JPH07323569A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To prevent possibility such that recording becomes impossible suddenly by the consumption of the ink in an ink tank or the life of an ink jet head itself in the ink tank separate type ink jet head of an ink jet recording apparatus. CONSTITUTION:An ink tank 12 supplying ink to a common liquid chamber 17 and an ink detection part 20 having a plurality of test heaters 22 different in breaking energy arranged in the common liquid chamber 17 in an electrically parallel state are provided in the common liquid chamber 17 having a single nozzle or a plurality of nozzles of the head chip 11 of an ink jet head 1. Further, a means for detecting the breaking of the test heaters 22 by the application of test voltage and a means for informing the generation of this breaking to a user are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus.

[0002]

2. Description of the Related Art An ink jet head in an ink jet recording apparatus can be classified into (1) an ink tank integrated type and (2) a separate type, focusing on the mounting mode of the ink tank. The former is an inseparable part of the head and the tank, and when the ink in the tank is used up, the head is configured to be replaced at the same time as the integrated tank, while the latter is configured to replace it in the ink tank. When the ink level becomes low and the ink becomes unusable, only the ink tank is replaced so that the head that can withstand long-term use is continuously used.

By the way, in the latter case where the ink tank and the head are provided separately, the life of the head itself such as the members forming the liquid chamber of the ink jet head and the drive element is limited, and suddenly during use of the head. Not recordable. This life is generally determined by the number of characters printed or the amount of ink used for recording. Naturally, this life is designed to be equal to or more than the amount of ink in one tank. Therefore, the former integrated head is designed so that the life of the head itself does not normally end when ink is still left in the tank. However, in the separate type head, it is possible that the life of the head itself is reached with ink still remaining in the tank.

[0004]

However, the conventional ink tank technology as described above has the following problems. That is, (1) since the integrated head is usually replaced before the life of the head itself is reached, there is a problem in terms of promoting resource recycling when the used integrated head is discarded. On the other hand, (2) the separate-type head in which the head and the ink tank are separate bodies solves the problems of the above-described integrated type, but it is difficult to manage the life of the head itself. In order to solve this problem, it is possible to manage the history of the head on the recording apparatus main body side. However,
As a usage pattern of the apparatus, there is a possibility that a plurality of types of heads may be alternately used in one recording apparatus main body, for example, a black ink head and a color ink head of the same design may be alternately used. The use history of the head is different for each head, and it is difficult to manage on the recording apparatus main body side. Therefore, from the viewpoint of life management, it is essential to write the usage history on the head itself by some method.

The present invention has been made in view of the above problems, and an object thereof is to provide means for solving the above problems in the life control of a head of this type.

[0006]

Therefore, according to the present invention, in this type of ink jet recording apparatus, a single or a plurality of flow paths having ink ejecting means, a common liquid chamber connected to the flow paths, and An ink tank that supplies ink to a common liquid chamber, an inkjet recording head that is electrically installed in parallel in the common liquid chamber, and has a plurality of test heaters having different breaking energies; Of the heaters, the heater having the lowest breaking energy does not break if there is ink in the liquid chamber, and a means for applying a test voltage one or more times under a driving condition that breaks if there is no ink, and the heater breaks. The above-mentioned object is achieved by being configured so as to have means for detecting whether or not the heater is broken and means for notifying the user of the fact when the heater is broken. It is intended to.

[0007]

With the above-described structure of the present invention, when the pulsed electric power is applied to the test heater, the heater temperature rise is remarkably different depending on whether the heater has liquid or not. By doing so, the situation can be notified to the user regardless of the consumption of ink in the tank and the life of the head itself, and effective utilization management can be performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plurality of embodiments of the present invention will be described below with reference to the drawings: (Embodiment 1) FIGS. 1 (a) to 1 (c) show a first embodiment of a recording head portion according to the present invention. FIG. (A) is a horizontal sectional view of a main part, (b) is a perspective view, and (c) is an enlarged plan view of an ink detection part.

In FIG. 1, a recording ink jet head 1 includes a head chip 11 and an ink container (tank) 1.
It has a configuration in which 2 is separated. That is, when the ink in the ink container 12 is used up, only the container 12 is replaced. The head chip 11 is guaranteed to have a service life of five ink containing portions 12. The Si substrate 13 is preliminarily formed with a 2.0 μm thick SiO ₂ film by thermal oxidation.

