JPS58166219A - Detector for remaining amount of liquid - Google Patents

Abstract

PURPOSE:To enable the detection of the amt. of the ink in an ink storage device in which the level of the ink is not constant by providing a temp. measuring element connected to a heating means in the liquid storage device, and detecting the amt. of the liquid from the change in the temp. changing with the amt. of the liquid. CONSTITUTION:While ink 8 is kept filled, the quantity of the heat generated by self heating is absorbed by the ink 8 having large heat capacity existing in a large amt. around a temp. measuring element 3, and the temp. of the element 3 itself is balanced and changes hardly. The current value flowing in the element 3 in this stage is measured with a current detector 10 and the current value in this stage is used as a reference value. When the ink 8 decreases, the ink 8 hardly exists around the element 3; therefore, the temp. of the element 3 itself rises on account of self-heating, and the resistance value of a temp. measuring resistor 1 changes, thus the current value changes and from said change, the remaining amt. of the ink 8 is known.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the remaining amount of recording liquid such as ink in an ink jet recording apparatus. The following will explain the ink reservoir of an inkjet recording apparatus as an example.

In an inkjet recording device, the ink reservoir is generally located inside the device, and the remaining amount of ink cannot be monitored. If you drive the inkjet head when the ink is out, not only will air bubbles get mixed into the pressure chamber, making it impossible to eject ink, but it will also have a negative effect on the inkjet head itself as it is being driven idly, which will be unnecessary when filling it with ink next time. maintenance will be required.

Conventionally, the remaining amount of ink has mainly been detected by detecting the liquid level in an ink reservoir.

However, the method of detecting the remaining amount of ink by detecting the position of the liquid level can only be detected when the ink reservoir is always fixed. Furthermore, since the liquid surface is in contact with the outside air, gas dissolves into the ink. For example, in the case of an inkjet head that uses an electromechanical transducer, the gas that dissolves into the ink is generated again in the pressure chamber, resulting in unstable ink discharge or ink discharge. This can easily lead to an impossible situation. Furthermore, if the liquid surface is in contact with the outside air, the particles in the outside air will melt into the ink and cause nozzle clogging in the inkjet head.

The present invention is characterized in that the ink in the ink reservoir is isolated from the outside air,
The present invention provides a means for draining the remaining amount of ink when the liquid level does not need to be constant, for example when the ink reservoir is in the form of a flexible thin bag.

The present invention is characterized in that a temperature measuring resistor is installed within the ink reservoir. An embodiment of the present invention will be described in detail below.

A resistance temperature sensor is a substance whose resistance value changes significantly in response to changes in attitude. In general, those with a positive temperature coefficient include nickel, platinum, m, etc., and those with a negative temperature coefficient include metal oxides. The present invention uses this temperature measuring resistor to detect the remaining amount of rain. A resistance thermometer is originally used to measure temperature as a resistance thermometer, but in the present invention, it is possible to use a temperature measurement device that includes a resistance thermometer, which has the function of temperature measurement as well as the desire to keep the value as low as possible when measuring temperature. The feature is that the self-heating of the element system is used in reverse.

An embodiment of the invention is shown in FIGS. 1 and 2.

Figure M1 is filled with ink 8, Figure 2 is filled with ink 8.
This indicates that the amount remaining is low.

The temperature measuring element 3 has a temperature measuring resistor 1 and a lead wire 2 inside, and is installed in an ink 8 filled in a flexible ink bag 4 which disconnects the outside air from the ink. 6 is an ink inlet/outlet, and 6 is an opening provided in the ink reservoir protective case 7. When a constant voltage is now applied to the temperature measuring element 3 from the power supply 9, the temperature measuring element 3 generates Joule heat and self-heats. Generally, the amount of heat generated in the lead wire 2 is greater than the amount of heat generated in the resistance temperature detector 1, and the amount of heating can be adjusted by appropriately selecting the material, length, and diameter of the lead wire 2.
A resistor is provided in the lead wire 2, and the resistance value is used.

Now, in the state where the ink 8 is filled as shown in FIG. The temperature of the temperature measuring element 3 itself hardly changes as long as nPl is kept in balance. The current value flowing through the temperature measuring element 3 at this time is measured by the current detection device 10, and the current value at this time is used as a reference value. Next, as shown in FIG. 2, when the ink 8 is low, there is almost no ink 8 around the temperature measuring element 3, so the temperature of the temperature measuring element 3 itself increases due to self-heating, and the resistance temperature detector The resistance value of 1 changes. Therefore, the current value changes, and the remaining amount of ink 8 can be determined from that value.

Figure 'M3 shows the relationship between the ink t and the current value when nickel, which has a positive and large temperature coefficient, is used as the resistance temperature detector 1. As the nickel increases once, the resistance also increases, so the current value decreases.

If the current value A when the ink amount B requires ink replenishment is checked in advance, an alarm can be issued based on that value. A feature of this remaining ink amount detecting device is that the state in which the amount of ink is decreasing can be continuously determined by the current value, which is a major difference from other remaining ink amount detecting devices. Further, as a method of detecting the remaining amount of ink, the differential value of the current value may be checked. Since the graph of the current value is a curve, its differential value also changes with the amount of ink. The feature of this method is that it is more stable against changes in ambient temperature than the method of examining the current value itself.

Shows the relationship between current values. In the case of gold S oxide, the resistance decreases as the temperature increases, so the current value increases. In this case, as in FIG. 3, the ink f can be known from the change in the current value.

As explained above, the present invention disposes a self-heating temperature measuring element having a temperature measuring resistor in an ink reservoir, and captures the temperature change of the temperature measuring element itself, which changes with the amount of ink, as a current change. This ink remaining amount detection device is characterized by the following effects.

(1) The ink liquid level is not exposed to the outside air. That is, it is possible to detect the amount of ink in an ink reservoir where the ink level is not constant.

(2) Since the state in which ink is decreasing can be continuously detected as a change in current value, it is also possible to know the amount of ink used.

[Brief explanation of drawings]

FIGS. 1 and 2 are block diagrams showing an embodiment of the liquid remaining amount detection device according to the present invention, and FIGS. 3 and 4 show resistance temperature sensors having positive and negative temperature coefficients as temperature measuring elements, respectively. FIG. 3 is a diagram showing the relationship between the amount of ink and the current value when used. 1... Measuring resistor, 2... Lead wire,
3...Temperature measurement element, 4...Ink reservoir, 6...Ink inlet/outlet, 6...Opening, 7...Ink reservoir protective case , 8...
...Ink, 9...Power supply, 1o...Current detection device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 □ Figure 3 Ink amount □ Figure 4

Claims (1)

[Claims] (1) A temperature measuring element connected to a heating means is disposed in the liquid reservoir, and the liquid leaf is detected by a change of 2.1 degrees that changes with the amount of liquid. Liquid level detection device. (2) The liquid remaining amount detecting device according to claim 1, wherein a part of the heating means is incorporated in the temperature measuring element. (3) Claims 1 or 2 characterized in that a temperature measuring resistor whose resistance changes as the fan degree changes is conveniently used as the temperature measuring element, and the remaining amount of liquid is detected by the current value. The liquid remaining amount detection device according to No. Isunka. (4) Claims 1 or 2, characterized in that a temperature measuring resistor whose resistance changes with temperature changes is used as a temperature measuring element, and the remaining amount of liquid is detected by the differential value of the current value. The liquid remaining amount detection device according to any one of paragraphs. (6) The liquid remaining amount detecting device according to claim 1, wherein the liquid reservoir is constituted by a flexible bag that blocks external air and liquid.