JPH1044456A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine running out of ink by measuring the sound velocity in the ink passage from an ink tank to an ink jet head and comparing the sound velocities measured when the ink is jetted and not jetted. SOLUTION: Each ink tank 51-54 comprises an ink container 55 made of a porous material, e.g. urethane form, where an ink of each color is impregnated into a hollow container which is provided, through one side wall thereof, with an opening for supplying ink. A sound wave generator 60 and a sound wave detector 61 are disposed in an ink supply tube 47 in order to measure the time to be elapsed before detecting a sound wave after generation thereof. When the ink is not present in the ink supply tube 47, a significantly longer time is elapsed as compared with the case where the ink is present regardless of whether printing operation is in progress or not. When the ink is not present, the required time is invariant. Consequently, a decision can be made that the ink is running out when the sound velocity is invariant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording apparatus, and more particularly, to an ink-jet recording apparatus capable of detecting a shortage of ink in an ink tank, that is, an ink-out condition. is there.

[0002]

2. Description of the Related Art In an ink jet recording apparatus, printing is performed by holding ink in an ink tank and jetting the ink onto a printing paper or the like by an ink jet head using, for example, a piezoelectric element. If the ink tank runs out of ink, printing cannot be performed. Therefore, it is necessary to replace the ink tank with a new ink tank to replenish the ink. Since it is impossible to judge how much ink is in the ink tank from the outside of the ink tank, conventionally, it has often been noticed that there is no ink until printing cannot be performed due to ink exhaustion. for that reason,
For example, there is a case where printing cannot be performed suddenly while printing on one sheet of printing paper. For this reason, it has been desired that shortage of ink is detected shortly before the ink runs out so that a notice can be given.

[0003] In view of the above, there has been proposed an ink-out notice method utilizing the fact that the light transmittance differs depending on the presence or absence of ink. That is, there is a method of detecting the remaining ink amount by irradiating light from a light emitting element such as an LED from one end outside the ink tank and receiving transmitted light at a light receiving element at the other end. By appropriately setting the path of the light beam, when the remaining amount of ink becomes equal to or less than a certain amount, the amount of received light changes.

[0004]

However, the external environment of the ink tank is not always good. The outside of the ink tank may become dirty due to ink leaking or touching with dirty hands. In the conventional method, since the change in light transmittance due to contamination of the outside of the ink tank cannot be distinguished, even if the amount of ink in the ink tank is low, the ink is sufficient and the ink is depleted. There are things you can't do.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and detects the fact that the amount of ink is low irrespective of the external environment of the ink tank.
An object of the present invention is to provide an ink jet recording apparatus that can issue a warning.

[0006]

According to a first aspect of the present invention, there is provided an ink jet recording apparatus for supplying an ink from an ink tank to an ink jet head and discharging the ink from the ink jet head onto a recording medium to perform recording. The apparatus has a sound speed measuring means for measuring a sound speed in an ink path from an ink tank to an ink jet head, and compares the sound speed when ink is ejected from the ink jet head and when it is not. When there is no difference, it is determined that ink is exhausted.

In this ink jet recording apparatus, the sound speed measuring means measures the sound speed in the ink path from the ink tank to the ink jet head. When the ink is in the ink path and when it is not (ie, the speed of sound in air)
Although there is a difference in the sound speed, the sound speed also differs depending on whether there is a flow of ink. That is,
When the ink flows from the ink tank toward the ink jet head and when there is no flow, the speed of sound traveling through the ink is different. However, if the ink disappears from the ink path, no ink flow occurs, so that the sound speed does not change. By utilizing this fact, the change in the sound velocity when ink is ejected and when it is not ejected is measured, and when the change is eliminated, it can be determined that ink has run out in the ink path. It should be noted that even if there is no ink in the ink path, there is a small amount of ink remaining in the ink jet head, so that printing cannot be immediately stopped.

According to a second aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the sound velocity measuring means includes a sound wave generator and a sound wave detector provided in the ink path. It is characterized by measuring the speed of sound based on the time until the sound wave is detected.

