JPH071745A - Method for detecting and correcting intrusion of air to printing head - Google Patents

Abstract

PURPOSE: To prevent the damage of a printer by measuring the temp. of a printhead at a time of printing work and performing the correction o the intrusion of air into the printhead, that is, the refilling or replacement of ink when the measured temp. exceeds a predetermined threshold value. CONSTITUTION: A temp. sensor 52 of which the resistance value is changed by temp. is provided to a printhead substrate 50 and the dropped voltage between the temp. sensor 52 and a thermistor 62 is read through an A/D converter 64 to be inputted to a microprocessor 66. A threshold value calculated by adding equilibrium idle temp. to a constant threshold value delta 68 is inputted to the microprocessor 66. Then, the threshold value temp. is compared with data related to measured temp. by the microprocessor 66 and, when the threshold value temp. is higher, printing work is continued while, when the threshold value temp. is lower, the imperfect filling of ink or the reduction of an ink source is judged to perform the refilling or replacement of ink.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION This invention relates generally to the field of ink jet printing, and more particularly to the proper flow of ink into the ink chamber of an ink jet printhead.

[0002]

BACKGROUND OF THE INVENTION Inkjet printers are widely accepted. These printers are W. J. Lloyd and H. T. Taub's "Ink Jet Device (Ink Jet
Devices ", Chapter 13," Output Hardcopy Devices (Outpu
Hardcopy Devices) "(Ed. RC Darbeck,
S. Shell Editing, Academic Press, San Diego,
1988) and U.S. Pat. No. 4,490,728. Inkjet printers provide high quality prints, are compact and portable, and print only quickly, but quietly, because only the ink strikes the paper. The main categories of inkjet printer technology include continuous inkjet, intermittent inkjet, and drop on demand ink jet. The drop-on-demand category can be divided into piezo electric inkjet printers and thermal inkjet printers. Drop-on-demand ink jet printers produce drops by rapidly reducing the volume of a small ink chamber because they force a pressure wave to pass a single drop through a nozzle. The ink chamber is refilled by capillary action. Typical inkjet
A printhead is an inkjet printer that incorporates an array of ink chambers that receive liquid ink (ie, dye dissolved or dispersed in a solvent) from an ink reservoir.
It has an array of precisely formed nozzles mounted on a printhead substrate. Thermal inkjet
In the printhead, each ink chamber is located near a nozzle or opposite a “firing resistor”.
ng resistor) '',
Ink collects between this and the nozzle. The electrical printing pulse heats the firing resistor, vaporizing a small portion of the ink in its vicinity and ejecting a drop of ink from the printhead. In a piezoelectric inkjet printhead, each ink chamber has a piezoelectric transducer located near or opposite the nozzle, where the ink collects between it and the nozzle. The electrical print pulse causes the diaphragm of the piezoelectric transducer to flex and eject ink drops from the nozzle. Properly aligned nozzles form a dot matrix pattern. Move the printhead through the paper by properly ordering the movements of each nozzle,
Form characters or images on paper.

Conventional inkjet printers cannot detect the shortage of their ink source. Therefore, these inkjet printers try to print despite the lack of ink source. Another problem that inkjet printers have is the entry of air bubbles into the ink chamber. The entry of air bubbles deprime the ink chamber (ie, air enters the ink chamber and replaces the ink), and many, if not all, of the printhead's ink chamber. The size of the air bubble grows until it is empty. Since the ink chamber is refilled by capillary action, once the ink chamber is emptied, the ink runs out until the printhead is refilled. On the other hand, the printer attempts to print and the firing resistor consumes the energy required to fire a drop. However, with a deprimed printhead substrate, it is not possible to eject ink drops and typically must absorb the energy that carries the ejected ink drops from the printhead. By absorbing this energy,
The temperature of the printhead substrate rises significantly.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, detect incomplete ink filling or ink source depletion, and quickly refill ink without raising the temperature of the printhead. It is to provide a method of exchanging.