The head chip 11 has a joint structure of a substrate 13 made of Si and a top plate 14 made of glass, and a plurality of ejection ports (nozzles) 15 arranged in the vertical direction are provided on the ejection surface side of these joints. Are formed. These outlets 1
5 are connected to one common liquid chamber (liquid chamber) 17 by a plurality of liquid passages 16 that communicate with each other. The wall portion between the plurality of liquid passages (flow passages) 16 is formed of a material such as an ultraviolet curable resin. The common liquid chamber 17 is
The tube 18 communicates with the inside of the ink containing portion 12.

On the upper surface of the substrate 13, electrothermal conversion elements (ejection heaters) 19 serving as a plurality of ejection energy generating elements, one positioned in each liquid passage 16, and these electrothermal conversion elements 19 are individually provided. Wiring such as Al for supplying electric power is formed by a film forming technique.

Reference numeral 20 in FIG. 1A is an ink detecting portion. Details of this are shown in FIG. The ink detection portion is formed on the Si substrate 13, and FIG. 7C is a plan view thereof. That is, the Al wiring 23 shown by diagonal lines is formed on the ink consumption detection heater 22 by sputtering. The material of the detection heater 22 is
As will be described later, oxygen is mixed with Ar gas during sputtering in order to intentionally reduce durability.

As shown in FIG. 3C, there are five detection heaters R ₁ , R ₂ , R ₃ and R each having a width W and different lengths.
₄ , R ₅ (the lengths are l ₁ , l ₂ , l ₃ , l ₄ , l
₅ ) are connected in parallel. The common electrode of these heaters 22 is connected to the test power generator at the pad portion 21 of the substrate 13 in FIG. Each detection heater 22R
The sizes of ₁ , R ₂ , R ₃ , R ₄ and R ₅ are all W
= 40 μm, the length is l ₁ = 40 μm, l ₂ = 60 μm,
l ₃ = 90 μm, l ₄ = 135 μm, l ₅ = 202 μm
Is. The sheet resistance is 40Ω / □.

The resistance value from the pad portion 21 to the detection heater 22 is 20Ω, and the wiring resistance between the heaters is negligible as compared with it. These five heaters 22
Has a higher breakdown voltage in the order of R _{1 to} R ₅ . Specifically, a pulse of 1.5 μsec width is 0.5 at 20 KHz.
When applied for 10 seconds (10 ⁴ times), the breaking voltage of each heater is as shown in Table 1.

[0015]

[Table 1]

FIG. 2 is a flow chart showing the ink consumption detecting sequence in the above-mentioned structure. That is, after recording is started in step S1, the resistance value R ^* of the detection heater 22 system is measured on the recording apparatus main body side for each recording of one sheet in step S2 (step S3). Thus, out of five heaters 22R ₁ to R _5, it determines how many is open. Specifically, D
The C voltage is applied to measure the current value in the main body or the voltage across the monitor resistor in the main body.

Assuming that the measured resistance value is R ^* , in step S4, if R ^* ≦ 20Ω, it means that none of the five heaters 22 is open. Hereinafter, in steps S6 to S12, 20Ω <R ^* ≦ 35Ω
If it is 35Ω <R ^* ≦ 60Ω, then 2 wires, 60Ω
It can be seen that if <R ^* ≦ 150Ω, three are open, if 150Ω <R ^* <∞, four are open, and if R ^* = ∞, five are all open.

Therefore, in step S5, a voltage that surely breaks when no ink is present on the heater having the lowest breaking voltage among the remaining heaters is applied. For example, if 20Ω <R ^* ≦ 35Ω between steps S4 and S6,
Since it can be seen that only R ₁ is broken, as the test voltage Vtest, the voltage only the resistance R ₂ is broken (9.
9.3 V (0 V or more and 12.0 V or less) is selected in step S5. If exhausted the ink in the ink accommodating portion 12, the ink in the common liquid chamber 17 is also empty, since there is no ink on the resistor R _2, the voltage application in step S15, the resistor R ₂ is broken. On the contrary, if there is ink on the resistance R ₂ , it will not break.

Therefore, in order to determine either of the above,
The resistance value R ^* is measured again in step S16. The measuring method is the same as in step S3. As a result of the measurement, the resistance value R ^*
Is significantly different from that at step S3 (specifically, if it is 35Ω or more one step higher), the resistance R ₂
Indicates that the fracture has occurred. If so, step S
At 20, the user is prompted to replace the ink containing portion 12 and the recording is stopped.

