JPH06110270A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device by which excellent copying performance is obtained even for a photosensitive body having temperature dependency. CONSTITUTION:An a-Si drum 1 being the photosensitive body mainly having the temperature dependency, a heat roller 4 heating a paper 2 fed to the drum 1, a thermistor 5 installed in the drum 1 and detecting the temperature of the drum 1, and a controller 6 or the like controlling the heat roller 4 when the supplied and fed paper 2 reaches the drum 1 so that the temperature of the paper 2 may be equal to the temperature of the drum 1 detected by the thermistor 5 are provided around the paper feed mechanism of this image forming device, for example, a copying machine A1. By such constitution, the excellent copying performance is obtained even for the photosensitive body having the temperature dependency.

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, and more particularly to an image forming apparatus in which a photosensitive drum having temperature dependency can be mounted.

[0002]

2. Description of the Related Art Conventionally, in order to prevent a decrease in copying performance such as a defect in an image or a decrease in transfer efficiency due to a change in the atmosphere around an electrophotographic apparatus (for example, a copying machine), a heating means is provided so that a paper sheet or the like is provided. A technique for dehumidifying is known (Japanese Patent Laid-Open No. 3-179465, etc.). FIG. 3 is a schematic diagram showing a schematic configuration around a paper feed mechanism in an example of such a conventional copying machine A ₀ . As shown in FIG. 3, around the sheet feeding mechanism of the conventional copying machine A _0, a sheet feeding cassette 3 which is a supply source of the photoconductor 1 and the sheet 2 mainly, a heater 4 provided therebetween,
A sensor 5 for detecting temperature and / or humidity is provided. Then, in the copying process, the sensor 5 detects the temperature and / or humidity of the surrounding atmosphere, operates the heater 4 according to the detected value, and removes the moisture of the paper 2 and the photoconductor 1. By dehumidifying the paper 2 and the like in this manner, a clear image is obtained over the entire environment.

[0003]

When an amorphous silicon drum (hereinafter referred to as an a-Si drum) is mounted as the photoconductor 1 on the conventional copying machine A ₀ as described above, the following problems are likely to occur. That is, the a-Si drum has been widely used in recent years in place of the conventional selenium drum and the like due to its excellent photoelectric properties and the like. Figure 4 (a)
As shown in Fig. 4, the potential of the blank portion of this a-Si drum has temperature dependency as compared with the conventional selenium drum shown in Fig. 4 (b).
It is necessary to keep it in the range of 0 ° C. However, in a normal copying state, the paper supplied to the drum draws heat from the drum, so that the drum temperature drops according to the number of passed paper. Although the conventional copying machine A ₀ dehumidifies the paper and the like, it is not always possible to prevent the drop of the drum temperature, and therefore it may be difficult to control the drum temperature. SUMMARY OF THE INVENTION It is an object of the present invention to improve an image forming apparatus in order to solve the above problems in the conventional technique, and to provide an image forming apparatus capable of obtaining a good copying performance even for a photoconductor having temperature dependency. It is a thing.

[0004]

In order to achieve the above object, a first aspect of the present invention is to provide a heating means for heating a sheet fed to a photosensitive drum, and a temperature of the drum attached to the photosensitive drum. And a control means for controlling the heating means so that when the paper reaches the photoconductor drum, the temperature of the paper becomes equal to the temperature of the drum detected by the detection means. The image forming apparatus includes the image forming apparatus. A second aspect of the present invention includes a heating unit that heats a sheet fed to the photosensitive drum, a first detecting unit that is attached to the photosensitive drum and detects the temperature of the drum, and the photosensitive drum. A second detecting device which is disposed between the heating means and the heating means and detects the temperature of the sheet heated by the heating means; the temperature of the drum detected by the first detecting means; The image forming apparatus includes a control unit that controls the heating unit so that the temperature of the sheet detected by the detection unit is equal. Further, in the image forming apparatus, the photosensitive drum is an amorphous silicon drum.

[0005]

