Liquid surface detector, image forming apparatus, and method for controlling liquid surface detector

Patent metadata

Field	Value
Publication number	US-11568190-B2
Application number	US-202117207064-A
Country	US
Kind code	B2
Filing date	Mar 19, 2021
Priority date	Mar 25, 2020
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

A liquid surface detector includes an electrode pad, a coil, a memory, and a detection control circuit. The electrode pad is attached to an outer side surface of a tank of the image forming apparatus. The coil is connected to the electrode pad. The memory stores initial values. The detection control circuit determines a capacitance (first capacitance) of a first resonance circuit including the coil and the tank with the electrode pad. When determining a liquid surface level value, the detection control circuit subtracts an error value from the first capacitance so as to determine a first corrected capacitance, and determines the liquid surface level value based on the first corrected capacitance and the initial value.

First claim

What is claimed is:

1. A liquid surface detector attached to an image forming apparatus, the detector comprising:
an electrode pad attached to an outer side surface of a tank for containing liquid disposed in the image forming apparatus, the tank being removable from the image forming apparatus;
a coil connected to the electrode pad, the coil being a part of a first resonance circuit;
a second resonance circuit that is not connected to the electrode pad and that includes a capacitor;
a memory for storing an initial value in a nonvolatile manner; and
a detection control circuit
that senses a resonance frequency of the first resonance circuit and determines capacitance of the first resonance circuit on the basis of the sensed resonance frequency and
that senses a resonance frequency of the second resonance circuit and determines a capacitance of the second resonance circuit on the basis of the sensed resonance frequency of the second resonance circuit, wherein

the memory stores an initial empty value, an initial upper end value, and a temperature compensating capacitance as the initial value,
the initial empty value is a value obtained by measurement before attachment to the image forming apparatus, and is the capacitance of the first resonance circuit with no liquid,
the initial upper end value is a value obtained by measurement before attachment to the image forming apparatus, and is the capacitance of the first resonance circuit when the liquid surface height is the same as an upper end height of the electrode pad,
when storing the initial value in the memory, the detection control circuit determines, before attachment to the image forming apparatus, the capacitance of the first resonance circuit as the initial empty value in a state where the electrode pad is removed from the image forming apparatus and is attached to the tank that is empty or in a state where the electrode pad is not attached to the tank,
the detection control circuit determines, before attachment to the image forming apparatus, the capacitance of the first resonance circuit as the initial upper end value in a state where the electrode pad is attached to the tank removed from the image forming apparatus and empty and the liquid surface of the liquid coincides with the upper end of the electrode pad,
the detection control circuit determines, before attachment to the image forming apparatus, the capacitance of the second resonance circuit as the temperature compensating capacitance,
the memory stores the determined initial empty value, the determined initial upper end value, and the determined temperature compensating capacitance as the initial value,
when storing an error value in the memory, the detection control circuit determines, after attachment to the image forming apparatus, the capacitance of the first resonance circuit in a state where the electrode pad is attached to the tank removed from the image forming apparatus and filled with the liquid or in a state where the tank is not attached to the image forming apparatus and accordingly the electrode pad is not attached to the tank,
the memory stores the error value based on a difference between the initial empty value and the capacitance of the first resonance circuit determined after attachment to the image forming apparatus, and
when determining a liquid surface level value as a value indicating a liquid surface height of the liquid in a height direction of the electrode pad, the detection control circuit
determines the capacitance of the first resonance circuit in a state where the electrode pad is attached to the tank attached to the image forming apparatus and empty,
determines a first corrected capacitance by subtracting the error value from the determined capacitance of the first resonance circuit,
determines the capacitance of the second resonance circuit,
determines a second corrected capacitance by correcting the first corrected capacitance by performing a predetermined calculation based on the temperature compensating capacitance and the capacitance of the second resonance circuit determined after attachment to the image forming apparatus, and
determines the liquid surface level value by performing a calculation of (D−E)/(F−E), where D represents the second corrected capacitance, E represents the initial empty value, and F represents the initial upper end value.

2. The liquid surface detector according to claim 1 , further comprising one detecting circuit board, wherein
the detecting circuit board includes the memory, the detection control circuit, and the coil, and is connected to the electrode pad via a signal line.

3. The liquid surface detector according to claim 1 , wherein
the detection control circuit determines the error value by subtracting the initial empty value from the capacitance of the first resonance circuit with no liquid obtained after attachment to the image forming apparatus.

4. The liquid surface detector according to claim 1 , further comprising a detecting circuit board, wherein
the detecting circuit board includes the memory, the detection control circuit, the coil, and the second resonance circuit, and is connected to the electrode pad via a signal line.

5. A liquid surface detector attached to an image forming apparatus, the detector comprising:
an electrode pad attached to an outer side surface of a tank for containing liquid disposed in the image forming apparatus;
a coil connected to the electrode pad, the coil being a part of a first resonance circuit;
a memory for storing an initial value in a nonvolatile manner; and
a second resonance circuit that is not connected to the electrode pad and that includes a capacitor;
a detection control circuit
that senses a resonance frequency of the first resonance circuit in which the tank with the attached electrode pad is used as a capacitor and determines a capacitance of the first resonance circuit on the basis of the sensed resonance frequency and
that senses a resonance frequency of the second resonance circuit and determines as a capacitance of the second resonance circuit on the basis of the sensed resonance frequency of the second resonance circuit, wherein

the memory stores an initial empty value, an initial upper end value, and a temperature compensating capacitance as the initial value,
the initial empty value is a value obtained by measurement before attachment to the image forming apparatus, and is the capacitance of the first resonance circuit with no liquid,
the initial upper end value is a value obtained by measurement before attachment to the image forming apparatus, and is the capacitance of the first resonance circuit when the liquid surface height is the same as the upper end height of the electrode pad,
when storing the initial value in the memory, the detection control circuit determines, before attachment to the image forming apparatus, the capacitance of the first resonance circuit as the initial empty value in a state where the electrode pad is removed from the image forming apparatus and is attached to the tank that is empty or in a state where the electrode pad is not attached to the tank,
the detection control circuit determines, before attachment to the image forming apparatus, the capacitance of the first resonance circuit as the initial upper end value in a state where the electrode pad is attached to the tank removed from the image forming apparatus and empty and the liquid surface of the liquid coincides with the upper end of the electrode pad,
the detection control circuit determines, before attachment to the image forming apparatus, the capacitance of the second resonance circuit as the temperature compensating capacitance,
the memory stores the determined initial empty value, the determined initial upper end value, and the determine

Assignees

• Kyocera Document Solutions Inc

Inventors

• Kawai Hisaji

Classifications

• B41J2002/1728

  Operations & Transport · mapped topic

• B41J29/393

  Devices for controlling or analysing the entire machine {; Controlling or analysing mechanical parameters involving printing of test patterns} · CPC title

• G06K15/4075 Primary

  Determining remaining quantities of ink or toner · CPC title

• G06K15/002 Primary

  Interacting with the operator · CPC title

• G01F23/266

  measuring circuits therefor · CPC title