTth for non-discharge determination
The head rank and the thermal characteristics of the recording head are determined as follows.

ΔTth = 0.571 · ΔT _S + bHR + 14 In the above equation, bHR is a value determined by the head rank, and FIG. 13 shows a table for determining bHR from the head rank.

In the first and second embodiments, the control for changing the driving pulse used for the idle discharge in the non-discharge detection by the head rank or the like is performed. However, the recording head has sufficient durability and is described above. When it is considered that there is no possibility that the durability is degraded due to the discharge heater driving, the control can be simplified by performing the idle discharge with a fixed pulse as in the present embodiment.

Further, the variation of ΔTi due to the heat generation characteristics (mainly the head rank) of the recording head and the variation due to the heat storage characteristics (as described above, the heat characteristics of the present embodiment mainly reflect the heat storage characteristics. In particular, when they are combined and the overall variation of ΔTi is large, performing the correction for each main cause of the variation as in the present embodiment increases the accuracy of the non-ejection determination. Is effective.

In this embodiment, the thermal characteristics of the recording head are corrected using a calculation formula, and the correction based on the head rank is performed by selecting a value from a table. However, the present invention is not limited to this configuration. . For example, a configuration may be used in which both the correction based on the thermal characteristics and the correction based on the head rank are used to correct the determination threshold using a calculation formula.

The heater provided in the printing apparatus may be driven before the non-discharge detection is performed. This is effective when the ink has high viscosity and it is difficult to discharge normally even if the discharge heater is driven as it is, but it becomes easier to discharge by raising the temperature of the ink. In the configuration of the present embodiment, the sub-heater 20F which is a heater for controlling the temperature of the printing apparatus is used.
It is effective to keep the print head warm before detecting non-ejection by driving the. This is because the sub-heater is designed not to come into direct contact with the ink in the recording head, and even if a large amount of energy is applied in a short time, the ink foams, and adverse effects such as generation of bubbles in the recording head are unlikely to occur. .

Furthermore, after driving the sub-heater before detecting non-discharge, waiting for non-discharge detection for a period required for the temperature of the recording head to stabilize to a certain extent is also effective for improving the accuracy of non-discharge determination. It is.

(Fourth Embodiment) In the fourth embodiment, non-ejection detection is corrected in accordance with the characteristics of the printing apparatus main body. In the present embodiment, as an example, the variation of the drive voltage of the main body power supply for driving the heater of the printing apparatus is corrected. The power supply voltage is measured at the time of manufacturing the recording apparatus, and is stored in the information storage means (EEPROM, NVRAM, etc.) of the main body of the recording apparatus. In the first embodiment, the head rank is determined based on the sheet resistance of the recording head, and the driving of idle discharge for measuring the thermal characteristic value ΔTs of the discharge heater and detecting non-discharge of the recording head is selected from the basic waveform. It is. In the present embodiment, correction is performed when selecting a drive waveform from the above-described basic waveform due to variations in the power supply voltage of the main body of the printing apparatus. Thereby, even if the voltage of the main body power supply of the recording apparatus varies, it is possible to correct the input energy and the magnitude of heat generation. As a result, non-discharge detection can be performed with higher accuracy. Specifically, a correction value corresponding to the magnitude of the power supply voltage variation is selected at the time of manufacturing the recording apparatus main body, and is written into the EEPROM on the recording apparatus main body. FIG. 14 shows the correspondence between the power supply voltage and the correction value. In order to measure the thermal characteristic value of the discharge heater and perform idle discharge for non-discharge detection, when selecting a drive pulse waveform from the table of the above basic waveforms, the drive pulse corresponding to the value obtained by adding the correction value to the head rank Select a waveform.

With the drive pulse waveform thus selected,
Measurement of the thermal characteristic value of the discharge heater and idle discharge for non-discharge detection are performed. Specific thermal characteristic values of the discharge heater, a method of detecting non-discharge, and a method of determining non-discharge are the same as those in the first embodiment.

In this embodiment, the selection of the driving condition from the basic waveform is corrected in accordance with the variation in the driving voltage of the recording apparatus main body. However, the configuration of the present invention is not limited to this. ΔT according to the variation of the drive voltage of the printing apparatus main body
s and ΔTi may be corrected, or may be corrected by changing the condition of the non-discharge determination.

