JPH0362061A - Developing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image density control device in an image forming apparatus such as an electrophotographic apparatus.

Conventional technology In an electrophotographic device using a two-component development method, the environment (
Especially due to changes in temperature), the developing housing member (material: P)
Due to the bimetallic effect caused by the difference in linear expansion coefficient between the developer layer thickness regulating member (material: S resin, etc.) and the developer layer thickness regulating member (material: 20 μm or less, referred to as a doctor blade), the gap between the image carrier and the developer carrier (hereinafter referred to as The image density changes because the doctor gap (called the doctor gap) changes from the set value and the amount of developer supplied to the image carrier changes.
As the value of G becomes smaller, the amount of developer supplied to the image carrier decreases, resulting in a decrease in image density. Conversely, when the temperature rises, the image density increases excessively. According to the applicant's analysis results, the material of the developer housing is 5BS,
When the material of the doctor blade is Cu, the reference temperature (
Considering temperature rise inside the machine) ±17 as 32.5°C
．． When a temperature change of 6°C was applied, the variation in the doctor gap was ±0.1 fl.

Problems to be Solved by the Invention Conventionally, as a countermeasure against changes in image density due to environmental changes, the temperature near the developing device was detected and the bias voltage applied to the developer carrier in the developing device was controlled according to the detected temperature. (
) to prevent changes in image density. However, this method requires a temperature sensing element (sensor and circuit) and is expensive. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an inexpensive apparatus and to prevent changes in image density due to changes in environment (temperature).

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problems is to fix the developer layer thickness regulating member to the developer housing member through an elastic material having excellent ozone resistance. This prevents the doctor gap from changing due to changes (in particular, temperature) and, as a result, the image density from changing.

action The effect of this technical means is as follows.

That is, the bimetallic effect caused by the difference in linear expansion coefficient between the developer housing member and the developer layer thickness regulating member due to changes in the environment (especially temperature) can be suppressed by fixing the developer layer thickness regulating member to the developer housing member with screws. Since the elastic force of the elastic intervening member is buffered, the doctor gap can always be kept at a constant reference value.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a developing section of an electrophotographic apparatus according to the present invention.

In FIG. 1, 1 is a photosensitive drum that is an electrostatic latent image carrier, and a developer carrier 2 (hereinafter referred to as a sleeve) carries a developer, which is a mixed powder of toner 8 and carrier 7, on its surface. The toner 8 is applied onto the electrostatic latent image on the photosensitive drum 1.
Attach. A constant developing bias voltage for controlling the amount of toner 8 attached to the sleeve is generated and applied from a high voltage power source 13 for developing bias.

The developer is triboelectrically charged by stirring by the developer stirring paddle 4, adheres to the sleeve 2, is smoothed to an appropriate layer thickness by the doctor blade 5, and is conveyed to the development area. Said,
Sleeve 2. A rotational drive source such as the photosensitive drum 1 receives driving force from an external motor via a gear train. Reference numeral 10 denotes a toner concentration detection element, which detects the toner concentration in the developer flowing from the doctor blade 6 onto the scraper 9. 12 is a hopper housing section for storing toner 8; by driving a hopper motor (not shown), toner row/l/11 provided in the hopper housing 12 rotates, and the toner 8 is transferred to the developing housing. It will be replenished within 3 days.

Further, toner concentration control is performed by the toner concentration detection element 10.
Toner replenishment is performed to keep the output signal level constant. Further, the doctor blade 5 is fixed at both ends to the developer housing 3 with a fixing screw 14 with an elastic intervening member 6 interposed therebetween.

Here, the coefficient of linear expansion of the developing housing 3 is 5x1o.
-5/'C, linear expansion coefficient of doctor blade 5 is 1,7
Let it be X10'/°C. If an environmental change occurs, since the linear expansion coefficient of the developing housing 3 is about three times that of the doctor blade 5, the developing housing 3
This deformation is in a state where the doctor blade 5 is deformed. Furthermore, although the deformation direction of the developing housing 3 itself is mostly only in the longitudinal direction, since the doctor blade 5 is fixed with screws, deformation also occurs in the vertical direction. As a result, the position of the developer carrier 2 also changes, and the doctor blade 6 also deforms.
cormorant. However, in order to fix the doctor blade 5 to the developer housing 3, the elastic intervening member 6 made of chloroprene rubber is interposed and the doctor blade 5 is screwed, so the bimetallic effect described above is suppressed by the elastic force of the elastic intervening member. Since the deformation of the developing housing 3 occurs only in the longitudinal direction, the doctor gap maintains the reference value.

Effects of the Invention The present invention prevents changes in image density due to environmental changes in a simple manner by fixing a doctor blade to a developing housing via an elastic intervening member, without using an expensive temperature sensing element.

[Brief explanation of drawings]

FIG. 1 is a main sectional view of a developing section of an electrophotographic apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1...Photosensitive drum, 2...Developer carrier, 5...Doctor blade, 6...Elastic intervening member.

Claims (1)

[Claims] A developer carrier is arranged relative to the image carrier, and is configured to be able to carry a developer on its surface and to be rotatable; 1. A developing device having a developer layer thickness regulating member, wherein the developer layer thickness regulating member is fixed to a developer housing member through an elastic material by screwing or the like.