JPH09193396A - Image-forming apparatus and method for discriminating state of print head for the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to effectively decide the propriety of mounting by the direct detection of the state of a print head with a simple circuit configuration without providing a detector by deciding the state of the head according to the detected discharge time of a capacitor. SOLUTION: Since the charge stored in an electrolytic capacitor is instantaneously discharged if a print head and a flexible cable are electrically conducted therebetween, a terminal voltage is relatively rapidly lowered to a ground level. Fig. (a) shows the discharge characteristics at the time of contact failure and Fig. (b) shows the discharge characteristics at the time of contact. The contact state between the head and the cable is directly decided by utilizing the difference of the discharge characteristics. The propriety of the contact is decided according to the voltage value after a plurality of monitoring are conducted by using the counter value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for printing characters, figures, images and the like using a print head in the form of a removable cartridge such as an ink jet head cartridge, and a state determination of the print head for the apparatus. Regarding the method, in particular, the improvement of the quality determination method for mounting the print head on the apparatus main body is attempted.

[0002]

2. Description of the Related Art Conventionally, a printing apparatus for printing on a print medium such as paper, OHP sheet, cloth (hereinafter also referred to as recording paper or simply paper) has a form in which a print head is mounted by various printing methods. Has been proposed by. The print head includes a wire dot system, a thermal system, a thermal transfer system, and an inkjet system.

In particular, the ink jet method is a method of ejecting ink directly onto a print medium, and therefore has attracted attention as a quiet printing method with low running cost and low noise, and has been rapidly popularized in recent years.

In the ink jet system, therefore, a print head is used which has an element for generating energy used for ejecting ink in an ejection member such as a nozzle of a print head, and a large number of these ejection members are aligned. Things are now commonplace. More specifically, for example, the head is heated by energizing a heating element (hereinafter, referred to as an ejection heater) provided in a minute liquid path communicating with an ejection port for ejecting ink, thereby generating ink around the heater. This is due to the method of printing by ejecting ink droplets from the ejection port (such as the bubble jet method advocated by Canon Inc.) by utilizing the rapid volume change that occurs during heating or foaming. A large number of discharge members (hereinafter also referred to as nozzles) including outlets, liquid paths, and discharge heaters are arranged in a predetermined direction.

In such a print head or a printing apparatus using the print head, a so-called block division drive system is generally used in which nozzles are divided into groups by a predetermined number and an ejection heater is driven in each group (block). . This is an effective method for downsizing the power supply system such as the power supply for driving the head, the power supply connector and the flexible cable. Also, in order to perform stable ejection operation in consideration of the characteristics of the ejection heater and ink, it is necessary to suppress fluctuations in the voltage supplied to the head as much as possible, so it is necessary to finely adjust the voltage value for the inkjet head power supply. Therefore, the above method is also effective in simplifying such fine adjustment.

Further, since the head is mounted on the printing apparatus of the serial printing system, energy is supplied from the controller on the main body side through the flexible cable, so that it is necessary to stably supply the voltage. Is. For this reason, an electrolytic capacitor is generally provided on the controller side to suppress voltage fluctuations.

By the way, this type of printing apparatus may be provided with a judging means for judging whether or not the print head cartridge is set at the correct position with respect to the apparatus main body. As a conventional determination means, there is one that forms a switch circuit by providing a print wiring or the like in the print head cartridge and makes a determination based on the ON / OFF state of the switch circuit when the cartridge is mounted. In other words, the circuit of the main body of the device configures the switch circuit to turn on if the cartridge is properly set, and keeps the off state otherwise, and makes a determination by detecting these on / off signals. The means to do was adopted.

[0008]

However, in this conventional determination means, it is necessary to form a switch circuit by the printed wiring in a part of the print head, and the apparatus main body is also provided with a detection circuit responsive to the switch circuit. There is a problem in that the circuit configuration must be provided and the circuit configuration becomes complicated. Also,
This is an indirect judgment based on the relative position (mechanical positional relationship) between the print head cartridge and the main body of the apparatus, and is not a direct judgment of the connection state of the drive signal or control signal transmission terminals. There was also the problem of low reliability.

The present invention solves such a conventional problem and eliminates the need to provide a detection circuit in the printhead cartridge, and directly detects the state of the printhead with a simple circuit structure to ensure the quality of mounting. The purpose is to be able to judge.

[0010]

To this end, the present invention provides
In an image forming apparatus that forms an image using a print head, a capacitor inserted in a power line between the print head and the print head to stabilize the voltage supplied to the print head, and a discharge of the capacitor. It is characterized by comprising means for detecting time, and means for judging the state of the print head based on the detected discharge time.