If all five heaters 22 are broken, R ^* = ∞ in step S18.
The user is prompted to replace the head itself in 19 and the recording is stopped in step S21. If the user selects each resistor R ₁ ~
When recording is started by mounting the head 1 in which all R ₅ are broken, in step S14, the user is urged to replace the head itself for each recording, but recording is continued without detecting the remaining amount of ink. However, the recording is not stopped.

This is to allow the user to continue recording when the spare head is not at hand, after recognizing that the head 1 has a short life. The control sequence of the flowchart shown in FIG. 2 is performed by the microprocessor in the recording apparatus main body.

In this embodiment, since the remaining ink amount in the common liquid chamber 17 is detected for each recording of one non-recording material, the ink volume between the detection heater 22 and the nozzle 15 is detected. It is necessary to be able to record one sheet.

This volume is, specifically, A4 1 sheet printing rate 5
In the case of%, it is approximately 50 mm ³ . Therefore, in this embodiment, the volume of the common liquid chamber 17 is 150 mm ³ , and the detection heater 22 is arranged at a position as far as possible from the nozzle 15 in the common liquid chamber 17.

In the present embodiment, several kinds of breaking voltage and breaking pulse width are set by changing the length of the detection heater 22, but the present invention is not limited to this, and other than that. Can also be set by changing the width of the heater, the sheet resistance of the heater, the wiring resistance value, the film configuration such as a protective film, the number of pulse application times, and the like.

[0025]

[Equation 1]

By the way, when the fine bubbles generated from the nozzle 15 are combined in the common liquid chamber 17 and happen to be present on the detection heater 22, the detection sequence of this embodiment does not require ink consumption. In some cases, each detection heater may be accidentally broken. In order to prevent an error due to such a problem, the following two measures can be considered. That is, firstly, a plurality of detection heaters having the same breaking voltage are arranged in the common liquid chamber 17 at positions that are not close to each other, and when all of these break, the ink shortage is recognized. . The second is to perform the above-described detection sequence immediately after the recovery operation in the common liquid chamber 17.

(Other Embodiments) In the first embodiment,
Each time _{one of the} detection heaters R _{1 to} R ₅ is cut off, the test voltage Vt
Although est was raised stepwise, the test voltage Vtest
It is possible to simplify the drive circuit by changing the width of each applied pulse rather than by changing.

Therefore, in this embodiment, the first embodiment is used.
1 is used, but the test voltage Vtest is set to 15V (constant). At this time, the pulse width leading to breakage is as shown in Table 2.

[0029]

[Table 2]

Therefore, the heater R _i (i = 1, 2, 3,
4, 5) pulse widths τ _i (i = 1, ..., 5) given to detect whether or not ink is present are τ ₁ = 1.0 μsec, τ ₂ = 1.4 μsec, τ, respectively. ₃ =
2.0 μsec, τ ₄ = 2.8 μsec, τ ₅ = 4.3
μsec. The sequence flow for detecting ink consumption is the same as that in the first embodiment except that the test voltage Vtest is kept constant and the pulse width is made variable.

In the above-described embodiment, the present invention can be more effectively carried out by using a material having a large absolute value of the change rate with respect to the temperature of the detection heater 22.

Generally, when ink is not present on the detection heater 22, the heat generated by the heater 22 is difficult to escape to a gas having a lower thermal conductivity than liquid, so that the temperature is remarkably higher than that when ink is present. To rise. At this time, whether the electric power consumed by the heater 22 further increases or decreases conversely depends on the wiring resistance R _A , the sheet resistance R _D of the heater, the heater width W, the heater length l, and each of the heaters. It is determined by the temperature coefficient (rate of temperature change of resistance value) α _D. Since the temperature of the wiring resistance hardly changes depending on the pulse waveform except for the vicinity of the heater connection portion, the change of the wiring resistance R _A with temperature can be ignored.

[0033]

[Equation 2]

In order to more reliably detect the ink shortage, there is the following method; the circuit shown in FIG. 3 is a circuit for supplying electric power to the Al (aluminum) resistor 23. As an example, this is generally called a holdback type current limiting circuit. 121 the DC voltage E _in ,
By applying the pulse signals 123 to 122, respectively, the relationship between the voltage E applied to the load resistance R _L and the current i becomes as shown in the characteristic diagram of FIG.

That is, the characteristic along the straight line 131 or 132 is shown depending on the magnitude of the value of the load resistance R _L. Figure 4
E _m , E _L , i _S , and i _{L in} are respectively given by the following equations.

