JPH0749984B2 - Liquid level detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for automatically detecting the amount of a conductive liquid in a container, and particularly to an ink for detecting the amount of ink in an ink container in a printer or the like. Level detector

[Prior Art] Ink jet printers, which are widely used as output devices at present, notify the user by automatically detecting the remaining amount of ink or ink shortage by various methods and turning on a display lamp. One of the methods is to utilize the conductivity of ink. Many printers that detect the remaining amount of ink using this method have a predetermined voltage (hereinafter referred to as a search voltage or a search voltage) on one of a pair of electrodes arranged at the same height in an ink container. (Referred to as a search signal), and the ink remaining amount is detected by detecting the potential of the other electrode at this time. When the height of the ink surface in the ink container is higher than the height of the tips of the pair of electrodes, the voltage applied to one of the pair of electrodes transfers the conductive ink to the other. However, if the height of the ink surface is lower than the height of the tips of the pair of electrodes, the voltage applied to one of the pair of electrodes is not transmitted to the other electrode. Therefore, if the potential of the other electrode is detected, it is determined whether the height of the ink surface is higher or lower than the height of the tip of the electrode. That is, the remaining amount of ink is detected based on one detection level, which is the height of the tips of the pair of electrodes. To what height the ink is contained in the container in such a manner (hereinafter, this “height” is called an ink level),
That is, in order to detect the remaining amount of ink more accurately, it may be considered to use a plurality of pairs of electrodes arranged at a plurality of different heights in the ink container. Hereinafter, such an electrode is referred to as a detection electrode.

As an example of such a case, FIG. 3 is a diagram showing an example of an ink level detection mechanism that can be considered when detecting the ink remaining amount of each color in a color printer based on two detection levels. Referring to the drawing, the ink container 1 containing the yellow (Y) ink has two pairs of detection electrodes ey1.
And ey2 are arranged, the ink container 2 containing magenta (M) ink is also arranged with two pairs of detection electrodes em1 and em2, and the ink container 3 containing cyan (C) ink is arranged.
Are also provided with two pairs of detection electrodes ec1 and ec2, and two pairs of detection electrodes eb1 and eb2 are also provided in the ink container 4 containing the black (b) ink. The tips of each of these two pairs of detection electrodes are located at different heights, level 1 and level 2, in each ink container. The detection circuit 11 is
By detecting the potential of the other when a predetermined voltage is applied to one of the detection electrodes of each pair (hereinafter, this is referred to as a detection voltage), the height of the ink in the container, that is, The ink level is detected and a detection output according to the detection result is output. For example, referring to the drawing, the ink levels of the ink container 1 are level 1 and level 2.
Is in between. Therefore, in this case, level 1
Since the detection electrodes of the detection electrode pair ey1 located at the height of are isolated from each other, even if a search voltage is applied to one detection electrode, no current flows to the other detection electrode and the potential of the other detection electrode is It does not change. However, the detection electrodes of the detection electrode pair ey2 located at the height of level 2 are connected to each other via the conductive ink. Therefore, the detection electrode pair ey
When a search voltage is applied to one of the two detection electrodes, a current flows through the other detection electrode and the potential of the other detection electrode changes. Therefore, different detection voltages are obtained from the detection electrode pairs ey1 and ey2. In this case, the detection circuit 11
A detection output indicating that there is still a margin before the ink runs out is output.

Next, in the case of the ink container 2, the ink level is higher than the level 1. Therefore, a detection voltage indicating that the ink level is higher than that level is obtained from both the detection electrodes em1 and em2. In this case, the detection circuit 11 outputs a detection output indicating that the remaining amount of ink is sufficient.

Next, in the case of the ink container 3, the ink level is lower than the level 2. Therefore, the detection voltage indicating that the ink level is lower than that level is obtained from both the detection electrode pairs ec1 and ec2. In this case, the detection circuit 11
Outputs a detection output indicating that the ink remaining amount is small.

