JPS61217756A - Detector for amount of fine magnetic substance - Google Patents

Abstract

PURPOSE:To obtain an apparatus of a low production cost with a simple construction which can detect the amount of fine magnetic substance very easily, by arranging one of two series connection bodies of an inductance element and a resistance to be a detector section while the other thereof to be a comparator section to compare voltages at division points set with the application of a DC voltage. CONSTITUTION:A first series connection body 2 of an inductance 1 having a space allowing the insertion of a fine magnetic substance in own magnetic path and a resistance is arranged as a detector section while a second series connection body 3 of another inductance element 1' and a resistance as comparator section. Then, as a voltage is applied to the connection bodies 2 and 3, the voltage at arbitrary division points C, D and E of the connection bodies 2 and 3 varies with a time constant and an inductance/resistance and the initial value or final value differ depending on the division rate. When a proper time passes after the application of the voltage, voltages at the division points C, D and E set on the connection bodies 2 and 3 are compared with voltage comparators 5a and 5b. Thus, the amount of magnetic substance on the detection side can be detected depending on the amount of known magnetic substance determined by the voltage for comparison.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a device for detecting minute magnetic substances contained in developer powder or fluid used in, for example, electrophotographic copying machines and link machines. In particular, the present invention relates to a detection device for a minute magnetic material that compares the amount of magnetic material with a predetermined amount.

(Prior Art) Conventional micromagnetic material quantity detection devices detect the amount of magnetic material by forming an oscillation circuit with an inductance element and a capacitor, and utilizing the fact that the oscillation frequency changes according to changes in the inductance of the magnetic material. Alternatively, there are various methods, such as those that detect changes in inductance as changes in voltage, and those that improve detection sensitivity by forming a resonant circuit.

Further, in order to detect the amount of magnetic material in multiple stages, there is a method that uses a plurality of inductance elements as shown in FIG. 3, which is disclosed in Japanese Patent Application Laid-Open No. 57-132171, for example.

(Problems to be Solved by the Invention) Conventional detection devices that use such inductance elements in the magnetic material detection section have complicated circuit configurations, such as
In a device that uses changes in the oscillation frequency of an inductance element as magnetic substance detection information, it is necessary to convert the difference between the oscillation frequency and a fixed oscillation frequency that serves as a reference, and the circuit is complicated, making it difficult to use in the above-mentioned copying machine. had the disadvantage of high circuit cost. In addition, in multi-stage detection, the number of inductance elements increases in order to improve accuracy, so it is necessary to increase the volume of the object to be detected, which makes it difficult to detect minute objects.

The present invention is intended to solve the drawbacks of the above-mentioned conventional devices.The present invention has a simple circuit configuration, and is capable of detecting multi-stage minute magnetic substances using only one detection inductance element. The present invention provides a device for detecting the amount of magnetic material.

(Means for Solving the Problems) The present invention uses a first series connection body of an inductance element and a resistor, which has a space in its magnetic path into which a minute magnetic material can be inserted, as a detection part, and A second series connection body consisting of an inductance element and a resistor is provided as a comparison section, and a DC voltage is applied to these at the same time to calculate the applied voltage at a selected comparison point on each of the first and second series connection bodies. and holding the detection signal, the amount of magnetic material of the object inserted into the space in the magnetic path of the inductance element of the first series-connected body is determined by the amount of magnetic material on the second series-connected body. The above-mentioned problem is solved by a configuration in which the amount of magnetic material is detected as corresponding to the comparison point voltage.

(Function) In the present invention, by applying a voltage (pulse) to a series connection body of an inductance element and a resistance element with the above configuration, the voltage at any dividing point of the series connection body is determined by the time constant, the inductance [ Since the initial value or terminal value of the voltage varies depending on the division ratio, the first voltage on the detection side is By comparing the voltage at the division point set in the series connection body with the voltage at the division point set in the second series connection body for comparison,
The amount of magnetic material on the detected side can be detected as being larger or smaller than the known amount of magnetic material determined by the above voltage for comparison, and by increasing the dividing points, multiple detections can be performed, that is, multi-stage micromagnetic Body mass can be detected.

