JP2000108373A - Ink residual amount detection apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantitatively and more accurately realize the detection of the ink residual amt. within an ink tank in low cost. SOLUTION: An ink tank 24 filled with ink to be supplied to an ink emitting head and having an elongated ink residual amt. detecting window and a sensor 20 relatively scanned in the longitudinal direction of the ink residual amt. detecting window and detecting the presence of ink at each position of this scanning are provided. The ink residual amt. detecting window is arranged so that the boundary surface of the presence and absence of ink moves in the longitudinal direction of the ink residual amt. detecting window accompanied by the consumption of the ink in the ink tank and constituted of the prism formed on the inner wall of the ink tank. As the sensor 20, a reflection type optical sensor is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet image forming apparatus, and more particularly, to an apparatus for detecting the remaining amount of ink in an ink tank or ink cartridge for storing ink.

[0002]

2. Description of the Related Art Conventionally, in an ink jet printing method, an ink is discharged on demand, and an image can be formed. The printed image changes from a black-and-white image to a color image.
Image formation is performed with magenta yellow, dark and light inks, and black inks, and there are many image forming apparatuses having a structure in which an ink tank for each color can be attached and detached. The ink of each color is stored in an ink tank or an ink cartridge. In the present specification, an ink container that can be attached to and detached from an ink ejection head having an ink ejection nozzle is referred to as an ink tank, and an ink container in which the head and the ink container are integrated is referred to as an ink cartridge. It is called an ink tank.

[0003] The ink consumption in each ink tank is not uniform, and the user can replace the depleted ink tank, replenish the ink in the empty ink tank through a certain path, or use a so-called pit-in method or tubing. The ink is replenished by a method or the like.

Conventionally, control relating to replacement of an ink tank, generation of an alarm for ink replenishment, or automatic replenishment is performed based on an estimated amount of used ink by counting the number of ejected ink droplets. Was. That is, when it is estimated that the used ink amount has reached a certain amount, control is performed to determine that the ink tank is empty or that the ink needs to be replenished. The counting of the number of ejected ink droplets (dot counting) is actually performed by a counter circuit attached to a signal circuit related to a command of a heat pulse or an actuating pulse for ejecting ink.

[0005] However, such detection of the remaining amount of ink by dot counting requires a storage device such as a shift register or a RAM to store the dot count value, and the circuit configuration becomes large. Also, if the ink tank is replaced before the dot count value reaches a value corresponding to the empty state of the ink tank, ink consumption other than printing, such as suction operation (purge processing), preliminary ejection (pre-pulse), It is difficult to accurately detect the remaining amount of ink in consideration of the case where the ink is not consumed due to drying or non-discharge or the like. Regarding the replacement of the ink tank before the ink tank is emptied, it is conceivable to initialize the dot count on the assumption that the ink tank has been replaced with a new ink tank by attaching and detaching the ink tank. In such a case, when the mere attachment / detachment without replacement of the ink tank is performed, the correlation between the dot count value and the remaining ink amount cannot be obtained. With the so-called pit-in method or tubing method, it is more difficult to detect the remaining amount of ink.

As described above, the detection of the remaining amount of ink by the dot count is based solely on the guess, and the display of “no ink” appears even though the remaining amount of ink is sufficient for printing. In some cases, the display of "ink present" is displayed or the display of "no ink" is not performed even though the amount of ink remaining is not sufficient for printing.

There is also known an apparatus which directly detects the presence or absence of ink using an optical sensor. However, since this detects the presence or absence of ink at a certain position of the ink tank, the display of the ink remaining amount is not performed, and the `` no ink '' display is displayed only when the ink amount reaches a certain specific amount. It was conducted. Therefore, before the ink tank needs to be replaced or refilled, the user cannot know the current remaining amount of the ink.

In the method of directly detecting the presence or absence of ink using an optical sensor, it is difficult to detect the ink with a reflective optical sensor if the ink has a high transmittance such as yellow ink. In addition, since it is difficult to detect with a transmission type optical sensor using an ink having a low reflectance such as black ink, there is a problem that the detection method must be changed depending on the ink.

Japanese Patent Application Laid-Open No. 8-108543 discloses a method in which a float is placed in each ink tank and the displacement of the float position is detected by a transmission optical sensor (see FIG. 2 of the same publication). According to this technology, the problem of direct detection of ink by the optical sensor is solved,
By incorporating such a movable float in each ink tank, the number of components is increased and the cost of the ink tank is increased.

Although a method of detecting the remaining amount of ink using electrodes has also been proposed, there are problems such as deterioration and oxidation of the electrode surface over time and deterioration due to ionization decomposition of the ink itself.

JP-A-8-108543 and JP-A-9-226149 also disclose a technique for detecting the remaining amount of ink by combining a light reflection prism and a reflection type optical sensor arranged at the bottom of an ink tank. (See FIG. 6 of the former and FIG. 4 of the latter). However, only the binary detection of the presence or absence of ink is performed, and the user cannot recognize the current remaining amount.

[0012]

Recently, the required image quality and image types are increasing, and the image forming apparatus is provided with a plurality of ink tanks, has various output forms, and is required to have a long output. Accordingly, a mechanism has been devised in which the capacity of the ink tank increases and ink is replenished. With the increase in the capacity of the ink tank and the replenishment mechanism, it is preferable to be able to detect not only the presence or absence of ink in the ink tank, but also the quantitative change (amount) of the remaining amount of ink. If possible, a method for detecting the liquid level of the ink liquid in the ink tank directly at a relatively low cost is desired.