In this ink jet recording apparatus, a sound wave generator and a sound wave detector are used as means for measuring the speed of sound. That is, a sound wave generator is installed at one end in the ink path to generate sound waves. Further, a sound wave detector is installed at the other end in the ink path, and the sound wave generated by the sound wave generator is detected. The speed of sound can be measured by measuring the time required from generation of a sound wave to detection.

According to a third aspect of the invention, there is provided the ink jet recording apparatus according to the second aspect, wherein the sound wave generator and the sound wave detector are provided in an ink supply tube connecting the ink tank and the ink jet head. It is characterized by the following.

In this ink jet recording apparatus, the flow path of the ink supply tube connecting the ink tank and the ink jet head is narrower than that of the ink tank or the ink jet head. Flow occurs. Therefore, when there is ink, a difference in sound speed due to the flow is clearly generated. Therefore, by installing a sound wave generator and a sound wave detector in this portion, it is easy to know whether there is ink.

According to a fourth aspect of the present invention, there is provided the ink jet recording apparatus according to the second aspect, wherein the sound wave generator and the sound wave detector are provided in a manifold of the ink jet head.

The ink that has flowed into the ink jet head through the ink supply tube flows into the opening of each channel in the manifold, and is jetted from the nozzle surface to the recording medium. Therefore, even in the manifold, a flow of ink occurs during ink discharge. Therefore, when there is ink, a difference in sound speed due to the flow is clearly generated. Therefore, by installing a sound wave generator and a sound wave detector in this portion, it is easy to know whether there is ink.

According to a fifth aspect of the present invention, there is provided the ink jet recording apparatus according to any one of the first to fourth aspects, wherein the ink out detecting means is configured to recover the ink jet head by forced ejection or forced suction. It is characterized by receiving the sound speed when the operation is being performed and the sound speed when the ink jet head is at rest, and judging out of ink based on the difference.

In this ink jet recording apparatus, during the recovery operation of the ink jet head, forced ejection or forced suction is performed. By measuring the speed of sound at that time,
The speed of sound can be measured with the ink flowing. Further, by measuring the sound speed while the ink jet head is stopped, the sound speed when there is no flow can be measured. This 2
Out of ink can be detected by comparing the types of sound speeds.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. An ink jet recording apparatus 10 according to the present embodiment uses a piezoelectric element type ink jet head.
The schematic configuration shown in FIG.

In the schematic perspective view of FIG. 1, a cylindrical platen roller 81 for conveying a recording sheet S is disposed on a frame 80 of the ink jet recording apparatus 10 so as to be rotatable around an axis. Then, the platen roller 81
A guide rod 82 and a guide rail 83 are provided in parallel with the carriage, and the carriage 84 can be moved in parallel with the platen roller 81 while being supported by these. The carriage 84 is driven via a belt 86 by a CR motor 85 provided below the frame 80. The carriage 84 has four colors (black, cyan, and black) for performing full-color printing by discharging ink from nozzles.
(Magenta, yellow) inkjet head 70 is mounted. Further, the frame 80 includes a wiper 87 for wiping the nozzle surface and a purge for sucking the deteriorated ink covering the nozzle surface as a recovery system for recovering the ink discharge state of the inkjet head 70 when the ink discharge state deteriorates. A cap 88 is provided. Further, a PF motor 89 for driving a platen roller 81 and a recovery system is mounted.

Further, the head holder 41 is mounted on the carriage 84. As shown in FIG. 2, the head holder 41 has a box shape with the surface opposite to the inkjet head 70 opened, and has a partition wall 42 that partitions the inside into four parts. The partition wall 42 is provided in the head holder 41 with a black storage portion 41a for mounting the black ink tank 51 and a cyan storage portion 41 for mounting the cyan ink tank 52.
b, a magenta accommodating section 41c for accommodating the magenta ink tank 53 and a yellow accommodating section 41d for accommodating the yellow ink tank 54 are formed. Head holder 41
Is connected to an ink jet head 70 having a plurality of ink jet nozzles.

