JPH0446370A - Developing device - Google Patents

Abstract

PURPOSE:To attain the detection of the residual quantity of toner and the application of a development bias voltage and to obtain an electrophotographic device having high fidelity by arranging a conductive developer carrier, a thin layer forming member for a conductive developer and an electric current control means in series. CONSTITUTION:When a toner 3 is sufficiently present on a toner storage part 9, a toner layer having the specified thickness is formed on a developing roller 1 and a fixed grounded resistance is generated between the developing roller 1 and a blade 2 and a fixed voltage is imparted to the developing roller 1 and the voltage is used as a developing bias means. When the toner 3 is consumed and the blade 2 begins the contact with the developing roller 1, the voltage of the developing roller 1 exceeds the specified value and a comparator 7 and a residual toner detection circuit 11 are activated and the shortage of the residual toner is detected. With this means, the inconvenience that while the residual quantity detection means indicates sufficiently the residual quantity, the development can not be actually performed due to the shortage of the residual toner is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device such as an electrophotographic device using a one-component developer, which is provided with means for detecting an effective amount of developer supplied onto a developing roller.

2. Description of the Related Art Conventionally, in a developing device such as an electrophotographic apparatus using a -component developer, a developing bias means and a remaining developer amount detecting means are provided separately, and various types of developer remaining amount detecting means are provided. Sensors, etc. were used.

Problems to be Solved by the Invention In a developing device such as an electrophotographic device using a one-component developer, various sensors as a means for detecting the remaining amount of developer are usually installed in the developer (toner) storage section, so they are not electrostatically charged. The remaining amount including developer that cannot be supplied to the latent image carrier is detected. Although the various sensors indicate that there is a sufficient amount of developer remaining, there has been a problem in that actual printing is not developed due to insufficient developer.

The present invention solves the above problems, and provides an excellent developing device such as an electrophotographic device having a means for accurately detecting the amount of effective developer supplied to an electrostatic latent image carrier. It is an object.

Means for Solving the Problems In order to achieve the above object, the present invention arranges a conductive developer carrier, a conductive developer thinning member, and a current limiting means in series, and applies an electric field to the conductive developer carrier, the conductive developer thinning member, and the current limiting means. This voltage is applied as a means for detecting the remaining amount of developer by comparing the voltage at a predetermined position with a reference voltage, and this voltage is also used as a means for applying a developing bias potential.

Effect of the present invention With the above-described configuration, the resistance value between the developer carrier and the developer thinning member changes depending on the presence or absence of the amount of developer on the developer carrier, so that the remaining amount of developer can be controlled. Can be detected.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a schematic configuration of a developing device in an embodiment of the present invention, and FIG. 2 is an enlarged view of the vicinity of the developer carrier of the developer thinning member pressed against the developer carrier. It is. In Figure 81, 1 is a developing roller as a conductive developer carrier, 2 is a blade as a conductive developer thinning member, 3 is toner as a developer, 4 is a resistor as a current limiting means, 5 is a voltage generation source that applies a voltage in series to the developer carrier, the developer thinning member, and the current limiting means;
6 is a photoreceptor carrying an electrostatic latent image; 7 is a comparison circuit that compares the base signal level with the voltage level at a predetermined position; 8 is a replenishment roller that supplies developer to the developing roller 1 as a developer carrier; Reference numeral 9 indicates a toner storage unit, and reference numeral 1o indicates an agitator 111 for stirring the toner, which is a toner remaining amount detection circuit.

The operation of the developing device with a remaining toner amount detection mechanism of this embodiment configured as described above will be described below. Here, the toner 3 present in the toner storage section 9 is supplied onto the developing roller 1 while being neutrally charged by the replenishing roller 8, and is made into a thin layer by the blade 2 and further triboelectrically charged. First, when there is enough toner 3 in the toner storage section 9, a toner layer is formed on the developing roller 1 with a predetermined thickness as shown in FIG. The developing roller 1 has a constant resistance value, and a constant potential determined by the ratio with the resistor 4 is applied to the developing roller 1. This potential is used as a developing bias means.

Next, when the toner 3 in the toner storage section 9 is consumed as the number of sheets printed increases, the toner 3 is not sufficiently supplied onto the developing roller 1 by the replenishment roller 8, so that a predetermined toner layer thickness is formed on the developing roller 1. Only the following toner layers can be formed. When the toner 3 is further consumed and the blade 2 starts to come into contact with the developing roller 21 as shown in the second ilb, the previously constant resistance 1 becomes smaller and the potential of the developing roller 1 exceeds a predetermined value, so the comparator circuit 7 Then, the remaining toner amount detection circuit 11 is activated, and it is possible to detect that the remaining amount of toner is insufficient. When this method is used, the remaining amount of toner is detected based on the amount of toner (toner layer thickness) supplied onto the developing roller. This eliminates the influence of toner that cannot be supplied to the developing roller. As a result, the inconvenience of not being able to develop due to insufficient toner remaining amount even though the remaining amount detection means indicates that the remaining amount is sufficient is eliminated.Advantages of the Invention As described above, according to the present invention, the conductive developing roller and blade By applying a voltage in series to these using resistors, it is possible to construct a developing device that is simultaneously equipped with a remaining toner amount detecting means and a developing bias potential applying means without using various expensive sensors, etc., at a low cost, and is directly involved in printing. It is possible to provide a highly reliable electrophotographic developing device capable of detecting the remaining amount of toner.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a developing device according to an embodiment of the present invention, and FIG. 2 a is an enlarged explanatory diagram of the vicinity of the developing roller of a blade pressed against the developing roller with toner sandwiched therebetween when there is sufficient toner. , FIG. 2 is an enlarged explanatory view of the same part when toner becomes insufficient. 1...Developing roller (developer carrier), 2.・1
．． Flade (developer thinning member), 3...toner (developer), 4...resistance (current limiting means),
5... Voltage generation source (voltage application means), 6...
... Photoreceptor, 7... Comparison circuit (comparison means), 9...
. . . Toner storage unit, 11 . . . Toner remaining amount detection circuit (developer remaining amount detection means). Name of agent: Patent attorney Shigetaka Awano and one other person.
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Claims (2)

[Claims] (1) In a developing device having a conductive developer carrier in a one-component development system and a conductive developer thinning member that comes into pressure contact with the developer carrier to thin the developer, the developer current limiting means connected in series to the carrier and the developer thinning member; means for applying a voltage in series to the developer carrying member, the developer thinning member and the current limiting means;
Voltage detecting means for detecting the voltage of the current limiting means; Comparing means for comparing a reference signal level with a detection signal level of the voltage detecting means; and detecting the remaining amount of developer based on the output signal of the comparing means. A developing device comprising means. (2) The developing device according to claim 1, wherein the means for applying voltage in series also serves as a developing bias potential applying means.