[0005]

SUMMARY OF THE INVENTION An apparatus for automatically detecting and correcting air ingress into a printhead substrate regardless of whether the air ingress represents an imperfect fill of the printhead or a lack of ink source. It is advantageous to do so. Such a device prevents the printhead substrate from printing in the event of an incomplete fill and prevents the temperature of the printhead substrate from reaching dangerously high levels. High temperatures can damage the firing resistors in thermal ink jet printers, and boiling ink causes carbonized residue to build up on the firing resistors, causing drop volume when the printhead is refilled. Will decrease. In addition, such high temperatures can burn the print medium, burn the user when removing the printhead cartridge from the printer, and potentially cause a fire hazard. A lack of ink source and the ability to detect and correct underfilled printheads is an important feature of printheads installed in facsimile machines, as data can be lost if not printed out correctly. (If the receiver does not have a printed record of who the transmission was made from, this data will be irreversibly lost.) Detecting and correcting a missing ink source and an underfilled printhead. The ability to do so is an important feature of printers that create large color plots that require the expense of much ink and printing time that is lost when the printhead is empty while creating the plot. Large-capacity printers, where the user is not always near, must be able to detect and correct air ingress into the printhead board to avoid printing with an underfilled printhead board for a sustained period of time. I won't.

The present invention monitors the temperature of the printhead substrate with a "printhead substrate temperature sensor" (ie, a temperature-sensing resistive trace on the printhead surface) to indicate the entry of air into the printhead substrate. By comparing this temperature with a value temperature, the ingress of air into the printhead substrate is detected. The threshold value may be a constant, and the constant and the equilibrium idle temperature (equilibrium id
le temperature) or print density (pri
nt density) and / or “print mode” (ie, a label for the speed at which the inkjet cartridge moves across the page and the maximum density that can be printed at this speed). Corrective action is taken when the temperature of the printhead substrate exceeds a threshold temperature. In one embodiment of the present invention, the temperature of the printhead substrate must exceed a threshold for a predetermined period of time. The corrective action may interrupt the printing operation, causing the “printer cartridge” (ie, the mechanism that moves one or more inkjet cartridges across the media) to move to the inkjet cartridge (ie, inkjet printhead,
The ink source and external packaging) may be moved to a refilling service station. Another embodiment of the present invention, in which multiple inkjet cartridges are used, does not interrupt the printing operation, but shuts off power to the underfilled inkjet cartridge and re-installs the inkjet cartridge when the printing operation is complete. Fill. In yet another embodiment of the invention using a single ink cartridge, such as found on a fax machine, the printer stops printing and alerts the user that the ink cartridge is malfunctioning.

[0007]

The advantages and features of the present invention will be readily apparent to those skilled in the art from the following detailed description, taken in conjunction with the accompanying drawings.

FIG. 1A shows an air bubble 22 in an inkjet cartridge 20 that is relatively small and none of the ink chambers 24 have yet been partially filled. The air bubble 22 moves toward the ink chamber 24 with the flow of ink 26. It then reaches the ink chamber 24 and deprimes its filling. The spring 28 that presses against the film 30 creates a back pressure (or negative pressure) across the ink source shown in FIG. 1A. The back pressure prevents ink from spilling out of the nozzle 32, but causes more air to be taken into the underfilled ink chamber 24, which causes the air bubble 22 to grow. Figure 1
B shows the air bubble 22 after it has grown very large and some ink chambers 24 have been partially filled.

FIG. 1C illustrates the air bubble at the printer output 40 and the effect of growth of this air bubble. The printer output 40 is "blackout print" (i.e., all ink chambers are dissipating the power required to fire a drop of ink). Print sample 42 is an example of a blackout print when all nozzles 32 are ejecting ink drops. At position 44 of print sample 42, one air bubble causes 1
One nozzle 32 is empty. Print head 20
More air is drawn in here by the back pressure of the air bubbles, causing air bubbles 22 to grow. As the air bubble 22 grows, it empties more of the ink chamber 24 and creates a large blank space 46 in the print, which should be a solid black ink. In some cases, the air bubble 22 grows large enough to empty all printheads and blank the entire print sample 48.

When the ink source 26 is depleted, air replaces the ink, and the printhead substrate ink chamber 24 looks like that shown in FIG. 1B, and the printer output is similar to print sample 48 in FIG. 1C. Will be Partial remedy for this problem is the label 31 shown in FIG. 1B attached to the outer film 30 of the ink source 26, which when the ink source 26 is exhausted.
Gradually change its color from black to green. These labels are meaningless unless often inspected by the user.
Another drawback of these labels is that they are less sensitive to ink levels and prevent the printhead from printing with an empty ink cartridge.
When some ink is still in the cartridge,
The user has to replace the ink cartridge.