In this embodiment, when non-discharge detection and thermal characteristics are measured, the driving conditions are corrected in accordance with the variation in the driving voltage of the printing apparatus main body. It is also effective for printing on the recording device and for idle discharge for improving reliability, so that the input energy can be controlled with higher precision, improving the durability of the recording head, stabilizing the discharge amount, and the discharge state. Contributes to the stabilization of

In the first to fourth embodiments, the discharge heater characteristic (head rank) was measured from the resistance value of the dummy resistor provided on the recording head. However, in the present invention, the measurement of the head rank is not limited to this configuration. For example, a configuration may be adopted in which the head rank is measured at the time of manufacture of the head, the information storage means is provided in the recording head, the head rank information is stored in the recording head, and the recording is read by the recording apparatus main body. Further, the measurement of the head rank is not always performed by measuring the resistance value of the heater provided on the recording head. For example, printing may be performed under the condition that the temperature of the recording head does not rise, and the head rank may be determined from the print density of the printed matter. However, providing the recording head with the information storage means leads to some cost increase.

In the first to fourth embodiments, the measurement of the thermal characteristics of the discharge heater was performed by actually driving the discharge heater. However, the present invention is not limited to the configuration. For example, the heater board 20G having the configuration of the first embodiment is used.
Sub-heater 2 for controlling the recording head temperature configured above
The thermal characteristics may be measured by using 0F. However, in that case, some correction may be required to use the data as the data of the discharge heater. Alternatively, the recording head may be measured in advance at the time of manufacture, and the recording head may be provided with an information storage means and stored therein. Note that the method of driving the discharge heater in the printing apparatus main body to acquire the thermal characteristic value as in the present embodiment is performed when the characteristics of the print head change due to long-term driving, such as a change in the state of the surface of the discharge heater. In such a case, for example, there is an advantage that a change in the characteristics of the recording head can be dealt with by acquiring the thermal characteristic value at regular intervals.

[0074]

According to the present invention, it is possible to change the driving conditions for detecting non-discharge of the recording head and measuring the thermal characteristics of the recording head in accordance with the thermal characteristic information of the recording head and the recording apparatus, or By changing the determination condition of the non-ejection determination according to the thermal characteristic information of the printing apparatus and the printing apparatus, the printing head is protected from excessive temperature rise and the like, and the non-ejection of the printing head can be detected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an entire recording apparatus according to an embodiment.

FIG. 2 is a perspective view showing the structure of a recording head.

FIG. 3 is a diagram showing the inside of a heater board of a print head.

FIG. 4 is a perspective view showing a carriage.

FIG. 5 is a diagram mounted on a carriage of a recording head.

FIG. 6 is a diagram showing a correspondence between a head rank and a resistance value of a dummy resistor.

FIG. 7 is a diagram showing a basic waveform corresponding to a head rank in the first embodiment.

FIG. 8 shows a thermal characteristic ΔT of the recording head in the first embodiment.
Diagram showing measurement of s

FIG. 9 is a diagram showing measurement of the temperature rise and fall ΔTi due to idle discharge in non-discharge detection in the first embodiment.

FIG. 10 is a diagram showing a relationship between ΔTs and ΔTi in the first embodiment.

FIG. 11 is a diagram showing the correspondence between ΔTs and the number of idle ejections in the second embodiment.

FIG. 12 is a schematic diagram illustrating a temperature rise characteristic of a print head due to idle discharge in a second embodiment.

FIG. 13 shows b according to the head rank in the third embodiment.
Table for determining

FIG. 14 is a diagram showing the correspondence between the heater drive voltage and the correction value of the printing apparatus in the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Ink tank 3 Carriage 4 Recording head fixing lever 6 Guide shaft 7 Guide shaft 8 Timing belt 9 Pulley 10 Flexible cable 11 Platen roller 12 Media A Discharge port B Discharge heater 20C Di sensor 20D Discharge heater array 20E Dummy resistor 20F Sub Heater 20G heater board

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jin Sugimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hiromitsu Hirabayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Masaya Uezuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Miyuki Matsubara 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-133749 (JP, A) JP-A-2-188248 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/175 B41J 2 / 05

Claims (16)