Japanese Patent Application Laid-Open No. Hei 7-164626 discloses a technique for detecting the current remaining amount of ink in each ink tank, in which a large number of light receiving portions of a sensor are provided in the depth direction of the ink tank. See FIG. 25). However, this involves not only the use of the above-mentioned float but also a large number of sensor light-receiving parts, so that there is still a problem in terms of cost.

This publication further discloses an ink detecting means using a combination of a light reflecting prism and a reflection type optical sensor. FIGS. 26 and 27 disclose that a carriage on which an ink tank is mounted is moved with respect to a reflective optical sensor to detect a specific remaining amount of ink. However, the (relative) scanning of the reflective optical sensor with respect to the prism is performed in a direction along a plane parallel to the triangular cross section of the prism.
For this reason, the reflection-type optical sensor has a light-emitting element and a light-receiving element that constitute the reflection-type optical sensor, despite the fact that the interval between the incident light and the reflected light on the prism should change with the height of the ink liquid level. Is constant, it is not possible to cope with a change in ink liquid level, and it is considered difficult to accurately grasp the remaining amount of ink.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and an ink which can quantitatively and accurately detect the remaining amount of ink in an ink tank at lower cost. It is an object to provide a remaining amount detection device.

Further, in response to this, the image forming apparatus can appropriately provide the remaining ink amount information to the user, at the time of appropriate replacement of the ink tank or at the time of appropriate replenishment of the ink to the ink tank, and obtain the replenishment amount. The purpose is to provide.

[0017]

SUMMARY OF THE INVENTION An ink remaining amount detecting device according to the present invention is an ink remaining amount detecting device for an image forming apparatus for forming an image by an ink discharging method, wherein the ink to be supplied to an ink discharging head is provided. Is filled inside and has an elongated ink remaining amount detecting window, and the ink remaining amount detecting window is relatively scanned in the longitudinal direction to detect the presence or absence of ink at each position of the scanning. And an elongated ink remaining amount detection window,
It is characterized in that, with the consumption of the ink in the ink tank, the boundary surface of the presence or absence of the ink is arranged to move in the longitudinal direction of the window for detecting the remaining amount of the ink.

With such a configuration, it is not necessary to count an enormous number of ink ejection pulses (the number of dots) as in the prior art, and there is no need for a memory device for sequentially recording the counted number. No float or electrode is required for the ink cartridge or the ink tank, the problem of light transmittance that differs depending on various types of ink is eliminated, and more accurate detection of the remaining amount of ink can be performed.

The elongated ink remaining amount detecting window is constituted by, for example, one elongated prism formed on the inner wall of the ink tank, and the sensor is a reflection type optical sensor.

The elongated ink remaining amount detecting window may be formed on the inner wall of the ink tank such that a plurality of prisms are intermittently connected in the longitudinal direction. This makes it possible to recognize the length of the ink non-existence portion in the remaining ink amount detection window as bit information.

The window for detecting the remaining amount of ink can be disposed at the bottom of the ink tank so that its longitudinal direction is horizontal. In this case,
It is desirable to provide a means for defining a horizontal flow path through which ink finally reaches the ink discharge head.

The ink tank is mounted on a carriage which is reciprocally scanned, and the sensor is fixedly arranged in the image forming apparatus so as to face the ink detecting window of the ink tank to be scanned. This eliminates the need for special means for relative scanning of the sensor.

The window for detecting the remaining amount of ink may be arranged so that its longitudinal direction is inclined from a horizontal plane. This makes it possible to directly detect the position of the liquid surface in the ink tank. In this case, it is preferable that the sensor is provided with a sensor support unit that moves along the window surface for detecting the remaining amount of ink along the longitudinal direction of the window for detecting the remaining amount of ink according to the scanning of the carriage. In this configuration, a unit may be provided for retracting the sensor support unit from the scanning path of the carriage when scanning the carriage in one direction.

A plurality of the ink tanks are arranged on the carriage, and the sensor can be shared by the plurality of ink tanks. At this time, the prism portion formed on the inner wall of each ink tank extends in the arrangement direction of the plurality of ink tanks so that the sensor is shared.

The window for detecting the remaining amount of ink may be constituted by a prism formed on the inner wall of the ink tank, and the prism may be provided with an identification portion which can be identified by the sensor according to the type of the ink tank. This makes it possible to directly recognize the type of the ink tank from each ink tank.

Further, apart from the detection of the remaining amount of ink, at least one of the header portion and the footer portion for detecting the position of the ink tank may be formed in the same prism shape at the longitudinal end of the prism. Good. This makes it possible to clearly specify the range in which the remaining ink amount should be detected. These header section and footer section can be shared as the identification section.

The window for detecting the remaining amount of ink may be arranged on a horizontal plane or an inclined surface inclined from the horizontal plane, and may be arranged on a side portion of the ink tank so that its longitudinal direction is vertical, and the sensor may be disposed on the side. A configuration in which a scanning unit that scans along the ink remaining amount detection window is provided is also conceivable.

The image forming apparatus according to the present invention includes any one of the above-described ink remaining amount detecting devices, and has a display unit for displaying the detected remaining ink amount. Alternatively, when the ink remaining amount detecting device determines that ink replenishment is necessary,
The ink tank has means for automatically refilling the ink.

It is also possible to detect the remaining amount of ink in both the forward scan and the backward scan of the carriage, or in a plurality of scans, and determine the final amount of ink by averaging or the like based on the detection result. It is possible.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. In addition,
The following embodiments are merely examples, and various modifications and changes can be made.