The present invention monitors the temperature of the printhead substrate by a "printhead substrate temperature sensor" 52, shown in FIG. 2, and compares this temperature to a threshold to determine the lack of ink source and incomplete fill. Detect the printhead. (The details are shown in FIGS. 5 and 6.) The threshold value can be set to a constant value, or may be set to a constant value exceeding the ambient temperature. Alternatively, it may be changed according to the print density and / or print mode. Such an enumeration is for purposes of illustration only and is not limiting. The present invention includes all thresholds. The temperature of the printhead substrate is for a predetermined period (0 seconds in one embodiment and 10 seconds in another embodiment).
If the threshold is exceeded for a period of seconds or more), the corrective action is taken. The corrective action can also interrupt the printing operation, causing the printer carriage 10 to the service station 107 as shown in FIG. 9A.
Move 8 Here, the ink cartridge is automatically or manually reprimed. 8A, FIG. 8B, FIG. 9A, and FIG. 9B.
In another embodiment of the invention having a cartridge, the printing operation is not interrupted, but printing with this inkjet cartridge is stopped. After the print job is complete, the carriage 108 loads the print cartridge 116 into the service station 107 for refilling.
Move to. In some embodiments, such as found in facsimile machines equipped with a single ink cartridge, the corrective action stops printing and notifies the user.

A service station is provided with a mechanism for automatic refilling, wiping, and ink drop detection. Further testing can also determine if the printhead is simply underfilled or if the ink source is depleted (FIGS. 5 and 6).
reference).

FIG. 2 shows a portion of the printhead substrate 50 having the printhead substrate temperature sensor 52 provided therein. The print head substrate temperature sensor 52 is
It is composed of thin film aluminum, has a width of 8 μm, and is spaced apart from the ink chamber 54 by about 1 mm. The print head substrate temperature sensor 52 is a resistance trace whose resistance value changes with temperature. The printhead substrate temperature sensor 52 surrounds the ink chamber 53 and the ink slot 56, as shown in FIGS. 3A and 3B, and the silicon has a very high thermal conductivity so that the heat in one ink chamber is printed. It is a bulk printhead substrate temperature sensor as it travels throughout the head substrate 50.

The printhead substrate temperature sensor 52 is inexpensive to manufacture because it does not require any processing steps or materials that are already part of the thermal inkjet printhead manufacturing procedure. The printhead substrate temperature sensor 52 also has a plurality of functions. In addition to detecting the temperature of the printhead substrate 50 to detect an empty or depleted ink source,
This temperature sensor is part of the temperature control system for the printhead during its normal operation.

The resistance of the printhead substrate temperature sensor 52 is defined by the following equation:

[0016]

[Equation 1]

Here, T ₀ is the temperature of the printhead substrate 50 when the printer is not in use (idling) (that is, the printer is powered on but printing is not started), R _{TS | T0} has a temperature of T
The resistance value of the substrate 50 at ₀ , α is the change in the resistance value of the temperature sensor 52 due to the change in the temperature of the print head substrate 50, T is the current temperature of the print head substrate 50, R _TS
Is the current resistance of printhead substrate temperature sensor 52 when its temperature is equal to T. Solving this equation for T gives the temperature of the printhead substrate 50.

[0018]

[Equation 2]

The value of α is controlled accurately by the manufacturing process, but the value of R _{TS | T0} can be controlled, but each printhead substrate temperature sensor 52 must be mutually calibrated by a thermistor on the cartridge. I have to. The printhead is calibrated when it is powered on or continuously. This is one of many ways to calibrate the printhead substrate temperature sensor 52. The present invention includes any method of calibrating this temperature sensor.

3A and 3B calibrate the printhead substrate temperature sensor 52 and the temperature sensor and measure their resistance to determine when the ink source is depleted, and
6 shows a circuit that determines when the printhead is incompletely filled. In one embodiment of the invention illustrated in FIG. 3A, the threshold is a constant threshold delta to "equilibrium idle temperature" (i.e., power is on, but the printhead board is at rest, most recently). Steady state temperature). If the printhead substrate temperature sensor 52 is frequently calibrated, such as once for each printing operation, T ₀ will be equal to the equilibrium substrate temperature. In another embodiment of the invention shown in FIG. 3B, the threshold is calculated by adding the equilibrium idle temperature to a threshold delta that varies with print density and print mode.

In FIGS. 3A and 3B, the circuit is 2
It consists of a voltage divider network including two matching resistors 58, 60, a precisely calibrated thermistor 62, a voltage source, and a printhead substrate temperature sensor 52. The A / D converter 64 is connected to this network to read the voltage drop between the thermistor 62 and the printhead substrate temperature sensor 52. By using the well-known network analysis techniques, it is possible to obtain the R _TS. With the exception of printhead substrate temperature sensor 52, this circuit is shown in FIGS.
It is arranged on a carriage board attached to the carriage 108 shown in B. This carriage is
A printhead carriage 116 containing a printhead substrate is moved along a slider rod 110 and to a service station 107. In addition, the circuit has a microprocessor 66 and software connected to the A / D converter 64 via a bus 65, a memory 67 in which the temperature and resistance values of the thermistor 62 and the substrate temperature sensor 52 are stored.

