JP2713790B2 - Ink jet recording device - Google Patents

Description

Description: 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 having a configuration for setting a supply voltage for driving a recording head.

[Prior Art] In recent years, the practical use of digital copying machines and printers has been rapidly progressing. In particular, digital color printers and color copying machines have digital features such as easy color adjustment and image processing. It is becoming mainstream in the field of color printers and color copiers because it is utilized.

The recording methods of these recording devices include an electrophotographic method,
There are various methods such as an ink jet method and a thermal transfer method. However, the ink jet method, for example, a recording method such as a so-called bubble jet method in which ink droplets are ejected by heat generated by an ejection heater, has the following problems. There is.

FIG. 8 is a schematic side view showing a configuration example of an ink jet type full color printer.

In FIG. 1, the recording paper 9 stored in the cassette 10 is
The sheet is separated and conveyed by the sheet feeding roller 7,
As a result, the transfer timing is adjusted, and the transfer is performed by the transfer belt 5 in the direction of the arrow in the figure. The recording heads 1 to 4 of the ink jet system are full multi-heads in which ejection ports are arranged in accordance with the recording paper width. As the recording paper 9 is transported, cyan (C), magenta (M), and yellow (Y ) And black (K) in this order to print a full-color image. After that, the recording paper 9 is discharged
Is discharged out of the apparatus.

The recording head is, for example, A4 size 297 mm length 400
If recording is performed at a recording density of dpi, the number of ejection ports is 297 (mm) × 400 (dpi) ÷ 25.4 (mm) ≒ 4677.

In a bubble jet type recording head, a current of about 100 mA is required for one discharge port, that is, one discharge heater. Therefore, the current capacity per recording head is 0.1
(A) × 4677 = 467.7 (A). However, in practice, since one recording head is divided into about 1/50 and time-division driving is performed, the supply current for driving the recording head can be reduced to about 10A.

Further, a supply voltage for driving the recording head (hereinafter, referred to as a supply voltage)
Drive voltage) is 20V for bubble jet method
Approximately 40 V is required, and the voltage at which ink can be ejected by the recording head varies depending on the manufacturing process and the like. Therefore, it is necessary to change the drive voltage for each recording head.

FIG. 9 shows an example of a circuit configuration for driving a plurality of conventional recording heads.

That is, the volume resistances 11A to 14A are variable resistances, and the respective resistance values are set according to, for example, an appropriate drive voltage of the recording head which becomes apparent in a product inspection process. In the figure, the recording heads 11 to 14 are exchangeable and removable, so that the volume resistors 11 to store driving voltages having different values for each recording head.
A to 14A are provided together. The DC power supplies 21 to 24 are variable voltage stabilizing power supplies that supply an appropriate drive voltage based on the drive voltage information stored in the volume resistors 11A to 14A, respectively.

Since the DC power supplies 21 to 24 have a relatively large capacity as described above, they have to be arranged at a place away from the drive voltage signal,
When a direct drive voltage signal is input to a DC power supply, the signal may be mixed with noise or the like, resulting in an unstable operation. Therefore, the configuration shown in FIG. 9 prevents noise from being mixed. That is, using the multi-input A / D converter 15, the CPU 16 reads the volume resistance value of the head drive voltage information as drive voltage information.

The CPU 16 determines a set voltage value based on data obtained by sampling the information a plurality of times, and controls the output voltages of the DC power supplies 21 to 24 to D / A converters 17 to 20 arranged near the DC power supplies 21 to 24. Prints the number for The D / A converters 17 to 20 output a predetermined value of current or voltage according to the set numerical value.

[Problems to be Solved by the Invention] However, the above-described conventional example has the following problems.

(1) It is necessary to provide a storage element such as a volume resistor for setting the drive voltage value in the recording head, and also require a means such as an A / D converter for reading this value. I do. Therefore, the recording head and the configuration for driving the recording head are particularly complicated.

(2) A drive voltage value is experimentally checked, and a complicated process for setting the drive voltage value in use to the volume resistance is required at the time of manufacture of the recording head based on the drive voltage value, thereby increasing the manufacturing cost. Further, the cost is also increased due to the reason (1).

(3) The set driving voltage may change due to a change in the recording head's durability or the like. In this case, it is difficult for the user to reset the volume resistance value. A similar problem also occurs when the setting itself of the volume resistance changes due to a change in life or the like.

SUMMARY An advantage of some aspects of the invention is to solve a conventional problem in setting a printhead drive voltage described above. The present invention detects a result of ink discharge by a printhead, and based on the detection result, determines a drive voltage of the printhead. By setting and storing this, and recording based on this, it is possible to respond to the change in the set drive voltage due to the change in the recording head's durability, and it is also possible to simplify the print head manufacturing process It is an object of the present invention to provide an ink jet recording apparatus.