First, FIG. 1 shows a configuration example of an ink jet image forming apparatus to which the ink remaining amount detecting device of the present invention is applied. The image forming apparatus includes a central processing unit (CPU)
1, a temporary storage device (RAM) for temporarily storing various data and parameters, a non-volatile storage device (ROM) for storing control programs corresponding to various operation modes and various fixed data, an external host device 19 An interface unit 4 for controlling the interface of the CPU 1, an image processing unit 5 for processing image data from the host device 19 obtained through the interface unit 4, and print data from the image processing unit 5, And an ejection control section 6 for controlling the ink ejection of the ink ejection head 7 based on the above.
The image forming apparatus further includes a linear scale 13 for determining each reference dot position in the carriage scanning direction, a linear scale encoder 12 cooperating therewith, a media transport motor 9 for transporting media such as paper, and a CPU 1 under the control of the CPU 1. It has a media transport motor control mechanism 8 for controlling a motor, a carriage motor 11 for scanning the carriage, and a carriage motor control mechanism 10 for controlling this motor under the control of the CPU 1. The above configuration is a conventional configuration. In the present embodiment, the prism unit 15
And an ink remaining amount detection sensor 14. The prism section 15 is preferably formed integrally with the ink tank.

In this embodiment, when the carriage on which the ink tank and the head are mounted moves, the linear scale encoder 12 mounted on the carriage detects the relative movement amount or absolute position of the carriage (hence, the head). At this time, the ink remaining amount detection sensor 14
The remaining amount of ink (remaining amount) can be recognized based on the pulse width of the remaining ink amount detection signal from the printer and the carriage speed or the relative movement amount of the carriage corresponding to the pulse width. Further, it is possible to detect the remaining amount of ink by knowing the absolute position of the liquid surface by detecting the switching timing of the remaining ink amount detection signal and detecting the absolute position. Hereinafter, a specific configuration and operation for that will be described in detail.

Referring to FIG. 2, the principle of ink detection by a combination of a reflective optical sensor 20 as the remaining ink amount detection sensor 14 in FIG. 1 and a prism will be described. FIG. 2 (a)
As can be understood from FIG. 2, the reflection type optical sensor 20 includes a light emitting unit 21 for infrared light and a light receiving unit 22 for receiving reflected light of light emitted from the light emitting unit 21. The light emitting unit 21 and the light receiving unit 22 are each configured by a light emitting diode 81 and a phototransistor 82, for example, as shown in FIG. If the light receiving section 22, that is, the phototransistor 82 does not detect the reflected light, the phototransistor 8
2 does not conduct, and the output voltage at one end of the resistor 83 is low (L).
Remains at the level. When the phototransistor 82 receives light and conducts, the output voltage becomes high (H) level. As shown in FIG. 2B, the object 23 having no specific prism structure is used.
When light comes to the detection position of the optical reflective sensor 20, light does not reach the light receiving unit 22. Therefore, as shown in FIG. 2C, the ink tank 24 is formed of a light transmitting member, and the prism 25 is formed on a predetermined inner wall surface. In the case where the liquid 31, in this case, ink, exists in the portion of the prism 25, the incident light is reflected at the interface due to the difference in the refractive index of the light between the member (glass, poly-based material, etc.) forming the prism 25 and the liquid. Refraction occurs (FIG. 2C). At this time, as the incident angle α and the refraction angle β, the refractive index n (α → β) = sin
α / sinβ (> 1).

Further, the refractive index na of the air with respect to the ideal gas
= About 1.0, the refractive index ni of the ink is about 1.4, and the refractive index np of the polypropylene is about 1.5. Therefore, the refractive index when entering the ink from polypropylene is npi =
1.4 / 1.5 {0.93 {sin 68} / sin 90
It becomes ゜. This means that when the incident angle from the polypropylene to the ink is 68 °, the refraction angle is 90 °, that is, the incident light is refracted at the joint interface between the two objects in the direction of the vector in the interface. (The incident angle at this time is called a critical angle). That is, the incident angle α> 6
At 8 °, the incident light is totally reflected. On the other hand, the refractive index when entering the air from polypropylene is npa = 1.0 /
1.5 ≒ 0.67 ≒ sin42 ゜ / sin90 ゜. This means that when the angle of incidence when entering the air from the polypropylene is 42 °, the refraction angle is 90 °, that is, the incident light is refracted in the direction of the vector in the interface at the joint interface between the two objects. When the angle α> 42 ° (critical angle), it means that the incident light is totally reflected. Taking advantage of this, the infrared light from the light emitting unit 21 is set to 42 ゜ <α <
The container of the ink tank 24 having a prism structure having an incident angle of 68 ° is made of a polypropylene material, and is placed in the above-described installed state, whereby light refraction occurs when ink is present, and when ink is not present. The total reflection of light occurs (FIG. 2D). As a result, the light from the light emitting unit 21 reaches the light receiving unit 22, and the output voltage becomes high (H) level,
Information that there is no ink is obtained. In the present embodiment, the magnitude of the vertex angle γ of the prism 25 is 90 ° here, and the incident angle α of the infrared light is 45 °. Supplementally, the result obtained when the ink is present in FIG. 2C is the same as that in FIGS. 2A and 2B, and the detection using the present prism structure is performed as shown in FIG. Only in the case of d), information that there is no ink can be obtained. The above is the conventional detection method using a prism.

In this embodiment, first, a window for detecting the remaining amount of ink is elongated in a certain direction, and the window for detecting the remaining amount of ink has a prism structure. By performing scanning control of the mold optical sensor relatively in the longitudinal direction of the prism, the amount of remaining ink is quantitatively detected.