In the preferred embodiment of the present invention, the temperature difference between the carriage board and the printhead substrate 50 (see FIG. 2) is predictable so that calibration can be performed.
When the printer is turned on, the temperature difference is zero, and this averages after about 15 minutes (levels-off), about 5 minutes.
It rises at an exponential speed up to ° C. The temperature T ₀ of the printhead substrate 52 is obtained by subtracting this temperature difference from the temperature of the thermistor 62. R _{TS ｜ T0}
Is the resistance of the printhead substrate 50 at a temperature equal to T ₀ . The values of T ₀ and R _{TS |} T ₀ are stored in the memory 67 of the microprocessor 66,
6 is used when calculating the temperature of the printhead substrate 50.

The thresholds for deprime detection and depleted ink source detection are carefully selected to detect all underfilled and depleted ink sources without making false detections. There must be. The temperature of the printhead substrate depends on many factors in addition to the presence or absence of ink in the ink chamber shown in FIGS. 1A and 1B. Such factors include environmental temperature, printer box temperature rise, rate and duration of energy supply to the printhead substrate.

The rate at which the printhead is energized is a function of print density and print mode.
Print density is a measure of the number of dots per square inch associated with the image to be printed, which gives the percentage of pages covered by dots when a particular image is printed. In a preferred embodiment, print density can be measured by a densitometer.

In the "fast print mode", the printer has a maximum drop ejection velocity of 8 KHz and is capable of printing a matrix with 300 x 300 dots per inch. "High quality print mode"
, The printer still has a maximum drop ejection velocity of 8 kHz, but reduces the velocity of the horizontal motion to print a matrix of 300 × 600 dots per inch. In the fast mode, some printers heat the printhead substrate by non-printing pulses, which increases the size of the printed dots. Such heating has another effect on the temperature of the printhead substrate.

FIGS. 4A-4C show the temperature rise of a properly functioning printhead and a deprimed printhead for two different types of print densities and two different types of print modes. Shows. FIG. 4A shows the printer printing at maximum density known as blackout printing (ie, every nozzle fires a drop on every occasion and the print result is a filled black band). Is a plot of temperature versus time for a normally functioning printhead and an empty printhead. The temperature vs. time plot 80 is for a normally functioning printhead. The temperature versus time plot 82 is for the printhead that produces the print results of FIG. 1C. Point 85 is the equilibrium idle temperature of the printhead substrate when the printhead is powered on but in the rest position (ie, not printing). This is due to the ambient ambient temperature and the printer in the air around the resting printhead.
Affected by rising box temperature. The temperature rise of a partially filled printhead above the equilibrium idle temperature is on the order of 90 ° C. The temperature rise of a functioning printhead above the equilibrium idle temperature is less than 35 ° C. In FIG. 4A, the threshold 8 for the incomplete filling detector.
4 is set to 85 ° C. In this setting,
The incomplete fill detector signals an empty incomplete fill condition of 11 seconds.

FIG. 4B shows a plot of temperature versus time for a normal printhead and an underfilled printhead when printing standard density text in the fast print mode. Plot 86 shows the temperature rise of a normally functioning printhead substrate versus time. The maximum temperature rise exceeds the equilibrium idle temperature 91 by approximately 30 ° C. Plot 88 shows temperature rise versus time for an underfilled printhead substrate. The maximum temperature rise of the incompletely filled print head substrate is the equilibrium idle temperature 91.
Above about 40 ° C. Equilibrium idle temperature 91 of 4
The threshold 90 set at 0 ° C prevents false alarms,
An incomplete fill detector can be triggered in a few seconds when the fill is incomplete.

FIG. 4C shows a temperature vs. time plot for a normal printhead and an underfilled printhead when printing standard density text in the high quality print mode. The lower curve, plot 92, shows the temperature rise of a normally functioning printhead substrate versus time. Maximum temperature rise is about 15 ° from equilibrium idle temperature 93
It exceeds C. The upper curve, plot 94, shows the temperature rise versus time for an underfilled printhead substrate. The maximum temperature rise is about 40 ° from the equilibrium idle temperature 93
It exceeds C. The threshold value 96, set above the equilibrium idle temperature by about 30 ° C., prevents false alarms and can trigger an incomplete fill detector within seconds when an incomplete fill occurs.