The ink level of the ink container 4 is in the range lower than the level 1 and higher than the level 2 like the ink container 1. Therefore, from the detection electrode pair eb1 and eb2, the ink container 1
A detection voltage similar to the detection voltage obtained from the detection electrode pair ey1 and ey2 is obtained, and the detection circuit 11 outputs the same detection output as in the case of the ink container 1.

These detection outputs are used to cause a display unit such as a display lamp to inform the user of the remaining amount of ink.

As described above, the remaining ink amount (ink level) is level 1 or higher, level 2 or higher and level 1 or lower, and level 2
It is determined which one of the following three levels.

[Problems to be Solved by the Invention] As described above, in order to detect the remaining amount of ink more accurately, a plurality of pairs of detection electrodes whose tips are located at different heights are provided in each ink container. Will be distributed. Therefore, the number of ink colors, that is, the number of ink containers
When N is the number of detection levels, that is, the number of detection electrode pairs is L, the total number of detection electrodes arranged in the ink container for detecting the remaining amount of ink is represented by 2N × L. By the way, in order to accurately know the remaining amount of ink, many detection electrode pairs may be arranged at different heights to increase the number of detection levels. In that case, as the number of detection levels increases, the total number of detection electrodes increases in accordance with the above equation and becomes very large. However, there is a problem that such an increase in the number of detection electrodes increases the manufacturing cost of a device (a printer in this example) including the ink level detection mechanism.

An object of the present invention is to solve the above problems and reduce the number of detection electrodes for detecting the ink level, which is represented by the ink remaining amount detection of a color printer, and is used to detect the conductive liquid in a plurality of containers. It is an object of the present invention to provide a liquid level detecting device capable of accurately performing level detection.

[Means for Solving the Problems] A liquid level detection device for detecting the level of a conductive liquid according to the present invention in order to achieve the above-mentioned object is provided in a plurality of levels in each of a plurality of containers. At least one common electrode associated with each level and parallel to each of the plurality of containers, and one unique electrode disposed perpendicular to the level for each of the plurality of containers;
A detection unit that applies a common search voltage to each of the two common electrodes individually or to a plurality of unique electrodes to detect the potential change from each of the unique electrodes is provided.

[Operation] Since the liquid level detection device according to the present invention is configured as described above, the total number of detection electrodes arranged in the container is the number of containers and the number of common electrodes, that is, the number of detection levels. Is the sum of Therefore, the number of detection electrodes arranged in the container for detecting the liquid level in the container is smaller than that in the case where the same number of detection electrode pairs as the number of detection levels are provided in each container.

[Embodiment] FIG. 1 is a schematic block diagram of an ink level detecting apparatus for detecting the remaining amount of ink of each color of a color printer, showing an embodiment of the present invention. With reference to the drawing, this ink level detecting device has four ink containers 1 (yellow ink is stored), 2 (magenta ink is stored), and 3 cyan inks arranged side by side. Be accommodated. ), And 4 (containing black ink), the detection electrodes 1 and 12 provided in common, the detection electrodes e1, e2, e3 and e4 arranged in the respective ink containers, and the detection electrodes e1 to
An analog data selector 5 connected to e4, an analog switch 6, a search signal generator 7 for generating a pulsed search signal, and a reference voltage generator 8 for generating two different reference voltages V _ref1 and V _ref2. , CPU (central processing unit) 9 and a detection output generation unit 10. In the following description, the detection electrodes 1 and 12 are called common electrodes, and the detection electrodes e1, e2, e3, and e4 unique to each ink container are called unique electrodes. The heights of the tips of the unique electrodes e1, e2, e3, and e4 are equal in each ink container, and the heights of the common electrodes 1 and 12 are also equal in each ink container. The common electrodes 1 and l2 are parallel to each other. In the following description, the height of the common electrode 1 will be referred to as level 1 and the specific electrode
Level 2 of the height of each tip of e1, e2, e3, and e4
And In this embodiment, the common electrode 12 is grounded.

Next, the operation of the ink level detecting device will be described.

First, the CPU 9 outputs to the analog data selector 5 a detection ink selection signal that specifies which color of ink is to be detected, and whether to compare the ink level with level 1 or level 2 (selection of detection level). ) Is output to the analog switch 6.