According to the first aspect of the invention, the sheet fed to the photosensitive drum is heated by the heating means, and the temperature of the drum is detected by the detecting means attached to the photosensitive drum. When the paper reaches the photosensitive drum,
The heating means is controlled by the control means so that the temperature of the paper becomes equal to the temperature of the drum detected by the detection means. Therefore, when the paper passes through the drum, the heat balance between the two is lost, so that the temperature of the drum can be kept constant and stable control can be performed. Further, according to the second invention, the sheet supplied to the photoconductor drum is heated by the heating means, and the temperature of the drum is detected by the first detection means attached to the photoconductor drum. The temperature of the paper is detected by the second detection means arranged between the drum and the heating means. And the temperature of the drum detected by the first detecting means,
The heating means is controlled by the control means so that the temperature of the sheet detected by the second detection means becomes equal. Therefore, in this case, since the difference between the drum temperature and the paper temperature is strictly measured, the accuracy of the temperature control by the control means is improved. As a result, it is possible to obtain an image forming apparatus capable of obtaining good copying performance even on a photosensitive drum (for example, amorphous silicon drum) having temperature dependence.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. FIG. 1 is a schematic diagram showing a schematic structure around a sheet feeding mechanism of a copying machine A ₁ according to an embodiment of the first invention, and FIG. 2 is a copying machine A _{2 according} to an embodiment of the second invention. 3 is a schematic diagram showing a schematic configuration around a sheet feeding mechanism of FIG. First, an embodiment of the first invention will be described. As shown in FIG. 1, around the paper feed mechanism of the copying machine A ₁ (corresponding to an image forming apparatus) according to this embodiment,
An a-Si drum 1 (corresponding to a photosensitive drum) (hereinafter abbreviated as a drum), a paper feed cassette 3 that is a paper feed source of the paper 2, and a paper 2 fed from the paper feed cassette 3 to the drum 1 are mainly included. A heating roller 4 (corresponding to heating means) for heating, a thermistor 5 attached to the drum 1 for detecting the temperature of the drum 1, and a controller for controlling the heating temperature of the paper 2 by the heating roller 4. 6 and the like are provided. Then, in the copying process, the fed paper 2
When the drum reaches the drum 1, the controller 6
The heat roller 4 is controlled so that the temperature of 1 becomes equal to the temperature of the drum 1 detected by the thermistor 5. Therefore, in this copying machine A ₁ , when the paper 2 passes through the drum 1, there is no heat balance between them, so that the temperature of the drum 1 can be kept constant and stable control can be performed. As a result, keeping the relationship between the blank sheet potential and the exposure amount constant (Fig. 4 (a)
It is possible to effectively prevent a decrease in copying performance such as a defect in an image or a decrease in transfer efficiency. Then,
An embodiment of the second invention will be described. As shown in FIG. 2, the a-Si drum 1 is mainly provided around the sheet feeding mechanism of the copying machine A ₂ (corresponding to an image forming apparatus) according to this embodiment.
(Corresponding to a photosensitive drum) (hereinafter abbreviated as a drum), a paper feed cassette 3 as a supply source of the paper 2, and a heat roller 4 for heating the paper 2 fed from the paper feed cassette 3 to the drum 1.
(Corresponding to heating means), a thermistor 5a (corresponding to first detecting means) attached to the drum 1 for detecting the temperature of the drum 1, and a heat roller provided between the drum 1 and the heat roller 4. A thermistor 5b (corresponding to a second detecting means) for detecting the temperature of the paper 2 heated by the heat roller 4;
Controller 6'for controlling the heating temperature of the paper 2 by
(Corresponding to control means) and the like are provided. Then, in the copying process, the controller 6'is the thermistor 5a.
The heating roller 4 is controlled so that the temperature of the drum 1 detected by the above and the temperature of the paper 2 detected by the thermistor 5b become equal. Therefore, in this copying machine A ₂ , since the difference between the temperature of the drum 1 and the temperature of the paper 2 is strictly measured, the temperature control accuracy of the heat roller 4 is improved. This control is
This is particularly effective when the distance between the drum 1 and the heat roller 4 is short and the temperature drop of the paper 2 transferred between them is small enough to be ignored. However, when the temperature drop of the sheet 2 is large, the temperature of the thermistor 5b may be increased by an amount commensurate with this drop amount. As a result, the copying machine A ₂ can effectively prevent the deterioration of the copying performance. As described above, according to both of the above embodiments,
It was possible to obtain a copying machine which can obtain good copying performance with respect to a temperature-dependent photoconductor. In the copying machines A ₁ and A _{2 of} both the above-mentioned embodiments, the a-Si drum is mounted, but in actual use, the present invention can be applied to any drum having temperature dependency. ， In that case, the copying performance can be improved. In both of the above embodiments, a heat roller is used as the heating means.
Although the thermistor is used as the (first and second) detecting means, in actual use, other types of heating means (for example, an electric heater) or other types of detecting means (for example, a thermocouple) may be used. There is no problem.

[0007]

Since the image forming apparatus according to the first aspect of the present invention is configured as described above, when the paper passes through the drum, the heat balance between the two is lost and the temperature of the drum is kept constant. Stable control can be performed. Furthermore, the second
According to the invention, since the difference between the temperature of the drum and the heating temperature of the paper is strictly measured, the control accuracy of the heat roller is improved. Therefore, it is possible to effectively prevent a decrease in copying performance such as a defect in an image or a decrease in transfer efficiency. As a result, it is possible to obtain an image forming apparatus capable of obtaining good copying performance even for a photoconductor having temperature dependence.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration around a paper feed mechanism of a copying machine A _{1 according} to an embodiment of the first invention.

FIG. 2 is a schematic diagram showing a schematic configuration around a paper feed mechanism of a copying machine A _{2 according} to an embodiment of the second invention.

FIG. 3 is a schematic diagram showing a schematic configuration around a paper feed mechanism in an example of a conventional copying machine A ₀ .

FIG. 4 is a graph (a) showing the results of investigation of the temperature dependence of the blank sheet potential of an a-Si drum and a selenium drum.
(B).

[Explanation of symbols]

A ₁ , A ₂ ... Copier (corresponding to image forming apparatus) 1 ... Drum (corresponding to photoconductor drum) 2 ... Paper 4 ... Heater (corresponding to heating means) 5 ... Thermistor (corresponding to detection means) 5a, 5b ... Thermistor (corresponding to first and second detecting means) 6, 6 '... Controller (corresponding to control means)

Claims (3)

[Claims] 1. A heating unit for heating a sheet fed to a photosensitive drum, a detecting unit attached to the photosensitive drum for detecting the temperature of the drum, and the sheet reaching the photosensitive drum. At this time, the image forming apparatus is provided with a control means for controlling the heating means so that the temperature of the paper becomes equal to the temperature of the drum detected by the detection means. 2. A heating means for heating a sheet fed to a photosensitive drum, a first detecting means attached to the photosensitive drum for detecting the temperature of the drum, the photosensitive drum and the heating. A second detecting device which is disposed between the heating means and the temperature detecting means and detects the temperature of the sheet heated by the heating means; the temperature of the drum detected by the first detecting means; and the second detecting means. An image forming apparatus comprising: a control unit that controls the heating unit so that the temperature of the sheet detected by the control unit becomes equal. 3. The image forming apparatus according to claim 1, wherein the photosensitive drum is an amorphous silicon drum.