4 for plots 88, 86 of FIG. 4B.
If the threshold value of A 84 (85 ° C.) is employed, the underfilled printhead represented by plot 88 is not detected and printing is still underfilled. Similarly, the underfill detector of FIG.
Using (65 ° C) erroneously indicates a properly functioning printhead as an incomplete fill. Therefore, the desired threshold for certain types of print density and print mode results in printing and false alarms with an underfilled printhead that destroys the print.

5 and 6 are flow charts of two different embodiments of the present invention. The only difference between these two embodiments is the method of calculating the threshold value, and the other points are the same.

FIGS. 5 and 6 show, on the upper right side of the drawings, that the print head substrate temperature sensor 52 shown in FIGS. 2, 3A and 3B is calibrated after the printer is powered on. There is. This calibration procedure is described based on FIGS. 3A and 3B. After the calibration, the printing work is started. In a printer that scans approximately equal to the width of an average sheet of paper, the temperature of printhead substrate 50 is measured once per scan. For wider print media, such as plots having widths of several feet, the temperature of printhead substrate 50 may be measured multiple times as printhead substrate 50 scans across the media. The temperature is compared to the threshold.

In FIG. 5, the input from the densitometer or other device that gives the density of the printed dots on the page and the input regarding the print mode are the lookups.
Used to access the appropriate threshold delta from the look-up table. This threshold delta is the equilibrium idle temperature (eg, FIGS. 4A, 4B, 4C).
Items 85, 91, and 93) in the above, and the result is used as a threshold value. The threshold delta, which varies with print density and print mode, has the advantage that it can be set to the lowest value for each print density and print mode combination without false detection by the threshold. Have. This embodiment has an advantage that the print head can perform printing with low print density and, at the same time, detect the state of incomplete filling.

In FIG. 6, the threshold delta is constant and is about 8
It is 0 ° C. The threshold value can then be generated by adding the equilibrium idle temperature to it.
This threshold delta must be large to prevent false detections. The constant threshold delta has the advantage of being simple.

5 and 6, when the temperature of the print head substrate 50 is lower than the threshold value, printing is continued. When the temperature rises above the threshold, the detector may perform another test if the temperature is above the threshold for longer than the allotted time. The allotted time can be measured in milliseconds or the number of times the temperature exceeds a threshold or the persistence of the temperature above the threshold can be measured by another parameter. If the temperature does not exceed the threshold for more than the allotted time, the printer continues printing. If the threshold is exceeded, the printhead is sent to a service station, such as service station 107 shown in FIGS. 9A and 9B.

The service station 107 shown in FIGS. 9A and 9B is an example of the service station arranged in the desktop printer 100. In the present invention, a fully automatic cartridge selector or primer
Includes the use of any type of service station in any inkjet printing device, including service stations with. Protective front lid (protecti
A slide bar 110 for the carriage 108 is provided under the ve front lid 102. When an incomplete fill condition is detected, the carriage 108 moves to the service station 107 and the individual ink cartridges 116.
Are manually selected for refilling using the cartridge selector 114. Once the cartridge 116 is selected for refilling, the manual fill actuator 112 is used to fill the cartridge 116. After refilling the cartridge 116, the service station wipes the nozzle plate 33.

Another embodiment pulses the ink chambers 24 shown in FIGS. 1A and 1B to check if they eject ink drops. If the drop ejection fails, it warns that the ink source 26 is low and warns that the inkjet cartridge 20 should be replaced. If the inkjet cartridge 20 passes this test, then each time it passes this test several more times, the printhead 20 can continue printing. Otherwise, it is warned that the ink source 26 is low and then warns of replacement of the print cartridge 20.

FIG. 7 shows a flow chart of one embodiment of the present invention that avoids the high temperatures that can be reached when a dense print is made by an underfilled printhead or a depleted ink source. is doing. In this embodiment, refilling is not performed during the printing work. Instead, the current to the firing resistor of an underfilled printhead is shut off and allowed to cool.

The individual operations of the other embodiment shown in FIG.
It is very similar to that of the embodiment of FIG. 6 and the main difference between these embodiments is in the order of operation. Both flowcharts incorporate a constant threshold delta (approximately 8
0 ° C), and add it to the equilibrium idle temperature,
It starts by creating a threshold. in addition,
In both of the flowcharts, the print head substrate temperature sensor 52 shown in FIGS. 2, 3A, and 3B is calibrated before the printing operation is started.