FIG. 3 shows the relationship and arrangement of the prism 25 and the reflection type optical sensor 20 when the prism 25 is used as a window for detecting the remaining amount of ink which is elongated in a certain direction. FIG.
(A) shows the longitudinal direction of the prism 25 in one direction (x in the figure).
(Direction). In this case, the sensor 20 faces the bottom surface of the prism 25 and relatively scans the prism 25 in the x direction. In FIG. 3B, the relative movement of the sensor 20 with respect to the prism 25 is shown in FIG.
3A is the same as FIG. 3A, but differs from FIG. 3A in that both are inclined from the xy plane by an angle θ. How such a configuration is used for detecting the remaining amount of ink will be specifically described below.

FIG. 4 shows a schematic configuration example of an ink tank corresponding to the arrangement of FIG. As can be seen from FIG. 4A, in this example, the prism 25 is
The front surface of the prism 25 is disposed so as to face the sensor 20 at the front side. The bottom surface of the prism 25 forms a window for detecting the remaining amount of ink. The sensor 20 is scanned relative to the ink tank 24 along the longitudinal direction of the prism 25. Ink tank 24
In this example, a substantially spiral partition wall 2 for defining an ink flow path 33 for the ink ejection head 7 in this example.
7 is formed. As shown in FIG. 4B, the space between the spiral partition walls 27 is filled with an ink absorber 28 such as a sponge. This ink absorber 28
Is generally provided to stabilize the ink pressure in the ink ejection head section. Thus, ink can be supplied to the ink ejection head 7 at a stable pressure under a constant negative pressure of the ink absorber 28 regardless of the amount of remaining ink. The ink absorber 28 may be filled in the entire inside of the ink tank 24, but it is sufficient if it is arranged at a part of the lower part as shown in the figure.

After the ink in the ink tank 24 is consumed and reduced to the height of the partition wall 27, the ink flows along the spiral flow path of the ink partition wall 27 and decreases. Eventually, the decreasing interface between the presence / absence of the ink moves toward the head 7 along the longitudinal direction of the prism 25. The position of the boundary surface between the presence / absence of the ink and the presence / absence of the ink can be recognized based on a change in the output of the sensor 20 at the time of scanning relative to the prism 25 of the sensor 20 as described later.

The ink flow path is not limited to a spiral one as shown in the figure, but it is sufficient if a structure in which the boundary surface of the ink moves along the prism 25 can be obtained.

An example of a configuration for detecting the current scanning position of the sensor 20 will be described with reference to FIG. As shown in FIG. 5A, usually, an inkjet image forming apparatus includes a carriage 3 on which a head 7 and an ink tank 24 are mounted.
The above-described linear scale 13 is fixedly arranged along the scanning direction of 0. Linear scale encoder 1
2 has a linear scale sensor 29 for detecting the presence or absence of a regular slit provided on the linear scale 13. Based on the output of the linear scale encoder 12,
The current position of the carriage 30 and thus the head 7 can be recognized. In the present embodiment, relative scanning of the prism 20 of the sensor 20 with respect to the prism 25 is realized by the prism 25 of the ink tank 24 moving in front of the fixed sensor 20. The sensor 20 obtained at this time
By combining the state of the output with the current carriage position based on the linear scale encoder 12, a specific level of the remaining amount of ink can be determined.

However, when the ink tank as shown in FIG. 2 (c) is full (or the boundary surface of the ink liquid does not appear in the prism portion), the ink other than that shown in FIGS. It is indistinguishable from the case where the sensor 20 is outside the ink.
Therefore, preferably, a prism having the same shape as the prism for detecting the remaining amount of ink is provided in the ink tank, the carriage, or the ink tank holder as a header portion or a footer portion, so that the detection of the remaining ink amount is started / finished. The existence position, in other words, the start point / end point of the sequence that effectively takes in the detection output of the sensor output within the time when the sensor 20 scans the prism 25 of the ink tank can be clarified.

The area where the prism portion is provided and the area where the ink tank exists are stored in advance in the ROM or the like as configurationally known information, and the output value of the sensor 20 is monitored together with these known values. In such a case,
The header section and the footer section need not be provided.

In the example of FIGS. 4 and 5, the ink tank 2
After the ink in 4 has been reduced to the final ink flow path where the prism 25 exists, the remaining ink amount can be detected successively. In this example, the range of the remaining amount of ink that can be detected is a range that is very small compared to the ink capacity of the entire ink tank 24. However, since a certain amount of printing can be continued even with the ink remaining in the small range, the change in the ink remaining is notified to the user by some method (for example, numerical display or graphic display). By doing so, it is possible to have a countdown-like meaning until the ink replacement is required.

In order to detect relative scanning position information of the sensor 20, the linear scale 13 and the encoder 1 for reading the linear scale 13 are used.
2, the combination of a slit mounted on the motor shaft of the carriage motor 11 for driving the carriage and a rotary encoder can be used. Alternatively, when a stepping motor is used, a stepping motor is used. It is also possible to use an evening drive signal.

FIG. 6 shows a flowchart of the remaining ink amount detecting process by such an ink remaining amount detecting device.
This process is executed by the CPU 1 when the power switch (SW) is turned on. However, it is also possible to execute this processing at an arbitrary time based on a user's instruction or periodically during operation of the system.