The present invention also relates to a printhead used in an image forming apparatus having a capacitor inserted in a power line between the printhead and the printhead for stabilizing the voltage supplied to the printhead. In the state determination method, the discharge time of the capacitor is detected, and the state of the print head is determined based on the detected discharge time.

In these, the capacitor can be an electrolytic capacitor.

The determination is made based on the difference in the discharge time depending on the closed / open state of the power line.

The determination is made by determining the quality of the electrical connection with the print head based on the difference in the discharge time, and / or the quality of the mounting state of the print head, and / or the print head. It is possible to determine whether or not there is an abnormal state such as a disconnection of the power supply line inside.

Further, in the above, the print head has a plurality of ejection ports and a plurality of energy generating elements provided to generate energy used for ejecting ink from the plurality of ejection ports. It may have the form of an inkjet head.

Here, the print head may include, as the energy generating element, an electrothermal converting element that generates thermal energy that causes film boiling in the ink.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

(Example of Embodiment) FIG. 1 is a block diagram showing a schematic configuration of a control system of an ink jet printer according to one embodiment of the present invention. In the figure, a main controller 105 controls the operation of the entire printing apparatus, receives print data sent from the host computer 102, develops it into a print image, and prints it on a print medium such as paper. We are in control. The main controller 105 includes a CPU in the form of a microprocessor and the like, and a ROM 107 and a CP that store a control program for the CPU (a program or the like corresponding to the processing procedure described later with reference to FIG. 6) and various data.
It is connected to a RAM 108 or the like used as a work area for U and temporarily storing various data.

Reference numeral 101 denotes an AC adapter, which supplies power to this printing apparatus. Reference numeral 113 is a line feed motor for conveying a recording medium such as a print medium, and 111 is a carriage motor for scanning a carriage on which a print head is mounted. Reference numerals 110 and 112 denote motor drivers, which respectively input control signals from the main controller 105 and rotationally drive corresponding motors at appropriate times. A head driver 106 drives the print head 109 according to the print data stored in the RAM 108 to perform printing (print operation).

FIG. 2 is a perspective view showing the outline of the mechanical structure of an ink jet printer applicable to this embodiment. The carriage 201 mounts the print head 109 and the cartridge guide 202, and includes the guide shaft 203 and the guide shaft 2.
It is possible to drive on 04. Cartridge guide 2
A black ink cartridge 210 containing black ink and a color ink cartridge 209 containing three color inks of yellow, magenta, and cyan can be inserted into the ink cartridge 02. The supply path communicates with the inkjet print head 109. Further, the recording paper 205 is fed into the printer apparatus main body by the paper feed roller 206, and the paper feed roller 207, the pinch roller (not shown), the paper pressing plate 2
The sheet is nipped and conveyed by 08 and the printing is performed on the front surface of the inkjet head 109.

If the print head and the ink cartridge are such that the ink can be communicated with each other when the print head and the ink cartridge are mounted in the apparatus, the carriage is separately provided when the life of the head is exhausted or when the ink is exhausted. It may be detachable from the 201 or the cartridge guide 203, or may be detachably attached to the cartridge guide 203. Further, the mechanical mounting of the print head at a predetermined position and the connection of the connector for enabling the electrical connection to the apparatus main body are completed so that they are completed almost simultaneously with the mounting operation. The configuration of the mounted portion can be appropriately determined.

FIG. 3 is a schematic view for explaining the structure of the print head 109 of this example. Reference numeral 306 denotes a liquid path of the inkjet head, and the heating resistor 3 is provided in each liquid path 306.
04 (discharging heater) is provided. The heating resistor 304 generates heat when a predetermined current is applied by the head driver 106, and the heat causes film boiling in the ink to generate bubbles, and the ejection ports 302 are generated according to the growth of the bubbles. Ink droplets are ejected from. The heaters 304 are formed on the silicon substrate 301 by the same method as in the semiconductor manufacturing process. 3
Reference numeral 03 is a partition that defines each liquid passage 306, and 305 is a common liquid chamber that communicates with each liquid passage 306 and supplies ink. 307 is a top plate.

A control method for monitoring the contact state between the terminals on the print head side and the flexible cable side will be described below.

FIG. 4 is a block diagram for explaining the structure of the connection portion between the print head and the controller of this embodiment, and FIG. 5 is a timing chart showing the control signals output from the controller of FIG. 4 to the print head. is there.