As the work is printed, both systems (represented in FIGS. 6 and 7) monitor the temperature of all printhead substrates 50. In the system of FIG. 7, the temperature of one cartridge printhead board 50 (typically, there are four printhead boards in separate cartridges 20 as shown in FIG. 8) is the threshold. When exceeded, the printer will stop printing with that cartridge. This can be done in many ways. For example, stop sending ejection pulses to the ink chamber 24 of that cartridge, or
The energy of the "injection pulse" is eliminated by reducing its voltage or duration. Therefore, thermal
No current flows through the firing resistor of the inkjet printhead, which keeps the printhead temperature at a safe level. The current remains cut off after the printing job is completed.

Before starting the next printing operation, each cartridge is inspected by the drop detection system.
This, along with other problems that may occur, will detect cartridges that were underfilled during previous printing operations. In the embodiment described with reference to FIG. 7, replacement of a non-functioning cartridge has been described, but multiple cartridge recovery methods can also be implemented. (Eg refill, nozzle spitting (nozz
(le spitting), nozzle wiping, etc.) By delaying the servicing and recovery of the pen by the time interval between plots, an alternative, simpler algorithm to handle the print job can be used.

One of the advantages of the embodiment of FIG. 7 is that it handles print cartridge failures in low and high density print jobs alike. In the embodiment of FIG. 6, the failures that occur during low density print operations may not exceed the threshold and the print operation continues even when the cartridge is not printing.

The embodiment of the invention shown in FIG. 7 is implemented in a printer with a single ink jet cartridge, such as a printer of a facsimile machine, and when the printhead substrate temperature exceeds a threshold, the printer prints. Stop and inform the user.

8A and 8B show block diagrams of circuits used to implement the present invention. Four ink cartridges are provided, and each cartridge is
It includes an ink source held at a negative back pressure by a spring bag, a substrate, a temperature sensor on the substrate, and a tab circuit for transmitting the output of the temperature sensor to a flexible circuit. The output of the temperature sensor is A /
It is supplied to the D converter. The multiplexer connects each temperature sensor of the various print cartridges to a voltage divider network containing a precisely calibrated thermistor. The output of the thermistor is also supplied to the A / D converter. The output of the A / D converter is supplied to the microprocessor.

Inputs from memory, threshold tables, densitometers and print modes are used to calculate thresholds. (In an alternative embodiment with a constant threshold delta, only the input from memory is needed.) The microprocessor calculates the threshold and processes the data from the temperature sensor to determine the state of underfilling. Determine if there is.

The preferred embodiments of the present invention described above are provided to illustrate and explain the present invention. This is not to limit the invention to the precise details disclosed. It is therefore clear that many modifications and variations are possible. These examples were chosen because they are the best description of the best mode of the invention. Accordingly, the invention is defined by the claims that follow.