(57) [Claims] 1. A non-ejection of a recording head is performed by comparing a temperature change due to a temperature increase due to ejection of the recording head, a temperature change due to a decrease in temperature after ejection, or a sum of both temperature changes with a threshold value for determination. An ink jet recording apparatus having a non-discharge detecting means for detecting, wherein a driving condition changing means for changing a driving condition of a discharge performed for detecting the non-discharge according to thermal characteristic information of a recording head is provided. Inkjet recording device. 2. The ink jet recording apparatus according to claim 1, wherein the driving condition changing means changes the driving condition of the ejection performed for detecting the non-ejection according to the resistance value information of the ejection heater of the recording head. An inkjet recording apparatus. 3. The ink jet recording apparatus according to claim 1, wherein the driving condition changing means changes a waveform of a driving pulse or the number of driving pulses as a driving condition of ejection performed for detecting the non-ejection. Characteristic inkjet recording device. 4. A non-ejection of the recording head is performed by comparing a temperature change due to a temperature rise due to ejection of the recording head, a temperature change due to a decrease in temperature after ejection, or a sum of both temperature changes with a threshold value for determination. An ink jet recording apparatus having a non-discharge detection means for detecting, characterized in that it comprises a determination condition changing means for changing a non-discharge determination condition in the non-discharge detection means according to at least resistance value information of a discharge heater of a recording head. Inkjet recording apparatus. 5. An ink jet recording apparatus according to claim 4, wherein said determination condition changing means changes a non-discharge determination condition in said non-discharge detection means according to thermal characteristic information of a print head. apparatus. 6. A temperature caused by a rise in temperature accompanying ejection of a print head.
Change, temperature change due to temperature drop after discharge, or both
By comparing the sum of the temperature changes of the
It has a non-discharge detection means for detecting non-discharge of the print head
In Inkjet recording apparatus, in accordance with the thermal characteristic information of the recording head, the ink jet recording apparatus characterized by having a judgment condition changing means for changing the ejection failure judgment condition in the ejection failure detecting means. 7. The ink jet recording apparatus according to claim 6 , further comprising a judgment condition changing means for changing a non-ejection judgment condition in said non-ejection detection means in accordance with at least resistance value information of an ejection heater of the recording head. Characteristic inkjet recording device. 8. An ink jet recording apparatus according to claim 6 , wherein the information is based on resistance value information of a discharge heater of the recording head.
The driving condition of the ejection performed to detect the non-ejection
An ink jet recording apparatus comprising a driving condition changing means for changing a condition . 9. The ink jet recording apparatus according to claim 6 , wherein the thermal characteristics of the recording head are determined by a temperature change due to a rise in temperature or a temperature change due to a decrease in temperature by driving the discharge heater of the recording head, or a sum of both temperature changes. An ink jet recording apparatus comprising means for measuring. 10. The ink jet recording apparatus according to claim 9, wherein the resistance value of the discharge heater of the recording head is measured by the recording apparatus. 11. A method according to claim 1, wherein a temperature change due to a temperature rise due to ejection of the recording head, a temperature change due to a temperature decrease after ejection, or a sum of both temperature changes is compared with a threshold value for determination . In an ink jet recording apparatus having a non-ejection detecting unit for detecting non-ejection of a recording head, an information storage unit for storing power supply voltage information for driving a recording head, and according to the power supply voltage information stored in the information storage unit, An ink jet recording apparatus comprising a driving condition changing unit for changing a driving condition of a discharge performed to detect the non-discharge. 12. The ink jet printing apparatus according to claim 1, further comprising an information storage unit for storing power supply voltage information for driving a printhead, wherein the drive condition change is performed. An ink jet recording apparatus comprising: a driving condition changing unit configured to change a driving condition of a discharge performed to detect the non-discharge in accordance with the power supply voltage information stored in the information storage unit. 13. The ink jet recording apparatus according to claim 1, wherein a temperature control heater is provided on the recording head. 14. The ink jet recording apparatus according to claim 4, wherein the recording head is provided with a heater for adjusting temperature, and means for driving the heater for adjusting temperature before performing non-discharge detection. An ink jet recording apparatus characterized by the above-mentioned. 15. The ink jet recording apparatus according to claim 14, further comprising means for waiting for a predetermined period of time for non-discharge detection after driving of the temperature adjustment heater performed before non-discharge detection is completed. apparatus. 16. The ink jet recording apparatus according to claim 1, wherein said recording head discharges ink by thermal energy.