First, the control method during printing will be described. First, in order to supply the drive voltage VH to the print head 109, the DC / DC converter 104 for VH generation
Can be output. When the controller 404 receives the print data from the host computer 102, the controller 404 serially transfers the data to the print head 109 in synchronization with the clock signal SCLK shown in FIG. 5 (serial data shown in FIG. 5). The print head 109 used in this example has a structure of 128 nozzles, and therefore 128 bits of print data are sequentially fetched into a shift register provided in the print head. When the transfer of the print data for 128 bits is completed, the controller 4
A print signal 04 outputs a latch signal for determining the 128-bit print data to the print head 109, and sets print print data corresponding to each nozzle in the print head. And print head 109
It outputs a control signal for driving the.

The drive control signals are BlockENB [2-0], ODDBNB, EV as shown in FIG.
Block composed of ENBNB and HeatENB
128 nozzles are divided into 16 groups by a predetermined number by ENB [2-0], ODDENB, and EVENENB, and time-division driving is performed, and a discharge heater in the print head 109 is energized for each group by a HeatENB signal. As a result, printing is performed by ejecting ink from the ejection port.

Next, the control method for monitoring the contact state between the terminals on the print head side and the flexible cable side will be described in detail. The print head 109 is usually connected to the apparatus body side via a flexible cable 402 or the like, and the print head drive voltage VH is also supplied from the apparatus body to the print head via the flexible cable. However, since the print head drive voltage is required to have an accuracy of VH ± 0.3 V within the allowable fluctuation range,
A capacitor (preferably an electrolytic capacitor from the viewpoint of capacity) 403 is provided in the power line on the apparatus main body side for the purpose of suppressing fluctuations in the supply voltage to the head, that is, smoothing the supply voltage.

In this example, the contact state between the print head and the flexible cable is monitored by utilizing the discharge time constant of the electrolytic capacitor 403. The mode of monitoring will be described in detail below.

FIG. 6 is a flow chart showing the operation sequence at the time of contact detection. For example, when the power source of the apparatus is turned on, the print head and / or the ink cartridge is attached / detached, and the print operation is on standby, it is started at an appropriate timing. You can

When this procedure is activated, first, in order to supply the drive voltage VH to the print head 109, a VH generating D is generated.
The C / DC converter 104 can be output (step S1). In response to this, the VH generating DC / DC converter 104 starts charging the electrolytic capacitor 403 (step S3). At the same time, the A / D converter 401 takes in the terminal voltage of the electrolytic capacitor 403 to perform A / D conversion, and monitoring is started (step S5). When charging is completed, the controller 404 writes the A / D conversion value in the memory 405 (step S7), and turns off the output of the VH generating DC / DC converter (step S).
9).

After that, the controller 404 outputs the fixed test data provided for detecting the contact state between the print head and the flexible cable to the print head 10.
9 is serially transferred, and after the transfer is completed, a control signal is output (step S11), and the terminal voltage of the electrolytic capacitor 403 is monitored via the A / D converter 401 every predetermined set period. That is, after resetting a counter M (these timers or counters may be hardware or software) for monitoring the number of times of activation of a timer for determining a predetermined period (step S13), the timer is activated ( In step S15), the A / D value taken in when the timer counts up is verified (steps S17 to S21).

Focusing on the terminal voltage of the electrolytic capacitor 403, if the print head and the flexible cable are electrically connected, the electric charge charged in the electrolytic capacitor 403 is instantly discharged, so that the terminal voltage is It drops to ground level relatively quickly. On the other hand, when the printhead-flexible cable is electrically disconnected due to a poor connection, the electrolytic capacitor 403
Since the electric charge charged in is discharged gradually due to its time constant, it takes some time to complete the discharge.

FIG. 7 shows the discharge characteristics of the electrolytic capacitor 403. FIG. 7A shows the discharge characteristics when the contact is defective, and FIG. 7B shows the discharge characteristics when the contact is made. In this example, the contact state detection between the print head and the flexible cable is directly determined by utilizing the difference in the discharge characteristics, and the voltage value after performing the monitoring a plurality of times using the counter value M The quality of contact is determined by.

That is, if the discharge completion is not detected as a result of the verification in step S21 (step S23),
The value of the timer start counter is incremented by 1 to step S
When the discharge completion is detected (step S23), it is determined whether the timer starting number counter value M is smaller than the predetermined limit value N (step S27). If an affirmative determination is made here, it means that the discharge has been performed relatively quickly, so it is determined that the contact state is good (step S29), and control is transferred to normal processing, for example, preparation for printing operation or the like. be able to. On the other hand, if the determination is negative, it means that the discharge was not performed promptly, so it is determined that the contact state is bad (step S31), and a predetermined error mode, for example, an error message is displayed or an alarm sound is generated. It is possible to shift to a mode in which the processing of (1) is performed and prompt the operator to perform the required processing.