[Means for solving the problem]

Therefore, in the present invention, a recording head for ejecting ink droplets to perform recording, and a power supply for supplying power for the ejection to the recording head and varying the supplied power according to drive voltage data In an ink jet recording apparatus comprising: an ink adhering member that receives ink droplets ejected from the recording head and adheres the ink droplets;
An ink detecting unit for detecting the ink adhered on the ink adhering member, a conveying unit for conveying the ink adhering member relative to the recording head, and a conveying unit for conveying the ink adhering member by the conveying unit. Power supply voltage control means for changing drive voltage data supplied to the power supply; and when predetermined ink detection is performed by the ink detection means in accordance with the conveyance of the ink adhering member, the power supply voltage control means at the time of the detection. Driving voltage setting means for setting appropriate driving voltage data based on the driving voltage data supplied by the power supply, and driving the power supplied from the power supply with respect to the recording of the recording head by driving the appropriate driving voltage data set by the driving voltage setting means. Storage means for storing as voltage data.

[Action]

According to the above configuration, the power supply gradually changes the drive voltage for discharging ink to be supplied to the recording head, and detects the ink discharged onto the recording paper or the belt for transporting the recording paper in accordance with the drive voltage. By doing so, it is possible to set an appropriate driving voltage at the time of recording of the recording head based on a driving voltage at the time when ink is ejected (detected) for the first time, for example, and this voltage data is stored. It can be data of power supply at the time of recording.

〔Example〕

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

FIG. 1 is a block diagram showing a recording head driving configuration of an ink jet recording apparatus according to an embodiment of the present invention.

In FIG. 1, reference numerals 11 to 14 denote bubble jet type ink jet recording heads corresponding to the respective ink colors of cyan, magenta, yellow and black, and a plurality of ejection ports corresponding to the width of the recording paper being conveyed. Arrange.
Reference numeral 30 denotes an optical reading unit capable of optically detecting an image recorded by these recording heads. Reference numeral 16 denotes a CPU that controls the entire recording apparatus of the present embodiment. In the configuration shown in FIG. The drive voltage value is determined in accordance with the detection by 30 and stored in the RAM 16A, and this value is output to the D / A converter. The RAM 16A is composed of a nonvolatile memory, and stores the drive voltage value even when the recording apparatus is not used. 17 to 20 are D / A converters that convert drive voltage value data from the CPU 16 into analog data, 21 to 24 are powers of values according to the analog data from the D / A converters 17 to 20,
This is a head driving DC power supply to be supplied to the recording heads 11 to 14.

FIG. 2 is a schematic sectional view of the ink jet recording apparatus shown in FIG. 1, and is a view similar to FIG. The same elements as those shown in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted.

The difference from FIG. 8 is that the optical reading unit 30 is provided near the recording paper transport path, and details thereof are shown in FIGS. 3 (A) and (B).

In the figure, reference numeral 33 denotes a reading head, which stores a light source 33A and a sensor 33B. The head 33 is connected to a belt 31 stretched in a direction orthogonal to the recording paper conveyance direction via pulleys 31A and 31B, and the belt 31 is driven by a motor 32 via a pulley 31B, whereby a reading head is provided. The scanner 33 scans in a direction perpendicular to the recording paper transport direction, and can detect ink recorded on the recording paper.
This detection is performed based on a difference in light amount according to the reflectance when the light emitted from the light source 33A is reflected on the recording paper and received by the sensor 33B composed of a phototransistor.

The control procedure of the measurement and setting of the drive voltage by the ink jet recording apparatus of the present embodiment will be described with reference to the flowchart of FIG. 4 taking a cyan recording head as an example.

When an appropriate voltage setting process is instructed for the cyan head, this process is started, and firstly, an initial voltage V _O shown in FIG. 5 is set in step S41, and then, in step S42, this voltage V _{O is set.} To discharge ink at predetermined intervals, and convey the recording paper. At the same time, scanning of the reading unit 33 is performed in step S43, and in response to this, it is determined in step S44 whether or not ink has been detected. If this determination is negative, the drive voltage is increased by one step in step S45, and the process returns to step S42. While this process is repeated, when the drive voltage V _L (see FIG. 5) is reached, ink is ejected from any of the ejection ports for the first time, and thereafter the drive voltage is changed until ink is detected in step S44. As the height increases, the number of discharge ports sequentially discharged increases, and, for example, a recording result as shown in FIG. 6 is obtained. When the recording result reaches the optical reading unit 30 and the first recorded ink is detected by the driving voltage _VL , the step is performed.
In S46, the optical unit 3 is moved from the cyan recording head 11 to the optical unit 3.
The drive voltage _VL is obtained from the distance to 0, the speed at which the recording paper is conveyed, and the rate of change of the drive voltage shown in FIG. Next, in step S47, the appropriate drive voltage V _OP = K · _VL is obtained by multiplying the voltage _VL by the coefficient K.