The analog switch 6 selectively applies the search signal from the search signal generator 7 to the common electrode 1 or the specific electrodes e1, e2, e3, and e4 according to the detection level selection signal from the CPU 9, and also generates a reference voltage. Either the output voltage V _ref1 or V _ref2 from the unit 8 is input to the detection output generation unit 10. When the search signal is applied to the common electrode 1, the search signal is transmitted to the unique electrode arranged in the ink container whose ink level is higher than the level 1 but the ink level is lower than the level 1. The search signal is not transmitted to the unique electrode arranged in the container. That is, the ink level in each container is compared with the level 1 by applying the search signal to the common electrode 1. On the contrary, when the search signal is applied to the unique electrodes e1, e2, e3, and e4, the unique electrode arranged in the ink container whose ink level is higher than level 2 is the common electrode to which the ground potential is applied. Since it is connected to l2 via ink, the added search signal cannot be transmitted to the analog data selector 5. However, the search signal provided to the unique electrode arranged in the ink container whose ink level is lower than level 2 is directly input to the analog data selector 5. That is, the search signal is the specific electrodes e1, e2,
The ink level in each container is compared to level 2 by being applied to e3 and e4.

The analog data selector 5 selects one of the output voltages of the unique electrodes e1, e2, e3, and e4 in response to the detection ink selection signal from the CPU 9 and inputs it to the detection output generation unit 10. Specifically, the analog data selector 5 outputs the output voltage of each of the unique electrodes e1, e2, e3, and e4 to the detection ink selection signal that specifies the ink of each color of yellow, magenta, cyan, and black. Is output.

The detection output generation unit 10 receives the reference voltage V _ref1 or V from the reference voltage generation unit 8 input via the analog switch 6.
_{The ref2} is compared with the output voltage of the analog data selector 5, that is, the output voltage of the selected proper electrode, and the voltage of the level corresponding to the comparison result is output as the detection output. Which of the reference voltage V _ref1 and the reference voltage V _ref2 is input to the detection output generation unit 10 is a detection level selection signal given from the CPU 9 to the analog switch 6, that is, the ink level is compared with either level 1 or level 2. It depends on what you do. As described above, when the ink level is compared to level 1, the unique electrode transmits the search signal to the analog data selector 5 only when the ink level is above level 1. Conversely, when the ink level is compared to level 2, the unique electrode transmits the search signal to the analog data selector 5 only when the ink level is below level 2. That is, the ink level is level 1.
The output voltage from the specific electrode corresponding to the level of the ink level with respect to the detection level (level 1 or level 2) is different between the case of comparing with the level 2 and the case of comparing with the level 2. Therefore, the reference voltage is set so that the detection output from the detection output generation unit 10 is always at two levels indicating high and low with respect to the detection level of the ink level, regardless of the selection of the detection level.
V _ref1 and V _ref2 are set.

As described above, in this embodiment, the search signal is sent to the common electrode 1
By detecting the output voltage from each specific electrode when switching and applying to the specific electrodes e1, e2, e3, and e4,
The remaining ink amount of each color can be detected based on two detection levels. As described above, it is determined whether the ink level (remaining amount of ink) is level 1 or higher, level 2 or higher and 1 or lower, or level 2 or higher.

In the present embodiment, the search signal for detecting the ink level based on the two reference levels is set to 1 of the common electrode.
Then, although it is applied by switching to all the unique electrodes, it may be applied by switching only to the common electrode. FIG. 2 is a diagram showing an example of the configuration of the ink container portion in such a case.
Referring to the figure, the tips of the unique electrodes e1, e2, e3, and e4 arranged in the ink containers 1, 2, 3, and 4 are different from those in the previous embodiment in that the common electrodes 1 parallel to each other are provided. Lower than both and l2. Specific electrodes e1, e2, e3, and e4
Is connected only to the synalog data selector 5, and the common electrodes 1 and 12 are both connected to the analog switch 6. That is, in the previous embodiment, the common electrode 12 is connected to the terminals to which the unique electrodes e1, e3, e3, and e4 of the analog switch 6 are connected (see FIG. 1). Therefore, the search signal is given by switching to the common electrodes 1 and l2. In this case, when the search signal is applied to the common electrode 1, the ink level in each container is compared with the height of the common electrode 1 (level 1 in the figure), and the search signal is applied to the common electrode l2. The ink level in each container is compared with the height of the common electrode 12 (level 2 in the figure). In this case, the reference voltage applied to the detection output generator 10 according to the detection level setting does not need to be switched to a binary value and may be a constant value.