In the process of FIG. 6, when the power switch of the apparatus is turned on, after a predetermined initial operation S1, the carriage is moved (S2), and the home position is detected (S3). Thereafter, the absolute position of the carriage is determined according to the relative movement amount based on the output of the linear scale encoder 12. Then, the carriage is moved in the direction of arrow 2 so that the carriage (30 in FIG. 5) scans the window for detecting the remaining amount of ink.
6 (FIG. 5) (S3). At this time, of course, the sensor 20 is ON. Along with the carriage scanning, the sensor 20 detects a point in time when the signal (H) indicating the absence of ink changes to a signal (L) indicating the presence of ink (S4). When ink is present in the entire remaining ink amount detection window, the output of the sensor 20 remains at the L level during scanning in the direction of the arrow 26 regardless of the inside and outside of the remaining ink amount detection window. (As described with reference to FIG. 2, the sensor output in the ink remaining state detection window at the ink remaining amount detection window and the sensor output outside the ink remaining amount detection window are both L and cannot be distinguished.) When the ink is not present from the right end of the amount detection window, the sensor output changes from L to H when the sensor enters the ink non-existence part (the right side in the ink remaining amount detection window in the figure). The sensor output changes from H to L when the sensor changes into the ink existing portion. By checking the carriage position when the sensor output changes from H to L, the position of the ink boundary surface can be determined. This is because the position of each ink tank on the carriage is recorded in the ROM in advance as known, and the position of the sensor in the image forming apparatus is also recorded in the ROM in advance as known. This is because the relative positional relationship between the ink tank 24 and the ink tank 24 can be understood. Further, a configuration may be adopted in which the position of the ink tank is confirmed by detecting a prism portion provided as a header portion or a footer portion described later.

If the position of the boundary surface of the ink is known, the portion from that position to the left end of the window for detecting the remaining amount of ink is an ink existing portion, so that the position can be converted into the remaining amount of ink (S
5). In step S4, if no change from H to L is detected in the area where the relative scanning is performed by the sensor 20 with respect to the prism portion of the ink tank 24 or within that time, the ink remains in the entire remaining ink amount detection window. You can see that it is full.

In order to cope with erroneous recognition due to a liquid level change or the like in one ink remaining amount detection, the carriage is scanned in the reverse direction, and the same operation is performed. That is, after instructing the inversion and movement of the carriage (S7), the time point at which the sensor output changes from L to H is detected (S8).
Since the carriage scanning direction is opposite to the arrow 26, when viewed from the sensor 20, scanning is performed from the left end (the side where the head 7 is located) of the remaining ink amount detection window. As a result, if any ink remains in the ink tank, the sensor output remains at L from the position where the sensor is outside the ink remaining amount detection window, and the sensor output remains in the ink remaining amount detection window. When an absent part appears, the sensor output changes to the H level for the first time. By detecting the point in time when the sensor output changes from L to H and checking the carriage position, the position of the ink boundary surface can be determined. When no ink-free portion does not appear, the sensor output remains at L and does not change. In this case, it is determined that the entire ink remaining amount detection window is full of ink.

When at least one of the header portion and the footer portion is provided, the relationship between the position of the header portion and the position of the ink boundary surface can be detected when scanning from the header portion side, and when the scanning is reversed, the footer portion of the footer portion is detected. The relationship between the position and the position of the ink boundary surface can be detected, thereby making it easy to obtain the remaining amount of ink.

Then, the position of the ink boundary surface obtained in S8 is converted into the remaining ink amount in the same manner as in S5 (S5).
9). Therefore, the remaining ink amount obtained in S5 and the remaining ink amount obtained in S9 this time are compared, and if there is no large error between them, the average value is determined as the remaining ink amount (S
10). If there is an error equal to or greater than a predetermined size, the user may be notified that an error has occurred.

The amount of ink thus obtained is notified to the user by a numerical value or a graphic display as described above (S6). In addition, an alarm is issued to the user according to the remaining ink amount. In addition to instructing ink replacement or replenishment when the remaining amount of ink falls below a predetermined amount, the alarm also informs the user when the remaining amount of ink that requires replacement or replenishment of ink is detected soon. A gradual alarm can be given to alert you. As an aspect of each alarm, not only a message display but also an indicator lamp display, sound, and voice may be considered.

When the user is instructed to replace the ink tank or refill the ink, the user performs the work of replacing the ink tank or filling the ink. In addition, the ink filling operation may be automatically performed by the apparatus by a pit-in method or the like based on the ink remaining amount detection signal of the ink tank.

Next, FIG. 7 shows an example of the configuration of an ink tank 24 in which the window for detecting the remaining amount of ink has a constant angle θ with respect to the horizontal plane, corresponding to the prism arrangement of FIG. 3B. At this time, the ink level in the ink tank 24 is
When it drops to the position of 5, the liquid level becomes
The prism crosses both upper slopes diagonally. The bottom surface of the ink tank 24 is also inclined parallel to the bottom surface of the prism 25. For the ink tank 24 having such a configuration, the sensor 20 as shown in FIG. 8A has a sensor holder 80 (FIG. 8) having an upper surface adjusted to the inclination angle θ.
(B)). Such a prism-type reflective optical sensor is installed on the opposite side of the ink remaining amount detection window of the ink tank 24 as shown in FIG.