Here, K is a common coefficient for print heads of the same type and is larger than 1 and is necessary and sufficient to perform ink ejection from all ejection ports. In this example, the value is 1.7. .

In step S47, an appropriate drive voltage V _OP is obtained, and
The V _OP obtained and stored in RAM 16a, and terminates this processing procedure.

By the above processing, in the normal recording operation, the RAM 1
The value of V _OP read from 6A is output to the D / A converter 17,
Based on this, power supply of an appropriate voltage is performed from the power supply 21. Note that the nonvolatile memory of the RAM 16A is very commonly used in this type of recording device, and does not lead to an increase in cost.

By performing the above operation on the magenta, yellow, and black printheads in the same manner, an appropriate drive voltage is set and stored for each printhead, and power supply is performed based on this.

Note also drives the recording head by V _OP obtained by multiplying the coefficient K V _L, In the case where there is a discharge port of the discharge failure, for example, regarded as defective the recording head in product inspection using the above procedure You can also.

In the present embodiment, the recording paper is conveyed slowly while gradually increasing the drive voltage of the recording head, and the optical reading unit is scanned in accordance with this.However, the recording operation is performed at a predetermined constant voltage. The optical reading unit checks whether or not ink has been hit on the recording paper.If not, return the recording paper by reverse transport, increase the driving voltage slightly, repeat the recording operation again, and check the ink ejection voltage. It may be.

Instead of examining the ejection port that can be ejected first, it is also possible to examine the drive voltage at the time of ejection of the ejection port that is ejected last, and an appropriate voltage may be set based on that voltage. .

Further, the activation of the processing procedure of proper voltage measurement and setting may be instructed by an operator using a predetermined key or the like,
In addition, the drive voltage data stored in the RAM 16A is checked, and an abnormal value thereof, for example, the drive voltage data is not stored because the above-described processing has not been performed yet due to head replacement or the like.
The O _V, in the case of holding may automatically be started the procedure. Alternatively, a sensor for detecting the attachment / detachment of the head may be provided, and the above-described processing procedure may be started when the attachment of a new recording head due to head replacement is detected.

In the above embodiment, when measuring the proper drive voltage, ink is ejected onto the recording paper to detect this ink. However, at least one or more recording papers for each ink color are required. Become. In order to avoid this, ink may be ejected directly onto the transport belt and detected. In this case, since the transport belt is contaminated with ink, it is necessary to provide a cleaner or the like for wiping the transport belt, and it is necessary to set the color of the transport belt as a background of the ink to a color such as white for optical reading. There is.

Further, in the above embodiment, the ink detection is performed by optical reading. However, in particular, yellow ink has a low contrast with respect to reflected light, so that a margin for noise at the time of detection is low, and ink detection may be difficult. . To avoid this, the following may be used instead of the optical reading means.

In other words, utilizing the fact that the ink itself has conductivity,
The use of an ink detection device based on a change in resistance value enables stable detection regardless of the reflectance of ink.

For example, as shown in FIG. 7, two electrodes 40 are provided which are in contact with the recording paper so as to be orthogonal to the traveling direction of the recording paper,
What is necessary is just to detect the change in resistance between these electrodes. The advantages of this method are that it does not depend on the reflectivity of ink, the detection mechanism can be configured at low cost, and discontinuous portions of the recording result due to unstable and intermittent ejection of ink are detected. Instead, only the portion where continuous ejection is performed can be detected, so that the drive voltage can be set accurately.

Further, in the above embodiment, when performing optical reading, the detection scanning is performed by moving the sensor. However, if a line sensor corresponding to the ejection port arrangement of the recording head is used, the same operation can be performed without a movable part. It can run fast.

The line sensor is generally quite expensive, but if the device in this example is not a single recording device but has a reading unit such as a copying device or a facsimile device,
The output as shown in FIG. 6 which has been discharged once can be read by the reading section, and a reading means for setting an appropriate driving voltage can be constituted without newly providing a dedicated sensor.