It should be noted that the detection output from the detection signal generator 10 in the above-described two embodiments may be used to cause the display means for notifying the user of the remaining amount of ink. In general,
It is desirable to arrange all the common electrodes at a position higher than the tip of the unique electrode and switch the search signal to each of the common electrodes, as in the embodiment described later. In this case, since the number of detection levels is equal to the number of common electrodes, the total number of detection electrodes arranged in each ink container is the number of ink colors, that is, the number of ink containers is N and the number of detection levels is L. Then,
It can be represented by L + N. Therefore, the total number of detection electrodes is much smaller than the number in the ink level detection mechanism of the type shown in FIG. 3, that is, 2N × L. In particular, this effect becomes more remarkable when the number of detection levels is increased in order to accurately detect the remaining amount of ink. Further, as the total number of detection electrodes is reduced, the number of input / output ports in the ink level detection device is also reduced. The number of ink colors (the number of ink containers) and the number of detection levels are not limited to the values of 4 and 2 in the above embodiment, and may be set arbitrarily. Further, in the above embodiment, in order to reduce the number of circuit parts, the analog data selector is used as a means for individually taking out the output voltage of each specific electrode, but another one having a function similar to this may be used. Good. further,
Search signal common electrode (or unique electrode and common electrode)
The means for switching and applying to each of the above is not limited to the analog switch, and any means suitable for the input signal format of the detection output section may be used. Further, the type of search signal is not limited to the pulse type in this embodiment, but it must have an AC frequency and level that does not cause electrolysis of the ink. Also, the selection signal that specifies which color of ink remaining amount to detect and which ink level to compare with does not necessarily have to be output directly from the CPU, but from other control units, etc. May be.

Although the liquid level detecting device according to the present invention is used as the ink level detecting device of the color printer in the present embodiment, it may be used in another device for detecting the amount of the conductive liquid in the container. is there.

[Advantages of the Invention] As described above, according to the liquid level detection device of the present invention, the liquid level is compared with at least one detection level by using a smaller number of detection electrodes, and the liquid remaining in a plurality of containers is retained. The amount can be detected. Therefore, it is possible to accurately detect the remaining liquid amount in a plurality of containers while reducing the number of detection electrodes. As a result, the number of input / output ports in the device is reduced, and the manufacturing cost of various devices including the liquid level detecting device is also reduced. Therefore, if such a liquid level detecting device is used for a color printer or the like, it is possible to provide a printer or the like having a high-performance ink level detecting device capable of accurately detecting the remaining ink amount without increasing the manufacturing cost. .

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing another embodiment of the present invention, and FIG. 3 is a diagram showing an example of an ink level detection mechanism considered from the prior art. In the figure, 1, 2, 3, and 4 are ink containers, 5 is an analog data selector, 6 is an analog switch, 7 is a search signal generator, 8 is a reference voltage generator, 9 is a CPU, and 10 is a detection output generator. , 11 are detection circuits. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A liquid level detection device for detecting the level of a conductive liquid contained in a plurality of containers, the liquid level detection device being parallel to each level in relation to at least one level of each of the plurality of containers. And at least one common electrode provided commonly to the plurality of containers, one unique electrode disposed perpendicular to the level for each of the plurality of containers, and at least one common electrode A liquid level detection device, comprising: a detection unit that applies a search voltage to each of the individual electrodes or commonly to a plurality of specific electrodes to detect the potential change from each of the specific electrodes.