FIG. 10 shows a carriage 30 on which the ink tank 24 is mounted and the sensor holder 8 holding the sensor 20.
The relative relationship with 0 is shown. In the figure, the linear scale 13 is fixed, and the carriage 30 can move along the scale. On the other hand, the lower portion of the sensor holder 80 is supported by the elastic member 90 and constantly receives an upward urging force. The lower end of the elastic member 90 is fixed in the device. Therefore, the sensor holder 20 can move up and down in the vertical direction, but does not move in the horizontal direction. FIG. 10 shows a state in which the carriage 30 approaches the sensor holder 80 having such a structure from a remote position and contacts the sensor surface of the sensor holder 80.
(A). When the carriage 30 is further moved rightward in the figure, as shown in FIG. 10B, the sensor holder 80 is moved by the window for detecting the remaining amount of ink of the ink tank 24 on the upper inclined surface thereof. It is pushed downward against the elastic force and moves downward. As a result, the sensor 20 held by the sensor holder 80 scans the ink remaining amount detection window in the longitudinal direction. The scanning direction of the sensor 20 is from the upper side to the lower side of the window for detecting the remaining amount of ink. However, if the carriage 30 is returned from the state of FIG. The result is obtained.

As shown in FIG. 11, when the ink liquid level is located at the intermediate portion of the inclined prism 25, the output signal of the sensor 20 becomes H level in a portion where ink does not exist and L level in a portion where ink exists. By checking the output of the linear encoder when the sensor output changes, a specific level of the current ink remaining amount can be obtained. Although the flowchart of the processing for this is not particularly shown, the remaining ink amount is obtained by substantially the same processing as in FIG. In this case, since the level of the ink liquid level in the ink tank 24 is directly detected, significant information on the amount of remaining ink can be obtained from an earlier stage.

Next, a description will be given of a modification of the prism structure for determining the remaining amount of ink without using the linear scale 13. FIG. The prism 25 'shown in FIG. 12 has a configuration in which the prism 25 is divided into a plurality of prism portions at regular intervals along the longitudinal direction (referred to as an intermittent prism structure in this specification). Thus, when the sensor 20 scans the window for detecting the remaining amount of ink in the prism 25 ', the sensor output is changed between the H level and the L level according to the prism portion in the non-ink present portion of the window for detecting the remaining amount of ink. , A pulse waveform that changes is obtained. The reason will be understood from the description of FIG. Therefore, by counting the number of such pulses, the length of the ink non-existing portion in the ink remaining amount detection window is determined as bit information, and the remaining ink amount can be obtained from the bit information.

The example of applying such an intermittent prism structure to a prism tilted from a horizontal plane has been described. However, the present invention is not limited to this. The horizontal arrangement shown in FIG. The same can be applied to the case of the vertical arrangement.

FIG. 13 shows another means for determining the remaining ink level without using the linear scale. This is shown in FIG.
Is a modification of the embodiment described above. In this case, the sensor holder 80 has a light blocking flag 92 and the carriage 3
In response to the movement of 0, any one of the plurality of photointerrupters 93 arranged at regular intervals in the movement path of the sensor holder 80 is blocked. For example, a plurality of photointerrupters 93 are arranged like 93a, 93b, and 93c in FIG. 13, and each circuit is similar to the light emitting diode 81 described in FIG.
And the phototransistor 82.
Therefore, the photo interrupter is an equivalent optical sensor, and when the light is shielded by the light shielding flag 92, the output voltage becomes L. Therefore, in the case of FIG.
The configuration is such that the state of the flag position can be determined. Flag position 93a output 93b output 93c output 1LHH2LLH3HLH4HLLL5HHL Each of FIG. 13 (a) is a flag position 1 and FIG. 13 (b)
Indicates the state of the flag position 4. The sensor holder 80 and the light-shielding flag 92 always receive an urging force in the lower left direction in the figure by the elastic member 90 so that the sensor can scan the prism portion by the operation of the carriage on which the ink tank is mounted. The lower left end of the elastic member 90 is fixed in the apparatus, and is disposed at a position where it does not interfere with the photo interrupter 93. The sensor holder 80 and the light shielding flag 92 have the operations shown in FIGS. It is assumed that a slide guide (not shown in FIG. 13) that enables the above is provided.

In this way, when a change in the output of the sensor 20 is detected, the carriage position at that time can be obtained based on which photo interrupter 93 is shielded from light. Thus, the level of the remaining amount of ink can be determined as described above. Sensor holder 80
Is disposed at a position where the elastic member 90 does not conflict with the photo interrupter 93.

FIG. 14 shows another example of the arrangement of the prisms 25. As shown in FIG. 14A, in this example, the prism 25 is arranged on the side wall surface of the ink tank 24 so that the longitudinal direction of the prism is vertically oriented. That is,
The window for detecting the remaining amount of ink is provided on the side wall of the ink tank. Along with this, the sensor 20 needs to scan vertically opposite the window for detecting the remaining amount of ink. For this reason, the sensor 20 in this case is separately provided with a mechanism (not shown) that moves in the vertical direction at a predetermined position (for example, a home position) in the carriage movement direction. Further, the position of the sensor 20 in the vertical direction can be realized by another means (for example, when the sensor 20 is driven by a stepping motor, the number of motor drive pulses is counted).

Next, a case where a plurality of ink tanks 24 are arranged in parallel on a carriage as shown in FIG. 15 will be described.

