JPH01100575A - Toner-absence detecting method - Google Patents

Abstract

PURPOSE:To obtain the toner absence detecting mechanism which securely operates without reference to an environmental change before a decrease in image density is caused at low cost by composing the mechanism of a toner amount detection plate which follows up the top surface of toner, a movable body which is associated with it, and a converting device which converts the position of the movable body into an electric signal. CONSTITUTION:The toner amount detection plate 5 is on the top surface of the toner 2 in a toner tank 1 by its own weight and shifts down in position as the toner 2 is consumed. The motion of the toner amount detection plate 5 is transmitted to a movable lever 6 outside the toner tank 1 by a link mechanism and the position of the movable lever 6 corresponds to the rest of the toner. Namely, when the amount of the toner is sufficient, the movable lever 6 which is at a lower position, but the lever moves up as the toner rest decreases. Its position is inputted as an electric signal to a controller 8 through a microswitch 7. Consequently, the absence of toner can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an out-of-toner detection mechanism that clearly indicates when toner is to be supplied to a developing device in an image forming apparatus such as a printer or a copying machine using an electrophotographic method.

[Conventional technology]

A developing device of an electrophotographic image forming apparatus has a toner tank for storing toner, and the toner in the toner tank is conveyed by a roller in an appropriate amount and consumed by a regulating device. At this time, if the amount of toner in the toner tank becomes less than a certain amount, the amount of toner conveyed by the rollers will be less than the amount of brewed sake, and the image density will drop significantly. Therefore, a toner out detection mechanism is required that detects this toner out state before the amount of toner falls below a fixed amount and prompts the operator to supply toner. Conventionally, as a method of detecting this toner-free state, a method has been widely used that utilizes the dielectric constant of toner or electrically detects the state using a piezoelectric element installed on the wall of the toner tank from the outside.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, since the change in the amount of toner is measured indirectly, the operation is unstable due to changes in the environment, and the complicated process of amplifying and converting the signal obtained from the electric element of the detection section is This had the problem of requiring a circuit and resulting in an expensive product.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide a toner-free detection mechanism that is inexpensive, stable against environmental changes, and highly reliable.

[Means for solving problems]

The out-of-toner detection mechanism of the present invention is used in a developing unit of an electrophotographic image forming apparatus, and includes a toner amount detection plate that follows the displacement of the top surface of toner in a toner tank, a movable member that interlocks with the toner amount detection plate, and a movable member that is connected to the toner amount detection plate. The device is characterized in that it is comprised of a conversion device that converts a position into an electrical signal.

[Effect]

According to the toner out detection mechanism configured as above,
Since the toner detection plate follows the upper surface of the toner, regardless of changes in the toner physical properties due to the environment, the toner detection plate transmits changes in the amount of toner itself as a displacement of an interlocking movable object. By converting the displacement of the movable object into an electrical signal and extracting it when the amount of toner in the toner tank reaches a certain amount, toner can be removed without being affected by changes in the environment and without the need for complex electrical circuits. Absence detection can be performed.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
In the figure, the toner 2 stored in the developer toner tank 1 is
The amount is regulated by the blade 3, and an appropriate amount is conveyed by the developing roller 4 in the direction of the arrow and consumed. The toner amount detection plate 5 rests on the upper surface of the toner 2 in the toner tank 1 under its own weight, and its position lowers as the toner 2 is consumed. This movement of the toner amount detection plate 5 is transmitted to a movable lever 6 outside the toner tank 1 by a link mechanism, and the position of this movable lever 6 corresponds to the remaining amount of toner. That is, when the amount of toner is sufficient, the movable lever 6 is positioned downward (FIG. 1), and when the remaining amount of toner is low, it moves upward (FIG. 2). By taking in the toner, it is possible to detect the absence of toner. Alternatively, a non-contact switch such as an optical switch may be used to convert the signal into an electrical signal.

FIG. 3 shows another embodiment of the present invention, in which (a) is a left side view and (b) is a sectional view. In this embodiment, the toner amount detection plate 5 rotates around an axis substantially parallel to the developing roller, following the upper surface of the toner. An enabling lever 6 located on the side of the toner tank serves as one electrode of a direct switch, generating and transmitting a toner out signal to the controller. In this case, no new electrical parts are required, and the circuit can be made simple and inexpensive.

〔Effect of the invention〕

As explained above, the present invention includes a toner amount detection plate that follows the top surface of the toner, a movable object that is linked to the detection plate, and a conversion device that converts the position of the movable object into an electrical signal. It is possible to provide at a low cost, without using a complicated electric circuit, a toner-free detection mechanism that is not affected by changes in the toner density and operates reliably before a decrease in image density occurs.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the developing device showing the main aspects of the present application, Fig. 2 is a cross-sectional view showing what happens when a toner out signal is generated, and Fig. 3
The figures show another embodiment, in which (a) is a left side view and (b) is a sectional view of the developing device. 1... Toner tank 2... Toner 5... Toner amount detection plate 6... Possible lever or more Applicant Seiko Epson Corporation (a) (b)

Claims (1)

[Scope of Claims] 1) In a developing device of an electrophotographic image forming apparatus, a toner amount detection plate that follows the displacement of the top surface of toner in a toner tank, a movable object that interlocks with the toner amount detection plate, and the movable object. A toner-out detection mechanism characterized by comprising a conversion device that converts a position into an electrical signal.