[Others]

The present invention brings about an excellent effect particularly in a recording head and a recording apparatus of a bubble jet method among ink jet recording methods. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

As for the representative configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to a sheet or a liquid path holding a liquid (ink). Applying at least one drive signal corresponding to the recording information and providing a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, thereby causing the electrothermal transducer to generate thermal energy, thereby causing the recording head to emit heat energy. This is effective because it causes film boiling on the heat-acting surface, and as a result, it is possible to form bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.
US Pat. No. 4,446,335 describes this pulse-shaped drive signal.
Those described in Japanese Patent No. 9 and No. 4345262 are suitable. Further, when the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination configuration (a linear liquid flow path or a right-angled liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in the above-mentioned specification, a heat acting section is provided. U.S. Pat.
A configuration using the specifications of 4558333 and U.S. Pat. No. 4,459,600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, recording can be performed reliably and efficiently regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by the recording apparatus as described above. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head. in addition,
Even a serial-type print head that can be replaced with a replaceable chip-type print head that can be electrically connected to the device main body and supplied with ink by being attached to the device main body, or integrated with the print head itself The present invention is also effective when a cartridge type recording head provided in the above is used.

Further, it is preferable to add recovery means for the print head, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention since the printing result can be further stabilized. If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Also, the type and number of print heads to be mounted are, for example, not only one provided corresponding to a single color ink, but also a plurality of inks having different print colors and densities as in the above example. Alternatively, a plurality may be provided.

In addition, the form of the ink jet recording apparatus of the present invention includes a form used for an image output terminal of an information processing device such as a computer, a copying apparatus combined with a reader or the like, and a form of a facsimile apparatus having a transmission / reception function. It may be taken.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, the power supply gradually changes the drive voltage for ink discharge supplied to the print head, and the print paper or the belt for conveying the print paper is accordingly changed. For example, the first time ink is ejected (detected) by detecting the ink ejected to
It is possible to set an appropriate driving voltage at the time of recording of the recording head based on the driving voltage at the time or the like, and it is also possible to record this voltage data and use it as power supply data at the time of recording.

As a result, the operation of setting an appropriate voltage for each recording head is facilitated, and the setting operation is facilitated in the production process of the recording head, and this process can be used in the inspection process.

Further, when it is necessary to change the drive voltage due to the aging of the recording head, it is possible for the user to easily carry out the correction work, especially.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a recording head drive in an ink jet recording apparatus according to one embodiment of the present invention, FIG. 2 is a schematic side sectional view of the apparatus shown in FIG. 1, and FIG. 4) and 4 (B) are a schematic perspective view and a circuit diagram, respectively, showing details of the ink reading unit shown in FIGS. 1 and 2, and FIG. 4 is a diagram for appropriately driving a recording head according to an embodiment of the present invention. FIG. 5 is a flowchart showing a procedure for setting a voltage, FIG. 5 is a diagram conceptually showing how to increase the drive voltage in the above procedure, and FIG. 6 is a schematic diagram showing a recording result by ink ejection in the above procedure. FIG. 7 is a schematic plan view showing another embodiment of the ink reading unit, FIG. 8 is a schematic side sectional view showing a conventional example of an ink jet recording apparatus, and FIG. Recording device It is a block diagram showing a definitive recording head drive arrangement. 11-14: Recording head, 16: CPU, 16A: RAM, 17-20: D / A
Converter, 21 to 24 DC power supply, 30 Reading unit, 31
... belt, 31A, 31B ... pulley, 32 ... motor, 33 ... read head, 33A ... light source, 33B ... sensor, 40 ... electrode pair.

Claims (6)

(57) [Claims] A printhead for discharging ink droplets to perform printing, and a power supply for supplying power for the discharge to the printhead and varying the supplied power in accordance with drive voltage data. An ink jet recording apparatus comprising: an ink adhering member for receiving ink droplets ejected from the recording head and adhering the ink droplets; and an ink detecting means for detecting ink adhering on the ink adhering member. Conveying means for conveying the ink-adhering member relative to the recording head; and, in accordance with conveyance of the ink-adhering member by the conveying means,
Power supply voltage control means for changing drive voltage data to be supplied to the power supply; and when predetermined ink detection is performed by the ink detection means in accordance with conveyance of the ink adhesion member, the power supply voltage control means at the time of the detection. Driving voltage setting means for setting appropriate driving voltage data based on supplied driving voltage data; and appropriate driving voltage data set by the driving voltage setting means.
Storage means for storing as drive voltage data of power supplied by the power supply with respect to recording by the recording head. 2. An ink jet recording apparatus according to claim 1, wherein said ink adhering member is a recording medium conveyed during recording. 3. The apparatus according to claim 1, wherein said ink adhering member is a transport belt for transporting a recording medium.
3. The ink jet recording apparatus according to claim 1. 4. An ink jet recording apparatus according to claim 1, wherein said ink detecting means includes a sensor for optically discharging ink. 5. An ink jet recording apparatus according to claim 1, wherein said ink detecting means includes an electrode for detecting the ink by using the electric resistance of the ink. 6. An ink jet recording apparatus according to claim 1, wherein said recording head ejects ink droplets by using thermal energy generated by an electrothermal transducer.