According to the above-described embodiment, by using the A / D converter 401 which is a resource in the main controller 105, a new detection circuit is used for detecting the connection state between the print head 109 and the apparatus main body. No longer needed. That is, the print head 109 is simply added by the control by software.
It is now possible to detect the connection state between the device and the main body of the device, and it is possible to improve the reliability of the determination with an inexpensive configuration.

(Other Embodiments) In the above example, the print head and the ink cartridge are separately or integrally attachable to and detachable from each other, and the configuration for determining whether or not the print head is mounted at the correct position has been described. By using the above configuration, it is possible to determine a failure or abnormality of the print head, such as a disconnection of the power supply line in the print head. That is, if the power line is broken,
This is because the electrical connection between the print head and the apparatus main body is cut off and the power line is opened, so that this can be detected by the same operation as described above.

The present invention can be effectively applied even if the print head is fixed to the apparatus. That is, in the case of accepting the operation of attachment / detachment by the operator, the above-described connection failure may occur due to operation failure or the like, so the present invention is effective in preventing this, but
This is because even if it is fixed, it is effective in detecting the above-mentioned failure or abnormality.

In addition, the present invention is limited to the above-described ink jet type image forming apparatus as long as the apparatus main body side is provided with a capacitor for stabilizing the voltage supply to the print head, that is, smoothing the supply voltage. I can't. That is, the present invention can be applied to an image forming apparatus using a print head of a thermal type or a thermal transfer type, for example.

(Others) When the present invention is applied to an ink jet system, means for generating heat energy as energy used for ejecting ink (for example, an electrothermal converter or laser light) ),
The present invention brings excellent effects in a print head and a printer of the type in which a change in the state of ink is caused by the heat energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. Applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding the nucleate boiling, causing the electrothermal transducer to generate thermal energy, causing film boiling on the heat acting surface of the printhead. This is effective because bubbles can be formed in the liquid (ink) corresponding to this drive signal on a one-to-one basis. Due to the growth and contraction of this bubble, the liquid (ink)
To form at least one droplet. When this drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the liquid (ink) having particularly excellent responsiveness can be obtained.
It is more preferable that the discharge can be achieved. As the pulse-shaped drive signal, US Pat. No. 4,463,359,
The one described in the specification of US Pat. No. 4,345,262 is suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

In addition to the combination of the ejection port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, the print head is constructed in the following manner. The present invention also includes a configuration using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose a configuration in which the heat acting portion is arranged in a bending region. In addition, for multiple electrothermal transducers,
Japanese Unexamined Patent Publication No. 59-123670, which discloses a configuration in which a common slit is used as the discharge portion of the electrothermal converter, and Japanese Laid-Open Patent Publication No. 59-63, which discloses a structure in which an opening for absorbing a pressure wave of thermal energy is associated with the discharge portion. The effects of the present invention are effective even with a configuration based on Japanese Patent Laid-Open No. 138461. That is, according to the present invention, recording can be performed reliably and efficiently regardless of the form of the print head.

Further, the present invention can be effectively applied to a full-line type print head having a length corresponding to the maximum width of a recording medium that can be printed by the printer. Such a print head may have a configuration that satisfies the length by combining a plurality of print heads, or a configuration as a single print head that is integrally formed.

Further, it is preferable to add a discharge recovery means for the print head, a preliminary auxiliary means, etc. as the constitution of the printer of the present invention because the effects of the present invention can be further stabilized. Specifically, heating is performed on the print head using capping means, cleaning means, pressurizing or suction means, an electrothermal converter, another heating element, or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

Also, regarding the type or number of print heads to be mounted, for example, it corresponds to 1 color ink.
In addition to those provided with only a plurality of inks, a plurality of inks may be provided corresponding to a plurality of inks having different recording colors and densities. That is, for example, the printing mode of the printer is not limited to a printing mode of only a mainstream color such as black, but may be any of a print head integrally formed or a combination of a plurality of print heads. The present invention is also very effective for an apparatus provided with at least one of the full-color recording modes by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change from the solid state of the ink to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying heat energy such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as a form of the ink jet printer to which the present invention can be applied, other than the one used as an image output terminal of information processing equipment such as a computer,
A copying machine combined with a reader or the like, or a facsimile machine having a transmission / reception function may be used.