E _m = E _in −V _BE (1) E _L = E _m −i _L R _SC (2) i _S = V _BE / R _SC (3) i _L = V _BE / R _SC + R ₁₁ / (R ₁₁ + R ₁₂ ) · E _m / R _SC (4) In these equations, V _BE is the base-emitter potential difference of the transistor Tr ₁ and is about 0.6 volt. The feature of this circuit is that when the load resistance R _L is E _L / i _L or less, R
_L power consumption is an increasing function of resistance. That is, as R _L increases due to the temperature rise, power consumption further increases. Therefore, if the ink is the resistors R _{1 to} R
_{If the} heat dissipation characteristics change depending on whether or not there is a vicinity of _5, the power consumption changes significantly. Therefore, by appropriately selecting the circuit constant, when there is no ink in the common liquid chamber 17, the resistor can be overheated and broken.

(Others) As described above, according to each of the above-described embodiments, it is possible to know the usage history of the recording head 1 from the main body side. Therefore, even for the head 1 in which the image density changes according to the usage amount, if the relationship between the head usage amount (specifically, the number of tank replacements) and the density change is quantitatively known in advance, For example, it becomes possible to automatically compensate the above-mentioned change by adjusting the driving condition such as the pulse width or adjusting the image processing method of the driving rate.

The present invention is not limited to the energy for ejecting and recording ink due to the thermal energy of the heater, and is also applicable to an ink jet head using a piezo element type or an electrostatic force. It is possible to Further, the present invention can be applied to a head that ejects ink by thermal energy and a head of a type that foams and ejects ink by energy of laser light without using a heater.

[0039]

As described above, according to the present invention,
Since it is possible to prevent the possibility of sudden recording becoming impossible due to ink exhaustion during recording by the separate inkjet head, and it is possible to reliably record the number of times the ink tank (container) is replaced on the head itself. As a result, the user can manage the life of the head itself. That is, it is possible to inform the user of the recording apparatus whether the ink in the tank is exhausted or the life of the head itself has expired.

[Brief description of drawings]

FIG. 1 is an explanatory view of a main part of the first embodiment.

FIG. 2 is a flow chart of an ink consumption detection sequence.

FIG. 3 An example of a holdback type current limiting circuit

FIG. 4 is a current-voltage characteristic diagram of FIG.

[Explanation of symbols]

1 Inkjet Head 11 Head Chip 12 Ink Storage Section (Tank) 13 Substrate 14 Top Plate 15 Discharge Port (Nozzle) 16 Liquid Path (Flow Path) 17 Common Liquid Chamber 19 Discharge Heater 20 Ink Detection Section 21 Pad Section 22 Ink Detection Heater R _{1 to} R ₅ 23 Al wiring

Claims (7)

[Claims] 1. A single or a plurality of flow paths having an ink ejecting means, a common liquid chamber connected to the flow paths, an ink tank for supplying ink to the common liquid chamber, and an electrical connection in the common liquid chamber. An ink jet recording head having a plurality of test heaters that are installed in parallel and have different breaking energies, and the heater with the lowest breaking energy among the existing heaters at a predetermined time breaks if there is ink in the liquid chamber. Without applying the ink, a means for applying the test voltage one or more times under a driving condition that would break, a means for detecting whether or not the heater was broken, and a notification to that effect when the heater was broken. An inkjet recording apparatus comprising: a unit for notifying a user of the apparatus. 2. The ink jet head recording apparatus according to claim 1, wherein the ink jet head is of an ink tank exchange system. 3. The test voltage according to claim 1, wherein the driving condition is such that film boiling bubbles are generated on the heater when ink is present in the liquid chamber. Inkjet head device. 4. The inkjet head recording apparatus according to claim 1, wherein the application of the test voltage is performed after the recording apparatus is powered on and before recording is started. 5. The ink jet recording apparatus according to claim 1, further comprising a device for sucking ink from an ink jet head, and applying the test voltage to the test heater immediately after performing the suction operation. An inkjet recording device characterized by the above. 6. An ink jet recording apparatus according to claim 1, wherein the driving method of the ink ejecting means is changed according to the number of broken test heaters. 7. The ink jet recording apparatus according to claim 1, which has a function of determining an ink ejection rate from image data, and changes the ink ejection rate in accordance with the number of test heaters that are broken. An inkjet recording apparatus characterized in that it is configured to.