Further, as shown by a yellow ink ejecting mechanism in FIG. 2, an ink supply tube 47 having a passage for supplying ink to the ink jet head 70 is provided in the head holder 41, and the ink supply tube 47 and the ink supply tube A seal member 48 for sealing between the tank 54 and the tank 54 is formed. Ink supply tube 4 for each color
Reference numeral 7 extends through the wall of the ink holder accommodating portion of the head holder 41 on the side of the ink jet head 70, and connects the ink tank 54 and the ink jet head 70. Inkjet head 7 of ink supply tube 47
The end opposite to 0 protrudes into the ink tank accommodating portion, and a seal member 48 is fitted around the outer periphery of the protruding portion. The passage in the ink supply tube 47 has an opening on the ink tank storage section side covered by a filter 49.

Each of the ink tanks 51, 52, 53, 54
Has an ink container 55 made of a porous material such as urethane foam impregnated with ink of each color in a hollow container, and an opening for ink supply is formed through one side wall of the container. Each of the ink tanks 51, 52, 53,
54 to the corresponding ink tank housings 41a, 41
b, 41c and 41d, the ink supply tube 47 fits into the opening of the ink tank 54 and enters the ink tank 54, as schematically shown by the yellow ink tank 54 in FIGS. Then, the opening of the passage is pressed against the ink container 55. Further, the opening of the ink tank 54 comes into contact with the seal member 48 to prevent the ink from leaking to the outside. In this state, the ink in the ink container 55 flows into the respective ink jet nozzles of the ink jet head 70 from the passage of the ink supply tube 47 through the filter 49, and jets toward the recording medium under the control of each ink jet nozzle.

Further, as shown in FIG. 3, a sound wave generator 60 and a sound wave detector 61 are provided in the ink supply tube 47. In the figure, the sound wave generator 6 is provided on the ink tank 54 side.
0, the sound wave detector 61 is provided on the inkjet head 70 side, but these arrangements may be reversed. Further, as a second embodiment, as shown in FIG. 4, a sound wave generator 60 and a sound wave detector 61 can be installed in a manifold 71 of an ink jet head 70. Here, the sound wave generator 60 is installed at a position relatively close to the ink supply tube 47 in the manifold 71, and the sound wave detector 61 is installed at a position far from the ink supply tube 47.

Next, a control system of the ink jet recording apparatus 10 will be described. As shown in FIG. 5, the control system mainly includes a head driver 30, a gate array 31, and a CPU 32. 5, the head driver 30
And an ink jet head 70 are mounted on a carriage 84, and the others (except for the host 78) are installed in the apparatus main body. The head driver 30 is a circuit that applies a drive signal to each channel of the inkjet head 70. The gate array 31 is a circuit that receives print data (code data) from a host (a personal computer or the like) 78 via the interface 33, develops the print data into image data, transfers the print data to the head driver 30, and the like. Further, the gate array 31 is provided with an image memory 34 for storing developed image data.

The CPU 32 controls the ink jet recording apparatus 1
0 is a one-chip microcomputer that performs overall control of the entire operation. The CPU 32 and the gate array 31 are connected by a bus 35 so that data and timing signals can be exchanged. ROM 36 and RAM 37
Is also connected. Further, the CPU 32 is also connected to an ink remaining amount detection circuit 40. The ink remaining amount detection circuit 40 includes a sound wave generator 60 and a sound wave detector 61. Further, the CPU 32 is also connected to a switch panel 38 for setting and displaying print parameters and the like and a drive system 39 of a mechanical part. Here, the drive system 39 includes C
An R motor 85 and a PF motor 89 and a position sensor and the like for them are included.