Although the embodiments of the present invention have been described in detail above, the respective embodiments of the present invention will be listed below. (1) A method of detecting and correcting air intrusion of a print head including the following steps (a) to (e). (A) measure the temperature of the printhead during the printing operation, (b) generate a threshold temperature representing air ingress of the printhead, and (c) compare the threshold temperature with the temperature of the printhead. , (D) If the print head temperature is lower than the threshold temperature, continue the printing operation,
(E) When the temperature of the print head is higher than the threshold temperature, the air ingress of the print head is corrected. (2) The step (b) of the threshold generation further includes a step of changing the threshold temperature by changing the equilibrium idle temperature, and detecting the air intrusion of the print head according to the above (1), How to fix it. (3) The power supply to a print head having a temperature higher than a threshold value is shut off, the print work is completed, and when the print work is completed, the step of adjusting the print head is further included. This is a method of detecting and correcting air intrusion of the print head described in (2). (4) The method for detecting and correcting air intrusion of the print head according to (2) above, which further comprises the step of refilling the print head and continuing printing. (5) The method for detecting and correcting air intrusion of the print head according to the above item (1), which includes a step of changing the threshold temperature according to a change in print density. (6) The step of shutting off the power supplied to the print head having a temperature higher than the threshold value, completing the print operation, and further adjusting the print head when the print operation is completed. This is a method for detecting and correcting air intrusion of the print head described in (5). (7) The method for detecting and correcting air intrusion of the print head according to the above item (5), which includes the step of refilling the print head and continuing printing. (8) A method for detecting and correcting air intrusion of a print head according to the above item (1), which includes a step of changing a threshold temperature depending on a print mode. (9) The method for detecting and correcting air intrusion of the print head according to the above item (1), which includes a step of changing the threshold temperature by changing the print density and the print mode. (10) The correcting step (e) shuts off the power supplied to the print head having a temperature higher than a threshold value,
When the print work is completed and the print work is completed,
The method for detecting and correcting air intrusion of the print head according to the above item (1), further comprising the step of adjusting the print head. (11) The method (e) of correcting includes a step of terminating the printing operation and notifying the user, and is a method for detecting and correcting air intrusion of the print head according to the above item (1). (12) The correcting step (e) includes the step of refilling the print head and completing the printing operation by the refilled print head.
This is a method of detecting and correcting air intrusion of the print head described in (1). (13) The step (e) of correcting includes the step of refilling the print head and starting another printing operation, and detects and corrects the air intrusion of the print head according to the above item (1). Is the way. (14) A method of detecting and correcting air intrusion of the print head, which includes the following steps (f) to (m). (F) To calibrate the resistance temperature sensor provided on the print head, (g) measure the equilibrium idle temperature of the print head, (h) start the printing operation, and (i) measure the temperature of the print head. And using a resistance temperature sensor provided on the printhead to generate a threshold temperature (j) that signals the ingress of air into the printhead,
(K) comparing the threshold temperature and the printhead temperature,
(L) If the printhead is below the threshold temperature,
The printing operation is continued, and (m) when the temperature of the print head is higher than the threshold temperature, the print head is corrected for air intrusion. (15) The above-mentioned item (14), further including a step of changing the threshold temperature by changing the equilibrium idle temperature.
A method of detecting and correcting air ingress of a print head as described. (16) The method further comprising the step of shutting off the power supplied to the print head having a temperature higher than a threshold value, completing the print operation, and adjusting the print head when the print operation is completed. (14) A method for detecting and correcting air intrusion of the print head. (17) The method for detecting and correcting air intrusion of the print head according to the above (14), which includes the steps of refilling the print head and continuing printing. (18) A method for detecting and correcting air intrusion of the print head according to the preceding paragraph (14), which comprises the step of reading the output of the densitometer and changing the threshold temperature by changing the output of the densitometer. is there. (19) The method further comprises the steps of shutting off the power supplied to the print head having a temperature higher than the threshold value, completing the print work, and adjusting the print head when the print work is completed. This is a method for detecting and correcting air intrusion of the print head as described in (17) above. (20) The method for detecting and correcting air intrusion of the print head according to the above item (17), which includes the steps of refilling the print head and continuing printing.

[0047]

As described above, the present invention can be installed in either printer system having a single ink cartridge or a plurality of ink cartridges, and the cartridge is incompletely filled (caused by growth of air bubbles or ink consumption). ) Is easily detected,
After the printing operation is interrupted or completed, the printing operation and the movement of the cartridge can be controlled so that the ink can be replenished or the cartridge can be replaced.

[Brief description of drawings]

FIG. 1A is a schematic diagram of an inkjet cartridge with air bubbles.

FIG. 1B is a schematic diagram of an inkjet cartridge with large air bubbles that empty multiple ink chambers.

FIG. 1C is a diagram showing printout with an incompletely filled inkjet cartridge.

FIG. 2 is a block diagram of a printhead substrate temperature sensor provided on the printhead substrate used in the present invention.

FIG. 3A is a circuit diagram of a printhead substrate temperature sensor circuit used in an embodiment of the present invention.

FIG. 3B is a circuit diagram of a printhead substrate temperature sensor circuit used in another embodiment of the present invention.

FIG. 4A is a diagram showing printhead temperature change to compare the effect of incomplete filling of an inkjet cartridge.

FIG. 4B is a diagram showing printhead temperature changes for comparing the effects of incomplete filling of inkjet cartridges.

FIG. 4C is a diagram showing printhead temperature change to compare the effect of incomplete filling of an inkjet cartridge.

FIG. 5 is a flowchart for explaining the operation of the embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of another embodiment of the present invention.

FIG. 7 is a flow chart for explaining the operation of another embodiment of the present invention.

FIG. 8A is a block diagram of a circuit used in an embodiment of the present invention.

FIG. 8B is a block diagram of a circuit used in an embodiment of the present invention.

FIG. 9A is a schematic diagram of a desktop printer including a service station.

9B is a partial detailed view of FIG. 9A.