(Example) Fig. 1 is a circuit configuration diagram of a minute magnetic substance amount detection device according to an example of the present invention, where ■ is an inductance element of the detection part, and at least the detected object is in the magnetic path. A space is formed into which a magnetic material is inserted. Reference numeral 2 denotes a first series connection body on the detection side consisting of an inductance element 1 and a resistance element, and 3 a second series connection body of an inductance element 1' and a resistance element on the comparison side. A voltage (pulse) is applied to the series connection body 2.3 from a power supply circuit (not shown) via a comparator (hereinafter referred to as a voltage comparator) 4. 5a and 5b are also comparators (voltage comparators), and from the voltage comparator 4 at the division point C of the first series connection body on the detection side and the division point E on the second series connection body 3 on the comparison side. Compare the voltage caused by the pulse. In the figure, the second series connection body has multiple division points, but the first
There can be a plurality of serially connected bodies, and both may have the same number of collars. 6a and 6b are signal holding circuits, 7 is a comparator (voltage comparator), and the signal holding circuit 6a,
A holding signal, which will be described later, is applied to 6b to hold the voltage comparison result. 8 is an RC circuit which delays the voltage (pulse) applied from point A by an appropriate time and sends it to the voltage comparator 7, the output of which is used as the above-mentioned holding signal.

FIG. 2 is a timing chart illustrating the operation of the circuit in FIG. 1, where A' to J' indicate voltages corresponding to points A to 5 in FIG. The voltage relationships at the dividing points C, D, and E above are different (A), (
(b) and (c) are drawn in three rows, and the amount of minute magnetic material in the subject is α.

When β (α<β), the first . Second division points C, D and E have been selected. Therefore, the changes in C' to J' of the voltage at points C to 5 are, respectively, when the amount of minute magnetic material is less than α, when it is more than α and less than β,
For the three ways above β, (a), (b) and (
c) The result will be as shown in the column. Incidentally, as shown in column (C), the level of F' is output at the (L) level even though it is at the (H) level at a later point in time, but this is input to the signal holding circuit 6a. This is because the input of the holding signal H' is after the above-mentioned level change point.

As can be seen from the above explanation of the present invention for the case of two-point detection, the present invention detects the amount of minute magnetic material by a combination of voltage levels at five points and has an easy configuration. Although the embodiment uses voltage detection at two points, it goes without saying that it is extremely easy to perform multi-stage detection using the same method.

(Effects of the Invention) As is clear from the above explanation, the present invention can detect the minute amount of magnetic material extremely easily, has a simple configuration, and has low manufacturing costs. It is extremely effective when used to detect the amount of magnetic material contained.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of an apparatus according to an embodiment of the present invention, FIG. 2 is a timing diagram of each part of FIG. 1, and FIG. 3 is an explanatory diagram of main parts of a conventional example. 1.1'...Inductance element, 2...
(Detection side) Series connection body, 3... (Comparison side) Series connection body, 4, 5a, 5b, 7... Comparator (voltage comparator), 6a, 6b... Signal holding circuit. Patent applicant Matsushita Electric Industrial Co., Ltd. Figure 1 aRC mouth Figure 2

Claims (1)

[Claims] A first series connection of an inductance element having a space in the magnetic path into which a minute magnetic material can be inserted and a resistor is used as a detection section, and a second series connection of another inductance element and a resistance is used as a comparison section. The applied voltages at the comparison points selected on each of the first and second series connected bodies are compared with each other by applying a voltage to these simultaneously, and the comparison detection signal is transmitted to the voltage applied to the first and second series connected bodies. The amount of magnetic material of the object inserted into the space in the magnetic path of the inductance element of the first series-connected body is calculated from the signal held after a certain period of time has elapsed from the second series-connected body. What is claimed is: 1. A micromagnetic material amount detection device that detects a magnetic material amount by comparing it with a magnetic material amount corresponding to a comparison point voltage.