Next, the operation of generating and detecting a sound wave will be described with reference to FIG. In FIG. 6, t is time,
T0 represents the time at which the sound wave was generated. FIG. 6A shows a sound wave generation signal from the sound wave generator 60. FIGS. 6B to 6E show detection signals of the sound wave detector 61. FIG. The time from sound wave generation to sound wave detection is from t1 to t4. FIG.
(B), (c) and (d) show the case where the ink is in the ink supply tube 47, (b) when the ink is not flowing, (c) and the sound wave detector 61 upstream and downstream, respectively. (D) shows a case where the sound wave generator 60 is arranged at the upstream side and there is a flow of ink, and (d) shows a case where the sound wave generator 60 is arranged at the upstream side and the sound wave detector 61 is arranged at the downstream side and there is an ink flow. . The required times t1, t2, and t3 are different from each other, and have a relationship of t3 <t1 <t2.

On the other hand, when ink is not in the ink supply tube 47, it takes much longer time t4 than when there is ink, regardless of whether or not a printing operation is being performed. This is because the speed of sound is faster in liquid than in liquid. In this case, even during the printing operation, there is no air flow that has an effect on the speed of sound. Therefore, when there is no ink, it can be all shown in FIG.
That is, when there is no ink, the required time is t4, and there is no change. Therefore, when there is no change in the sound speed, it can be determined that the ink has run out.

In the second embodiment, a sound wave generator 6 is provided in a manifold 71 of an ink jet head 70.
In the case where the zero and the sound wave detector 61 are arranged, the ink flows from the ink supply tube 47 into the ink jet head 70, flows from the open one of the openings 72 of each channel, and is arranged on the nozzle surface 73. The ink is ejected from the nozzle onto the recording medium. Therefore, when there is ink, a flow of ink occurs in the manifold 71 during ink ejection, as in the ink supply tube 47. Therefore, as in the first embodiment, by detecting the difference between the sound speeds during ink ejection and during pause, it can be determined that there is no ink when there is no difference in sound speed.

Next, the ink remaining amount detecting process will be described with reference to the flowchart of FIG. First, the CPU 32 causes the sound wave generator 60 to generate a sound wave while performing ink ejection, and detects the sound wave with the sound wave detector 61 to measure the elapsed time (S100). The required time is tA
And Next, the time from generation of a sound wave to detection is similarly measured without performing ink ejection (S101). The required time at that time is assumed to be tB. Next, the two types of times tA and tB are compared (S102). If tA = tB (S10
2: YES), since there is no ink in the ink supply tube 47, it is in a state of running out of ink soon, and a process for running out of ink is performed (S103). Examples of the process for running out of ink include a warning such as lamp lighting and buzzer sounding, and forced printing stop. If tA ≠ tB (S10
2: NO), since there is still enough ink, print recording is continued.

In the present embodiment, the propagation time of the sound wave when there is a flow of ink as described above is used instead of measuring the propagation time of the sound wave only once and judging the presence or absence of ink based on the length. The time tA and the propagation time tB when there is no ink flow are detected, and the presence or absence of the ink is determined by comparing these two. This is because even if the amount of ink is the same, the propagation time of the sound wave may fluctuate due to environmental changes such as temperature changes and the installation environment and operation conditions of the inkjet recording apparatus 10, thereby preventing erroneous determination due to this. That's why.

In the case of making a judgment based on the above-mentioned single measurement, if the characteristics of the sound wave generator 60 and the sound wave detector 61 are made uniform and the accuracy of the installation position is not strictly controlled, each ink jet recording apparatus 10 The propagation time of the sound wave to be detected varies. For this reason, it is difficult to accurately detect out-of-ink. However, according to the present embodiment, the above-described management is not required, and it is possible to cause all the individuals to accurately detect the lack of ink.

Further, since the propagation time of the sound wave varies depending on the type of ink stored in the ink tank 54,
In the case of making a determination based on the above-described single measurement, a threshold value serving as a criterion for determination must be reset for each type of ink. However, if the present embodiment is adopted, it is possible to determine the presence or absence of ink under the same conditions regardless of the type of ink.

