JPH09160473A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of developer caused by temperature change by driving/stopping a cooling means or switching the driving direction based on measured value by a temperature sensor detecting the temperature of a developing machine. SOLUTION: The temperature sensor 2 is attached to the developing machine 1. The sensor 2 mainly detects heat generated in the case where the developer is stirred by a developer stirring member provided in the developing machine 1. A value detected by the sensor 2 is converted into a digital value by an A/D converter 6, and the temperature of the developing machine 1 is adjusted or the setting of a developing condition is changed by using a control means 8 such as a microcomputer based on the digital value. By providing a cooling fan 3 as the cooling means for the developing machine 1, the temperature of the developing machine 1 is kept constant. By driving the fan 3 while the temperature of the developing machine 1 is low such as at the beginning of starting printing, warm air from a heat generation part 7 is introduced in a direction shown by arrow (a), and the flow of air is switched to a direction shown by arrow (b) at the time of attaining the specified temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a laser printer or a copying machine, and more particularly to an image forming apparatus which prevents deterioration of a developer in a developing machine due to temperature change.

[0002]

2. Description of the Related Art In recent years, the body of an image forming apparatus of this type has been downsized, but due to the downsizing, it is important to consider heat generation inside the body.

[0003]

The above-mentioned heat is generated from, for example, the fixing device and other drive systems that constitute the image forming apparatus. When this heat reaches the developing machine, the developer in the developing machine is deteriorated. You may end up

An object of the present invention is to provide an image forming apparatus which prevents deterioration of a developer due to temperature change.

[0005]

The above object is to provide a temperature sensor for detecting the temperature of a developing machine, a cooling means for cooling the developing machine, and a drive / stop of the cooling means based on a measured value of the temperature sensor. Alternatively, it is achieved by having a control means for switching the driving direction.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a temperature sensor 2 is attached to the developing machine 1. Here, the temperature sensor 2
Mainly detects the heat generated when the developer is stirred by a developer stirring member (not shown) provided in the developing machine 1.
The value detected by the temperature sensor 2 is detected as a voltage change associated with a resistance change of a resistor such as a thermistor. This value is amplified by the isolation amplifier 5, and the A / D converter 6 converts the value into a digital value. Based on this digital value, the temperature of the developing machine is adjusted by using the control means 8 such as a microcomputer, and the setting of the developing condition (developing bias potential, toner density, etc.) is changed. In this embodiment, the cooling fan 3 is provided as the cooling means of the developing machine, and the temperature of the developing machine is kept constant by this, but in addition to the cooling fan,
You may make it the structure which cools the heat generating part and the middle of the developing machine,
Further, the heat generating portion may be directly cooled. In addition,
In the figure, 4 is a photoconductor.

A temperature sensor 2'is provided to separate each heat generation, and the temperature sensor 2 and the temperature sensor 2'are provided.
The parameters relating to heat generation may be separated by comparing the results of the above. By providing the temperature sensors at a plurality of locations in this way, it becomes possible to improve the cooling efficiency.

The temperature of the developer rises as it is printed, and tends to stabilize when the temperature reaches a temperature higher than the ambient temperature. Therefore, the image quality is likely to change before the temperature becomes stable. Therefore, in the present invention, as shown in the figure, during a period when the temperature of the developing device is low, such as at the beginning of printing, the fan 3 is driven to introduce warm air from the heat generating portion 7 in the direction of arrow a, and when a predetermined temperature is reached. The air flow is switched in the direction of arrow b. In order to perform this control with high accuracy, proportional + integral + derivative control (PID; Proportion-Integ
It is advisable to incorporate ral-Differential) control.

[0009]

According to the present invention, it is possible to provide an image forming apparatus in which the developer is less likely to deteriorate due to temperature changes.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Developer, 2 ... Temperature sensor, 2 '... Temperature sensor, 3 ...
Fan, 4 ... Photoconductor, 5 ... Isolation amplifier, 6
... A / D converter, 7 ... Heating section, 8 ... Control means

Claims (1)

[Claims] 1. A temperature sensor for detecting a temperature of a developing machine, a cooling means for cooling the developing machine, and a control means for driving / stopping the cooling means or switching a driving direction based on a measured value of the temperature sensor. An image forming apparatus comprising: