JP2002248786A - Ink jet printer and ink tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of inability to accurately measure a quantity of residual ink when an ink drop is adhered to a reflection face in a residual ink quantity detecting means that detects the quantity of the residual ink by reflecting a light at two optical reflection faces contacting the ink liquid in an ink tank. SOLUTION: A means for removing ink drops from the reflection face by vibrating the ink tank is provided, thereby preventing the ink drops from being adhered to the reflection face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer which discharges ink droplets from a recording head and records an image on a recording medium. And improvement of the ink tank.

[0002]

2. Description of the Related Art An apparatus disclosed in Japanese Patent Application Laid-Open No. 9-29989 is known as a method for detecting the remaining amount of ink in an ink tank in the above-described ink jet printer. This ink remaining amount detecting device is shown in FIG.
7, the light emitted from the light emitting element L1 is reflected by the upper reflecting surface R1 and then reflected by the lower reflecting surface R2.
It is configured to reach the light receiving element L2. The upper reflecting surface R1 and the lower reflecting surface R2 are not wet with the ink when the ink tank T does not have sufficient ink I as shown in FIG.
Although the light is reflected as indicated by a broken line, when it is wet with the ink I, it functions as a prism type reflection mechanism that transmits light. Therefore, when the ink I in the tank T reaches a level higher than the upper reflection surface as shown in FIG.
Is transmitted through the upper reflection surface L1 and does not reach the light receiving element L2, so that it is possible to determine that there is ink by detecting the output from the light receiving element L1. When the ink gradually decreases and there is an ink level between the upper reflecting surface L1 and the lower reflecting surface L2 as shown in FIG. 6, light emitted from the light emitting element L1 is reflected by the upper reflecting surface R1. Is transmitted through the lower reflection surface R2 and does not reach the light receiving element L2, so that it is also determined that there is ink. After all, when the level of the ink I reaches a level lower than the lower reflecting surface R2 as shown in FIG. 7, the light emitted from the light emitting element L1 as described above is reflected by the reflecting surface R2 which is the upper reflecting surface R1. The light is reflected on both sides and reaches the light receiving element L2, and a determination is made that there is no ink. As described above, the ink remaining amount detecting device according to the prior art described above reflects the detection light from outside the tank and reflects the detection light again outside the tank when the reflection surface is not wet with the ink, and the reflection surface reflects the ink. It can be said that it uses the principle of a prism that transmits when it is wet and does not reflect outside the tank.

[0003]

Since the above-mentioned prior art uses the above-described prism mechanism as the principle of detecting the presence or absence of ink, it also has the following disadvantages. That is, as shown in FIG. 8A, even if the level of the ink I is higher than the lower reflecting surface R2, the lower reflecting surface R
If the air bubble B1 adheres to the reflecting portion of the light-receiving portion L2, the light from the light-emitting portion L1 is reflected here.
There is a problem that light reaches the device and an erroneous determination of no ink occurs. Also, as shown in FIG. 8B, if the ink droplet B2 adheres to the reflecting portion of the upper reflecting surface R1, light from the light emitting portion L1 is transmitted through the upper reflecting surface R1.
There is a problem that an erroneous determination of the presence of ink occurs even though the determination that there is no ink should be performed. Similarly, as shown in FIG. 8C, even though the ink has run out, the ink droplet B
If 3 adheres, a light ray to be reflected on the lower reflection surface R2 passes through the ink droplet B3, and the light does not reach the light receiving portion L2. The present invention
An object of the present invention is to solve the problems inherent in the conventional technology as described above.

[0004]

In order to achieve the above object, an ink jet printer according to the present invention comprises an ink tank for discharging ink droplets from a recording head and storing ink for recording an image on a recording medium. When the reflecting surface is not wet with ink, the detection light from outside the tank is
And the detection light is reflected out of the tank again.
An ink jet printer having a prism type reflection mechanism that transmits light when the reflection surface is wet with ink and does not reflect the light to the outside of the tank, wherein the ink jet printer includes a removal unit that removes ink droplets or bubbles attached to the reflection surface. Is configured as By providing the means for removing ink droplets and bubbles in this manner, erroneous detection of the remaining amount of ink due to ink droplets and air bubbles attached to the reflection surface is eliminated. As an example of the above-mentioned removing means, one configured by a vibrating mechanism for applying vibration to the above-mentioned reflecting surface is proposed. The vibration mechanism is
Since the configuration can be made relatively easily, the device can be configured at low cost. A vibration mechanism including an electrostrictive element is proposed as the vibration mechanism. The electrostrictive element does not need to have a movable part, is small in size, has a low price, can vibrate at a high frequency, and is effective in removing ink droplets and the like. Further, the vibrating mechanism may be constituted by a drive source for driving the recording head in the main scanning direction. In this case, since a drive source for driving the recording head in the main operation direction is more essential for the ink jet printer than in the past, it is not necessary to provide a new drive source, and the configuration can be inexpensive. Further, the vibration by the vibration mechanism may be performed by input means for inputting forward and reverse drive signals to the drive source. This configuration can be achieved by a simple change of the drive circuit of the conventional recording head, and will not increase the cost. When inputting the forward and reverse drive signals to the drive source, a high-frequency signal within the self-starting frequency is used as the drive signal, so that a high-frequency vibration can be given, and the attached ink droplets or bubbles Is surely removed. Further, as a vibration method, it is conceivable to cause the carriage of the recording head to collide with a predetermined stopper. With this configuration, a large collision force can be obtained, and ink droplets and the like can be reliably removed. The present invention can be understood as the configuration of the ink tank itself. That is, an ink tank for discharging ink droplets from a recording head and storing ink for recording an image on a recording medium. When the reflection surface is not wet with ink, detection light from outside the tank is applied twice. In the ink tank which has a prism type reflection mechanism that reflects the detection light to the outside of the tank again and reflects it when the reflection surface is wet with ink and does not reflect outside the tank, at least the reflection surface below An ink tank that has been subjected to a low-affinity treatment for lowering the affinity for ink is also an example of the present invention. In the present invention,
As in the first aspect, erroneous detection of the remaining amount of ink due to ink droplets or air bubbles attached to the reflection surface will be eliminated. Also,
As an example of the process for reducing the affinity for the ink, it is conceivable to perform a total reflection process on the upper reflective surface. This idea is based on the fact that the upper reflection surface in the ink remaining amount detection device using the above two reflection surfaces does not affect the detection accuracy even when the total reflection is always performed. Can be easily achieved by, for example, applying a mirror surface treatment or forming an ink tank structure in which ink does not enter the reflection surface, so that the cost can be reduced while increasing the detection accuracy.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The following embodiments and examples are specific examples of the present invention and do not limit the technical scope of the present invention.
FIG. 1 is a sectional view showing the concept of a device for removing ink droplets and the like used in an ink jet printer according to an embodiment of the present invention, FIG. 2 is a sectional view showing the operation of the device shown in FIG. 1, and FIG. FIG. 4 is a conceptual diagram of an apparatus in which droplet removal is to be achieved by a driving device of an ink carriage. FIG. 4 is a cross-sectional view showing the concept of an embodiment in which a process is performed to make it difficult for ink droplets or the like to adhere to a reflection surface. . When the upper and lower reflecting surfaces R1 and R2 of the ink tank T used in this embodiment are not wet with the ink, the tank T is used.
The detection light from the outside issuing unit is reflected, and the detection light is reflected again to the light receiving unit outside the tank. When the respective reflection surfaces are wet with ink, the detection light is transmitted and reflected to the light receiving unit outside the tank T. A prism type reflection mechanism R is provided. An ink jet printer having a tank T according to this embodiment is different from the related art in that an ink carriage T on which an ink tank T is mounted and moved is attached to each of the reflection surfaces R1 and R2 of the prism type reflection mechanism R. A piezoelectric element 1 is provided as an example of a removing unit for removing ink droplets or bubbles. When a predetermined voltage is applied to the piezoelectric element 1, the piezoelectric element 1 vibrates, and an ink tank T in contact with the piezoelectric element 1 is moved. It is a point that vibrates. Here, the piezoelectric element 1
Is an example of an electrostrictive element, and it goes without saying that any element that generates distortion by applying a predetermined voltage can be applied.

When such a piezoelectric element 1 is mounted in contact with the ink tank T and, for example, a predetermined voltage is applied to the piezoelectric element 1 periodically or at an appropriate time, as shown in FIG. When the air bubble B1 is below the ink surface, the air bubbles B1 adhering to the lower reflecting surface R2 are lifted off the lower reflecting surface R2 due to the vibration, and light rays reaching the lower reflecting surface R2 as shown in FIG. The air bubbles B1 do not reflect as shown by the solid line, but penetrate into the ink I as shown by the dashed line, eliminating the problem of erroneous determination that there is no ink even though there is sufficient ink. The same applies to a case where an erroneous determination is made because ink droplets adhere to the reflection surface. For example, as shown in FIG. 2B, the ink droplet B2 or B3 adheres to the upper reflecting surface R1 or the emitting surface R2 even though there is almost no ink, so that FIG. As shown by the solid arrow, the piezoelectric element 1 can be erroneously determined to be present due to transmission through the ink droplets B2 or B3.
By vibrating the prism type reflection mechanism R together with the ink tank T and causing the ink droplets B2 or B3 to flow as shown in FIG. 2B, the erroneous determination described above is solved. In the above-described method of applying vibration to the prism type reflection mechanism R using the electrostrictive element such as the piezoelectric element 1 or the like, it is not necessary to provide a movable portion, so that the life is long and the size can be reduced. Can be provided, and the advantage that the cost can be reduced can be enjoyed.

[0007]

In the above embodiment, an electronic element such as the piezoelectric element 1 is used as means for removing ink droplets.
In the first embodiment described below, vibration is applied to the ink tank T by mechanical means. FIG. 3 shows an example of a drive system of the ink carriage C. That is, the driving pulley P1 connected to the motor M and the driven pulley P2
The ink carriage C is attached to the belt V, and the ink carriage C reciprocates in the main scanning direction by the forward or reverse rotation of the motor M to perform a printing operation. . In the first embodiment, the motor M is supplied with a forward / reverse signal at a high frequency within the self-starting frequency, whereby high-frequency vibration is excited in the ink carriage C and ink droplets adhered to the reflection surface Alternatively, bubbles are removed. Since the principle of these removals is the same as that shown in FIGS. 2 and 8 as described above, the description is omitted here. The mechanism for mechanically removing ink droplets and the like as described above can also be achieved by causing the ink carriage C to collide with the stopper S1 or S2 which is located outside the scanning range (range K in FIG. 3) of the ink jet printer. It is possible. In such an apparatus, large vibration can be obtained, and ink droplets and the like can be reliably removed.

Further, the third embodiment of the present invention is configured as an ink tank in which at least the lower reflection surface has been subjected to a low affinity process for reducing the affinity for ink.
As described above, the present invention employs a reflecting surface R2 as an upper reflecting surface R1.
Is used, but what is particularly important is the lower reflecting surface. Because the upper reflecting surface R1 is
For example, a mirror is formed so as to be able to always reflect, or an air reservoir A is formed in a portion in contact with the upper reflecting surface as shown in FIG. In this case, there is no problem, however, because the lower reflective surface may cause an erroneous determination that the reflection / transmission is not definitely switched depending on the presence or absence of the ink. For this reason, in the third embodiment, as shown in FIG. 4, the lower reflection surface R2 is subjected to a process for lowering the affinity for ink.
An example of the process for lowering the affinity is an ink-repellent process. This is a process for preventing ink droplets from adhering, for example, by applying silicon or wax.
With this configuration, an ink droplet does not adhere to the lower reflection surface, and an erroneous determination that there is ink even when ink does not exist can be avoided. Since such a process is simple, it does not cause an increase in cost.

[0009]

As described above, the system according to the present invention ejects ink droplets from the recording head and wets the reflection surface with the ink in the ink tank for storing the ink for recording the image on the recording medium. When it is not, the detection light from the outside of the tank is reflected twice and the detection light is reflected again to the outside of the tank. When the reflection surface is wet with ink, a prism type reflection mechanism that transmits and does not reflect outside the tank is used. The ink jet printer is provided with a removing means for removing ink droplets or bubbles adhering to the reflection surface. By providing the means for removing ink droplets and bubbles in this manner, erroneous detection of the remaining amount of ink due to ink droplets and bubbles attached to the reflection surface is eliminated. As an example of the above-mentioned removing means, one configured by a vibrating mechanism for applying vibration to the above-mentioned reflecting surface is proposed. Since the vibrating mechanism can be configured relatively easily, the apparatus can be configured at low cost. A vibration mechanism including an electrostrictive element is proposed as the vibration mechanism. The electrostrictive element does not need to have a movable part, is small in size, has a low price, can vibrate at a high frequency, and is effective in removing ink droplets and the like. Further, the vibrating mechanism may be constituted by a drive source for driving the recording head in the main scanning direction. In this case, since a drive source for driving the recording head in the main operation direction is more essential for the ink jet printer than in the past, it is not necessary to provide a new drive source, and the configuration can be inexpensive. Further, the vibration by the vibration mechanism may be performed by input means for inputting forward and reverse drive signals to the drive source. This configuration can be achieved by a simple change of the drive circuit of the conventional recording head, and will not increase the cost. When inputting the forward and reverse drive signals to the drive source, a high-frequency signal within the self-starting frequency is used as the drive signal, so that a high-frequency vibration can be given, and the attached ink droplets or bubbles Etc. are surely removed. Further, as a vibration method, it is conceivable to cause the carriage of the recording head to collide with a predetermined stopper.
With this configuration, a large collision force can be obtained, and ink droplets and the like can be reliably removed.

According to the present invention, which has been grasped as a configuration of an ink tank itself, ink droplets are ejected from a recording head.
An ink tank that stores ink for recording an image on a recording medium. When the reflective surface is not wet with ink, it reflects the detection light from outside the tank twice and reflects the detection light again outside the tank. In addition, in an ink tank provided with a prism type reflection mechanism that transmits when the reflection surface is wet with ink and does not reflect outside the tank, at least the lower reflection surface has a low affinity for ink. It is configured as an ink tank that has been subjected to affinity processing.
In the present invention, similarly to the first aspect, erroneous detection of the remaining ink amount due to ink droplets or bubbles attached to the reflection surface will be eliminated. Further, as an example of the process for reducing the affinity for the ink, it is conceivable to perform a total reflection process on the upper reflective surface. This idea is based on the fact that the upper reflection surface in the ink remaining amount detection device using the above two reflection surfaces does not affect the detection accuracy even if it is totally reflected at all times. Can be easily achieved by, for example, applying a mirror surface treatment or forming an ink tank structure in which ink does not enter the reflection surface, so that the cost can be reduced while increasing the detection accuracy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating the concept of a device for removing ink droplets and the like used in an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an operation of the device shown in FIG. 1;

FIG. 3 is a conceptual diagram of an apparatus according to an embodiment in which ink droplet removal is to be achieved by a driving device of an ink carriage.

FIG. 4 is a cross-sectional view showing the concept of an embodiment in which a process for making it difficult for ink droplets or the like to adhere to a reflection surface is performed.

FIG. 5 is a sectional view showing an outline of a conventional ink remaining amount detecting mechanism.

FIG. 6 is a sectional view showing an outline of a conventional ink remaining amount detecting mechanism.

FIG. 7 is a sectional view showing an outline of a conventional ink remaining amount detecting mechanism.

FIG. 8 is a conceptual diagram of a reflection mechanism for explaining a conventional problem.

[Explanation of symbols]

 1: Piezoelectric element A: Air reservoir B: Ink droplet or bubble C: Ink carriage I: Ink K: Scanning range L1: Light emitting unit L2: Light receiving unit

Claims (10)

[Claims] An ink tank for ejecting ink droplets from a recording head and storing ink for recording an image on a recording medium receives detection light from outside the tank when the reflection surface is not wet with ink. In the inkjet printer equipped with a prism type reflection mechanism that reflects the light once and reflects the detection light out of the tank again, and transmits when the reflection surface is wet with ink and does not reflect outside the tank, the detection light adheres to the reflection surface. An ink jet printer comprising a removing means for removing ink droplets or bubbles. 2. The ink jet printer according to claim 1, wherein said removing means comprises a vibrating mechanism for applying vibration to said reflecting surface. 3. The ink jet printer according to claim 2, wherein said vibration mechanism includes an electrostrictive element. 4. The ink jet printer according to claim 1, wherein said vibrating mechanism is a drive source for driving said recording head in a main scanning direction. 5. The ink jet printer according to claim 4, wherein the vibration by the vibration mechanism is performed by input means for inputting forward and reverse drive signals to the drive source. 6. The ink jet printer according to claim 5, wherein said drive signal is a signal having a high frequency within a self-starting frequency. 7. The ink jet printer according to claim 4, wherein the vibration is performed by causing a carriage of the recording head to collide with a predetermined stopper. 8. An ink tank for discharging ink droplets from a recording head and storing ink for recording an image on a recording medium, and detecting light from outside the tank when the reflection surface is not wet with ink. An upper reflecting surface and a lower reflecting surface that reflect the light twice and reflect the detection light out of the tank again, and a prism type reflection that transmits when the reflecting surface is wet with ink and does not reflect out of the tank. An ink tank provided with a mechanism, wherein at least a lower reflection surface is subjected to a low-affinity treatment for reducing affinity for ink. 9. The ink tank according to claim 8, wherein the upper reflecting surface is configured to constantly reflect the detection light. 10. The ink tank according to claim 8, wherein said upper reflecting surface is subjected to total reflection processing.