[0047]

As is apparent from the above description, according to the present invention, it is not necessary to provide a special switch or a detection circuit on the print head or the apparatus main body side, and in order to stabilize the supply of the print head driving voltage. Since the presence or absence of electrical connection between the print head and the main body of the device is determined by using the time constant when the capacitor provided in It becomes possible to directly and surely determine the presence or absence.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a control system of an inkjet printer according to an example of an embodiment of the present invention.

FIG. 2 is a perspective view showing an outline of a mechanical configuration of an inkjet printer applicable to the above example.

FIG. 3 is a schematic diagram for explaining the structure of a print head used in the printer of FIG.

FIG. 4 is a block diagram for explaining a configuration of a connection portion between a print head and a controller in the above example.

5 is a timing chart showing control signals output from the controller of FIG. 4 to a print head.

FIG. 6 is a flowchart showing an example of an operation sequence when a contact is detected according to the above example.

7A and 7B are diagrams showing discharge characteristics when a connection between the print head and the apparatus main body of the capacitor used in the above example is detected.

[Explanation of symbols]

 101 AC Adapter 102 Host Computer 103 DC5V Generation DC / DC Converter 104 Head Drive Voltage Generation DC / DC Converter 105 Main Controller 106 Head Driver 107 ROM 108 RAM 109 Printhead 110 Carriage Motor Driver 111 Carriage Motor 112 Line Feed Motor Driver 113 Lines Feed motor 201 Carriage 202 Cartridge guide 203 Guide shaft 204 Guide shaft 205 Print paper 206 Paper feed roller 207 Paper feed roller 208 Paper pressure plate 209 Color ink cartridge 210 Black ink cartridge 301 Silicon substrate 302 Discharge roller 303 Nozzle partition 304 Heat generating resistor ( Heater) 305 Common liquid chamber 306 Ink jet Head of the nozzle 307 top plate 401 A / D converter 402 the flexible cable 403 electrolytic capacitor 404 controller 405 memory

Claims (14)

[Claims] 1. An image forming apparatus for forming an image using a print head, comprising: a capacitor inserted in a power line between the print head and the print head for stabilizing a voltage supplied to the print head. An image forming apparatus comprising: means for detecting a discharge time of the capacitor; and means for determining a state of the print head based on the detected discharge time. 2. The image forming apparatus according to claim 1, wherein the capacitor is an electrolytic capacitor. 3. The image forming apparatus according to claim 1, wherein the determination unit makes the determination based on a difference in the discharge time according to a closed / open state of the power line. 4. The determination means determines whether the electrical connection with the print head is good or bad based on the difference in the discharge time, and determines whether the mounting state of the print head is good or bad. The image forming apparatus described. 5. The determination unit determines whether or not there is an abnormal state of the print head by determining the quality of electrical connection with the print head based on the difference in the discharge time. The image forming apparatus described. 6. The ink jet head according to claim 6, wherein the print head has a plurality of ejection ports and a plurality of energy generating elements provided to generate energy used for ejecting ink from the plurality of ejection ports. The image forming apparatus according to any one of claims 1 to 5, which has a form. 7. The image forming apparatus according to claim 6, wherein the print head includes, as the energy generating element, an electrothermal conversion element that generates heat energy that causes film boiling in the ink. 8. A method of determining the state of the print head used in an image forming apparatus having a capacitor inserted in a power line between the print head and the print head to stabilize the voltage supplied to the print head. The method for determining the state of a printhead for an image forming apparatus, wherein the discharge time of the capacitor is detected, and the state of the printhead is determined based on the detected discharge time. 9. The method for determining the state of a printhead for an image forming apparatus according to claim 8, wherein the capacitor is an electrolytic capacitor. 10. The state determination of the print head for an image forming apparatus according to claim 8, wherein the determination is performed based on a difference in the discharge time according to a closed / open state of the power line. Method. 11. The image forming apparatus according to claim 10, wherein the quality of the electrical connection with the print head is determined based on the difference in the discharge time, and the quality of the mounting state of the print head is determined. Method for print head condition determination. 12. The image forming apparatus according to claim 10, wherein the presence or absence of an abnormal state of the print head is determined by determining whether the electrical connection with the print head is good or not based on the difference in the discharge time. Method for print head condition determination. 13. The ink jet head according to claim 13, wherein the print head has a plurality of ejection ports and a plurality of energy generating elements provided to generate energy used for ejecting ink from the plurality of ejection ports. 13. The method for determining the state of a printhead for an image forming apparatus according to claim 8, which has a form. 14. The print for an image forming apparatus according to claim 13, wherein the print head has, as the energy generating element, an electrothermal conversion element that generates thermal energy that causes film boiling of ink. Head status determination method.