In the case of an image forming apparatus having a plurality of ink tanks, the above prism structure is applied to all the ink tanks, and the elongated ink remaining amount detecting windows of all the ink tanks are arranged in a straight line. It is possible to detect the remaining amount of ink in all the ink tanks with one sensor 20. Further, in order to identify the colors of the respective ink tanks and detect the remaining amount of ink for each color, the respective ink tanks are placed on an extension of the ink remaining amount detection window of each ink tank 24 in a certain direction. There is provided an identification unit for identifying the color. As the identification section, the header section or the footer section described above can be used. In the illustrated example, one end of the prism 25 is projected outside the ink tank 24, and the amount of projection is uniquely changed according to the ink color of the ink tank. The projecting portions (identifying portions) 151 and 152 function as a header portion or a footer portion with respect to the sensor 20 depending on the scanning direction.
Of course, both may be provided in one ink tank by protruding the prisms 25 on both sides of the ink tank. The protruding portions 151 and 152 set the sensor output to the H level as shown in FIG. 16 (see FIG. 2D). By obtaining the lengths L1 and L2 of the period of the H level of the sensor output with reference to the linear encoder output,
The lengths of the corresponding projections 151 and 152 can be obtained. From the result, it is possible to identify the ink color of the ink tank related to the scan. If the positions of the individual ink tanks are known and the known values are stored, there is no need for an identification unit for identifying each ink tank.

In FIG. 16, the amount of remaining ink can be determined by obtaining the position (P1, P2) where the sensor output changes within the window for detecting the amount of remaining ink in the same manner as described above. To determine the positions P1 and P2, it is necessary to determine the absolute position of the linear scale 13.
Instead, by counting the output of the linear encoder 12 during the period when the sensor output is at the H level, the length of the non-ink present portion in the ink remaining amount detection window can be obtained. That is, it is also possible to obtain the remaining ink amount. In this case, it is not necessary to determine the absolute position of the linear scale. Further, if the individual ink tanks can be identified by the header section or the footer section, it is not necessary to store each ink tank position based on the absolute position as a known value.

The intermittent prism structure can also be used in the header or footer or the window for detecting the remaining amount of ink.

Further, even if the pattern of the projections is not changed for each ink tank, the number of the projections is counted in a series of operations for scanning the windows for detecting the remaining amount of ink in the plurality of ink tanks. It is possible to recognize the order of the ink tank being scanned at the time of the scanning, and it is also possible to identify the color of the ink tank.

FIG. 17 shows a configuration corresponding to FIG. 16 when the prism 25 is inclined from the horizontal plane. In this case, the structures of the sensor 20 and the sensor holder 80 are the same as those shown in FIG. However, a plurality of ink tanks 2
Arrow 4 to share one sensor 20 for
When scanning the carriage 30 in the direction 6, the same operation as that shown in FIG. 10 is performed, but when scanning the carriage 30 in the direction opposite to the arrow 26, the support 93 of the elastic member 90 is moved in the direction of the arrow 32. As a result, the sensor holder 80
To the position where it does not collide with the ink tank 24. The mechanism for this is not specifically shown, but those skilled in the art will appreciate that it can be implemented by any known technique. The rod-shaped member extending downward from the sensor holder 80 in FIG. 17B is for ensuring the vertical sliding of the sensor holder 80.

While the preferred embodiment of the present invention has been described above, various modifications and changes can be made. For example, in the above embodiment, the prism portion in the ink tank was described as being directly exposed to the outside,
As shown in FIG. 18, when the ink tank 24 is held in the ink tank holder 191 so as to be able to reach the ink tank holder 191, a prism part detection window 192 is provided at a position corresponding to the prism part of the ink tank holder 191. The remaining amount of ink can be detected via the control unit.

[0068]

According to the present invention, the ink remaining amount in the ink tank can be relatively reduced by forming a simple ink remaining amount detecting window which can directly scan the ink liquid level in a certain direction. Accurate detection is possible, and it is possible to replace the ink cartridge or the ink tank or to perform appropriate ink replenishment based on the detected amount of the remaining ink.

Further, by employing a prism having an intermittent structure, the detection signal of the sensor can be obtained as a pulse signal, and the remaining amount of ink can be detected without depending on a linear scale or the like.

In an image forming apparatus in which a plurality of ink tanks can be mounted, the remaining amount of ink in each ink tank can be detected by one sensor, and each ink tank in an ink jet image forming apparatus which is an on-demand type recording apparatus. This is extremely effective for detecting the remaining amount of ink in the printer.

[0071]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of an inkjet image forming apparatus to which an ink remaining amount detection device according to the present invention is applied.

FIGS. 2A and 2B are principle diagrams of ink detection in various cases (a) to (d) by a combination of a reflective optical sensor 20 as the remaining ink amount detection sensor 14 in FIG. 1 and a prism.

FIG. 3 is a diagram showing a relationship between two typical cases (a) and (b) of a prism 25 and a reflective optical sensor 20 when a prism 25 is used as a structural window for detecting the remaining amount of ink which is elongated in a certain direction. .

FIG. 4 is a perspective view (a), (b) and a side view (c) showing a schematic configuration of an ink tank corresponding to the arrangement of FIG. 3 (a).

5A and 5B are explanatory diagrams of an example of a configuration for detecting a current scanning position of a sensor 20 in the configuration of FIG. 4;

FIG. 6 is a flowchart of a remaining ink amount detection process by the remaining ink amount detection device as shown in FIG. 5;

FIG. 7 is a diagram illustrating a configuration example of an ink tank 24 in which a window for detecting the remaining amount of ink has a predetermined angle θ with respect to a horizontal plane, corresponding to the prism arrangement of FIG. 3B; is there.

8 is an explanatory diagram of a sensor holder (b) and a sensor (a) having an upper surface adjusted to an inclination angle θ with respect to an ink tank having a configuration as shown in FIG. 7;

FIG. 9 is a circuit diagram showing a configuration example of a reflection type optical sensor used in the present invention.

FIG. 10 shows an ink tank having a configuration as shown in FIG.
7A and 7B show a relative relationship between a carriage on which an ink tank is mounted and a sensor holder holding a sensor.
It is.