[Explanation of symbols]

 20: Inkjet Cartridge 22: Air Bubble 32: Nozzle 33: Nozzle Plate 24, 54: Ink Chamber 50: Printhead Substrate 52: Printhead Substrate Temperature Sensor 66: Microprocessor 67: Memory 68: Threshold Delta 70: Concentration Total 100: Desktop Printer 107: Service Station

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Janet E. Mebane San Diego, California, United States Vista La Questa Court 10020 (72) Inventor William Jay Walsh San Diego, California, United States Hawk Street 4234 ( 72) Inventor Inouen Poway, California, USA Sagewood Drive 13856

Claims (20)

[Claims] 1. A method of detecting and correcting air ingress of a printhead comprising the following steps (a) to (e): (A) measuring the temperature of the printhead during a printing operation, (b) generating a threshold temperature representative of air ingress of the printhead, and (c) the threshold temperature and the printhead. Comparing the temperatures, (d) if the temperature of the print head is lower than the threshold temperature, the printing operation is continued, and (e) if the temperature of the print head is higher than the threshold temperature, the printing is performed. Correct the air ingress of the head. 2. The air ingress of the printhead of claim 1 wherein step (b) of threshold generation further comprises the step of altering the threshold temperature by changing the equilibrium idle temperature. How to detect and fix. 3. The method further comprises the steps of shutting off power supplied to a print head having a temperature higher than the threshold value, completing the print operation, and adjusting the print head when the print operation is completed. The method of detecting and correcting air ingress of a printhead according to claim 2, wherein: 4. Refilling the printhead,
The method of detecting and correcting air ingress of a print head according to claim 2, further comprising the step of continuing the printing. 5. The method of detecting and correcting air ingress of a printhead as recited in claim 1, including the step of changing said threshold temperature by a change in print density. 6. A step of shutting off power supplied to the print head having a temperature higher than the threshold value to complete the print operation, and when the print operation is completed, adjusting the print head is further performed. The method of detecting and correcting printhead air ingress according to claim 5, comprising: 7. Refilling the printhead,
The method of detecting and correcting air ingress of a printhead as recited in claim 5, including the step of continuing the print. 8. The method of detecting and correcting air ingress of a printhead as recited in claim 1, including the step of changing a threshold temperature depending on the print mode. 9. A method of detecting and correcting air ingress of a printhead according to claim 1, including the step of changing the threshold temperature by changing the print density and the print mode. . 10. The modifying step (e) includes shutting off power supplied to the print head having a temperature higher than the threshold value to complete the printing operation, and when the printing operation is completed, the printing operation is completed. The method of detecting and correcting air ingress of a printhead of claim 1, further comprising the step of adjusting the head. 11. The method according to claim 1, wherein the modifying step (e) includes the step of terminating the printing operation and notifying the user of the print head. Method. 12. The method of claim 1, wherein the modifying step (e) comprises refilling the printhead and completing the printing operation with the refilled printhead. To detect and correct air ingress in your printhead. 13. The printhead air ingress of claim 1 wherein said modifying step (e) includes the steps of refilling said printhead and initiating another print job. How to detect and fix. 14. A method of detecting and correcting printhead air ingress comprising the steps (f) to (m) below. (F) The resistance temperature sensor provided in the print head is calibrated, (g) the equilibrium idle temperature of the print head is measured, (h) the printing operation is started, and (i)
A resistance temperature sensor provided on the print head is used to measure the temperature of the print head,
(J) generating a threshold temperature indicating the invasion of air in the printhead, (k) comparing the threshold temperature with the temperature of the printhead, and (l) the printhead has the threshold temperature. If the temperature is lower than the threshold temperature, the printing operation is continued, and (m) if the temperature of the print head is higher than the threshold temperature, correction of air intrusion of the print head is performed. 15. The method of detecting and correcting printhead air ingress of claim 14, further comprising modifying the threshold temperature by changing the equilibrium idle temperature. 16. A step of shutting off the power supplied to the print head having a temperature higher than the threshold value to complete the print operation, and adjusting the print head when the print operation is completed. 15. A method of detecting and correcting printhead air ingress according to claim 14 including. 17. The method of detecting and correcting air ingress of a printhead of claim 14 including the steps of refilling the printhead and continuing the print. 18. The method according to claim 14, further comprising the step of reading the output of the densitometer and changing the threshold temperature by changing the output of the densitometer. , How to fix. 19. The electric power supplied to the print head having a temperature higher than the threshold value is cut off to complete the printing operation, and when the printing operation is completed,
18. The method of detecting and correcting air ingress of a printhead of claim 17, further comprising the step of adjusting the printhead. 20. A method of detecting and correcting printhead air ingress according to claim 17, comprising the steps of refilling the printhead and continuing the print.