As described above in detail, according to the present embodiment, the sound wave generator 60 is provided in the ink supply tube 47.
And a sound wave detector 61 for detecting the difference between the sound speeds at the time of ink ejection and at the time of non-ejection to detect and warn of running out of ink regardless of the external environment of the ink tank such as contamination of the ink tank. It is possible to provide an ink jet recording apparatus which can be used. Alternatively, according to the second embodiment, the sound wave generator 60 and the sound wave detector 61 are provided in the manifold 71 of the ink jet head 70, and the difference in sound speed between when the ink is ejected and when the ink is not ejected is detected. It is possible to provide an ink jet recording apparatus capable of detecting out of ink and issuing a warning regardless of the external environment of the ink tank such as contamination.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various improvements and modifications can be made without departing from the scope of the present invention.

[0033]

As is apparent from the above description, according to the first aspect of the present invention, it is determined that ink is exhausted when there is no difference in sound speed between when ink is ejected and when ink is not ejected in the ink path. Therefore, it is possible to detect out-of-ink irrespective of the external environment such as the contamination of the ink tank and the fluctuation of the temperature, and the installation environment and operation state of the inkjet recording apparatus. Further, according to the second aspect of the present invention, the sound wave generator and the sound wave detector are provided on the ink path, and the time from the generation of the sound wave to the reception of the sound wave is measured, so that the difference in the sound speed used in the first embodiment can be detected. .

Further, according to the third aspect of the present invention, since the sound wave generator and the sound wave detector are provided in the ink supply tube, the flow of ink at the time of ink ejection is generated, and The difference is easy to detect. Furthermore, according to the invention of claim 4, since the sound wave generator and the sound wave detector are provided in the manifold, the flow of ink at the time of ink ejection occurs,
The difference in sound speed used in the first aspect is easily detected. Further, according to the invention of claim 5, since the sound speed is measured at the time of forced ejection or forced suction by the recovery operation, it is possible to generate the timing at which the flow of ink occurs.
It is easy to detect the difference in the speed of sound used in.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an ink jet recording apparatus according to the present invention.

FIG. 2 is a perspective view showing a structure of an ink tank and a head holder of the present invention.

FIG. 3 is a sectional view showing the structure of an ink tank and an inkjet head according to a first embodiment of the present invention.

FIG. 4 is a perspective view showing a structure of an ink jet head according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a control system of the inkjet recording apparatus of the present invention.

FIG. 6 is a timing chart of generation and detection of a sound wave.

FIG. 7 is a flowchart of ink out detection.

[Explanation of symbols]

 Reference Signs List 10 inkjet recording device 41 head holder 47 ink supply tube 51, 52, 53, 54 ink tank 55 ink container 60 sound wave generator 61 sound wave detector 70 ink jet head 71 manifold 84 carriage

Claims (5)

[Claims] 1. An ink jet recording apparatus which supplies ink from an ink tank to an ink jet head and discharges the ink from each nozzle of the ink jet head onto a recording medium to perform recording. A sound velocity measuring means for measuring a sound velocity in an ink path communicating with the ink jet head; receiving the respective sound velocities when the ink is ejected from the ink jet head and when the ink is not ejected from the ink velocity measuring means; And an out-of-ink detecting means for determining that the ink has run out when there is no difference. 2. The ink jet recording apparatus according to claim 1, wherein the sound velocity measuring means includes a sound wave generator and a sound wave detector provided in the ink path, and the sound speed measuring means determines the time from sound wave generation to sound wave reception. An ink jet recording apparatus for measuring the speed of sound. 3. The ink-jet recording apparatus according to claim 2, wherein the sound wave generator and the sound wave detector are provided in an ink supply tube connecting the ink tank and the ink-jet head. Recording device. 4. The ink jet recording apparatus according to claim 2, wherein the sound wave generator and the sound wave detector are provided in a manifold of the ink jet head. 5. The ink jet recording apparatus according to claim 1, wherein said ink out detecting means is configured to perform a recovery operation by forcible ejection or forcible suction of said inkjet head. An ink jet recording apparatus, comprising: receiving a sound speed and a sound speed when the ink jet head is at rest, and judging out of ink based on a difference therebetween.