FIG. 11 is an explanatory diagram of an output signal of a sensor when an ink liquid level is located at an intermediate portion of a tilted prism.

FIG. 12 is a view corresponding to FIG. 11 for an intermittent prism structure.

FIGS. 13A and 13B are explanatory diagrams showing another means for determining the remaining ink level without depending on the linear scale. FIGS.

FIGS. 14A and 14B are explanatory diagrams illustrating an example of an arrangement in which prisms are arranged in a vertical direction. FIGS.

FIG. 15 is an explanatory diagram of an embodiment in a case where a plurality of ink tanks are arranged in a carriage.

16 is an explanatory diagram of a sensor output in the configuration of FIG.

17A is a diagram illustrating a configuration corresponding to FIG. 16 when the prism is inclined from a horizontal plane, and FIG. 17B is an explanatory diagram of a sensor holder suitable for this configuration.

FIG. 18 is an explanatory diagram of a prism part detection window in a case where the ink tank is held so as to be able to reach the ink tank holder.

[Explanation of symbols]

7 ... ink ejection head, 20 ... reflection type optical sensor, 21
... Light-emitting part, 22 ... Light-receiving part, 24 ... Ink tank, 25 ...
Prism, 25 '... intermittent structure prism, 27 ... partition wall,
28: ink absorber, 29: linear scale sensor, 3
0 ... carriage, 31 ... liquid, 32 ... arrow, 33 ... ink flow path, 80 ... sensor holder, 90 ... elastic member, 92 ...
Flag, 93 ... Photo interrupter, 151, 152 ...
Protruding part (identifying part), 191 ... ink tank holder.

Claims (14)

[Claims] An ink remaining amount detecting device for an image forming apparatus for forming an image by an ink discharging method, wherein an ink to be supplied to an ink discharging head is filled therein, and an elongated ink remaining amount detecting window is provided. An elongated ink remaining amount detection window, comprising: a sensor that scans in a longitudinal direction relative to the ink remaining amount detection window and detects presence / absence of ink at each position of the scanning; Is a device for detecting the remaining amount of ink, wherein the boundary surface of the presence or absence of ink moves in the longitudinal direction of the window for detecting remaining amount of ink as the ink in the ink tank is consumed. 2. The ink remaining amount detecting device according to claim 1, wherein said elongated ink remaining amount detecting window is constituted by one elongated prism formed on an inner wall of said ink tank, and said sensor is a reflection type optical sensor. . 3. The ink remaining amount detecting device according to claim 1, wherein the elongated ink remaining amount detecting window is formed on an inner wall of the ink tank such that a plurality of prisms are intermittently connected in a longitudinal direction thereof. apparatus. 4. The ink remaining amount detecting window is disposed at the bottom of the ink tank so that the longitudinal direction thereof is horizontal, and the inside of the ink tank is provided for the ink to reach the ink discharge head. 4. The remaining ink amount detecting device according to claim 1, further comprising means for defining a horizontal flow path which finally passes. 5. The image forming apparatus according to claim 1, wherein the ink tank is mounted on a carriage that is reciprocally scanned, and the sensor is fixedly arranged in the image forming apparatus so as to face the ink detection window of the ink tank to be scanned. An ink remaining amount detecting device according to any one of claims 1 to 4. 6. The ink remaining amount detection window is disposed so that its longitudinal direction is inclined from a horizontal plane, and the sensor is arranged so that the ink remaining amount along the longitudinal direction of the ink remaining amount detecting window in accordance with the scanning of the carriage. 4. The remaining ink amount detecting device according to claim 1, further comprising a sensor supporting means that moves along the amount detecting window surface. 7. An apparatus according to claim 6, further comprising means for retracting said sensor support means from a scanning path of said carriage during scanning in one direction of said carriage. 8. A plurality of ink tanks are arranged on the carriage, and a prism portion formed on an inner wall of each of the plurality of ink tanks includes a plurality of prisms formed on the inner wall of each of the plurality of ink tanks. The ink remaining amount detecting device according to any one of claims 1 to 7, which extends in an arrangement direction of the ink tanks. 9. The ink remaining amount detecting window is constituted by a prism formed on the inner wall of the ink tank, and the prism has an identification portion that can be identified by the sensor according to the type of the ink tank. Ink remaining amount detection device. 10. The ink remaining amount detection window is constituted by a prism formed on the inner wall of the ink tank, and is provided at an end in the longitudinal direction thereof to detect the position of the ink tank separately from the detection of the ink remaining amount. 10. The remaining ink amount detecting device according to claim 1, wherein at least one of the header portion and the footer portion is formed in a similar prism shape. 11. A scanning means for positioning the window for detecting the remaining amount of ink on a side portion of the ink tank so that a longitudinal direction thereof is vertical, and scanning the sensor along the window for detecting the remaining amount of ink. 4. The ink remaining amount detecting device according to claim 1, further comprising: 12. An image forming apparatus comprising: the ink remaining amount detecting device according to claim 1; and display means for displaying the detected ink remaining amount. 13. An ink remaining amount detecting device according to claim 1, wherein when the ink remaining amount detecting device determines that replenishment of the ink is necessary, the ink tank is automatically stored in the ink tank. Image forming apparatus having a unit for replenishing toner. 14. An ink remaining amount detecting device according to claim 1, wherein the ink remaining amount is detected both at the time of forward scanning and at the time of backward scanning of the carriage, or by a plurality of scans. And an image forming apparatus for determining a final ink remaining amount based on the detection result.